WHC Shell: keyboard-first Android terminal over SSH to local Termux

Vendored Termux terminal-emulator/renderer (Apache 2.0) with kitty keyboard
protocol, modifyOtherKeys and any-event mouse tracking; sshj client with
Ed25519 key login and TOFU host keys; Termux font/colors/cursor sync;
mouse selection, context menu, zoom and fullscreen shortcuts.

.gitignore

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+.gradle/
+build/
+app/build/
+local.properties
+*.keystore
+*.jks
+keystore.properties
+.idea/
+*.iml

NOTICE

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+WHC Shell
+Copyright 2026 whc
+
+This product includes software from the Termux project
+(https://github.com/termux/termux-app, tag v0.118.3), licensed under the
+Apache License, Version 2.0 (see third_party/Apache-2.0.txt and
+third_party/termux-LICENSE.md):
+
+  app/src/main/java/com/termux/terminal/*   (terminal-emulator module)
+  app/src/main/java/com/termux/view/TerminalRenderer.java   (terminal-view module)
+
+Modifications made for WHC Shell:
+  - TerminalSessionClient: removed callbacks that take a TerminalSession.
+  - ByteQueue: made public.
+  - TerminalRenderer: added getFontLineSpacingAndAscent().
+
+The terminal emulator in Termux is itself based on Jack Palevich's
+Android-Terminal-Emulator (Apache License, Version 2.0).
+
+Runtime dependencies (Apache License 2.0 / MIT):
+  sshj (com.hierynomus:sshj), Bouncy Castle (bcprov, bcpkix), SLF4J.

app/build.gradle

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+plugins {
+    id "com.android.application"
+}
+
+android {
+    namespace "xyz.whcself.whcshell"
+    compileSdk 35
+
+    defaultConfig {
+        applicationId "xyz.whcself.whcshell"
+        minSdk 26
+        targetSdk 35
+        versionCode 1
+        versionName "0.1.0"
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+        }
+    }
+
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_17
+        targetCompatibility JavaVersion.VERSION_17
+    }
+
+    testOptions {
+        unitTests.returnDefaultValues = true
+    }
+
+    packaging {
+        resources {
+            excludes += [
+                "META-INF/versions/9/OSGI-INF/MANIFEST.MF",
+                "META-INF/DEPENDENCIES",
+                "META-INF/LICENSE*",
+                "META-INF/NOTICE*",
+            ]
+        }
+    }
+}
+
+dependencies {
+    implementation "com.hierynomus:sshj:0.39.0"
+    implementation "org.bouncycastle:bcprov-jdk18on:1.80"
+    implementation "org.bouncycastle:bcpkix-jdk18on:1.80"
+    implementation "org.slf4j:slf4j-nop:2.0.16"
+
+    testImplementation "junit:junit:4.13.2"
+}

app/src/main/AndroidManifest.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="com.termux.permission.RUN_COMMAND" />
+
+    <queries>
+        <package android:name="com.termux" />
+    </queries>
+
+    <application
+        android:name=".WhcApp"
+        android:allowBackup="false"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:supportsRtl="false"
+        android:theme="@style/Theme.WhcShell">
+
+        <activity
+            android:name=".MainActivity"
+            android:configChanges="keyboard|keyboardHidden|navigation|orientation|screenLayout|screenSize|smallestScreenSize|density|uiMode|fontScale|locale|layoutDirection"
+            android:exported="true"
+            android:launchMode="singleTask"
+            android:windowSoftInputMode="adjustResize|stateAlwaysHidden">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+    </application>
+</manifest>

app/src/main/java/com/termux/terminal/ByteQueue.java

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+package com.termux.terminal;
+
+/** A circular byte buffer allowing one producer and one consumer thread. */
+public final class ByteQueue {
+
+    private final byte[] mBuffer;
+    private int mHead;
+    private int mStoredBytes;
+    private boolean mOpen = true;
+
+    public ByteQueue(int size) {
+        mBuffer = new byte[size];
+    }
+
+    public synchronized void close() {
+        mOpen = false;
+        notify();
+    }
+
+    public synchronized int read(byte[] buffer, boolean block) {
+        while (mStoredBytes == 0 && mOpen) {
+            if (block) {
+                try {
+                    wait();
+                } catch (InterruptedException e) {
+                    // Ignore.
+                }
+            } else {
+                return 0;
+            }
+        }
+        if (!mOpen) return -1;
+
+        int totalRead = 0;
+        int bufferLength = mBuffer.length;
+        boolean wasFull = bufferLength == mStoredBytes;
+        int length = buffer.length;
+        int offset = 0;
+        while (length > 0 && mStoredBytes > 0) {
+            int oneRun = Math.min(bufferLength - mHead, mStoredBytes);
+            int bytesToCopy = Math.min(length, oneRun);
+            System.arraycopy(mBuffer, mHead, buffer, offset, bytesToCopy);
+            mHead += bytesToCopy;
+            if (mHead >= bufferLength) mHead = 0;
+            mStoredBytes -= bytesToCopy;
+            length -= bytesToCopy;
+            offset += bytesToCopy;
+            totalRead += bytesToCopy;
+        }
+        if (wasFull) notify();
+        return totalRead;
+    }
+
+    /**
+     * Attempt to write the specified portion of the provided buffer to the queue.
+     * <p/>
+     * Returns whether the output was totally written, false if it was closed before.
+     */
+    public boolean write(byte[] buffer, int offset, int lengthToWrite) {
+        if (lengthToWrite + offset > buffer.length) {
+            throw new IllegalArgumentException("length + offset > buffer.length");
+        } else if (lengthToWrite <= 0) {
+            throw new IllegalArgumentException("length <= 0");
+        }
+
+        final int bufferLength = mBuffer.length;
+
+        synchronized (this) {
+            while (lengthToWrite > 0) {
+                while (bufferLength == mStoredBytes && mOpen) {
+                    try {
+                        wait();
+                    } catch (InterruptedException e) {
+                        // Ignore.
+                    }
+                }
+                if (!mOpen) return false;
+                final boolean wasEmpty = mStoredBytes == 0;
+                int bytesToWriteBeforeWaiting = Math.min(lengthToWrite, bufferLength - mStoredBytes);
+                lengthToWrite -= bytesToWriteBeforeWaiting;
+
+                while (bytesToWriteBeforeWaiting > 0) {
+                    int tail = mHead + mStoredBytes;
+                    int oneRun;
+                    if (tail >= bufferLength) {
+                        // Buffer: [.............]
+                        // ________________H_______T
+                        // =>
+                        // Buffer: [.............]
+                        // ___________T____H
+                        // onRun= _____----_
+                        tail = tail - bufferLength;
+                        oneRun = mHead - tail;
+                    } else {
+                        oneRun = bufferLength - tail;
+                    }
+                    int bytesToCopy = Math.min(oneRun, bytesToWriteBeforeWaiting);
+                    System.arraycopy(buffer, offset, mBuffer, tail, bytesToCopy);
+                    offset += bytesToCopy;
+                    bytesToWriteBeforeWaiting -= bytesToCopy;
+                    mStoredBytes += bytesToCopy;
+                }
+                if (wasEmpty) notify();
+            }
+        }
+        return true;
+    }
+}

app/src/main/java/com/termux/terminal/KeyHandler.java

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+package com.termux.terminal;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import static android.view.KeyEvent.KEYCODE_BACK;
+import static android.view.KeyEvent.KEYCODE_BREAK;
+import static android.view.KeyEvent.KEYCODE_DEL;
+import static android.view.KeyEvent.KEYCODE_DPAD_CENTER;
+import static android.view.KeyEvent.KEYCODE_DPAD_DOWN;
+import static android.view.KeyEvent.KEYCODE_DPAD_LEFT;
+import static android.view.KeyEvent.KEYCODE_DPAD_RIGHT;
+import static android.view.KeyEvent.KEYCODE_DPAD_UP;
+import static android.view.KeyEvent.KEYCODE_ENTER;
+import static android.view.KeyEvent.KEYCODE_ESCAPE;
+import static android.view.KeyEvent.KEYCODE_F1;
+import static android.view.KeyEvent.KEYCODE_F10;
+import static android.view.KeyEvent.KEYCODE_F11;
+import static android.view.KeyEvent.KEYCODE_F12;
+import static android.view.KeyEvent.KEYCODE_F2;
+import static android.view.KeyEvent.KEYCODE_F3;
+import static android.view.KeyEvent.KEYCODE_F4;
+import static android.view.KeyEvent.KEYCODE_F5;
+import static android.view.KeyEvent.KEYCODE_F6;
+import static android.view.KeyEvent.KEYCODE_F7;
+import static android.view.KeyEvent.KEYCODE_F8;
+import static android.view.KeyEvent.KEYCODE_F9;
+import static android.view.KeyEvent.KEYCODE_FORWARD_DEL;
+import static android.view.KeyEvent.KEYCODE_INSERT;
+import static android.view.KeyEvent.KEYCODE_MOVE_END;
+import static android.view.KeyEvent.KEYCODE_MOVE_HOME;
+import static android.view.KeyEvent.KEYCODE_NUMPAD_0;
+import static android.view.KeyEvent.KEYCODE_NUMPAD_1;
+import static android.view.KeyEvent.KEYCODE_NUMPAD_2;
+import static android.view.KeyEvent.KEYCODE_NUMPAD_3;
+import static android.view.KeyEvent.KEYCODE_NUMPAD_4;
+import static android.view.KeyEvent.KEYCODE_NUMPAD_5;
+import static android.view.KeyEvent.KEYCODE_NUMPAD_6;
+import static android.view.KeyEvent.KEYCODE_NUMPAD_7;
+import static android.view.KeyEvent.KEYCODE_NUMPAD_8;
+import static android.view.KeyEvent.KEYCODE_NUMPAD_9;
+import static android.view.KeyEvent.KEYCODE_NUMPAD_ADD;
+import static android.view.KeyEvent.KEYCODE_NUMPAD_COMMA;
+import static android.view.KeyEvent.KEYCODE_NUMPAD_DIVIDE;
+import static android.view.KeyEvent.KEYCODE_NUMPAD_DOT;
+import static android.view.KeyEvent.KEYCODE_NUMPAD_ENTER;
+import static android.view.KeyEvent.KEYCODE_NUMPAD_EQUALS;
+import static android.view.KeyEvent.KEYCODE_NUMPAD_MULTIPLY;
+import static android.view.KeyEvent.KEYCODE_NUMPAD_SUBTRACT;
+import static android.view.KeyEvent.KEYCODE_NUM_LOCK;
+import static android.view.KeyEvent.KEYCODE_PAGE_DOWN;
+import static android.view.KeyEvent.KEYCODE_PAGE_UP;
+import static android.view.KeyEvent.KEYCODE_SPACE;
+import static android.view.KeyEvent.KEYCODE_SYSRQ;
+import static android.view.KeyEvent.KEYCODE_TAB;
+
+public final class KeyHandler {
+
+    public static final int KEYMOD_ALT = 0x80000000;
+    public static final int KEYMOD_CTRL = 0x40000000;
+    public static final int KEYMOD_SHIFT = 0x20000000;
+    public static final int KEYMOD_NUM_LOCK = 0x10000000;
+
+    private static final Map<String, Integer> TERMCAP_TO_KEYCODE = new HashMap<>();
+
+    static {
+        // terminfo: http://pubs.opengroup.org/onlinepubs/7990989799/xcurses/terminfo.html
+        // termcap: http://man7.org/linux/man-pages/man5/termcap.5.html
+        TERMCAP_TO_KEYCODE.put("%i", KEYMOD_SHIFT | KEYCODE_DPAD_RIGHT);
+        TERMCAP_TO_KEYCODE.put("#2", KEYMOD_SHIFT | KEYCODE_MOVE_HOME); // Shifted home
+        TERMCAP_TO_KEYCODE.put("#4", KEYMOD_SHIFT | KEYCODE_DPAD_LEFT);
+        TERMCAP_TO_KEYCODE.put("*7", KEYMOD_SHIFT | KEYCODE_MOVE_END); // Shifted end key
+
+        TERMCAP_TO_KEYCODE.put("k1", KEYCODE_F1);
+        TERMCAP_TO_KEYCODE.put("k2", KEYCODE_F2);
+        TERMCAP_TO_KEYCODE.put("k3", KEYCODE_F3);
+        TERMCAP_TO_KEYCODE.put("k4", KEYCODE_F4);
+        TERMCAP_TO_KEYCODE.put("k5", KEYCODE_F5);
+        TERMCAP_TO_KEYCODE.put("k6", KEYCODE_F6);
+        TERMCAP_TO_KEYCODE.put("k7", KEYCODE_F7);
+        TERMCAP_TO_KEYCODE.put("k8", KEYCODE_F8);
+        TERMCAP_TO_KEYCODE.put("k9", KEYCODE_F9);
+        TERMCAP_TO_KEYCODE.put("k;", KEYCODE_F10);
+        TERMCAP_TO_KEYCODE.put("F1", KEYCODE_F11);
+        TERMCAP_TO_KEYCODE.put("F2", KEYCODE_F12);
+        TERMCAP_TO_KEYCODE.put("F3", KEYMOD_SHIFT | KEYCODE_F1);
+        TERMCAP_TO_KEYCODE.put("F4", KEYMOD_SHIFT | KEYCODE_F2);
+        TERMCAP_TO_KEYCODE.put("F5", KEYMOD_SHIFT | KEYCODE_F3);
+        TERMCAP_TO_KEYCODE.put("F6", KEYMOD_SHIFT | KEYCODE_F4);
+        TERMCAP_TO_KEYCODE.put("F7", KEYMOD_SHIFT | KEYCODE_F5);
+        TERMCAP_TO_KEYCODE.put("F8", KEYMOD_SHIFT | KEYCODE_F6);
+        TERMCAP_TO_KEYCODE.put("F9", KEYMOD_SHIFT | KEYCODE_F7);
+        TERMCAP_TO_KEYCODE.put("FA", KEYMOD_SHIFT | KEYCODE_F8);
+        TERMCAP_TO_KEYCODE.put("FB", KEYMOD_SHIFT | KEYCODE_F9);
+        TERMCAP_TO_KEYCODE.put("FC", KEYMOD_SHIFT | KEYCODE_F10);
+        TERMCAP_TO_KEYCODE.put("FD", KEYMOD_SHIFT | KEYCODE_F11);
+        TERMCAP_TO_KEYCODE.put("FE", KEYMOD_SHIFT | KEYCODE_F12);
+
+        TERMCAP_TO_KEYCODE.put("kb", KEYCODE_DEL); // backspace key
+
+        TERMCAP_TO_KEYCODE.put("kd", KEYCODE_DPAD_DOWN); // terminfo=kcud1, down-arrow key
+        TERMCAP_TO_KEYCODE.put("kh", KEYCODE_MOVE_HOME);
+        TERMCAP_TO_KEYCODE.put("kl", KEYCODE_DPAD_LEFT);
+        TERMCAP_TO_KEYCODE.put("kr", KEYCODE_DPAD_RIGHT);
+
+        // K1=Upper left of keypad:
+        // t_K1 <kHome> keypad home key
+        // t_K3 <kPageUp> keypad page-up key
+        // t_K4 <kEnd> keypad end key
+        // t_K5 <kPageDown> keypad page-down key
+        TERMCAP_TO_KEYCODE.put("K1", KEYCODE_MOVE_HOME);
+        TERMCAP_TO_KEYCODE.put("K3", KEYCODE_PAGE_UP);
+        TERMCAP_TO_KEYCODE.put("K4", KEYCODE_MOVE_END);
+        TERMCAP_TO_KEYCODE.put("K5", KEYCODE_PAGE_DOWN);
+
+        TERMCAP_TO_KEYCODE.put("ku", KEYCODE_DPAD_UP);
+
+        TERMCAP_TO_KEYCODE.put("kB", KEYMOD_SHIFT | KEYCODE_TAB); // termcap=kB, terminfo=kcbt: Back-tab
+        TERMCAP_TO_KEYCODE.put("kD", KEYCODE_FORWARD_DEL); // terminfo=kdch1, delete-character key
+        TERMCAP_TO_KEYCODE.put("kDN", KEYMOD_SHIFT | KEYCODE_DPAD_DOWN); // non-standard shifted arrow down
+        TERMCAP_TO_KEYCODE.put("kF", KEYMOD_SHIFT | KEYCODE_DPAD_DOWN); // terminfo=kind, scroll-forward key
+        TERMCAP_TO_KEYCODE.put("kI", KEYCODE_INSERT);
+        TERMCAP_TO_KEYCODE.put("kN", KEYCODE_PAGE_UP);
+        TERMCAP_TO_KEYCODE.put("kP", KEYCODE_PAGE_DOWN);
+        TERMCAP_TO_KEYCODE.put("kR", KEYMOD_SHIFT | KEYCODE_DPAD_UP); // terminfo=kri, scroll-backward key
+        TERMCAP_TO_KEYCODE.put("kUP", KEYMOD_SHIFT | KEYCODE_DPAD_UP); // non-standard shifted up
+
+        TERMCAP_TO_KEYCODE.put("@7", KEYCODE_MOVE_END);
+        TERMCAP_TO_KEYCODE.put("@8", KEYCODE_NUMPAD_ENTER);
+    }
+
+    static String getCodeFromTermcap(String termcap, boolean cursorKeysApplication, boolean keypadApplication) {
+        Integer keyCodeAndMod = TERMCAP_TO_KEYCODE.get(termcap);
+        if (keyCodeAndMod == null) return null;
+        int keyCode = keyCodeAndMod;
+        int keyMod = 0;
+        if ((keyCode & KEYMOD_SHIFT) != 0) {
+            keyMod |= KEYMOD_SHIFT;
+            keyCode &= ~KEYMOD_SHIFT;
+        }
+        if ((keyCode & KEYMOD_CTRL) != 0) {
+            keyMod |= KEYMOD_CTRL;
+            keyCode &= ~KEYMOD_CTRL;
+        }
+        if ((keyCode & KEYMOD_ALT) != 0) {
+            keyMod |= KEYMOD_ALT;
+            keyCode &= ~KEYMOD_ALT;
+        }
+        if ((keyCode & KEYMOD_NUM_LOCK) != 0) {
+            keyMod |= KEYMOD_NUM_LOCK;
+            keyCode &= ~KEYMOD_NUM_LOCK;
+        }
+        return getCode(keyCode, keyMod, cursorKeysApplication, keypadApplication);
+    }
+
+    public static String getCode(int keyCode, int keyMode, boolean cursorApp, boolean keypadApplication) {
+        boolean numLockOn = (keyMode & KEYMOD_NUM_LOCK) != 0;
+        keyMode &= ~KEYMOD_NUM_LOCK;
+        switch (keyCode) {
+            case KEYCODE_DPAD_CENTER:
+                return "\015";
+
+            case KEYCODE_DPAD_UP:
+                return (keyMode == 0) ? (cursorApp ? "\033OA" : "\033[A") : transformForModifiers("\033[1", keyMode, 'A');
+            case KEYCODE_DPAD_DOWN:
+                return (keyMode == 0) ? (cursorApp ? "\033OB" : "\033[B") : transformForModifiers("\033[1", keyMode, 'B');
+            case KEYCODE_DPAD_RIGHT:
+                return (keyMode == 0) ? (cursorApp ? "\033OC" : "\033[C") : transformForModifiers("\033[1", keyMode, 'C');
+            case KEYCODE_DPAD_LEFT:
+                return (keyMode == 0) ? (cursorApp ? "\033OD" : "\033[D") : transformForModifiers("\033[1", keyMode, 'D');
+
+            case KEYCODE_MOVE_HOME:
+                // Note that KEYCODE_HOME is handled by the system and never delivered to applications.
+                // On a Logitech k810 keyboard KEYCODE_MOVE_HOME is sent by FN+LeftArrow.
+                return (keyMode == 0) ? (cursorApp ? "\033OH" : "\033[H") : transformForModifiers("\033[1", keyMode, 'H');
+            case KEYCODE_MOVE_END:
+                return (keyMode == 0) ? (cursorApp ? "\033OF" : "\033[F") : transformForModifiers("\033[1", keyMode, 'F');
+
+            // An xterm can send function keys F1 to F4 in two modes: vt100 compatible or
+            // not. Because Vim may not know what the xterm is sending, both types of keys
+            // are recognized. The same happens for the <Home> and <End> keys.
+            // normal vt100 ~
+            // <F1> t_k1 <Esc>[11~ <xF1> <Esc>OP *<xF1>-xterm*
+            // <F2> t_k2 <Esc>[12~ <xF2> <Esc>OQ *<xF2>-xterm*
+            // <F3> t_k3 <Esc>[13~ <xF3> <Esc>OR *<xF3>-xterm*
+            // <F4> t_k4 <Esc>[14~ <xF4> <Esc>OS *<xF4>-xterm*
+            // <Home> t_kh <Esc>[7~ <xHome> <Esc>OH *<xHome>-xterm*
+            // <End> t_@7 <Esc>[4~ <xEnd> <Esc>OF *<xEnd>-xterm*
+            case KEYCODE_F1:
+                return (keyMode == 0) ? "\033OP" : transformForModifiers("\033[1", keyMode, 'P');
+            case KEYCODE_F2:
+                return (keyMode == 0) ? "\033OQ" : transformForModifiers("\033[1", keyMode, 'Q');
+            case KEYCODE_F3:
+                return (keyMode == 0) ? "\033OR" : transformForModifiers("\033[1", keyMode, 'R');
+            case KEYCODE_F4:
+                return (keyMode == 0) ? "\033OS" : transformForModifiers("\033[1", keyMode, 'S');
+            case KEYCODE_F5:
+                return transformForModifiers("\033[15", keyMode, '~');
+            case KEYCODE_F6:
+                return transformForModifiers("\033[17", keyMode, '~');
+            case KEYCODE_F7:
+                return transformForModifiers("\033[18", keyMode, '~');
+            case KEYCODE_F8:
+                return transformForModifiers("\033[19", keyMode, '~');
+            case KEYCODE_F9:
+                return transformForModifiers("\033[20", keyMode, '~');
+            case KEYCODE_F10:
+                return transformForModifiers("\033[21", keyMode, '~');
+            case KEYCODE_F11:
+                return transformForModifiers("\033[23", keyMode, '~');
+            case KEYCODE_F12:
+                return transformForModifiers("\033[24", keyMode, '~');
+
+            case KEYCODE_SYSRQ:
+                return "\033[32~"; // Sys Request / Print
+            // Is this Scroll lock? case Cancel: return "\033[33~";
+            case KEYCODE_BREAK:
+                return "\033[34~"; // Pause/Break
+
+            case KEYCODE_ESCAPE:
+            case KEYCODE_BACK:
+                return "\033";
+
+            case KEYCODE_INSERT:
+                return transformForModifiers("\033[2", keyMode, '~');
+            case KEYCODE_FORWARD_DEL:
+                return transformForModifiers("\033[3", keyMode, '~');
+
+            case KEYCODE_PAGE_UP:
+                return "\033[5~";
+            case KEYCODE_PAGE_DOWN:
+                return "\033[6~";
+            case KEYCODE_DEL:
+                String prefix = ((keyMode & KEYMOD_ALT) == 0) ? "" : "\033";
+                // Just do what xterm and gnome-terminal does:
+                return prefix + (((keyMode & KEYMOD_CTRL) == 0) ? "\u007F" : "\u0008");
+            case KEYCODE_NUM_LOCK:
+                if (keypadApplication) {
+                    return "\033OP";
+                } else {
+                    return null;
+                }
+            case KEYCODE_SPACE:
+                // If ctrl is not down, return null so that it goes through normal input processing (which may e.g. cause a
+                // combining accent to be written):
+                return ((keyMode & KEYMOD_CTRL) == 0) ? null : "\0";
+            case KEYCODE_TAB:
+                // This is back-tab when shifted:
+                return (keyMode & KEYMOD_SHIFT) == 0 ? "\011" : "\033[Z";
+            case KEYCODE_ENTER:
+                return ((keyMode & KEYMOD_ALT) == 0) ? "\r" : "\033\r";
+
+            case KEYCODE_NUMPAD_ENTER:
+                return keypadApplication ? transformForModifiers("\033O", keyMode, 'M') : "\n";
+            case KEYCODE_NUMPAD_MULTIPLY:
+                return keypadApplication ? transformForModifiers("\033O", keyMode, 'j') : "*";
+            case KEYCODE_NUMPAD_ADD:
+                return keypadApplication ? transformForModifiers("\033O", keyMode, 'k') : "+";
+            case KEYCODE_NUMPAD_COMMA:
+                return ",";
+            case KEYCODE_NUMPAD_DOT:
+                if (numLockOn) {
+                    return keypadApplication ? "\033On" : ".";
+                } else {
+                    // DELETE
+                    return transformForModifiers("\033[3", keyMode, '~');
+                }
+            case KEYCODE_NUMPAD_SUBTRACT:
+                return keypadApplication ? transformForModifiers("\033O", keyMode, 'm') : "-";
+            case KEYCODE_NUMPAD_DIVIDE:
+                return keypadApplication ? transformForModifiers("\033O", keyMode, 'o') : "/";
+            case KEYCODE_NUMPAD_0:
+                if (numLockOn) {
+                    return keypadApplication ? transformForModifiers("\033O", keyMode, 'p') : "0";
+                } else {
+                    // INSERT
+                    return transformForModifiers("\033[2", keyMode, '~');
+                }
+            case KEYCODE_NUMPAD_1:
+                if (numLockOn) {
+                    return keypadApplication ? transformForModifiers("\033O", keyMode, 'q') : "1";
+                } else {
+                    // END
+                    return (keyMode == 0) ? (cursorApp ? "\033OF" : "\033[F") : transformForModifiers("\033[1", keyMode, 'F');
+                }
+            case KEYCODE_NUMPAD_2:
+                if (numLockOn) {
+                    return keypadApplication ? transformForModifiers("\033O", keyMode, 'r') : "2";
+                } else {
+                    // DOWN
+                    return (keyMode == 0) ? (cursorApp ? "\033OB" : "\033[B") : transformForModifiers("\033[1", keyMode, 'B');
+                }
+            case KEYCODE_NUMPAD_3:
+                if (numLockOn) {
+                    return keypadApplication ? transformForModifiers("\033O", keyMode, 's') : "3";
+                } else {
+                    // PGDN
+                    return "\033[6~";
+                }
+            case KEYCODE_NUMPAD_4:
+                if (numLockOn) {
+                    return keypadApplication ? transformForModifiers("\033O", keyMode, 't') : "4";
+                } else {
+                    // LEFT
+                    return (keyMode == 0) ? (cursorApp ? "\033OD" : "\033[D") : transformForModifiers("\033[1", keyMode, 'D');
+                }
+            case KEYCODE_NUMPAD_5:
+                return keypadApplication ? transformForModifiers("\033O", keyMode, 'u') : "5";
+            case KEYCODE_NUMPAD_6:
+                if (numLockOn) {
+                    return keypadApplication ? transformForModifiers("\033O", keyMode, 'v') : "6";
+                } else {
+                    // RIGHT
+                    return (keyMode == 0) ? (cursorApp ? "\033OC" : "\033[C") : transformForModifiers("\033[1", keyMode, 'C');
+                }
+            case KEYCODE_NUMPAD_7:
+                if (numLockOn) {
+                    return keypadApplication ? transformForModifiers("\033O", keyMode, 'w') : "7";
+                } else {
+                    // HOME
+                    return (keyMode == 0) ? (cursorApp ? "\033OH" : "\033[H") : transformForModifiers("\033[1", keyMode, 'H');
+                }
+            case KEYCODE_NUMPAD_8:
+                if (numLockOn) {
+                    return keypadApplication ? transformForModifiers("\033O", keyMode, 'x') : "8";
+                } else {
+                    // UP
+                    return (keyMode == 0) ? (cursorApp ? "\033OA" : "\033[A") : transformForModifiers("\033[1", keyMode, 'A');
+                }
+            case KEYCODE_NUMPAD_9:
+                if (numLockOn) {
+                    return keypadApplication ? transformForModifiers("\033O", keyMode, 'y') : "9";
+                } else {
+                    // PGUP
+                    return "\033[5~";
+                }
+            case KEYCODE_NUMPAD_EQUALS:
+                return keypadApplication ? transformForModifiers("\033O", keyMode, 'X') : "=";
+        }
+
+        return null;
+    }
+
+    private static String transformForModifiers(String start, int keymod, char lastChar) {
+        int modifier;
+        switch (keymod) {
+            case KEYMOD_SHIFT:
+                modifier = 2;
+                break;
+            case KEYMOD_ALT:
+                modifier = 3;
+                break;
+            case (KEYMOD_SHIFT | KEYMOD_ALT):
+                modifier = 4;
+                break;
+            case KEYMOD_CTRL:
+                modifier = 5;
+                break;
+            case KEYMOD_SHIFT | KEYMOD_CTRL:
+                modifier = 6;
+                break;
+            case KEYMOD_ALT | KEYMOD_CTRL:
+                modifier = 7;
+                break;
+            case KEYMOD_SHIFT | KEYMOD_ALT | KEYMOD_CTRL:
+                modifier = 8;
+                break;
+            default:
+                return start + lastChar;
+        }
+        return start + (";" + modifier) + lastChar;
+    }
+}

app/src/main/java/com/termux/terminal/Logger.java

@@ -0,0 +1,80 @@
+package com.termux.terminal;
+
+import android.util.Log;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.io.StringWriter;
+
+public class Logger {
+
+    public static void logError(TerminalSessionClient client, String logTag, String message) {
+        if (client != null)
+            client.logError(logTag, message);
+        else
+            Log.e(logTag, message);
+    }
+
+    public static void logWarn(TerminalSessionClient client, String logTag, String message) {
+        if (client != null)
+            client.logWarn(logTag, message);
+        else
+            Log.w(logTag, message);
+    }
+
+    public static void logInfo(TerminalSessionClient client, String logTag, String message) {
+        if (client != null)
+            client.logInfo(logTag, message);
+        else
+            Log.i(logTag, message);
+    }
+
+    public static void logDebug(TerminalSessionClient client, String logTag, String message) {
+        if (client != null)
+            client.logDebug(logTag, message);
+        else
+            Log.d(logTag, message);
+    }
+
+    public static void logVerbose(TerminalSessionClient client, String logTag, String message) {
+        if (client != null)
+            client.logVerbose(logTag, message);
+        else
+            Log.v(logTag, message);
+    }
+
+    public static void logStackTraceWithMessage(TerminalSessionClient client, String tag, String message, Throwable throwable) {
+        logError(client, tag, getMessageAndStackTraceString(message, throwable));
+    }
+
+    public static String getMessageAndStackTraceString(String message, Throwable throwable) {
+        if (message == null && throwable == null)
+            return null;
+        else if (message != null && throwable != null)
+            return message + ":\n" + getStackTraceString(throwable);
+        else if (throwable == null)
+            return message;
+        else
+            return getStackTraceString(throwable);
+    }
+
+    public static String getStackTraceString(Throwable throwable) {
+        if (throwable == null) return null;
+
+        String stackTraceString = null;
+
+        try {
+            StringWriter errors = new StringWriter();
+            PrintWriter pw = new PrintWriter(errors);
+            throwable.printStackTrace(pw);
+            pw.close();
+            stackTraceString = errors.toString();
+            errors.close();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+        return stackTraceString;
+    }
+
+}

app/src/main/java/com/termux/terminal/TerminalBuffer.java

@@ -0,0 +1,497 @@
+package com.termux.terminal;
+
+import java.util.Arrays;
+
+/**
+ * A circular buffer of {@link TerminalRow}:s which keeps notes about what is visible on a logical screen and the scroll
+ * history.
+ * <p>
+ * See {@link #externalToInternalRow(int)} for how to map from logical screen rows to array indices.
+ */
+public final class TerminalBuffer {
+
+    TerminalRow[] mLines;
+    /** The length of {@link #mLines}. */
+    int mTotalRows;
+    /** The number of rows and columns visible on the screen. */
+    int mScreenRows, mColumns;
+    /** The number of rows kept in history. */
+    private int mActiveTranscriptRows = 0;
+    /** The index in the circular buffer where the visible screen starts. */
+    private int mScreenFirstRow = 0;
+
+    /**
+     * Create a transcript screen.
+     *
+     * @param columns    the width of the screen in characters.
+     * @param totalRows  the height of the entire text area, in rows of text.
+     * @param screenRows the height of just the screen, not including the transcript that holds lines that have scrolled off
+     *                   the top of the screen.
+     */
+    public TerminalBuffer(int columns, int totalRows, int screenRows) {
+        mColumns = columns;
+        mTotalRows = totalRows;
+        mScreenRows = screenRows;
+        mLines = new TerminalRow[totalRows];
+
+        blockSet(0, 0, columns, screenRows, ' ', TextStyle.NORMAL);
+    }
+
+    public String getTranscriptText() {
+        return getSelectedText(0, -getActiveTranscriptRows(), mColumns, mScreenRows).trim();
+    }
+
+    public String getTranscriptTextWithoutJoinedLines() {
+        return getSelectedText(0, -getActiveTranscriptRows(), mColumns, mScreenRows, false).trim();
+    }
+
+    public String getTranscriptTextWithFullLinesJoined() {
+        return getSelectedText(0, -getActiveTranscriptRows(), mColumns, mScreenRows, true, true).trim();
+    }
+
+    public String getSelectedText(int selX1, int selY1, int selX2, int selY2) {
+        return getSelectedText(selX1, selY1, selX2, selY2, true);
+    }
+
+    public String getSelectedText(int selX1, int selY1, int selX2, int selY2, boolean joinBackLines) {
+        return getSelectedText(selX1, selY1, selX2, selY2, joinBackLines, false);
+    }
+
+    public String getSelectedText(int selX1, int selY1, int selX2, int selY2, boolean joinBackLines, boolean joinFullLines) {
+        final StringBuilder builder = new StringBuilder();
+        final int columns = mColumns;
+
+        if (selY1 < -getActiveTranscriptRows()) selY1 = -getActiveTranscriptRows();
+        if (selY2 >= mScreenRows) selY2 = mScreenRows - 1;
+
+        for (int row = selY1; row <= selY2; row++) {
+            int x1 = (row == selY1) ? selX1 : 0;
+            int x2;
+            if (row == selY2) {
+                x2 = selX2 + 1;
+                if (x2 > columns) x2 = columns;
+            } else {
+                x2 = columns;
+            }
+            TerminalRow lineObject = mLines[externalToInternalRow(row)];
+            int x1Index = lineObject.findStartOfColumn(x1);
+            int x2Index = (x2 < mColumns) ? lineObject.findStartOfColumn(x2) : lineObject.getSpaceUsed();
+            if (x2Index == x1Index) {
+                // Selected the start of a wide character.
+                x2Index = lineObject.findStartOfColumn(x2 + 1);
+            }
+            char[] line = lineObject.mText;
+            int lastPrintingCharIndex = -1;
+            int i;
+            boolean rowLineWrap = getLineWrap(row);
+            if (rowLineWrap && x2 == columns) {
+                // If the line was wrapped, we shouldn't lose trailing space:
+                lastPrintingCharIndex = x2Index - 1;
+            } else {
+                for (i = x1Index; i < x2Index; ++i) {
+                    char c = line[i];
+                    if (c != ' ') lastPrintingCharIndex = i;
+                }
+            }
+
+            int len = lastPrintingCharIndex - x1Index + 1;
+            if (lastPrintingCharIndex != -1 && len > 0)
+                builder.append(line, x1Index, len);
+
+            boolean lineFillsWidth = lastPrintingCharIndex == x2Index - 1;
+            if ((!joinBackLines || !rowLineWrap) && (!joinFullLines || !lineFillsWidth)
+                && row < selY2 && row < mScreenRows - 1) builder.append('\n');
+        }
+        return builder.toString();
+    }
+
+    public String getWordAtLocation(int x, int y) {
+        // Set y1 and y2 to the lines where the wrapped line starts and ends.
+        // I.e. if a line that is wrapped to 3 lines starts at line 4, and this
+        // is called with y=5, then y1 would be set to 4 and y2 would be set to 6.
+        int y1 = y;
+        int y2 = y;
+        while (y1 > 0 && !getSelectedText(0, y1 - 1, mColumns, y, true, true).contains("\n")) {
+            y1--;
+        }
+        while (y2 < mScreenRows && !getSelectedText(0, y, mColumns, y2 + 1, true, true).contains("\n")) {
+            y2++;
+        }
+
+        // Get the text for the whole wrapped line
+        String text = getSelectedText(0, y1, mColumns, y2, true, true);
+        // The index of x in text
+        int textOffset = (y - y1) * mColumns + x;
+
+        if (textOffset >= text.length()) {
+          // The click was to the right of the last word on the line, so
+          // there's no word to return
+          return "";
+        }
+
+        // Set x1 and x2 to the indices of the last space before x and the
+        // first space after x in text respectively
+        int x1 = text.lastIndexOf(' ', textOffset);
+        int x2 = text.indexOf(' ', textOffset);
+        if (x2 == -1) {
+            x2 = text.length();
+        }
+
+        if (x1 == x2) {
+          // The click was on a space, so there's no word to return
+          return "";
+        }
+        return text.substring(x1 + 1, x2);
+    }
+
+    public int getActiveTranscriptRows() {
+        return mActiveTranscriptRows;
+    }
+
+    public int getActiveRows() {
+        return mActiveTranscriptRows + mScreenRows;
+    }
+
+    /**
+     * Convert a row value from the public external coordinate system to our internal private coordinate system.
+     *
+     * <pre>
+     * - External coordinate system: -mActiveTranscriptRows to mScreenRows-1, with the screen being 0..mScreenRows-1.
+     * - Internal coordinate system: the mScreenRows lines starting at mScreenFirstRow comprise the screen, while the
+     *   mActiveTranscriptRows lines ending at mScreenFirstRow-1 form the transcript (as a circular buffer).
+     *
+     * External ↔ Internal:
+     *
+     * [ ...                            ]     [ ...                                     ]
+     * [ -mActiveTranscriptRows         ]     [ mScreenFirstRow - mActiveTranscriptRows ]
+     * [ ...                            ]     [ ...                                     ]
+     * [ 0 (visible screen starts here) ]  ↔  [ mScreenFirstRow                         ]
+     * [ ...                            ]     [ ...                                     ]
+     * [ mScreenRows-1                  ]     [ mScreenFirstRow + mScreenRows-1         ]
+     * </pre>
+     *
+     * @param externalRow a row in the external coordinate system.
+     * @return The row corresponding to the input argument in the private coordinate system.
+     */
+    public int externalToInternalRow(int externalRow) {
+        if (externalRow < -mActiveTranscriptRows || externalRow > mScreenRows)
+            throw new IllegalArgumentException("extRow=" + externalRow + ", mScreenRows=" + mScreenRows + ", mActiveTranscriptRows=" + mActiveTranscriptRows);
+        final int internalRow = mScreenFirstRow + externalRow;
+        return (internalRow < 0) ? (mTotalRows + internalRow) : (internalRow % mTotalRows);
+    }
+
+    public void setLineWrap(int row) {
+        mLines[externalToInternalRow(row)].mLineWrap = true;
+    }
+
+    public boolean getLineWrap(int row) {
+        return mLines[externalToInternalRow(row)].mLineWrap;
+    }
+
+    public void clearLineWrap(int row) {
+        mLines[externalToInternalRow(row)].mLineWrap = false;
+    }
+
+    /**
+     * Resize the screen which this transcript backs. Currently, this only works if the number of columns does not
+     * change or the rows expand (that is, it only works when shrinking the number of rows).
+     *
+     * @param newColumns The number of columns the screen should have.
+     * @param newRows    The number of rows the screen should have.
+     * @param cursor     An int[2] containing the (column, row) cursor location.
+     */
+    public void resize(int newColumns, int newRows, int newTotalRows, int[] cursor, long currentStyle, boolean altScreen) {
+        // newRows > mTotalRows should not normally happen since mTotalRows is TRANSCRIPT_ROWS (10000):
+        if (newColumns == mColumns && newRows <= mTotalRows) {
+            // Fast resize where just the rows changed.
+            int shiftDownOfTopRow = mScreenRows - newRows;
+            if (shiftDownOfTopRow > 0 && shiftDownOfTopRow < mScreenRows) {
+                // Shrinking. Check if we can skip blank rows at bottom below cursor.
+                for (int i = mScreenRows - 1; i > 0; i--) {
+                    if (cursor[1] >= i) break;
+                    int r = externalToInternalRow(i);
+                    if (mLines[r] == null || mLines[r].isBlank()) {
+                        if (--shiftDownOfTopRow == 0) break;
+                    }
+                }
+            } else if (shiftDownOfTopRow < 0) {
+                // Negative shift down = expanding. Only move screen up if there is transcript to show:
+                int actualShift = Math.max(shiftDownOfTopRow, -mActiveTranscriptRows);
+                if (shiftDownOfTopRow != actualShift) {
+                    // The new lines revealed by the resizing are not all from the transcript. Blank the below ones.
+                    for (int i = 0; i < actualShift - shiftDownOfTopRow; i++)
+                        allocateFullLineIfNecessary((mScreenFirstRow + mScreenRows + i) % mTotalRows).clear(currentStyle);
+                    shiftDownOfTopRow = actualShift;
+                }
+            }
+            mScreenFirstRow += shiftDownOfTopRow;
+            mScreenFirstRow = (mScreenFirstRow < 0) ? (mScreenFirstRow + mTotalRows) : (mScreenFirstRow % mTotalRows);
+            mTotalRows = newTotalRows;
+            mActiveTranscriptRows = altScreen ? 0 : Math.max(0, mActiveTranscriptRows + shiftDownOfTopRow);
+            cursor[1] -= shiftDownOfTopRow;
+            mScreenRows = newRows;
+        } else {
+            // Copy away old state and update new:
+            TerminalRow[] oldLines = mLines;
+            mLines = new TerminalRow[newTotalRows];
+            for (int i = 0; i < newTotalRows; i++)
+                mLines[i] = new TerminalRow(newColumns, currentStyle);
+
+            final int oldActiveTranscriptRows = mActiveTranscriptRows;
+            final int oldScreenFirstRow = mScreenFirstRow;
+            final int oldScreenRows = mScreenRows;
+            final int oldTotalRows = mTotalRows;
+            mTotalRows = newTotalRows;
+            mScreenRows = newRows;
+            mActiveTranscriptRows = mScreenFirstRow = 0;
+            mColumns = newColumns;
+
+            int newCursorRow = -1;
+            int newCursorColumn = -1;
+            int oldCursorRow = cursor[1];
+            int oldCursorColumn = cursor[0];
+            boolean newCursorPlaced = false;
+
+            int currentOutputExternalRow = 0;
+            int currentOutputExternalColumn = 0;
+
+            // Loop over every character in the initial state.
+            // Blank lines should be skipped only if at end of transcript (just as is done in the "fast" resize), so we
+            // keep track how many blank lines we have skipped if we later on find a non-blank line.
+            int skippedBlankLines = 0;
+            for (int externalOldRow = -oldActiveTranscriptRows; externalOldRow < oldScreenRows; externalOldRow++) {
+                // Do what externalToInternalRow() does but for the old state:
+                int internalOldRow = oldScreenFirstRow + externalOldRow;
+                internalOldRow = (internalOldRow < 0) ? (oldTotalRows + internalOldRow) : (internalOldRow % oldTotalRows);
+
+                TerminalRow oldLine = oldLines[internalOldRow];
+                boolean cursorAtThisRow = externalOldRow == oldCursorRow;
+                // The cursor may only be on a non-null line, which we should not skip:
+                if (oldLine == null || (!(!newCursorPlaced && cursorAtThisRow)) && oldLine.isBlank()) {
+                    skippedBlankLines++;
+                    continue;
+                } else if (skippedBlankLines > 0) {
+                    // After skipping some blank lines we encounter a non-blank line. Insert the skipped blank lines.
+                    for (int i = 0; i < skippedBlankLines; i++) {
+                        if (currentOutputExternalRow == mScreenRows - 1) {
+                            scrollDownOneLine(0, mScreenRows, currentStyle);
+                        } else {
+                            currentOutputExternalRow++;
+                        }
+                        currentOutputExternalColumn = 0;
+                    }
+                    skippedBlankLines = 0;
+                }
+
+                int lastNonSpaceIndex = 0;
+                boolean justToCursor = false;
+                if (cursorAtThisRow || oldLine.mLineWrap) {
+                    // Take the whole line, either because of cursor on it, or if line wrapping.
+                    lastNonSpaceIndex = oldLine.getSpaceUsed();
+                    if (cursorAtThisRow) justToCursor = true;
+                } else {
+                    for (int i = 0; i < oldLine.getSpaceUsed(); i++)
+                        // NEWLY INTRODUCED BUG! Should not index oldLine.mStyle with char indices
+                        if (oldLine.mText[i] != ' '/* || oldLine.mStyle[i] != currentStyle */)
+                            lastNonSpaceIndex = i + 1;
+                }
+
+                int currentOldCol = 0;
+                long styleAtCol = 0;
+                for (int i = 0; i < lastNonSpaceIndex; i++) {
+                    // Note that looping over java character, not cells.
+                    char c = oldLine.mText[i];
+                    int codePoint = (Character.isHighSurrogate(c)) ? Character.toCodePoint(c, oldLine.mText[++i]) : c;
+                    int displayWidth = WcWidth.width(codePoint);
+                    // Use the last style if this is a zero-width character:
+                    if (displayWidth > 0) styleAtCol = oldLine.getStyle(currentOldCol);
+
+                    // Line wrap as necessary:
+                    if (currentOutputExternalColumn + displayWidth > mColumns) {
+                        setLineWrap(currentOutputExternalRow);
+                        if (currentOutputExternalRow == mScreenRows - 1) {
+                            if (newCursorPlaced) newCursorRow--;
+                            scrollDownOneLine(0, mScreenRows, currentStyle);
+                        } else {
+                            currentOutputExternalRow++;
+                        }
+                        currentOutputExternalColumn = 0;
+                    }
+
+                    int offsetDueToCombiningChar = ((displayWidth <= 0 && currentOutputExternalColumn > 0) ? 1 : 0);
+                    int outputColumn = currentOutputExternalColumn - offsetDueToCombiningChar;
+                    setChar(outputColumn, currentOutputExternalRow, codePoint, styleAtCol);
+
+                    if (displayWidth > 0) {
+                        if (oldCursorRow == externalOldRow && oldCursorColumn == currentOldCol) {
+                            newCursorColumn = currentOutputExternalColumn;
+                            newCursorRow = currentOutputExternalRow;
+                            newCursorPlaced = true;
+                        }
+                        currentOldCol += displayWidth;
+                        currentOutputExternalColumn += displayWidth;
+                        if (justToCursor && newCursorPlaced) break;
+                    }
+                }
+                // Old row has been copied. Check if we need to insert newline if old line was not wrapping:
+                if (externalOldRow != (oldScreenRows - 1) && !oldLine.mLineWrap) {
+                    if (currentOutputExternalRow == mScreenRows - 1) {
+                        if (newCursorPlaced) newCursorRow--;
+                        scrollDownOneLine(0, mScreenRows, currentStyle);
+                    } else {
+                        currentOutputExternalRow++;
+                    }
+                    currentOutputExternalColumn = 0;
+                }
+            }
+
+            cursor[0] = newCursorColumn;
+            cursor[1] = newCursorRow;
+        }
+
+        // Handle cursor scrolling off screen:
+        if (cursor[0] < 0 || cursor[1] < 0) cursor[0] = cursor[1] = 0;
+    }
+
+    /**
+     * Block copy lines and associated metadata from one location to another in the circular buffer, taking wraparound
+     * into account.
+     *
+     * @param srcInternal The first line to be copied.
+     * @param len         The number of lines to be copied.
+     */
+    private void blockCopyLinesDown(int srcInternal, int len) {
+        if (len == 0) return;
+        int totalRows = mTotalRows;
+
+        int start = len - 1;
+        // Save away line to be overwritten:
+        TerminalRow lineToBeOverWritten = mLines[(srcInternal + start + 1) % totalRows];
+        // Do the copy from bottom to top.
+        for (int i = start; i >= 0; --i)
+            mLines[(srcInternal + i + 1) % totalRows] = mLines[(srcInternal + i) % totalRows];
+        // Put back overwritten line, now above the block:
+        mLines[(srcInternal) % totalRows] = lineToBeOverWritten;
+    }
+
+    /**
+     * Scroll the screen down one line. To scroll the whole screen of a 24 line screen, the arguments would be (0, 24).
+     *
+     * @param topMargin    First line that is scrolled.
+     * @param bottomMargin One line after the last line that is scrolled.
+     * @param style        the style for the newly exposed line.
+     */
+    public void scrollDownOneLine(int topMargin, int bottomMargin, long style) {
+        if (topMargin > bottomMargin - 1 || topMargin < 0 || bottomMargin > mScreenRows)
+            throw new IllegalArgumentException("topMargin=" + topMargin + ", bottomMargin=" + bottomMargin + ", mScreenRows=" + mScreenRows);
+
+        // Copy the fixed topMargin lines one line down so that they remain on screen in same position:
+        blockCopyLinesDown(mScreenFirstRow, topMargin);
+        // Copy the fixed mScreenRows-bottomMargin lines one line down so that they remain on screen in same
+        // position:
+        blockCopyLinesDown(externalToInternalRow(bottomMargin), mScreenRows - bottomMargin);
+
+        // Update the screen location in the ring buffer:
+        mScreenFirstRow = (mScreenFirstRow + 1) % mTotalRows;
+        // Note that the history has grown if not already full:
+        if (mActiveTranscriptRows < mTotalRows - mScreenRows) mActiveTranscriptRows++;
+
+        // Blank the newly revealed line above the bottom margin:
+        int blankRow = externalToInternalRow(bottomMargin - 1);
+        if (mLines[blankRow] == null) {
+            mLines[blankRow] = new TerminalRow(mColumns, style);
+        } else {
+            mLines[blankRow].clear(style);
+        }
+    }
+
+    /**
+     * Block copy characters from one position in the screen to another. The two positions can overlap. All characters
+     * of the source and destination must be within the bounds of the screen, or else an InvalidParameterException will
+     * be thrown.
+     *
+     * @param sx source X coordinate
+     * @param sy source Y coordinate
+     * @param w  width
+     * @param h  height
+     * @param dx destination X coordinate
+     * @param dy destination Y coordinate
+     */
+    public void blockCopy(int sx, int sy, int w, int h, int dx, int dy) {
+        if (w == 0) return;
+        if (sx < 0 || sx + w > mColumns || sy < 0 || sy + h > mScreenRows || dx < 0 || dx + w > mColumns || dy < 0 || dy + h > mScreenRows)
+            throw new IllegalArgumentException();
+        boolean copyingUp = sy > dy;
+        for (int y = 0; y < h; y++) {
+            int y2 = copyingUp ? y : (h - (y + 1));
+            TerminalRow sourceRow = allocateFullLineIfNecessary(externalToInternalRow(sy + y2));
+            allocateFullLineIfNecessary(externalToInternalRow(dy + y2)).copyInterval(sourceRow, sx, sx + w, dx);
+        }
+    }
+
+    /**
+     * Block set characters. All characters must be within the bounds of the screen, or else and
+     * InvalidParemeterException will be thrown. Typically this is called with a "val" argument of 32 to clear a block
+     * of characters.
+     */
+    public void blockSet(int sx, int sy, int w, int h, int val, long style) {
+        if (sx < 0 || sx + w > mColumns || sy < 0 || sy + h > mScreenRows) {
+            throw new IllegalArgumentException(
+                "Illegal arguments! blockSet(" + sx + ", " + sy + ", " + w + ", " + h + ", " + val + ", " + mColumns + ", " + mScreenRows + ")");
+        }
+        for (int y = 0; y < h; y++)
+            for (int x = 0; x < w; x++)
+                setChar(sx + x, sy + y, val, style);
+    }
+
+    public TerminalRow allocateFullLineIfNecessary(int row) {
+        return (mLines[row] == null) ? (mLines[row] = new TerminalRow(mColumns, 0)) : mLines[row];
+    }
+
+    public void setChar(int column, int row, int codePoint, long style) {
+        if (row  < 0 || row >= mScreenRows || column < 0 || column >= mColumns)
+            throw new IllegalArgumentException("TerminalBuffer.setChar(): row=" + row + ", column=" + column + ", mScreenRows=" + mScreenRows + ", mColumns=" + mColumns);
+        row = externalToInternalRow(row);
+        allocateFullLineIfNecessary(row).setChar(column, codePoint, style);
+    }
+
+    public long getStyleAt(int externalRow, int column) {
+        return allocateFullLineIfNecessary(externalToInternalRow(externalRow)).getStyle(column);
+    }
+
+    /** Support for http://vt100.net/docs/vt510-rm/DECCARA and http://vt100.net/docs/vt510-rm/DECCARA */
+    public void setOrClearEffect(int bits, boolean setOrClear, boolean reverse, boolean rectangular, int leftMargin, int rightMargin, int top, int left,
+                                 int bottom, int right) {
+        for (int y = top; y < bottom; y++) {
+            TerminalRow line = mLines[externalToInternalRow(y)];
+            int startOfLine = (rectangular || y == top) ? left : leftMargin;
+            int endOfLine = (rectangular || y + 1 == bottom) ? right : rightMargin;
+            for (int x = startOfLine; x < endOfLine; x++) {
+                long currentStyle = line.getStyle(x);
+                int foreColor = TextStyle.decodeForeColor(currentStyle);
+                int backColor = TextStyle.decodeBackColor(currentStyle);
+                int effect = TextStyle.decodeEffect(currentStyle);
+                if (reverse) {
+                    // Clear out the bits to reverse and add them back in reversed:
+                    effect = (effect & ~bits) | (bits & ~effect);
+                } else if (setOrClear) {
+                    effect |= bits;
+                } else {
+                    effect &= ~bits;
+                }
+                line.mStyle[x] = TextStyle.encode(foreColor, backColor, effect);
+            }
+        }
+    }
+
+    public void clearTranscript() {
+        if (mScreenFirstRow < mActiveTranscriptRows) {
+            Arrays.fill(mLines, mTotalRows + mScreenFirstRow - mActiveTranscriptRows, mTotalRows, null);
+            Arrays.fill(mLines, 0, mScreenFirstRow, null);
+        } else {
+            Arrays.fill(mLines, mScreenFirstRow - mActiveTranscriptRows, mScreenFirstRow, null);
+        }
+        mActiveTranscriptRows = 0;
+    }
+
+}

app/src/main/java/com/termux/terminal/TerminalColorScheme.java

@@ -0,0 +1,126 @@
+package com.termux.terminal;
+
+import java.util.Map;
+import java.util.Properties;
+
+/**
+ * Color scheme for a terminal with default colors, which may be overridden (and then reset) from the shell using
+ * Operating System Control (OSC) sequences.
+ *
+ * @see TerminalColors
+ */
+public final class TerminalColorScheme {
+
+    /** http://upload.wikimedia.org/wikipedia/en/1/15/Xterm_256color_chart.svg, but with blue color brighter. */
+    private static final int[] DEFAULT_COLORSCHEME = {
+        // 16 original colors. First 8 are dim.
+        0xff000000, // black
+        0xffcd0000, // dim red
+        0xff00cd00, // dim green
+        0xffcdcd00, // dim yellow
+        0xff6495ed, // dim blue
+        0xffcd00cd, // dim magenta
+        0xff00cdcd, // dim cyan
+        0xffe5e5e5, // dim white
+        // Second 8 are bright:
+        0xff7f7f7f, // medium grey
+        0xffff0000, // bright red
+        0xff00ff00, // bright green
+        0xffffff00, // bright yellow
+        0xff5c5cff, // light blue
+        0xffff00ff, // bright magenta
+        0xff00ffff, // bright cyan
+        0xffffffff, // bright white
+
+        // 216 color cube, six shades of each color:
+        0xff000000, 0xff00005f, 0xff000087, 0xff0000af, 0xff0000d7, 0xff0000ff, 0xff005f00, 0xff005f5f, 0xff005f87, 0xff005faf, 0xff005fd7, 0xff005fff,
+        0xff008700, 0xff00875f, 0xff008787, 0xff0087af, 0xff0087d7, 0xff0087ff, 0xff00af00, 0xff00af5f, 0xff00af87, 0xff00afaf, 0xff00afd7, 0xff00afff,
+        0xff00d700, 0xff00d75f, 0xff00d787, 0xff00d7af, 0xff00d7d7, 0xff00d7ff, 0xff00ff00, 0xff00ff5f, 0xff00ff87, 0xff00ffaf, 0xff00ffd7, 0xff00ffff,
+        0xff5f0000, 0xff5f005f, 0xff5f0087, 0xff5f00af, 0xff5f00d7, 0xff5f00ff, 0xff5f5f00, 0xff5f5f5f, 0xff5f5f87, 0xff5f5faf, 0xff5f5fd7, 0xff5f5fff,
+        0xff5f8700, 0xff5f875f, 0xff5f8787, 0xff5f87af, 0xff5f87d7, 0xff5f87ff, 0xff5faf00, 0xff5faf5f, 0xff5faf87, 0xff5fafaf, 0xff5fafd7, 0xff5fafff,
+        0xff5fd700, 0xff5fd75f, 0xff5fd787, 0xff5fd7af, 0xff5fd7d7, 0xff5fd7ff, 0xff5fff00, 0xff5fff5f, 0xff5fff87, 0xff5fffaf, 0xff5fffd7, 0xff5fffff,
+        0xff870000, 0xff87005f, 0xff870087, 0xff8700af, 0xff8700d7, 0xff8700ff, 0xff875f00, 0xff875f5f, 0xff875f87, 0xff875faf, 0xff875fd7, 0xff875fff,
+        0xff878700, 0xff87875f, 0xff878787, 0xff8787af, 0xff8787d7, 0xff8787ff, 0xff87af00, 0xff87af5f, 0xff87af87, 0xff87afaf, 0xff87afd7, 0xff87afff,
+        0xff87d700, 0xff87d75f, 0xff87d787, 0xff87d7af, 0xff87d7d7, 0xff87d7ff, 0xff87ff00, 0xff87ff5f, 0xff87ff87, 0xff87ffaf, 0xff87ffd7, 0xff87ffff,
+        0xffaf0000, 0xffaf005f, 0xffaf0087, 0xffaf00af, 0xffaf00d7, 0xffaf00ff, 0xffaf5f00, 0xffaf5f5f, 0xffaf5f87, 0xffaf5faf, 0xffaf5fd7, 0xffaf5fff,
+        0xffaf8700, 0xffaf875f, 0xffaf8787, 0xffaf87af, 0xffaf87d7, 0xffaf87ff, 0xffafaf00, 0xffafaf5f, 0xffafaf87, 0xffafafaf, 0xffafafd7, 0xffafafff,
+        0xffafd700, 0xffafd75f, 0xffafd787, 0xffafd7af, 0xffafd7d7, 0xffafd7ff, 0xffafff00, 0xffafff5f, 0xffafff87, 0xffafffaf, 0xffafffd7, 0xffafffff,
+        0xffd70000, 0xffd7005f, 0xffd70087, 0xffd700af, 0xffd700d7, 0xffd700ff, 0xffd75f00, 0xffd75f5f, 0xffd75f87, 0xffd75faf, 0xffd75fd7, 0xffd75fff,
+        0xffd78700, 0xffd7875f, 0xffd78787, 0xffd787af, 0xffd787d7, 0xffd787ff, 0xffd7af00, 0xffd7af5f, 0xffd7af87, 0xffd7afaf, 0xffd7afd7, 0xffd7afff,
+        0xffd7d700, 0xffd7d75f, 0xffd7d787, 0xffd7d7af, 0xffd7d7d7, 0xffd7d7ff, 0xffd7ff00, 0xffd7ff5f, 0xffd7ff87, 0xffd7ffaf, 0xffd7ffd7, 0xffd7ffff,
+        0xffff0000, 0xffff005f, 0xffff0087, 0xffff00af, 0xffff00d7, 0xffff00ff, 0xffff5f00, 0xffff5f5f, 0xffff5f87, 0xffff5faf, 0xffff5fd7, 0xffff5fff,
+        0xffff8700, 0xffff875f, 0xffff8787, 0xffff87af, 0xffff87d7, 0xffff87ff, 0xffffaf00, 0xffffaf5f, 0xffffaf87, 0xffffafaf, 0xffffafd7, 0xffffafff,
+        0xffffd700, 0xffffd75f, 0xffffd787, 0xffffd7af, 0xffffd7d7, 0xffffd7ff, 0xffffff00, 0xffffff5f, 0xffffff87, 0xffffffaf, 0xffffffd7, 0xffffffff,
+
+        // 24 grey scale ramp:
+        0xff080808, 0xff121212, 0xff1c1c1c, 0xff262626, 0xff303030, 0xff3a3a3a, 0xff444444, 0xff4e4e4e, 0xff585858, 0xff626262, 0xff6c6c6c, 0xff767676,
+        0xff808080, 0xff8a8a8a, 0xff949494, 0xff9e9e9e, 0xffa8a8a8, 0xffb2b2b2, 0xffbcbcbc, 0xffc6c6c6, 0xffd0d0d0, 0xffdadada, 0xffe4e4e4, 0xffeeeeee,
+
+        // COLOR_INDEX_DEFAULT_FOREGROUND, COLOR_INDEX_DEFAULT_BACKGROUND and COLOR_INDEX_DEFAULT_CURSOR:
+        0xffffffff, 0xff000000, 0xffffffff};
+
+    public final int[] mDefaultColors = new int[TextStyle.NUM_INDEXED_COLORS];
+
+    public TerminalColorScheme() {
+        reset();
+    }
+
+    private void reset() {
+        System.arraycopy(DEFAULT_COLORSCHEME, 0, mDefaultColors, 0, TextStyle.NUM_INDEXED_COLORS);
+    }
+
+    public void updateWith(Properties props) {
+        reset();
+        boolean cursorPropExists = false;
+        for (Map.Entry<Object, Object> entries : props.entrySet()) {
+            String key = (String) entries.getKey();
+            String value = (String) entries.getValue();
+            int colorIndex;
+
+            if (key.equals("foreground")) {
+                colorIndex = TextStyle.COLOR_INDEX_FOREGROUND;
+            } else if (key.equals("background")) {
+                colorIndex = TextStyle.COLOR_INDEX_BACKGROUND;
+            } else if (key.equals("cursor")) {
+                colorIndex = TextStyle.COLOR_INDEX_CURSOR;
+                cursorPropExists = true;
+            } else if (key.startsWith("color")) {
+                try {
+                    colorIndex = Integer.parseInt(key.substring(5));
+                } catch (NumberFormatException e) {
+                    throw new IllegalArgumentException("Invalid property: '" + key + "'");
+                }
+            } else {
+                throw new IllegalArgumentException("Invalid property: '" + key + "'");
+            }
+
+            int colorValue = TerminalColors.parse(value);
+            if (colorValue == 0)
+                throw new IllegalArgumentException("Property '" + key + "' has invalid color: '" + value + "'");
+
+            mDefaultColors[colorIndex] = colorValue;
+        }
+
+        if (!cursorPropExists)
+            setCursorColorForBackground();
+    }
+
+    /**
+     * If the "cursor" color is not set by user, we need to decide on the appropriate color that will
+     * be visible on the current terminal background. White will not be visible on light backgrounds
+     * and black won't be visible on dark backgrounds. So we find the perceived brightness of the
+     * background color and if its below the threshold (too dark), we use white cursor and if its
+     * above (too bright), we use black cursor.
+     */
+    public void setCursorColorForBackground() {
+        int backgroundColor = mDefaultColors[TextStyle.COLOR_INDEX_BACKGROUND];
+        int brightness = TerminalColors.getPerceivedBrightnessOfColor(backgroundColor);
+        if (brightness > 0) {
+            if (brightness < 130)
+                mDefaultColors[TextStyle.COLOR_INDEX_CURSOR] = 0xffffffff;
+            else
+                mDefaultColors[TextStyle.COLOR_INDEX_CURSOR] = 0xff000000;
+        }
+    }
+
+}

app/src/main/java/com/termux/terminal/TerminalColors.java

@@ -0,0 +1,96 @@
+package com.termux.terminal;
+
+import android.graphics.Color;
+
+/** Current terminal colors (if different from default). */
+public final class TerminalColors {
+
+    /** Static data - a bit ugly but ok for now. */
+    public static final TerminalColorScheme COLOR_SCHEME = new TerminalColorScheme();
+
+    /**
+     * The current terminal colors, which are normally set from the color theme, but may be set dynamically with the OSC
+     * 4 control sequence.
+     */
+    public final int[] mCurrentColors = new int[TextStyle.NUM_INDEXED_COLORS];
+
+    /** Create a new instance with default colors from the theme. */
+    public TerminalColors() {
+        reset();
+    }
+
+    /** Reset a particular indexed color with the default color from the color theme. */
+    public void reset(int index) {
+        mCurrentColors[index] = COLOR_SCHEME.mDefaultColors[index];
+    }
+
+    /** Reset all indexed colors with the default color from the color theme. */
+    public void reset() {
+        System.arraycopy(COLOR_SCHEME.mDefaultColors, 0, mCurrentColors, 0, TextStyle.NUM_INDEXED_COLORS);
+    }
+
+    /**
+     * Parse color according to http://manpages.ubuntu.com/manpages/intrepid/man3/XQueryColor.3.html
+     * <p/>
+     * Highest bit is set if successful, so return value is 0xFF${R}${G}${B}. Return 0 if failed.
+     */
+    static int parse(String c) {
+        try {
+            int skipInitial, skipBetween;
+            if (c.charAt(0) == '#') {
+                // #RGB, #RRGGBB, #RRRGGGBBB or #RRRRGGGGBBBB. Most significant bits.
+                skipInitial = 1;
+                skipBetween = 0;
+            } else if (c.startsWith("rgb:")) {
+                // rgb:<red>/<green>/<blue> where <red>, <green>, <blue> := h | hh | hhh | hhhh. Scaled.
+                skipInitial = 4;
+                skipBetween = 1;
+            } else {
+                return 0;
+            }
+            int charsForColors = c.length() - skipInitial - 2 * skipBetween;
+            if (charsForColors % 3 != 0) return 0; // Unequal lengths.
+            int componentLength = charsForColors / 3;
+            double mult = 255 / (Math.pow(2, componentLength * 4) - 1);
+
+            int currentPosition = skipInitial;
+            String rString = c.substring(currentPosition, currentPosition + componentLength);
+            currentPosition += componentLength + skipBetween;
+            String gString = c.substring(currentPosition, currentPosition + componentLength);
+            currentPosition += componentLength + skipBetween;
+            String bString = c.substring(currentPosition, currentPosition + componentLength);
+
+            int r = (int) (Integer.parseInt(rString, 16) * mult);
+            int g = (int) (Integer.parseInt(gString, 16) * mult);
+            int b = (int) (Integer.parseInt(bString, 16) * mult);
+            return 0xFF << 24 | r << 16 | g << 8 | b;
+        } catch (NumberFormatException | IndexOutOfBoundsException e) {
+            return 0;
+        }
+    }
+
+    /** Try parse a color from a text parameter and into a specified index. */
+    public void tryParseColor(int intoIndex, String textParameter) {
+        int c = parse(textParameter);
+        if (c != 0) mCurrentColors[intoIndex] = c;
+    }
+
+    /**
+     * Get the perceived brightness of the color based on its RGB components.
+     *
+     * https://www.nbdtech.com/Blog/archive/2008/04/27/Calculating-the-Perceived-Brightness-of-a-Color.aspx
+     * http://alienryderflex.com/hsp.html
+     *
+     * @param color The color code int.
+     * @return Returns value between 0-255.
+     */
+    public static int getPerceivedBrightnessOfColor(int color) {
+        return (int)
+            Math.floor(Math.sqrt(
+                Math.pow(Color.red(color), 2) * 0.241 +
+                    Math.pow(Color.green(color), 2) * 0.691 +
+                    Math.pow(Color.blue(color), 2) * 0.068
+            ));
+    }
+
+}

app/src/main/java/com/termux/terminal/TerminalOutput.java

@@ -0,0 +1,32 @@
+package com.termux.terminal;
+
+import java.nio.charset.StandardCharsets;
+
+/** A client which receives callbacks from events triggered by feeding input to a {@link TerminalEmulator}. */
+public abstract class TerminalOutput {
+
+    /** Write a string using the UTF-8 encoding to the terminal client. */
+    public final void write(String data) {
+        if (data == null) return;
+        byte[] bytes = data.getBytes(StandardCharsets.UTF_8);
+        write(bytes, 0, bytes.length);
+    }
+
+    /** Write bytes to the terminal client. */
+    public abstract void write(byte[] data, int offset, int count);
+
+    /** Notify the terminal client that the terminal title has changed. */
+    public abstract void titleChanged(String oldTitle, String newTitle);
+
+    /** Notify the terminal client that text should be copied to clipboard. */
+    public abstract void onCopyTextToClipboard(String text);
+
+    /** Notify the terminal client that text should be pasted from clipboard. */
+    public abstract void onPasteTextFromClipboard();
+
+    /** Notify the terminal client that a bell character (ASCII 7, bell, BEL, \a, ^G)) has been received. */
+    public abstract void onBell();
+
+    public abstract void onColorsChanged();
+
+}

app/src/main/java/com/termux/terminal/TerminalRow.java

@@ -0,0 +1,283 @@
+package com.termux.terminal;
+
+import java.util.Arrays;
+
+/**
+ * A row in a terminal, composed of a fixed number of cells.
+ * <p>
+ * The text in the row is stored in a char[] array, {@link #mText}, for quick access during rendering.
+ */
+public final class TerminalRow {
+
+    private static final float SPARE_CAPACITY_FACTOR = 1.5f;
+
+    /**
+     * Max combining characters that can exist in a column, that are separate from the base character
+     * itself. Any additional combining characters will be ignored and not added to the column.
+     *
+     * There does not seem to be limit in unicode standard for max number of combination characters
+     * that can be combined but such characters are primarily under 10.
+     *
+     * "Section 3.6 Combination" of unicode standard contains combining characters info.
+     * - https://www.unicode.org/versions/Unicode15.0.0/ch03.pdf
+     * - https://en.wikipedia.org/wiki/Combining_character#Unicode_ranges
+     * - https://stackoverflow.com/questions/71237212/what-is-the-maximum-number-of-unicode-combined-characters-that-may-be-needed-to
+     *
+     * UAX15-D3 Stream-Safe Text Format limits to max 30 combining characters.
+     * > The value of 30 is chosen to be significantly beyond what is required for any linguistic or technical usage.
+     * > While it would have been feasible to chose a smaller number, this value provides a very wide margin,
+     * > yet is well within the buffer size limits of practical implementations.
+     * - https://unicode.org/reports/tr15/#Stream_Safe_Text_Format
+     * - https://stackoverflow.com/a/11983435/14686958
+     *
+     * We choose the value 15 because it should be enough for terminal based applications and keep
+     * the memory usage low for a terminal row, won't affect performance or cause terminal to
+     * lag or hang, and will keep malicious applications from causing harm. The value can be
+     * increased if ever needed for legitimate applications.
+     */
+    private static final int MAX_COMBINING_CHARACTERS_PER_COLUMN = 15;
+
+    /** The number of columns in this terminal row. */
+    private final int mColumns;
+    /** The text filling this terminal row. */
+    public char[] mText;
+    /** The number of java chars used in {@link #mText}. */
+    private short mSpaceUsed;
+    /** If this row has been line wrapped due to text output at the end of line. */
+    boolean mLineWrap;
+    /** The style bits of each cell in the row. See {@link TextStyle}. */
+    final long[] mStyle;
+    /** If this row might contain chars with width != 1, used for deactivating fast path */
+    boolean mHasNonOneWidthOrSurrogateChars;
+
+    /** Construct a blank row (containing only whitespace, ' ') with a specified style. */
+    public TerminalRow(int columns, long style) {
+        mColumns = columns;
+        mText = new char[(int) (SPARE_CAPACITY_FACTOR * columns)];
+        mStyle = new long[columns];
+        clear(style);
+    }
+
+    /** NOTE: The sourceX2 is exclusive. */
+    public void copyInterval(TerminalRow line, int sourceX1, int sourceX2, int destinationX) {
+        mHasNonOneWidthOrSurrogateChars |= line.mHasNonOneWidthOrSurrogateChars;
+        final int x1 = line.findStartOfColumn(sourceX1);
+        final int x2 = line.findStartOfColumn(sourceX2);
+        boolean startingFromSecondHalfOfWideChar = (sourceX1 > 0 && line.wideDisplayCharacterStartingAt(sourceX1 - 1));
+        final char[] sourceChars = (this == line) ? Arrays.copyOf(line.mText, line.mText.length) : line.mText;
+        int latestNonCombiningWidth = 0;
+        for (int i = x1; i < x2; i++) {
+            char sourceChar = sourceChars[i];
+            int codePoint = Character.isHighSurrogate(sourceChar) ? Character.toCodePoint(sourceChar, sourceChars[++i]) : sourceChar;
+            if (startingFromSecondHalfOfWideChar) {
+                // Just treat copying second half of wide char as copying whitespace.
+                codePoint = ' ';
+                startingFromSecondHalfOfWideChar = false;
+            }
+            int w = WcWidth.width(codePoint);
+            if (w > 0) {
+                destinationX += latestNonCombiningWidth;
+                sourceX1 += latestNonCombiningWidth;
+                latestNonCombiningWidth = w;
+            }
+            setChar(destinationX, codePoint, line.getStyle(sourceX1));
+        }
+    }
+
+    public int getSpaceUsed() {
+        return mSpaceUsed;
+    }
+
+    /** Note that the column may end of second half of wide character. */
+    public int findStartOfColumn(int column) {
+        if (column == mColumns) return getSpaceUsed();
+
+        int currentColumn = 0;
+        int currentCharIndex = 0;
+        while (true) { // 0<2 1 < 2
+            int newCharIndex = currentCharIndex;
+            char c = mText[newCharIndex++]; // cci=1, cci=2
+            boolean isHigh = Character.isHighSurrogate(c);
+            int codePoint = isHigh ? Character.toCodePoint(c, mText[newCharIndex++]) : c;
+            int wcwidth = WcWidth.width(codePoint); // 1, 2
+            if (wcwidth > 0) {
+                currentColumn += wcwidth;
+                if (currentColumn == column) {
+                    while (newCharIndex < mSpaceUsed) {
+                        // Skip combining chars.
+                        if (Character.isHighSurrogate(mText[newCharIndex])) {
+                            if (WcWidth.width(Character.toCodePoint(mText[newCharIndex], mText[newCharIndex + 1])) <= 0) {
+                                newCharIndex += 2;
+                            } else {
+                                break;
+                            }
+                        } else if (WcWidth.width(mText[newCharIndex]) <= 0) {
+                            newCharIndex++;
+                        } else {
+                            break;
+                        }
+                    }
+                    return newCharIndex;
+                } else if (currentColumn > column) {
+                    // Wide column going past end.
+                    return currentCharIndex;
+                }
+            }
+            currentCharIndex = newCharIndex;
+        }
+    }
+
+    private boolean wideDisplayCharacterStartingAt(int column) {
+        for (int currentCharIndex = 0, currentColumn = 0; currentCharIndex < mSpaceUsed; ) {
+            char c = mText[currentCharIndex++];
+            int codePoint = Character.isHighSurrogate(c) ? Character.toCodePoint(c, mText[currentCharIndex++]) : c;
+            int wcwidth = WcWidth.width(codePoint);
+            if (wcwidth > 0) {
+                if (currentColumn == column && wcwidth == 2) return true;
+                currentColumn += wcwidth;
+                if (currentColumn > column) return false;
+            }
+        }
+        return false;
+    }
+
+    public void clear(long style) {
+        Arrays.fill(mText, ' ');
+        Arrays.fill(mStyle, style);
+        mSpaceUsed = (short) mColumns;
+        mHasNonOneWidthOrSurrogateChars = false;
+    }
+
+    // https://github.com/steven676/Android-Terminal-Emulator/commit/9a47042620bec87617f0b4f5d50568535668fe26
+    public void setChar(int columnToSet, int codePoint, long style) {
+        if (columnToSet  < 0 || columnToSet >= mStyle.length)
+            throw new IllegalArgumentException("TerminalRow.setChar(): columnToSet=" + columnToSet + ", codePoint=" + codePoint + ", style=" + style);
+
+        mStyle[columnToSet] = style;
+
+        final int newCodePointDisplayWidth = WcWidth.width(codePoint);
+
+        // Fast path when we don't have any chars with width != 1
+        if (!mHasNonOneWidthOrSurrogateChars) {
+            if (codePoint >= Character.MIN_SUPPLEMENTARY_CODE_POINT || newCodePointDisplayWidth != 1) {
+                mHasNonOneWidthOrSurrogateChars = true;
+            } else {
+                mText[columnToSet] = (char) codePoint;
+                return;
+            }
+        }
+
+        final boolean newIsCombining = newCodePointDisplayWidth <= 0;
+
+        boolean wasExtraColForWideChar = (columnToSet > 0) && wideDisplayCharacterStartingAt(columnToSet - 1);
+
+        if (newIsCombining) {
+            // When standing at second half of wide character and inserting combining:
+            if (wasExtraColForWideChar) columnToSet--;
+        } else {
+            // Check if we are overwriting the second half of a wide character starting at the previous column:
+            if (wasExtraColForWideChar) setChar(columnToSet - 1, ' ', style);
+            // Check if we are overwriting the first half of a wide character starting at the next column:
+            boolean overwritingWideCharInNextColumn = newCodePointDisplayWidth == 2 && wideDisplayCharacterStartingAt(columnToSet + 1);
+            if (overwritingWideCharInNextColumn) setChar(columnToSet + 1, ' ', style);
+        }
+
+        char[] text = mText;
+        final int oldStartOfColumnIndex = findStartOfColumn(columnToSet);
+        final int oldCodePointDisplayWidth = WcWidth.width(text, oldStartOfColumnIndex);
+
+        // Get the number of elements in the mText array this column uses now
+        int oldCharactersUsedForColumn;
+        if (columnToSet + oldCodePointDisplayWidth < mColumns) {
+            int oldEndOfColumnIndex = findStartOfColumn(columnToSet + oldCodePointDisplayWidth);
+            oldCharactersUsedForColumn = oldEndOfColumnIndex - oldStartOfColumnIndex;
+        } else {
+            // Last character.
+            oldCharactersUsedForColumn = mSpaceUsed - oldStartOfColumnIndex;
+        }
+
+        // If MAX_COMBINING_CHARACTERS_PER_COLUMN already exist in column, then ignore adding additional combining characters.
+        if (newIsCombining) {
+            int combiningCharsCount = WcWidth.zeroWidthCharsCount(mText, oldStartOfColumnIndex, oldStartOfColumnIndex + oldCharactersUsedForColumn);
+            if (combiningCharsCount >= MAX_COMBINING_CHARACTERS_PER_COLUMN)
+                return;
+        }
+
+        // Find how many chars this column will need
+        int newCharactersUsedForColumn = Character.charCount(codePoint);
+        if (newIsCombining) {
+            // Combining characters are added to the contents of the column instead of overwriting them, so that they
+            // modify the existing contents.
+            // FIXME: Unassigned characters also get width=0.
+            newCharactersUsedForColumn += oldCharactersUsedForColumn;
+        }
+
+        int oldNextColumnIndex = oldStartOfColumnIndex + oldCharactersUsedForColumn;
+        int newNextColumnIndex = oldStartOfColumnIndex + newCharactersUsedForColumn;
+
+        final int javaCharDifference = newCharactersUsedForColumn - oldCharactersUsedForColumn;
+        if (javaCharDifference > 0) {
+            // Shift the rest of the line right.
+            int oldCharactersAfterColumn = mSpaceUsed - oldNextColumnIndex;
+            if (mSpaceUsed + javaCharDifference > text.length) {
+                // We need to grow the array
+                char[] newText = new char[text.length + mColumns];
+                System.arraycopy(text, 0, newText, 0, oldNextColumnIndex);
+                System.arraycopy(text, oldNextColumnIndex, newText, newNextColumnIndex, oldCharactersAfterColumn);
+                mText = text = newText;
+            } else {
+                System.arraycopy(text, oldNextColumnIndex, text, newNextColumnIndex, oldCharactersAfterColumn);
+            }
+        } else if (javaCharDifference < 0) {
+            // Shift the rest of the line left.
+            System.arraycopy(text, oldNextColumnIndex, text, newNextColumnIndex, mSpaceUsed - oldNextColumnIndex);
+        }
+        mSpaceUsed += javaCharDifference;
+
+        // Store char. A combining character is stored at the end of the existing contents so that it modifies them:
+        //noinspection ResultOfMethodCallIgnored - since we already now how many java chars is used.
+        Character.toChars(codePoint, text, oldStartOfColumnIndex + (newIsCombining ? oldCharactersUsedForColumn : 0));
+
+        if (oldCodePointDisplayWidth == 2 && newCodePointDisplayWidth == 1) {
+            // Replace second half of wide char with a space. Which mean that we actually add a ' ' java character.
+            if (mSpaceUsed + 1 > text.length) {
+                char[] newText = new char[text.length + mColumns];
+                System.arraycopy(text, 0, newText, 0, newNextColumnIndex);
+                System.arraycopy(text, newNextColumnIndex, newText, newNextColumnIndex + 1, mSpaceUsed - newNextColumnIndex);
+                mText = text = newText;
+            } else {
+                System.arraycopy(text, newNextColumnIndex, text, newNextColumnIndex + 1, mSpaceUsed - newNextColumnIndex);
+            }
+            text[newNextColumnIndex] = ' ';
+
+            ++mSpaceUsed;
+        } else if (oldCodePointDisplayWidth == 1 && newCodePointDisplayWidth == 2) {
+            if (columnToSet == mColumns - 1) {
+                throw new IllegalArgumentException("Cannot put wide character in last column");
+            } else if (columnToSet == mColumns - 2) {
+                // Truncate the line to the second part of this wide char:
+                mSpaceUsed = (short) newNextColumnIndex;
+            } else {
+                // Overwrite the contents of the next column, which mean we actually remove java characters. Due to the
+                // check at the beginning of this method we know that we are not overwriting a wide char.
+                int newNextNextColumnIndex = newNextColumnIndex + (Character.isHighSurrogate(mText[newNextColumnIndex]) ? 2 : 1);
+                int nextLen = newNextNextColumnIndex - newNextColumnIndex;
+
+                // Shift the array leftwards.
+                System.arraycopy(text, newNextNextColumnIndex, text, newNextColumnIndex, mSpaceUsed - newNextNextColumnIndex);
+                mSpaceUsed -= nextLen;
+            }
+        }
+    }
+
+    boolean isBlank() {
+        for (int charIndex = 0, charLen = getSpaceUsed(); charIndex < charLen; charIndex++)
+            if (mText[charIndex] != ' ') return false;
+        return true;
+    }
+
+    public final long getStyle(int column) {
+        return mStyle[column];
+    }
+
+}

app/src/main/java/com/termux/terminal/TerminalSessionClient.java

@@ -0,0 +1,29 @@
+package com.termux.terminal;
+
+/**
+ * Callbacks from {@link TerminalEmulator} to its host.
+ *
+ * Modified for whc-shell: the TerminalSession-specific callbacks were removed because the
+ * emulator here is driven by an SSH channel instead of a local process.
+ */
+public interface TerminalSessionClient {
+
+    void onTerminalCursorStateChange(boolean state);
+
+    Integer getTerminalCursorStyle();
+
+    void logError(String tag, String message);
+
+    void logWarn(String tag, String message);
+
+    void logInfo(String tag, String message);
+
+    void logDebug(String tag, String message);
+
+    void logVerbose(String tag, String message);
+
+    void logStackTraceWithMessage(String tag, String message, Exception e);
+
+    void logStackTrace(String tag, Exception e);
+
+}

app/src/main/java/com/termux/terminal/TextStyle.java

@@ -0,0 +1,90 @@
+package com.termux.terminal;
+
+/**
+ * <p>
+ * Encodes effects, foreground and background colors into a 64 bit long, which are stored for each cell in a terminal
+ * row in {@link TerminalRow#mStyle}.
+ * </p>
+ * <p>
+ * The bit layout is:
+ * </p>
+ * - 16 flags (11 currently used).
+ * - 24 for foreground color (only 9 first bits if a color index).
+ * - 24 for background color (only 9 first bits if a color index).
+ */
+public final class TextStyle {
+
+    public final static int CHARACTER_ATTRIBUTE_BOLD = 1;
+    public final static int CHARACTER_ATTRIBUTE_ITALIC = 1 << 1;
+    public final static int CHARACTER_ATTRIBUTE_UNDERLINE = 1 << 2;
+    public final static int CHARACTER_ATTRIBUTE_BLINK = 1 << 3;
+    public final static int CHARACTER_ATTRIBUTE_INVERSE = 1 << 4;
+    public final static int CHARACTER_ATTRIBUTE_INVISIBLE = 1 << 5;
+    public final static int CHARACTER_ATTRIBUTE_STRIKETHROUGH = 1 << 6;
+    /**
+     * The selective erase control functions (DECSED and DECSEL) can only erase characters defined as erasable.
+     * <p>
+     * This bit is set if DECSCA (Select Character Protection Attribute) has been used to define the characters that
+     * come after it as erasable from the screen.
+     * </p>
+     */
+    public final static int CHARACTER_ATTRIBUTE_PROTECTED = 1 << 7;
+    /** Dim colors. Also known as faint or half intensity. */
+    public final static int CHARACTER_ATTRIBUTE_DIM = 1 << 8;
+    /** If true (24-bit) color is used for the cell for foreground. */
+    private final static int CHARACTER_ATTRIBUTE_TRUECOLOR_FOREGROUND = 1 << 9;
+    /** If true (24-bit) color is used for the cell for foreground. */
+    private final static int CHARACTER_ATTRIBUTE_TRUECOLOR_BACKGROUND= 1 << 10;
+
+    public final static int COLOR_INDEX_FOREGROUND = 256;
+    public final static int COLOR_INDEX_BACKGROUND = 257;
+    public final static int COLOR_INDEX_CURSOR = 258;
+
+    /** The 256 standard color entries and the three special (foreground, background and cursor) ones. */
+    public final static int NUM_INDEXED_COLORS = 259;
+
+    /** Normal foreground and background colors and no effects. */
+    final static long NORMAL = encode(COLOR_INDEX_FOREGROUND, COLOR_INDEX_BACKGROUND, 0);
+
+    static long encode(int foreColor, int backColor, int effect) {
+        long result = effect & 0b111111111;
+        if ((0xff000000 & foreColor) == 0xff000000) {
+            // 24-bit color.
+            result |= CHARACTER_ATTRIBUTE_TRUECOLOR_FOREGROUND | ((foreColor & 0x00ffffffL) << 40L);
+        } else {
+            // Indexed color.
+            result |= (foreColor & 0b111111111L) << 40;
+        }
+        if ((0xff000000 & backColor) == 0xff000000) {
+            // 24-bit color.
+            result |= CHARACTER_ATTRIBUTE_TRUECOLOR_BACKGROUND | ((backColor & 0x00ffffffL) << 16L);
+        } else {
+            // Indexed color.
+            result |= (backColor & 0b111111111L) << 16L;
+        }
+
+        return result;
+    }
+
+    public static int decodeForeColor(long style) {
+        if ((style & CHARACTER_ATTRIBUTE_TRUECOLOR_FOREGROUND) == 0) {
+            return (int) ((style >>> 40) & 0b111111111L);
+        } else {
+            return 0xff000000 | (int) ((style >>> 40) & 0x00ffffffL);
+        }
+
+    }
+
+    public static int decodeBackColor(long style) {
+        if ((style & CHARACTER_ATTRIBUTE_TRUECOLOR_BACKGROUND) == 0) {
+            return (int) ((style >>> 16) & 0b111111111L);
+        } else {
+            return 0xff000000 | (int) ((style >>> 16) & 0x00ffffffL);
+        }
+    }
+
+    public static int decodeEffect(long style) {
+        return (int) (style & 0b11111111111);
+    }
+
+}

app/src/main/java/com/termux/terminal/WcWidth.java

@@ -0,0 +1,566 @@
+package com.termux.terminal;
+
+/**
+ * Implementation of wcwidth(3) for Unicode 15.
+ *
+ * Implementation from https://github.com/jquast/wcwidth but we return 0 for unprintable characters.
+ *
+ * IMPORTANT:
+ * Must be kept in sync with the following:
+ * https://github.com/termux/wcwidth
+ * https://github.com/termux/libandroid-support
+ * https://github.com/termux/termux-packages/tree/master/packages/libandroid-support
+ */
+public final class WcWidth {
+
+    // From https://github.com/jquast/wcwidth/blob/master/wcwidth/table_zero.py
+    // from https://github.com/jquast/wcwidth/pull/64
+    // at commit 1b9b6585b0080ea5cb88dc9815796505724793fe (2022-12-16):
+    private static final int[][] ZERO_WIDTH = {
+        {0x00300, 0x0036f},  // Combining Grave Accent  ..Combining Latin Small Le
+        {0x00483, 0x00489},  // Combining Cyrillic Titlo..Combining Cyrillic Milli
+        {0x00591, 0x005bd},  // Hebrew Accent Etnahta   ..Hebrew Point Meteg
+        {0x005bf, 0x005bf},  // Hebrew Point Rafe       ..Hebrew Point Rafe
+        {0x005c1, 0x005c2},  // Hebrew Point Shin Dot   ..Hebrew Point Sin Dot
+        {0x005c4, 0x005c5},  // Hebrew Mark Upper Dot   ..Hebrew Mark Lower Dot
+        {0x005c7, 0x005c7},  // Hebrew Point Qamats Qata..Hebrew Point Qamats Qata
+        {0x00610, 0x0061a},  // Arabic Sign Sallallahou ..Arabic Small Kasra
+        {0x0064b, 0x0065f},  // Arabic Fathatan         ..Arabic Wavy Hamza Below
+        {0x00670, 0x00670},  // Arabic Letter Superscrip..Arabic Letter Superscrip
+        {0x006d6, 0x006dc},  // Arabic Small High Ligatu..Arabic Small High Seen
+        {0x006df, 0x006e4},  // Arabic Small High Rounde..Arabic Small High Madda
+        {0x006e7, 0x006e8},  // Arabic Small High Yeh   ..Arabic Small High Noon
+        {0x006ea, 0x006ed},  // Arabic Empty Centre Low ..Arabic Small Low Meem
+        {0x00711, 0x00711},  // Syriac Letter Superscrip..Syriac Letter Superscrip
+        {0x00730, 0x0074a},  // Syriac Pthaha Above     ..Syriac Barrekh
+        {0x007a6, 0x007b0},  // Thaana Abafili          ..Thaana Sukun
+        {0x007eb, 0x007f3},  // Nko Combining Short High..Nko Combining Double Dot
+        {0x007fd, 0x007fd},  // Nko Dantayalan          ..Nko Dantayalan
+        {0x00816, 0x00819},  // Samaritan Mark In       ..Samaritan Mark Dagesh
+        {0x0081b, 0x00823},  // Samaritan Mark Epentheti..Samaritan Vowel Sign A
+        {0x00825, 0x00827},  // Samaritan Vowel Sign Sho..Samaritan Vowel Sign U
+        {0x00829, 0x0082d},  // Samaritan Vowel Sign Lon..Samaritan Mark Nequdaa
+        {0x00859, 0x0085b},  // Mandaic Affrication Mark..Mandaic Gemination Mark
+        {0x00898, 0x0089f},  // Arabic Small High Word A..Arabic Half Madda Over M
+        {0x008ca, 0x008e1},  // Arabic Small High Farsi ..Arabic Small High Sign S
+        {0x008e3, 0x00902},  // Arabic Turned Damma Belo..Devanagari Sign Anusvara
+        {0x0093a, 0x0093a},  // Devanagari Vowel Sign Oe..Devanagari Vowel Sign Oe
+        {0x0093c, 0x0093c},  // Devanagari Sign Nukta   ..Devanagari Sign Nukta
+        {0x00941, 0x00948},  // Devanagari Vowel Sign U ..Devanagari Vowel Sign Ai
+        {0x0094d, 0x0094d},  // Devanagari Sign Virama  ..Devanagari Sign Virama
+        {0x00951, 0x00957},  // Devanagari Stress Sign U..Devanagari Vowel Sign Uu
+        {0x00962, 0x00963},  // Devanagari Vowel Sign Vo..Devanagari Vowel Sign Vo
+        {0x00981, 0x00981},  // Bengali Sign Candrabindu..Bengali Sign Candrabindu
+        {0x009bc, 0x009bc},  // Bengali Sign Nukta      ..Bengali Sign Nukta
+        {0x009c1, 0x009c4},  // Bengali Vowel Sign U    ..Bengali Vowel Sign Vocal
+        {0x009cd, 0x009cd},  // Bengali Sign Virama     ..Bengali Sign Virama
+        {0x009e2, 0x009e3},  // Bengali Vowel Sign Vocal..Bengali Vowel Sign Vocal
+        {0x009fe, 0x009fe},  // Bengali Sandhi Mark     ..Bengali Sandhi Mark
+        {0x00a01, 0x00a02},  // Gurmukhi Sign Adak Bindi..Gurmukhi Sign Bindi
+        {0x00a3c, 0x00a3c},  // Gurmukhi Sign Nukta     ..Gurmukhi Sign Nukta
+        {0x00a41, 0x00a42},  // Gurmukhi Vowel Sign U   ..Gurmukhi Vowel Sign Uu
+        {0x00a47, 0x00a48},  // Gurmukhi Vowel Sign Ee  ..Gurmukhi Vowel Sign Ai
+        {0x00a4b, 0x00a4d},  // Gurmukhi Vowel Sign Oo  ..Gurmukhi Sign Virama
+        {0x00a51, 0x00a51},  // Gurmukhi Sign Udaat     ..Gurmukhi Sign Udaat
+        {0x00a70, 0x00a71},  // Gurmukhi Tippi          ..Gurmukhi Addak
+        {0x00a75, 0x00a75},  // Gurmukhi Sign Yakash    ..Gurmukhi Sign Yakash
+        {0x00a81, 0x00a82},  // Gujarati Sign Candrabind..Gujarati Sign Anusvara
+        {0x00abc, 0x00abc},  // Gujarati Sign Nukta     ..Gujarati Sign Nukta
+        {0x00ac1, 0x00ac5},  // Gujarati Vowel Sign U   ..Gujarati Vowel Sign Cand
+        {0x00ac7, 0x00ac8},  // Gujarati Vowel Sign E   ..Gujarati Vowel Sign Ai
+        {0x00acd, 0x00acd},  // Gujarati Sign Virama    ..Gujarati Sign Virama
+        {0x00ae2, 0x00ae3},  // Gujarati Vowel Sign Voca..Gujarati Vowel Sign Voca
+        {0x00afa, 0x00aff},  // Gujarati Sign Sukun     ..Gujarati Sign Two-circle
+        {0x00b01, 0x00b01},  // Oriya Sign Candrabindu  ..Oriya Sign Candrabindu
+        {0x00b3c, 0x00b3c},  // Oriya Sign Nukta        ..Oriya Sign Nukta
+        {0x00b3f, 0x00b3f},  // Oriya Vowel Sign I      ..Oriya Vowel Sign I
+        {0x00b41, 0x00b44},  // Oriya Vowel Sign U      ..Oriya Vowel Sign Vocalic
+        {0x00b4d, 0x00b4d},  // Oriya Sign Virama       ..Oriya Sign Virama
+        {0x00b55, 0x00b56},  // Oriya Sign Overline     ..Oriya Ai Length Mark
+        {0x00b62, 0x00b63},  // Oriya Vowel Sign Vocalic..Oriya Vowel Sign Vocalic
+        {0x00b82, 0x00b82},  // Tamil Sign Anusvara     ..Tamil Sign Anusvara
+        {0x00bc0, 0x00bc0},  // Tamil Vowel Sign Ii     ..Tamil Vowel Sign Ii
+        {0x00bcd, 0x00bcd},  // Tamil Sign Virama       ..Tamil Sign Virama
+        {0x00c00, 0x00c00},  // Telugu Sign Combining Ca..Telugu Sign Combining Ca
+        {0x00c04, 0x00c04},  // Telugu Sign Combining An..Telugu Sign Combining An
+        {0x00c3c, 0x00c3c},  // Telugu Sign Nukta       ..Telugu Sign Nukta
+        {0x00c3e, 0x00c40},  // Telugu Vowel Sign Aa    ..Telugu Vowel Sign Ii
+        {0x00c46, 0x00c48},  // Telugu Vowel Sign E     ..Telugu Vowel Sign Ai
+        {0x00c4a, 0x00c4d},  // Telugu Vowel Sign O     ..Telugu Sign Virama
+        {0x00c55, 0x00c56},  // Telugu Length Mark      ..Telugu Ai Length Mark
+        {0x00c62, 0x00c63},  // Telugu Vowel Sign Vocali..Telugu Vowel Sign Vocali
+        {0x00c81, 0x00c81},  // Kannada Sign Candrabindu..Kannada Sign Candrabindu
+        {0x00cbc, 0x00cbc},  // Kannada Sign Nukta      ..Kannada Sign Nukta
+        {0x00cbf, 0x00cbf},  // Kannada Vowel Sign I    ..Kannada Vowel Sign I
+        {0x00cc6, 0x00cc6},  // Kannada Vowel Sign E    ..Kannada Vowel Sign E
+        {0x00ccc, 0x00ccd},  // Kannada Vowel Sign Au   ..Kannada Sign Virama
+        {0x00ce2, 0x00ce3},  // Kannada Vowel Sign Vocal..Kannada Vowel Sign Vocal
+        {0x00d00, 0x00d01},  // Malayalam Sign Combining..Malayalam Sign Candrabin
+        {0x00d3b, 0x00d3c},  // Malayalam Sign Vertical ..Malayalam Sign Circular
+        {0x00d41, 0x00d44},  // Malayalam Vowel Sign U  ..Malayalam Vowel Sign Voc
+        {0x00d4d, 0x00d4d},  // Malayalam Sign Virama   ..Malayalam Sign Virama
+        {0x00d62, 0x00d63},  // Malayalam Vowel Sign Voc..Malayalam Vowel Sign Voc
+        {0x00d81, 0x00d81},  // Sinhala Sign Candrabindu..Sinhala Sign Candrabindu
+        {0x00dca, 0x00dca},  // Sinhala Sign Al-lakuna  ..Sinhala Sign Al-lakuna
+        {0x00dd2, 0x00dd4},  // Sinhala Vowel Sign Ketti..Sinhala Vowel Sign Ketti
+        {0x00dd6, 0x00dd6},  // Sinhala Vowel Sign Diga ..Sinhala Vowel Sign Diga
+        {0x00e31, 0x00e31},  // Thai Character Mai Han-a..Thai Character Mai Han-a
+        {0x00e34, 0x00e3a},  // Thai Character Sara I   ..Thai Character Phinthu
+        {0x00e47, 0x00e4e},  // Thai Character Maitaikhu..Thai Character Yamakkan
+        {0x00eb1, 0x00eb1},  // Lao Vowel Sign Mai Kan  ..Lao Vowel Sign Mai Kan
+        {0x00eb4, 0x00ebc},  // Lao Vowel Sign I        ..Lao Semivowel Sign Lo
+        {0x00ec8, 0x00ece},  // Lao Tone Mai Ek         ..(nil)
+        {0x00f18, 0x00f19},  // Tibetan Astrological Sig..Tibetan Astrological Sig
+        {0x00f35, 0x00f35},  // Tibetan Mark Ngas Bzung ..Tibetan Mark Ngas Bzung
+        {0x00f37, 0x00f37},  // Tibetan Mark Ngas Bzung ..Tibetan Mark Ngas Bzung
+        {0x00f39, 0x00f39},  // Tibetan Mark Tsa -phru  ..Tibetan Mark Tsa -phru
+        {0x00f71, 0x00f7e},  // Tibetan Vowel Sign Aa   ..Tibetan Sign Rjes Su Nga
+        {0x00f80, 0x00f84},  // Tibetan Vowel Sign Rever..Tibetan Mark Halanta
+        {0x00f86, 0x00f87},  // Tibetan Sign Lci Rtags  ..Tibetan Sign Yang Rtags
+        {0x00f8d, 0x00f97},  // Tibetan Subjoined Sign L..Tibetan Subjoined Letter
+        {0x00f99, 0x00fbc},  // Tibetan Subjoined Letter..Tibetan Subjoined Letter
+        {0x00fc6, 0x00fc6},  // Tibetan Symbol Padma Gda..Tibetan Symbol Padma Gda
+        {0x0102d, 0x01030},  // Myanmar Vowel Sign I    ..Myanmar Vowel Sign Uu
+        {0x01032, 0x01037},  // Myanmar Vowel Sign Ai   ..Myanmar Sign Dot Below
+        {0x01039, 0x0103a},  // Myanmar Sign Virama     ..Myanmar Sign Asat
+        {0x0103d, 0x0103e},  // Myanmar Consonant Sign M..Myanmar Consonant Sign M
+        {0x01058, 0x01059},  // Myanmar Vowel Sign Vocal..Myanmar Vowel Sign Vocal
+        {0x0105e, 0x01060},  // Myanmar Consonant Sign M..Myanmar Consonant Sign M
+        {0x01071, 0x01074},  // Myanmar Vowel Sign Geba ..Myanmar Vowel Sign Kayah
+        {0x01082, 0x01082},  // Myanmar Consonant Sign S..Myanmar Consonant Sign S
+        {0x01085, 0x01086},  // Myanmar Vowel Sign Shan ..Myanmar Vowel Sign Shan
+        {0x0108d, 0x0108d},  // Myanmar Sign Shan Counci..Myanmar Sign Shan Counci
+        {0x0109d, 0x0109d},  // Myanmar Vowel Sign Aiton..Myanmar Vowel Sign Aiton
+        {0x0135d, 0x0135f},  // Ethiopic Combining Gemin..Ethiopic Combining Gemin
+        {0x01712, 0x01714},  // Tagalog Vowel Sign I    ..Tagalog Sign Virama
+        {0x01732, 0x01733},  // Hanunoo Vowel Sign I    ..Hanunoo Vowel Sign U
+        {0x01752, 0x01753},  // Buhid Vowel Sign I      ..Buhid Vowel Sign U
+        {0x01772, 0x01773},  // Tagbanwa Vowel Sign I   ..Tagbanwa Vowel Sign U
+        {0x017b4, 0x017b5},  // Khmer Vowel Inherent Aq ..Khmer Vowel Inherent Aa
+        {0x017b7, 0x017bd},  // Khmer Vowel Sign I      ..Khmer Vowel Sign Ua
+        {0x017c6, 0x017c6},  // Khmer Sign Nikahit      ..Khmer Sign Nikahit
+        {0x017c9, 0x017d3},  // Khmer Sign Muusikatoan  ..Khmer Sign Bathamasat
+        {0x017dd, 0x017dd},  // Khmer Sign Atthacan     ..Khmer Sign Atthacan
+        {0x0180b, 0x0180d},  // Mongolian Free Variation..Mongolian Free Variation
+        {0x0180f, 0x0180f},  // Mongolian Free Variation..Mongolian Free Variation
+        {0x01885, 0x01886},  // Mongolian Letter Ali Gal..Mongolian Letter Ali Gal
+        {0x018a9, 0x018a9},  // Mongolian Letter Ali Gal..Mongolian Letter Ali Gal
+        {0x01920, 0x01922},  // Limbu Vowel Sign A      ..Limbu Vowel Sign U
+        {0x01927, 0x01928},  // Limbu Vowel Sign E      ..Limbu Vowel Sign O
+        {0x01932, 0x01932},  // Limbu Small Letter Anusv..Limbu Small Letter Anusv
+        {0x01939, 0x0193b},  // Limbu Sign Mukphreng    ..Limbu Sign Sa-i
+        {0x01a17, 0x01a18},  // Buginese Vowel Sign I   ..Buginese Vowel Sign U
+        {0x01a1b, 0x01a1b},  // Buginese Vowel Sign Ae  ..Buginese Vowel Sign Ae
+        {0x01a56, 0x01a56},  // Tai Tham Consonant Sign ..Tai Tham Consonant Sign
+        {0x01a58, 0x01a5e},  // Tai Tham Sign Mai Kang L..Tai Tham Consonant Sign
+        {0x01a60, 0x01a60},  // Tai Tham Sign Sakot     ..Tai Tham Sign Sakot
+        {0x01a62, 0x01a62},  // Tai Tham Vowel Sign Mai ..Tai Tham Vowel Sign Mai
+        {0x01a65, 0x01a6c},  // Tai Tham Vowel Sign I   ..Tai Tham Vowel Sign Oa B
+        {0x01a73, 0x01a7c},  // Tai Tham Vowel Sign Oa A..Tai Tham Sign Khuen-lue
+        {0x01a7f, 0x01a7f},  // Tai Tham Combining Crypt..Tai Tham Combining Crypt
+        {0x01ab0, 0x01ace},  // Combining Doubled Circum..Combining Latin Small Le
+        {0x01b00, 0x01b03},  // Balinese Sign Ulu Ricem ..Balinese Sign Surang
+        {0x01b34, 0x01b34},  // Balinese Sign Rerekan   ..Balinese Sign Rerekan
+        {0x01b36, 0x01b3a},  // Balinese Vowel Sign Ulu ..Balinese Vowel Sign Ra R
+        {0x01b3c, 0x01b3c},  // Balinese Vowel Sign La L..Balinese Vowel Sign La L
+        {0x01b42, 0x01b42},  // Balinese Vowel Sign Pepe..Balinese Vowel Sign Pepe
+        {0x01b6b, 0x01b73},  // Balinese Musical Symbol ..Balinese Musical Symbol
+        {0x01b80, 0x01b81},  // Sundanese Sign Panyecek ..Sundanese Sign Panglayar
+        {0x01ba2, 0x01ba5},  // Sundanese Consonant Sign..Sundanese Vowel Sign Pan
+        {0x01ba8, 0x01ba9},  // Sundanese Vowel Sign Pam..Sundanese Vowel Sign Pan
+        {0x01bab, 0x01bad},  // Sundanese Sign Virama   ..Sundanese Consonant Sign
+        {0x01be6, 0x01be6},  // Batak Sign Tompi        ..Batak Sign Tompi
+        {0x01be8, 0x01be9},  // Batak Vowel Sign Pakpak ..Batak Vowel Sign Ee
+        {0x01bed, 0x01bed},  // Batak Vowel Sign Karo O ..Batak Vowel Sign Karo O
+        {0x01bef, 0x01bf1},  // Batak Vowel Sign U For S..Batak Consonant Sign H
+        {0x01c2c, 0x01c33},  // Lepcha Vowel Sign E     ..Lepcha Consonant Sign T
+        {0x01c36, 0x01c37},  // Lepcha Sign Ran         ..Lepcha Sign Nukta
+        {0x01cd0, 0x01cd2},  // Vedic Tone Karshana     ..Vedic Tone Prenkha
+        {0x01cd4, 0x01ce0},  // Vedic Sign Yajurvedic Mi..Vedic Tone Rigvedic Kash
+        {0x01ce2, 0x01ce8},  // Vedic Sign Visarga Svari..Vedic Sign Visarga Anuda
+        {0x01ced, 0x01ced},  // Vedic Sign Tiryak       ..Vedic Sign Tiryak
+        {0x01cf4, 0x01cf4},  // Vedic Tone Candra Above ..Vedic Tone Candra Above
+        {0x01cf8, 0x01cf9},  // Vedic Tone Ring Above   ..Vedic Tone Double Ring A
+        {0x01dc0, 0x01dff},  // Combining Dotted Grave A..Combining Right Arrowhea
+        {0x020d0, 0x020f0},  // Combining Left Harpoon A..Combining Asterisk Above
+        {0x02cef, 0x02cf1},  // Coptic Combining Ni Abov..Coptic Combining Spiritu
+        {0x02d7f, 0x02d7f},  // Tifinagh Consonant Joine..Tifinagh Consonant Joine
+        {0x02de0, 0x02dff},  // Combining Cyrillic Lette..Combining Cyrillic Lette
+        {0x0302a, 0x0302d},  // Ideographic Level Tone M..Ideographic Entering Ton
+        {0x03099, 0x0309a},  // Combining Katakana-hirag..Combining Katakana-hirag
+        {0x0a66f, 0x0a672},  // Combining Cyrillic Vzmet..Combining Cyrillic Thous
+        {0x0a674, 0x0a67d},  // Combining Cyrillic Lette..Combining Cyrillic Payer
+        {0x0a69e, 0x0a69f},  // Combining Cyrillic Lette..Combining Cyrillic Lette
+        {0x0a6f0, 0x0a6f1},  // Bamum Combining Mark Koq..Bamum Combining Mark Tuk
+        {0x0a802, 0x0a802},  // Syloti Nagri Sign Dvisva..Syloti Nagri Sign Dvisva
+        {0x0a806, 0x0a806},  // Syloti Nagri Sign Hasant..Syloti Nagri Sign Hasant
+        {0x0a80b, 0x0a80b},  // Syloti Nagri Sign Anusva..Syloti Nagri Sign Anusva
+        {0x0a825, 0x0a826},  // Syloti Nagri Vowel Sign ..Syloti Nagri Vowel Sign
+        {0x0a82c, 0x0a82c},  // Syloti Nagri Sign Altern..Syloti Nagri Sign Altern
+        {0x0a8c4, 0x0a8c5},  // Saurashtra Sign Virama  ..Saurashtra Sign Candrabi
+        {0x0a8e0, 0x0a8f1},  // Combining Devanagari Dig..Combining Devanagari Sig
+        {0x0a8ff, 0x0a8ff},  // Devanagari Vowel Sign Ay..Devanagari Vowel Sign Ay
+        {0x0a926, 0x0a92d},  // Kayah Li Vowel Ue       ..Kayah Li Tone Calya Plop
+        {0x0a947, 0x0a951},  // Rejang Vowel Sign I     ..Rejang Consonant Sign R
+        {0x0a980, 0x0a982},  // Javanese Sign Panyangga ..Javanese Sign Layar
+        {0x0a9b3, 0x0a9b3},  // Javanese Sign Cecak Telu..Javanese Sign Cecak Telu
+        {0x0a9b6, 0x0a9b9},  // Javanese Vowel Sign Wulu..Javanese Vowel Sign Suku
+        {0x0a9bc, 0x0a9bd},  // Javanese Vowel Sign Pepe..Javanese Consonant Sign
+        {0x0a9e5, 0x0a9e5},  // Myanmar Sign Shan Saw   ..Myanmar Sign Shan Saw
+        {0x0aa29, 0x0aa2e},  // Cham Vowel Sign Aa      ..Cham Vowel Sign Oe
+        {0x0aa31, 0x0aa32},  // Cham Vowel Sign Au      ..Cham Vowel Sign Ue
+        {0x0aa35, 0x0aa36},  // Cham Consonant Sign La  ..Cham Consonant Sign Wa
+        {0x0aa43, 0x0aa43},  // Cham Consonant Sign Fina..Cham Consonant Sign Fina
+        {0x0aa4c, 0x0aa4c},  // Cham Consonant Sign Fina..Cham Consonant Sign Fina
+        {0x0aa7c, 0x0aa7c},  // Myanmar Sign Tai Laing T..Myanmar Sign Tai Laing T
+        {0x0aab0, 0x0aab0},  // Tai Viet Mai Kang       ..Tai Viet Mai Kang
+        {0x0aab2, 0x0aab4},  // Tai Viet Vowel I        ..Tai Viet Vowel U
+        {0x0aab7, 0x0aab8},  // Tai Viet Mai Khit       ..Tai Viet Vowel Ia
+        {0x0aabe, 0x0aabf},  // Tai Viet Vowel Am       ..Tai Viet Tone Mai Ek
+        {0x0aac1, 0x0aac1},  // Tai Viet Tone Mai Tho   ..Tai Viet Tone Mai Tho
+        {0x0aaec, 0x0aaed},  // Meetei Mayek Vowel Sign ..Meetei Mayek Vowel Sign
+        {0x0aaf6, 0x0aaf6},  // Meetei Mayek Virama     ..Meetei Mayek Virama
+        {0x0abe5, 0x0abe5},  // Meetei Mayek Vowel Sign ..Meetei Mayek Vowel Sign
+        {0x0abe8, 0x0abe8},  // Meetei Mayek Vowel Sign ..Meetei Mayek Vowel Sign
+        {0x0abed, 0x0abed},  // Meetei Mayek Apun Iyek  ..Meetei Mayek Apun Iyek
+        {0x0fb1e, 0x0fb1e},  // Hebrew Point Judeo-spani..Hebrew Point Judeo-spani
+        {0x0fe00, 0x0fe0f},  // Variation Selector-1    ..Variation Selector-16
+        {0x0fe20, 0x0fe2f},  // Combining Ligature Left ..Combining Cyrillic Titlo
+        {0x101fd, 0x101fd},  // Phaistos Disc Sign Combi..Phaistos Disc Sign Combi
+        {0x102e0, 0x102e0},  // Coptic Epact Thousands M..Coptic Epact Thousands M
+        {0x10376, 0x1037a},  // Combining Old Permic Let..Combining Old Permic Let
+        {0x10a01, 0x10a03},  // Kharoshthi Vowel Sign I ..Kharoshthi Vowel Sign Vo
+        {0x10a05, 0x10a06},  // Kharoshthi Vowel Sign E ..Kharoshthi Vowel Sign O
+        {0x10a0c, 0x10a0f},  // Kharoshthi Vowel Length ..Kharoshthi Sign Visarga
+        {0x10a38, 0x10a3a},  // Kharoshthi Sign Bar Abov..Kharoshthi Sign Dot Belo
+        {0x10a3f, 0x10a3f},  // Kharoshthi Virama       ..Kharoshthi Virama
+        {0x10ae5, 0x10ae6},  // Manichaean Abbreviation ..Manichaean Abbreviation
+        {0x10d24, 0x10d27},  // Hanifi Rohingya Sign Har..Hanifi Rohingya Sign Tas
+        {0x10eab, 0x10eac},  // Yezidi Combining Hamza M..Yezidi Combining Madda M
+        {0x10efd, 0x10eff},  // (nil)                   ..(nil)
+        {0x10f46, 0x10f50},  // Sogdian Combining Dot Be..Sogdian Combining Stroke
+        {0x10f82, 0x10f85},  // Old Uyghur Combining Dot..Old Uyghur Combining Two
+        {0x11001, 0x11001},  // Brahmi Sign Anusvara    ..Brahmi Sign Anusvara
+        {0x11038, 0x11046},  // Brahmi Vowel Sign Aa    ..Brahmi Virama
+        {0x11070, 0x11070},  // Brahmi Sign Old Tamil Vi..Brahmi Sign Old Tamil Vi
+        {0x11073, 0x11074},  // Brahmi Vowel Sign Old Ta..Brahmi Vowel Sign Old Ta
+        {0x1107f, 0x11081},  // Brahmi Number Joiner    ..Kaithi Sign Anusvara
+        {0x110b3, 0x110b6},  // Kaithi Vowel Sign U     ..Kaithi Vowel Sign Ai
+        {0x110b9, 0x110ba},  // Kaithi Sign Virama      ..Kaithi Sign Nukta
+        {0x110c2, 0x110c2},  // Kaithi Vowel Sign Vocali..Kaithi Vowel Sign Vocali
+        {0x11100, 0x11102},  // Chakma Sign Candrabindu ..Chakma Sign Visarga
+        {0x11127, 0x1112b},  // Chakma Vowel Sign A     ..Chakma Vowel Sign Uu
+        {0x1112d, 0x11134},  // Chakma Vowel Sign Ai    ..Chakma Maayyaa
+        {0x11173, 0x11173},  // Mahajani Sign Nukta     ..Mahajani Sign Nukta
+        {0x11180, 0x11181},  // Sharada Sign Candrabindu..Sharada Sign Anusvara
+        {0x111b6, 0x111be},  // Sharada Vowel Sign U    ..Sharada Vowel Sign O
+        {0x111c9, 0x111cc},  // Sharada Sandhi Mark     ..Sharada Extra Short Vowe
+        {0x111cf, 0x111cf},  // Sharada Sign Inverted Ca..Sharada Sign Inverted Ca
+        {0x1122f, 0x11231},  // Khojki Vowel Sign U     ..Khojki Vowel Sign Ai
+        {0x11234, 0x11234},  // Khojki Sign Anusvara    ..Khojki Sign Anusvara
+        {0x11236, 0x11237},  // Khojki Sign Nukta       ..Khojki Sign Shadda
+        {0x1123e, 0x1123e},  // Khojki Sign Sukun       ..Khojki Sign Sukun
+        {0x11241, 0x11241},  // (nil)                   ..(nil)
+        {0x112df, 0x112df},  // Khudawadi Sign Anusvara ..Khudawadi Sign Anusvara
+        {0x112e3, 0x112ea},  // Khudawadi Vowel Sign U  ..Khudawadi Sign Virama
+        {0x11300, 0x11301},  // Grantha Sign Combining A..Grantha Sign Candrabindu
+        {0x1133b, 0x1133c},  // Combining Bindu Below   ..Grantha Sign Nukta
+        {0x11340, 0x11340},  // Grantha Vowel Sign Ii   ..Grantha Vowel Sign Ii
+        {0x11366, 0x1136c},  // Combining Grantha Digit ..Combining Grantha Digit
+        {0x11370, 0x11374},  // Combining Grantha Letter..Combining Grantha Letter
+        {0x11438, 0x1143f},  // Newa Vowel Sign U       ..Newa Vowel Sign Ai
+        {0x11442, 0x11444},  // Newa Sign Virama        ..Newa Sign Anusvara
+        {0x11446, 0x11446},  // Newa Sign Nukta         ..Newa Sign Nukta
+        {0x1145e, 0x1145e},  // Newa Sandhi Mark        ..Newa Sandhi Mark
+        {0x114b3, 0x114b8},  // Tirhuta Vowel Sign U    ..Tirhuta Vowel Sign Vocal
+        {0x114ba, 0x114ba},  // Tirhuta Vowel Sign Short..Tirhuta Vowel Sign Short
+        {0x114bf, 0x114c0},  // Tirhuta Sign Candrabindu..Tirhuta Sign Anusvara
+        {0x114c2, 0x114c3},  // Tirhuta Sign Virama     ..Tirhuta Sign Nukta
+        {0x115b2, 0x115b5},  // Siddham Vowel Sign U    ..Siddham Vowel Sign Vocal
+        {0x115bc, 0x115bd},  // Siddham Sign Candrabindu..Siddham Sign Anusvara
+        {0x115bf, 0x115c0},  // Siddham Sign Virama     ..Siddham Sign Nukta
+        {0x115dc, 0x115dd},  // Siddham Vowel Sign Alter..Siddham Vowel Sign Alter
+        {0x11633, 0x1163a},  // Modi Vowel Sign U       ..Modi Vowel Sign Ai
+        {0x1163d, 0x1163d},  // Modi Sign Anusvara      ..Modi Sign Anusvara
+        {0x1163f, 0x11640},  // Modi Sign Virama        ..Modi Sign Ardhacandra
+        {0x116ab, 0x116ab},  // Takri Sign Anusvara     ..Takri Sign Anusvara
+        {0x116ad, 0x116ad},  // Takri Vowel Sign Aa     ..Takri Vowel Sign Aa
+        {0x116b0, 0x116b5},  // Takri Vowel Sign U      ..Takri Vowel Sign Au
+        {0x116b7, 0x116b7},  // Takri Sign Nukta        ..Takri Sign Nukta
+        {0x1171d, 0x1171f},  // Ahom Consonant Sign Medi..Ahom Consonant Sign Medi
+        {0x11722, 0x11725},  // Ahom Vowel Sign I       ..Ahom Vowel Sign Uu
+        {0x11727, 0x1172b},  // Ahom Vowel Sign Aw      ..Ahom Sign Killer
+        {0x1182f, 0x11837},  // Dogra Vowel Sign U      ..Dogra Sign Anusvara
+        {0x11839, 0x1183a},  // Dogra Sign Virama       ..Dogra Sign Nukta
+        {0x1193b, 0x1193c},  // Dives Akuru Sign Anusvar..Dives Akuru Sign Candrab
+        {0x1193e, 0x1193e},  // Dives Akuru Virama      ..Dives Akuru Virama
+        {0x11943, 0x11943},  // Dives Akuru Sign Nukta  ..Dives Akuru Sign Nukta
+        {0x119d4, 0x119d7},  // Nandinagari Vowel Sign U..Nandinagari Vowel Sign V
+        {0x119da, 0x119db},  // Nandinagari Vowel Sign E..Nandinagari Vowel Sign A
+        {0x119e0, 0x119e0},  // Nandinagari Sign Virama ..Nandinagari Sign Virama
+        {0x11a01, 0x11a0a},  // Zanabazar Square Vowel S..Zanabazar Square Vowel L
+        {0x11a33, 0x11a38},  // Zanabazar Square Final C..Zanabazar Square Sign An
+        {0x11a3b, 0x11a3e},  // Zanabazar Square Cluster..Zanabazar Square Cluster
+        {0x11a47, 0x11a47},  // Zanabazar Square Subjoin..Zanabazar Square Subjoin
+        {0x11a51, 0x11a56},  // Soyombo Vowel Sign I    ..Soyombo Vowel Sign Oe
+        {0x11a59, 0x11a5b},  // Soyombo Vowel Sign Vocal..Soyombo Vowel Length Mar
+        {0x11a8a, 0x11a96},  // Soyombo Final Consonant ..Soyombo Sign Anusvara
+        {0x11a98, 0x11a99},  // Soyombo Gemination Mark ..Soyombo Subjoiner
+        {0x11c30, 0x11c36},  // Bhaiksuki Vowel Sign I  ..Bhaiksuki Vowel Sign Voc
+        {0x11c38, 0x11c3d},  // Bhaiksuki Vowel Sign E  ..Bhaiksuki Sign Anusvara
+        {0x11c3f, 0x11c3f},  // Bhaiksuki Sign Virama   ..Bhaiksuki Sign Virama
+        {0x11c92, 0x11ca7},  // Marchen Subjoined Letter..Marchen Subjoined Letter
+        {0x11caa, 0x11cb0},  // Marchen Subjoined Letter..Marchen Vowel Sign Aa
+        {0x11cb2, 0x11cb3},  // Marchen Vowel Sign U    ..Marchen Vowel Sign E
+        {0x11cb5, 0x11cb6},  // Marchen Sign Anusvara   ..Marchen Sign Candrabindu
+        {0x11d31, 0x11d36},  // Masaram Gondi Vowel Sign..Masaram Gondi Vowel Sign
+        {0x11d3a, 0x11d3a},  // Masaram Gondi Vowel Sign..Masaram Gondi Vowel Sign
+        {0x11d3c, 0x11d3d},  // Masaram Gondi Vowel Sign..Masaram Gondi Vowel Sign
+        {0x11d3f, 0x11d45},  // Masaram Gondi Vowel Sign..Masaram Gondi Virama
+        {0x11d47, 0x11d47},  // Masaram Gondi Ra-kara   ..Masaram Gondi Ra-kara
+        {0x11d90, 0x11d91},  // Gunjala Gondi Vowel Sign..Gunjala Gondi Vowel Sign
+        {0x11d95, 0x11d95},  // Gunjala Gondi Sign Anusv..Gunjala Gondi Sign Anusv
+        {0x11d97, 0x11d97},  // Gunjala Gondi Virama    ..Gunjala Gondi Virama
+        {0x11ef3, 0x11ef4},  // Makasar Vowel Sign I    ..Makasar Vowel Sign U
+        {0x11f00, 0x11f01},  // (nil)                   ..(nil)
+        {0x11f36, 0x11f3a},  // (nil)                   ..(nil)
+        {0x11f40, 0x11f40},  // (nil)                   ..(nil)
+        {0x11f42, 0x11f42},  // (nil)                   ..(nil)
+        {0x13440, 0x13440},  // (nil)                   ..(nil)
+        {0x13447, 0x13455},  // (nil)                   ..(nil)
+        {0x16af0, 0x16af4},  // Bassa Vah Combining High..Bassa Vah Combining High
+        {0x16b30, 0x16b36},  // Pahawh Hmong Mark Cim Tu..Pahawh Hmong Mark Cim Ta
+        {0x16f4f, 0x16f4f},  // Miao Sign Consonant Modi..Miao Sign Consonant Modi
+        {0x16f8f, 0x16f92},  // Miao Tone Right         ..Miao Tone Below
+        {0x16fe4, 0x16fe4},  // Khitan Small Script Fill..Khitan Small Script Fill
+        {0x1bc9d, 0x1bc9e},  // Duployan Thick Letter Se..Duployan Double Mark
+        {0x1cf00, 0x1cf2d},  // Znamenny Combining Mark ..Znamenny Combining Mark
+        {0x1cf30, 0x1cf46},  // Znamenny Combining Tonal..Znamenny Priznak Modifie
+        {0x1d167, 0x1d169},  // Musical Symbol Combining..Musical Symbol Combining
+        {0x1d17b, 0x1d182},  // Musical Symbol Combining..Musical Symbol Combining
+        {0x1d185, 0x1d18b},  // Musical Symbol Combining..Musical Symbol Combining
+        {0x1d1aa, 0x1d1ad},  // Musical Symbol Combining..Musical Symbol Combining
+        {0x1d242, 0x1d244},  // Combining Greek Musical ..Combining Greek Musical
+        {0x1da00, 0x1da36},  // Signwriting Head Rim    ..Signwriting Air Sucking
+        {0x1da3b, 0x1da6c},  // Signwriting Mouth Closed..Signwriting Excitement
+        {0x1da75, 0x1da75},  // Signwriting Upper Body T..Signwriting Upper Body T
+        {0x1da84, 0x1da84},  // Signwriting Location Hea..Signwriting Location Hea
+        {0x1da9b, 0x1da9f},  // Signwriting Fill Modifie..Signwriting Fill Modifie
+        {0x1daa1, 0x1daaf},  // Signwriting Rotation Mod..Signwriting Rotation Mod
+        {0x1e000, 0x1e006},  // Combining Glagolitic Let..Combining Glagolitic Let
+        {0x1e008, 0x1e018},  // Combining Glagolitic Let..Combining Glagolitic Let
+        {0x1e01b, 0x1e021},  // Combining Glagolitic Let..Combining Glagolitic Let
+        {0x1e023, 0x1e024},  // Combining Glagolitic Let..Combining Glagolitic Let
+        {0x1e026, 0x1e02a},  // Combining Glagolitic Let..Combining Glagolitic Let
+        {0x1e08f, 0x1e08f},  // (nil)                   ..(nil)
+        {0x1e130, 0x1e136},  // Nyiakeng Puachue Hmong T..Nyiakeng Puachue Hmong T
+        {0x1e2ae, 0x1e2ae},  // Toto Sign Rising Tone   ..Toto Sign Rising Tone
+        {0x1e2ec, 0x1e2ef},  // Wancho Tone Tup         ..Wancho Tone Koini
+        {0x1e4ec, 0x1e4ef},  // (nil)                   ..(nil)
+        {0x1e8d0, 0x1e8d6},  // Mende Kikakui Combining ..Mende Kikakui Combining
+        {0x1e944, 0x1e94a},  // Adlam Alif Lengthener   ..Adlam Nukta
+        {0xe0100, 0xe01ef},  // Variation Selector-17   ..Variation Selector-256
+    };
+
+    // https://github.com/jquast/wcwidth/blob/master/wcwidth/table_wide.py
+    // from https://github.com/jquast/wcwidth/pull/64
+    // at commit 1b9b6585b0080ea5cb88dc9815796505724793fe (2022-12-16):
+    private static final int[][] WIDE_EASTASIAN = {
+        {0x01100, 0x0115f},  // Hangul Choseong Kiyeok  ..Hangul Choseong Filler
+        {0x0231a, 0x0231b},  // Watch                   ..Hourglass
+        {0x02329, 0x0232a},  // Left-pointing Angle Brac..Right-pointing Angle Bra
+        {0x023e9, 0x023ec},  // Black Right-pointing Dou..Black Down-pointing Doub
+        {0x023f0, 0x023f0},  // Alarm Clock             ..Alarm Clock
+        {0x023f3, 0x023f3},  // Hourglass With Flowing S..Hourglass With Flowing S
+        {0x025fd, 0x025fe},  // White Medium Small Squar..Black Medium Small Squar
+        {0x02614, 0x02615},  // Umbrella With Rain Drops..Hot Beverage
+        {0x02648, 0x02653},  // Aries                   ..Pisces
+        {0x0267f, 0x0267f},  // Wheelchair Symbol       ..Wheelchair Symbol
+        {0x02693, 0x02693},  // Anchor                  ..Anchor
+        {0x026a1, 0x026a1},  // High Voltage Sign       ..High Voltage Sign
+        {0x026aa, 0x026ab},  // Medium White Circle     ..Medium Black Circle
+        {0x026bd, 0x026be},  // Soccer Ball             ..Baseball
+        {0x026c4, 0x026c5},  // Snowman Without Snow    ..Sun Behind Cloud
+        {0x026ce, 0x026ce},  // Ophiuchus               ..Ophiuchus
+        {0x026d4, 0x026d4},  // No Entry                ..No Entry
+        {0x026ea, 0x026ea},  // Church                  ..Church
+        {0x026f2, 0x026f3},  // Fountain                ..Flag In Hole
+        {0x026f5, 0x026f5},  // Sailboat                ..Sailboat
+        {0x026fa, 0x026fa},  // Tent                    ..Tent
+        {0x026fd, 0x026fd},  // Fuel Pump               ..Fuel Pump
+        {0x02705, 0x02705},  // White Heavy Check Mark  ..White Heavy Check Mark
+        {0x0270a, 0x0270b},  // Raised Fist             ..Raised Hand
+        {0x02728, 0x02728},  // Sparkles                ..Sparkles
+        {0x0274c, 0x0274c},  // Cross Mark              ..Cross Mark
+        {0x0274e, 0x0274e},  // Negative Squared Cross M..Negative Squared Cross M
+        {0x02753, 0x02755},  // Black Question Mark Orna..White Exclamation Mark O
+        {0x02757, 0x02757},  // Heavy Exclamation Mark S..Heavy Exclamation Mark S
+        {0x02795, 0x02797},  // Heavy Plus Sign         ..Heavy Division Sign
+        {0x027b0, 0x027b0},  // Curly Loop              ..Curly Loop
+        {0x027bf, 0x027bf},  // Double Curly Loop       ..Double Curly Loop
+        {0x02b1b, 0x02b1c},  // Black Large Square      ..White Large Square
+        {0x02b50, 0x02b50},  // White Medium Star       ..White Medium Star
+        {0x02b55, 0x02b55},  // Heavy Large Circle      ..Heavy Large Circle
+        {0x02e80, 0x02e99},  // Cjk Radical Repeat      ..Cjk Radical Rap
+        {0x02e9b, 0x02ef3},  // Cjk Radical Choke       ..Cjk Radical C-simplified
+        {0x02f00, 0x02fd5},  // Kangxi Radical One      ..Kangxi Radical Flute
+        {0x02ff0, 0x02ffb},  // Ideographic Description ..Ideographic Description
+        {0x03000, 0x0303e},  // Ideographic Space       ..Ideographic Variation In
+        {0x03041, 0x03096},  // Hiragana Letter Small A ..Hiragana Letter Small Ke
+        {0x03099, 0x030ff},  // Combining Katakana-hirag..Katakana Digraph Koto
+        {0x03105, 0x0312f},  // Bopomofo Letter B       ..Bopomofo Letter Nn
+        {0x03131, 0x0318e},  // Hangul Letter Kiyeok    ..Hangul Letter Araeae
+        {0x03190, 0x031e3},  // Ideographic Annotation L..Cjk Stroke Q
+        {0x031f0, 0x0321e},  // Katakana Letter Small Ku..Parenthesized Korean Cha
+        {0x03220, 0x03247},  // Parenthesized Ideograph ..Circled Ideograph Koto
+        {0x03250, 0x04dbf},  // Partnership Sign        ..Cjk Unified Ideograph-4d
+        {0x04e00, 0x0a48c},  // Cjk Unified Ideograph-4e..Yi Syllable Yyr
+        {0x0a490, 0x0a4c6},  // Yi Radical Qot          ..Yi Radical Ke
+        {0x0a960, 0x0a97c},  // Hangul Choseong Tikeut-m..Hangul Choseong Ssangyeo
+        {0x0ac00, 0x0d7a3},  // Hangul Syllable Ga      ..Hangul Syllable Hih
+        {0x0f900, 0x0faff},  // Cjk Compatibility Ideogr..(nil)
+        {0x0fe10, 0x0fe19},  // Presentation Form For Ve..Presentation Form For Ve
+        {0x0fe30, 0x0fe52},  // Presentation Form For Ve..Small Full Stop
+        {0x0fe54, 0x0fe66},  // Small Semicolon         ..Small Equals Sign
+        {0x0fe68, 0x0fe6b},  // Small Reverse Solidus   ..Small Commercial At
+        {0x0ff01, 0x0ff60},  // Fullwidth Exclamation Ma..Fullwidth Right White Pa
+        {0x0ffe0, 0x0ffe6},  // Fullwidth Cent Sign     ..Fullwidth Won Sign
+        {0x16fe0, 0x16fe4},  // Tangut Iteration Mark   ..Khitan Small Script Fill
+        {0x16ff0, 0x16ff1},  // Vietnamese Alternate Rea..Vietnamese Alternate Rea
+        {0x17000, 0x187f7},  // (nil)                   ..(nil)
+        {0x18800, 0x18cd5},  // Tangut Component-001    ..Khitan Small Script Char
+        {0x18d00, 0x18d08},  // (nil)                   ..(nil)
+        {0x1aff0, 0x1aff3},  // Katakana Letter Minnan T..Katakana Letter Minnan T
+        {0x1aff5, 0x1affb},  // Katakana Letter Minnan T..Katakana Letter Minnan N
+        {0x1affd, 0x1affe},  // Katakana Letter Minnan N..Katakana Letter Minnan N
+        {0x1b000, 0x1b122},  // Katakana Letter Archaic ..Katakana Letter Archaic
+        {0x1b132, 0x1b132},  // (nil)                   ..(nil)
+        {0x1b150, 0x1b152},  // Hiragana Letter Small Wi..Hiragana Letter Small Wo
+        {0x1b155, 0x1b155},  // (nil)                   ..(nil)
+        {0x1b164, 0x1b167},  // Katakana Letter Small Wi..Katakana Letter Small N
+        {0x1b170, 0x1b2fb},  // Nushu Character-1b170   ..Nushu Character-1b2fb
+        {0x1f004, 0x1f004},  // Mahjong Tile Red Dragon ..Mahjong Tile Red Dragon
+        {0x1f0cf, 0x1f0cf},  // Playing Card Black Joker..Playing Card Black Joker
+        {0x1f18e, 0x1f18e},  // Negative Squared Ab     ..Negative Squared Ab
+        {0x1f191, 0x1f19a},  // Squared Cl              ..Squared Vs
+        {0x1f200, 0x1f202},  // Square Hiragana Hoka    ..Squared Katakana Sa
+        {0x1f210, 0x1f23b},  // Squared Cjk Unified Ideo..Squared Cjk Unified Ideo
+        {0x1f240, 0x1f248},  // Tortoise Shell Bracketed..Tortoise Shell Bracketed
+        {0x1f250, 0x1f251},  // Circled Ideograph Advant..Circled Ideograph Accept
+        {0x1f260, 0x1f265},  // Rounded Symbol For Fu   ..Rounded Symbol For Cai
+        {0x1f300, 0x1f320},  // Cyclone                 ..Shooting Star
+        {0x1f32d, 0x1f335},  // Hot Dog                 ..Cactus
+        {0x1f337, 0x1f37c},  // Tulip                   ..Baby Bottle
+        {0x1f37e, 0x1f393},  // Bottle With Popping Cork..Graduation Cap
+        {0x1f3a0, 0x1f3ca},  // Carousel Horse          ..Swimmer
+        {0x1f3cf, 0x1f3d3},  // Cricket Bat And Ball    ..Table Tennis Paddle And
+        {0x1f3e0, 0x1f3f0},  // House Building          ..European Castle
+        {0x1f3f4, 0x1f3f4},  // Waving Black Flag       ..Waving Black Flag
+        {0x1f3f8, 0x1f43e},  // Badminton Racquet And Sh..Paw Prints
+        {0x1f440, 0x1f440},  // Eyes                    ..Eyes
+        {0x1f442, 0x1f4fc},  // Ear                     ..Videocassette
+        {0x1f4ff, 0x1f53d},  // Prayer Beads            ..Down-pointing Small Red
+        {0x1f54b, 0x1f54e},  // Kaaba                   ..Menorah With Nine Branch
+        {0x1f550, 0x1f567},  // Clock Face One Oclock   ..Clock Face Twelve-thirty
+        {0x1f57a, 0x1f57a},  // Man Dancing             ..Man Dancing
+        {0x1f595, 0x1f596},  // Reversed Hand With Middl..Raised Hand With Part Be
+        {0x1f5a4, 0x1f5a4},  // Black Heart             ..Black Heart
+        {0x1f5fb, 0x1f64f},  // Mount Fuji              ..Person With Folded Hands
+        {0x1f680, 0x1f6c5},  // Rocket                  ..Left Luggage
+        {0x1f6cc, 0x1f6cc},  // Sleeping Accommodation  ..Sleeping Accommodation
+        {0x1f6d0, 0x1f6d2},  // Place Of Worship        ..Shopping Trolley
+        {0x1f6d5, 0x1f6d7},  // Hindu Temple            ..Elevator
+        {0x1f6dc, 0x1f6df},  // (nil)                   ..Ring Buoy
+        {0x1f6eb, 0x1f6ec},  // Airplane Departure      ..Airplane Arriving
+        {0x1f6f4, 0x1f6fc},  // Scooter                 ..Roller Skate
+        {0x1f7e0, 0x1f7eb},  // Large Orange Circle     ..Large Brown Square
+        {0x1f7f0, 0x1f7f0},  // Heavy Equals Sign       ..Heavy Equals Sign
+        {0x1f90c, 0x1f93a},  // Pinched Fingers         ..Fencer
+        {0x1f93c, 0x1f945},  // Wrestlers               ..Goal Net
+        {0x1f947, 0x1f9ff},  // First Place Medal       ..Nazar Amulet
+        {0x1fa70, 0x1fa7c},  // Ballet Shoes            ..Crutch
+        {0x1fa80, 0x1fa88},  // Yo-yo                   ..(nil)
+        {0x1fa90, 0x1fabd},  // Ringed Planet           ..(nil)
+        {0x1fabf, 0x1fac5},  // (nil)                   ..Person With Crown
+        {0x1face, 0x1fadb},  // (nil)                   ..(nil)
+        {0x1fae0, 0x1fae8},  // Melting Face            ..(nil)
+        {0x1faf0, 0x1faf8},  // Hand With Index Finger A..(nil)
+        {0x20000, 0x2fffd},  // Cjk Unified Ideograph-20..(nil)
+        {0x30000, 0x3fffd},  // Cjk Unified Ideograph-30..(nil)
+    };
+
+
+    private static boolean intable(int[][] table, int c) {
+        // First quick check f|| Latin1 etc. characters.
+        if (c < table[0][0]) return false;
+
+        // Binary search in table.
+        int bot = 0;
+        int top = table.length - 1; // (int)(size / sizeof(struct interval) - 1);
+        while (top >= bot) {
+            int mid = (bot + top) / 2;
+            if (table[mid][1] < c) {
+                bot = mid + 1;
+            } else if (table[mid][0] > c) {
+                top = mid - 1;
+            } else {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /** Return the terminal display width of a code point: 0, 1 || 2. */
+    public static int width(int ucs) {
+        if (ucs == 0 ||
+            ucs == 0x034F ||
+            (0x200B <= ucs && ucs <= 0x200F) ||
+            ucs == 0x2028 ||
+            ucs == 0x2029 ||
+            (0x202A <= ucs && ucs <= 0x202E) ||
+            (0x2060 <= ucs && ucs <= 0x2063)) {
+            return 0;
+        }
+
+        // C0/C1 control characters
+        // Termux change: Return 0 instead of -1.
+        if (ucs < 32 || (0x07F <= ucs && ucs < 0x0A0)) return 0;
+
+        // combining characters with zero width
+        if (intable(ZERO_WIDTH, ucs)) return 0;
+
+        return intable(WIDE_EASTASIAN, ucs) ? 2 : 1;
+    }
+
+    /** The width at an index position in a java char array. */
+    public static int width(char[] chars, int index) {
+        char c = chars[index];
+        return Character.isHighSurrogate(c) ? width(Character.toCodePoint(c, chars[index + 1])) : width(c);
+    }
+
+    /**
+     * The zero width characters count like combining characters in the `chars` array from start
+     * index to end index (exclusive).
+     */
+    public static int zeroWidthCharsCount(char[] chars, int start, int end) {
+        if (start < 0 || start >= chars.length)
+            return 0;
+
+        int count = 0;
+        for (int i = start; i < end && i < chars.length;) {
+            if (Character.isHighSurrogate(chars[i])) {
+                if (width(Character.toCodePoint(chars[i], chars[i + 1])) <= 0) {
+                    count++;
+                }
+                i += 2;
+            } else {
+                if (width(chars[i]) <= 0) {
+                    count++;
+                }
+                i++;
+            }
+        }
+        return count;
+    }
+
+}

app/src/main/java/com/termux/view/TerminalRenderer.java

@@ -0,0 +1,253 @@
+package com.termux.view;
+
+import android.graphics.Canvas;
+import android.graphics.Paint;
+import android.graphics.PorterDuff;
+import android.graphics.Typeface;
+
+import com.termux.terminal.TerminalBuffer;
+import com.termux.terminal.TerminalEmulator;
+import com.termux.terminal.TerminalRow;
+import com.termux.terminal.TextStyle;
+import com.termux.terminal.WcWidth;
+
+/**
+ * Renderer of a {@link TerminalEmulator} into a {@link Canvas}.
+ * <p/>
+ * Saves font metrics, so needs to be recreated each time the typeface or font size changes.
+ */
+public final class TerminalRenderer {
+
+    final int mTextSize;
+    final Typeface mTypeface;
+    private final Paint mTextPaint = new Paint();
+
+    /** The width of a single mono spaced character obtained by {@link Paint#measureText(String)} on a single 'X'. */
+    final float mFontWidth;
+    /** The {@link Paint#getFontSpacing()}. See http://www.fampennings.nl/maarten/android/08numgrid/font.png */
+    final int mFontLineSpacing;
+    /** The {@link Paint#ascent()}. See http://www.fampennings.nl/maarten/android/08numgrid/font.png */
+    private final int mFontAscent;
+    /** The {@link #mFontLineSpacing} + {@link #mFontAscent}. */
+    final int mFontLineSpacingAndAscent;
+
+    private final float[] asciiMeasures = new float[127];
+
+    public TerminalRenderer(int textSize, Typeface typeface) {
+        mTextSize = textSize;
+        mTypeface = typeface;
+
+        mTextPaint.setTypeface(typeface);
+        mTextPaint.setAntiAlias(true);
+        mTextPaint.setTextSize(textSize);
+
+        mFontLineSpacing = (int) Math.ceil(mTextPaint.getFontSpacing());
+        mFontAscent = (int) Math.ceil(mTextPaint.ascent());
+        mFontLineSpacingAndAscent = mFontLineSpacing + mFontAscent;
+        mFontWidth = mTextPaint.measureText("X");
+
+        StringBuilder sb = new StringBuilder(" ");
+        for (int i = 0; i < asciiMeasures.length; i++) {
+            sb.setCharAt(0, (char) i);
+            asciiMeasures[i] = mTextPaint.measureText(sb, 0, 1);
+        }
+    }
+
+    /** Render the terminal to a canvas with at a specified row scroll, and an optional rectangular selection. */
+    public final void render(TerminalEmulator mEmulator, Canvas canvas, int topRow,
+                             int selectionY1, int selectionY2, int selectionX1, int selectionX2) {
+        final boolean reverseVideo = mEmulator.isReverseVideo();
+        final int endRow = topRow + mEmulator.mRows;
+        final int columns = mEmulator.mColumns;
+        final int cursorCol = mEmulator.getCursorCol();
+        final int cursorRow = mEmulator.getCursorRow();
+        final boolean cursorVisible = mEmulator.shouldCursorBeVisible();
+        final TerminalBuffer screen = mEmulator.getScreen();
+        final int[] palette = mEmulator.mColors.mCurrentColors;
+        final int cursorShape = mEmulator.getCursorStyle();
+
+        if (reverseVideo)
+            canvas.drawColor(palette[TextStyle.COLOR_INDEX_FOREGROUND], PorterDuff.Mode.SRC);
+
+        float heightOffset = mFontLineSpacingAndAscent;
+        for (int row = topRow; row < endRow; row++) {
+            heightOffset += mFontLineSpacing;
+
+            final int cursorX = (row == cursorRow && cursorVisible) ? cursorCol : -1;
+            int selx1 = -1, selx2 = -1;
+            if (row >= selectionY1 && row <= selectionY2) {
+                if (row == selectionY1) selx1 = selectionX1;
+                selx2 = (row == selectionY2) ? selectionX2 : mEmulator.mColumns;
+            }
+
+            TerminalRow lineObject = screen.allocateFullLineIfNecessary(screen.externalToInternalRow(row));
+            final char[] line = lineObject.mText;
+            final int charsUsedInLine = lineObject.getSpaceUsed();
+
+            long lastRunStyle = 0;
+            boolean lastRunInsideCursor = false;
+            boolean lastRunInsideSelection = false;
+            int lastRunStartColumn = -1;
+            int lastRunStartIndex = 0;
+            boolean lastRunFontWidthMismatch = false;
+            int currentCharIndex = 0;
+            float measuredWidthForRun = 0.f;
+
+            for (int column = 0; column < columns; ) {
+                final char charAtIndex = line[currentCharIndex];
+                final boolean charIsHighsurrogate = Character.isHighSurrogate(charAtIndex);
+                final int charsForCodePoint = charIsHighsurrogate ? 2 : 1;
+                final int codePoint = charIsHighsurrogate ? Character.toCodePoint(charAtIndex, line[currentCharIndex + 1]) : charAtIndex;
+                final int codePointWcWidth = WcWidth.width(codePoint);
+                final boolean insideCursor = (cursorX == column || (codePointWcWidth == 2 && cursorX == column + 1));
+                final boolean insideSelection = column >= selx1 && column <= selx2;
+                final long style = lineObject.getStyle(column);
+
+                // Check if the measured text width for this code point is not the same as that expected by wcwidth().
+                // This could happen for some fonts which are not truly monospace, or for more exotic characters such as
+                // smileys which android font renders as wide.
+                // If this is detected, we draw this code point scaled to match what wcwidth() expects.
+                final float measuredCodePointWidth = (codePoint < asciiMeasures.length) ? asciiMeasures[codePoint] : mTextPaint.measureText(line,
+                    currentCharIndex, charsForCodePoint);
+                final boolean fontWidthMismatch = Math.abs(measuredCodePointWidth / mFontWidth - codePointWcWidth) > 0.01;
+
+                if (style != lastRunStyle || insideCursor != lastRunInsideCursor || insideSelection != lastRunInsideSelection || fontWidthMismatch || lastRunFontWidthMismatch) {
+                    if (column == 0) {
+                        // Skip first column as there is nothing to draw, just record the current style.
+                    } else {
+                        final int columnWidthSinceLastRun = column - lastRunStartColumn;
+                        final int charsSinceLastRun = currentCharIndex - lastRunStartIndex;
+                        int cursorColor = lastRunInsideCursor ? mEmulator.mColors.mCurrentColors[TextStyle.COLOR_INDEX_CURSOR] : 0;
+                        boolean invertCursorTextColor = false;
+                        if (lastRunInsideCursor && cursorShape == TerminalEmulator.TERMINAL_CURSOR_STYLE_BLOCK) {
+                            invertCursorTextColor = true;
+                        }
+                        drawTextRun(canvas, line, palette, heightOffset, lastRunStartColumn, columnWidthSinceLastRun,
+                            lastRunStartIndex, charsSinceLastRun, measuredWidthForRun,
+                            cursorColor, cursorShape, lastRunStyle, reverseVideo || invertCursorTextColor || lastRunInsideSelection);
+                    }
+                    measuredWidthForRun = 0.f;
+                    lastRunStyle = style;
+                    lastRunInsideCursor = insideCursor;
+                    lastRunInsideSelection = insideSelection;
+                    lastRunStartColumn = column;
+                    lastRunStartIndex = currentCharIndex;
+                    lastRunFontWidthMismatch = fontWidthMismatch;
+                }
+                measuredWidthForRun += measuredCodePointWidth;
+                column += codePointWcWidth;
+                currentCharIndex += charsForCodePoint;
+                while (currentCharIndex < charsUsedInLine && WcWidth.width(line, currentCharIndex) <= 0) {
+                    // Eat combining chars so that they are treated as part of the last non-combining code point,
+                    // instead of e.g. being considered inside the cursor in the next run.
+                    currentCharIndex += Character.isHighSurrogate(line[currentCharIndex]) ? 2 : 1;
+                }
+            }
+
+            final int columnWidthSinceLastRun = columns - lastRunStartColumn;
+            final int charsSinceLastRun = currentCharIndex - lastRunStartIndex;
+            int cursorColor = lastRunInsideCursor ? mEmulator.mColors.mCurrentColors[TextStyle.COLOR_INDEX_CURSOR] : 0;
+            boolean invertCursorTextColor = false;
+            if (lastRunInsideCursor && cursorShape == TerminalEmulator.TERMINAL_CURSOR_STYLE_BLOCK) {
+                invertCursorTextColor = true;
+            }
+            drawTextRun(canvas, line, palette, heightOffset, lastRunStartColumn, columnWidthSinceLastRun, lastRunStartIndex, charsSinceLastRun,
+                measuredWidthForRun, cursorColor, cursorShape, lastRunStyle, reverseVideo || invertCursorTextColor || lastRunInsideSelection);
+        }
+    }
+
+    private void drawTextRun(Canvas canvas, char[] text, int[] palette, float y, int startColumn, int runWidthColumns,
+                             int startCharIndex, int runWidthChars, float mes, int cursor, int cursorStyle,
+                             long textStyle, boolean reverseVideo) {
+        int foreColor = TextStyle.decodeForeColor(textStyle);
+        final int effect = TextStyle.decodeEffect(textStyle);
+        int backColor = TextStyle.decodeBackColor(textStyle);
+        final boolean bold = (effect & (TextStyle.CHARACTER_ATTRIBUTE_BOLD | TextStyle.CHARACTER_ATTRIBUTE_BLINK)) != 0;
+        final boolean underline = (effect & TextStyle.CHARACTER_ATTRIBUTE_UNDERLINE) != 0;
+        final boolean italic = (effect & TextStyle.CHARACTER_ATTRIBUTE_ITALIC) != 0;
+        final boolean strikeThrough = (effect & TextStyle.CHARACTER_ATTRIBUTE_STRIKETHROUGH) != 0;
+        final boolean dim = (effect & TextStyle.CHARACTER_ATTRIBUTE_DIM) != 0;
+
+        if ((foreColor & 0xff000000) != 0xff000000) {
+            // Let bold have bright colors if applicable (one of the first 8):
+            if (bold && foreColor >= 0 && foreColor < 8) foreColor += 8;
+            foreColor = palette[foreColor];
+        }
+
+        if ((backColor & 0xff000000) != 0xff000000) {
+            backColor = palette[backColor];
+        }
+
+        // Reverse video here if _one and only one_ of the reverse flags are set:
+        final boolean reverseVideoHere = reverseVideo ^ (effect & (TextStyle.CHARACTER_ATTRIBUTE_INVERSE)) != 0;
+        if (reverseVideoHere) {
+            int tmp = foreColor;
+            foreColor = backColor;
+            backColor = tmp;
+        }
+
+        float left = startColumn * mFontWidth;
+        float right = left + runWidthColumns * mFontWidth;
+
+        mes = mes / mFontWidth;
+        boolean savedMatrix = false;
+        if (Math.abs(mes - runWidthColumns) > 0.01) {
+            canvas.save();
+            canvas.scale(runWidthColumns / mes, 1.f);
+            left *= mes / runWidthColumns;
+            right *= mes / runWidthColumns;
+            savedMatrix = true;
+        }
+
+        if (backColor != palette[TextStyle.COLOR_INDEX_BACKGROUND]) {
+            // Only draw non-default background.
+            mTextPaint.setColor(backColor);
+            canvas.drawRect(left, y - mFontLineSpacingAndAscent + mFontAscent, right, y, mTextPaint);
+        }
+
+        if (cursor != 0) {
+            mTextPaint.setColor(cursor);
+            float cursorHeight = mFontLineSpacingAndAscent - mFontAscent;
+            if (cursorStyle == TerminalEmulator.TERMINAL_CURSOR_STYLE_UNDERLINE) cursorHeight /= 4.;
+            else if (cursorStyle == TerminalEmulator.TERMINAL_CURSOR_STYLE_BAR) right -= ((right - left) * 3) / 4.;
+            canvas.drawRect(left, y - cursorHeight, right, y, mTextPaint);
+        }
+
+        if ((effect & TextStyle.CHARACTER_ATTRIBUTE_INVISIBLE) == 0) {
+            if (dim) {
+                int red = (0xFF & (foreColor >> 16));
+                int green = (0xFF & (foreColor >> 8));
+                int blue = (0xFF & foreColor);
+                // Dim color handling used by libvte which in turn took it from xterm
+                // (https://bug735245.bugzilla-attachments.gnome.org/attachment.cgi?id=284267):
+                red = red * 2 / 3;
+                green = green * 2 / 3;
+                blue = blue * 2 / 3;
+                foreColor = 0xFF000000 + (red << 16) + (green << 8) + blue;
+            }
+
+            mTextPaint.setFakeBoldText(bold);
+            mTextPaint.setUnderlineText(underline);
+            mTextPaint.setTextSkewX(italic ? -0.35f : 0.f);
+            mTextPaint.setStrikeThruText(strikeThrough);
+            mTextPaint.setColor(foreColor);
+
+            // The text alignment is the default Paint.Align.LEFT.
+            canvas.drawTextRun(text, startCharIndex, runWidthChars, startCharIndex, runWidthChars, left, y - mFontLineSpacingAndAscent, false, mTextPaint);
+        }
+
+        if (savedMatrix) canvas.restore();
+    }
+
+    public float getFontWidth() {
+        return mFontWidth;
+    }
+
+    public int getFontLineSpacing() {
+        return mFontLineSpacing;
+    }
+
+    public int getFontLineSpacingAndAscent() {
+        return mFontLineSpacingAndAscent;
+    }
+}

app/src/main/java/xyz/whcself/whcshell/Appearance.java

@@ -0,0 +1,91 @@
+package xyz.whcself.whcshell;
+
+import android.graphics.Typeface;
+import android.util.Log;
+
+import com.termux.terminal.TerminalEmulator;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.InputStreamReader;
+import java.io.Reader;
+import java.nio.charset.StandardCharsets;
+import java.util.Properties;
+
+/**
+ * Look and feel copied from Termux's ~/.termux (font.ttf, colors.properties, termux.properties),
+ * so the terminal looks the same as in the Termux app.
+ */
+final class Appearance {
+
+    /** Files mirrored from the remote ~/.termux directory. */
+    static final String[] FILES = {"font.ttf", "colors.properties", "termux.properties"};
+
+    final Typeface typeface;
+    /** Null when Termux has no colors.properties. */
+    final Properties colors;
+    final int cursorStyle;
+    /** Cursor blink period in milliseconds, 0 for a steady cursor. */
+    final int blinkMs;
+    final float marginHorizontalDp;
+    final float marginVerticalDp;
+
+    private Appearance(Typeface typeface, Properties colors, Properties props) {
+        this.typeface = typeface;
+        this.colors = colors;
+        switch (props.getProperty("terminal-cursor-style", "block").trim()) {
+            case "underline":
+                cursorStyle = TerminalEmulator.TERMINAL_CURSOR_STYLE_UNDERLINE;
+                break;
+            case "bar":
+                cursorStyle = TerminalEmulator.TERMINAL_CURSOR_STYLE_BAR;
+                break;
+            default:
+                cursorStyle = TerminalEmulator.TERMINAL_CURSOR_STYLE_BLOCK;
+        }
+        int blink = intProp(props, "terminal-cursor-blink-rate", 0);
+        blinkMs = blink < 100 ? 0 : Math.min(blink, 2000);
+        marginHorizontalDp = Math.max(0, Math.min(100, intProp(props, "terminal-margin-horizontal", 3)));
+        marginVerticalDp = Math.max(0, Math.min(100, intProp(props, "terminal-margin-vertical", 0)));
+    }
+
+    static File dir(File filesDir) {
+        return new File(filesDir, "termux");
+    }
+
+    static Appearance load(File filesDir) {
+        File d = dir(filesDir);
+        Typeface tf = Typeface.MONOSPACE;
+        File font = new File(d, "font.ttf");
+        if (font.isFile()) {
+            try {
+                tf = Typeface.createFromFile(font);
+            } catch (RuntimeException e) {
+                Log.w("whc-shell", "bad font.ttf", e);
+            }
+        }
+        Properties colors = read(new File(d, "colors.properties"));
+        Properties props = read(new File(d, "termux.properties"));
+        return new Appearance(tf, colors, props == null ? new Properties() : props);
+    }
+
+    private static Properties read(File f) {
+        if (!f.isFile()) return null;
+        Properties p = new Properties();
+        try (Reader r = new InputStreamReader(new FileInputStream(f), StandardCharsets.UTF_8)) {
+            p.load(r);
+            return p;
+        } catch (Exception e) {
+            Log.w("whc-shell", "cannot read " + f, e);
+            return null;
+        }
+    }
+
+    private static int intProp(Properties p, String key, int def) {
+        try {
+            return Integer.parseInt(p.getProperty(key, "").trim());
+        } catch (NumberFormatException e) {
+            return def;
+        }
+    }
+}

app/src/main/java/xyz/whcself/whcshell/KeyEncoder.java

@@ -0,0 +1,144 @@
+package xyz.whcself.whcshell;
+
+import android.view.KeyEvent;
+
+import com.termux.terminal.KeyHandler;
+
+/**
+ * Turns a key press into the bytes a terminal application expects.
+ *
+ * Function keys use xterm's encoding (from {@link KeyHandler}). Text keys with modifiers follow,
+ * in order of preference, the kitty keyboard protocol (flag 1, "disambiguate"), xterm's
+ * modifyOtherKeys, or the legacy control-character / ESC-prefix encoding.
+ */
+final class KeyEncoder {
+
+    static final int SHIFT = 1;
+    static final int ALT = 2;
+    static final int CTRL = 4;
+
+    /** Terminal state that affects key encoding. */
+    static final class Modes {
+        boolean cursorApp;
+        boolean keypadApp;
+        int kittyFlags;
+        int modifyOtherKeys;
+    }
+
+    private KeyEncoder() {
+    }
+
+    /**
+     * @param keyCode Android key code
+     * @param base    the code point of the key without any modifier (e.g. 'a' for Shift+A), or 0
+     * @param text    the code point the key types with Shift applied (e.g. 'A'), or 0
+     * @param mods    {@link #SHIFT} | {@link #ALT} | {@link #CTRL}
+     * @param numLock whether Num Lock is on
+     * @return the bytes to send as a string, or null if the key produces nothing
+     */
+    static String encode(int keyCode, int base, int text, int mods, boolean numLock, Modes m) {
+        boolean kitty = (m.kittyFlags & 1) != 0;
+        int param = 1 + mods;
+
+        switch (keyCode) {
+            case KeyEvent.KEYCODE_ESCAPE:
+                if (kitty) return mods == 0 ? "\033[27u" : "\033[27;" + param + "u";
+                return (mods & ALT) != 0 ? "\033\033" : "\033";
+            case KeyEvent.KEYCODE_ENTER:
+            case KeyEvent.KEYCODE_NUMPAD_ENTER:
+                if (keyCode == KeyEvent.KEYCODE_NUMPAD_ENTER && m.keypadApp) break;
+                return special(13, "\r", mods, m);
+            case KeyEvent.KEYCODE_TAB:
+                if (!kitty && m.modifyOtherKeys < 2 && (mods & ~SHIFT) == 0)
+                    return mods == 0 ? "\t" : "\033[Z";
+                return special(9, "\t", mods, m);
+            case KeyEvent.KEYCODE_DEL:
+                return special(127, "\u007f", mods, m);
+            case KeyEvent.KEYCODE_PAGE_UP:
+                return mods == 0 ? "\033[5~" : "\033[5;" + param + "~";
+            case KeyEvent.KEYCODE_PAGE_DOWN:
+                return mods == 0 ? "\033[6~" : "\033[6;" + param + "~";
+            case KeyEvent.KEYCODE_SPACE:
+                return textKey(' ', ' ', mods, m);
+            default:
+                break;
+        }
+
+        int keyMode = 0;
+        if ((mods & SHIFT) != 0) keyMode |= KeyHandler.KEYMOD_SHIFT;
+        if ((mods & ALT) != 0) keyMode |= KeyHandler.KEYMOD_ALT;
+        if ((mods & CTRL) != 0) keyMode |= KeyHandler.KEYMOD_CTRL;
+        if (numLock) keyMode |= KeyHandler.KEYMOD_NUM_LOCK;
+        String code = KeyHandler.getCode(keyCode, keyMode, m.cursorApp, m.keypadApp);
+        if (code != null) return code;
+
+        if (text == 0) return null;
+        return textKey(base == 0 ? text : base, text, mods, m);
+    }
+
+    /** Enter, Tab and Backspace: legacy bytes unless a modifier makes them ambiguous. */
+    private static String special(int cp, String plain, int mods, Modes m) {
+        if (mods == 0) return plain;
+        if ((m.kittyFlags & 1) != 0) return "\033[" + cp + ";" + (1 + mods) + "u";
+        if (m.modifyOtherKeys >= 2 || (m.modifyOtherKeys == 1 && cp == 13))
+            return "\033[27;" + (1 + mods) + ";" + cp + "~";
+        if (cp == 127 && (mods & CTRL) != 0) plain = "\b";
+        return (mods & ALT) != 0 ? "\033" + plain : plain;
+    }
+
+    private static String textKey(int base, int text, int mods, Modes m) {
+        boolean ctrl = (mods & CTRL) != 0, alt = (mods & ALT) != 0;
+        if (!ctrl && !alt) return new String(Character.toChars(text));
+
+        if ((m.kittyFlags & 1) != 0) {
+            if (base >= 'A' && base <= 'Z') base += 'a' - 'A';
+            return "\033[" + base + ";" + (1 + mods) + "u";
+        }
+
+        int legacy = ctrl ? ctrlChar(text) : text;
+        boolean hasLegacy = !ctrl || legacy != text;
+        // Ctrl+Shift+letter would collapse onto Ctrl+letter.
+        if (ctrl && (mods & SHIFT) != 0 && Character.isLetter(text)) hasLegacy = false;
+        if (m.modifyOtherKeys >= 2 || (m.modifyOtherKeys == 1 && !hasLegacy))
+            return "\033[27;" + (1 + mods) + ";" + text + "~";
+
+        StringBuilder sb = new StringBuilder(4);
+        if (alt) sb.append('\033');
+        sb.appendCodePoint(legacy);
+        return sb.toString();
+    }
+
+    /** The control character xterm sends for Ctrl plus {@code cp}, or {@code cp} if there is none. */
+    static int ctrlChar(int cp) {
+        if (cp >= 'a' && cp <= 'z') return cp - 'a' + 1;
+        if (cp >= 'A' && cp <= 'Z') return cp - 'A' + 1;
+        switch (cp) {
+            case ' ':
+            case '2':
+            case '@':
+                return 0;
+            case '3':
+            case '[':
+                return 27;
+            case '4':
+            case '\\':
+                return 28;
+            case '5':
+            case ']':
+                return 29;
+            case '6':
+            case '^':
+                return 30;
+            case '7':
+            case '-':
+            case '_':
+            case '/':
+                return 31;
+            case '8':
+            case '?':
+                return 127;
+            default:
+                return cp;
+        }
+    }
+}

app/src/main/java/xyz/whcself/whcshell/MainActivity.java

@@ -0,0 +1,343 @@
+package xyz.whcself.whcshell;
+
+import android.app.Activity;
+import android.app.AlertDialog;
+import android.content.ClipData;
+import android.content.ClipboardManager;
+import android.content.Intent;
+import android.content.SharedPreferences;
+import android.content.pm.PackageManager;
+import android.graphics.Insets;
+import android.os.Build;
+import android.os.Bundle;
+import android.text.InputType;
+import android.util.Log;
+import android.util.TypedValue;
+import android.view.ContextMenu;
+import android.view.WindowInsets;
+import android.view.WindowInsetsController;
+import android.widget.EditText;
+import android.widget.FrameLayout;
+import android.widget.LinearLayout;
+import android.widget.TextView;
+import android.widget.Toast;
+
+import com.termux.terminal.TerminalColors;
+
+import java.util.Properties;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.function.Consumer;
+
+public final class MainActivity extends Activity implements TermSession.Host, TermView.Actions {
+
+    private static final float DEFAULT_SP = 14f;
+    private static final float MIN_SP = 6f;
+    private static final float MAX_SP = 40f;
+    private static final String RUN_COMMAND_PERMISSION = "com.termux.permission.RUN_COMMAND";
+    private static final int REQ_RUN_COMMAND = 1;
+
+    private TermSession session;
+    private TermView view;
+    private SharedPreferences prefs;
+    private float textSp;
+    private boolean fullscreen;
+    private Appearance appearance;
+    private String primary;
+    private Consumer<Boolean> pendingSshdReply;
+
+    @Override
+    protected void onCreate(Bundle state) {
+        super.onCreate(state);
+        prefs = getSharedPreferences("ui", MODE_PRIVATE);
+        textSp = prefs.getFloat("text_sp", DEFAULT_SP);
+        fullscreen = prefs.getBoolean("fullscreen", false);
+
+        FrameLayout root = new FrameLayout(this);
+        view = new TermView(this);
+        root.addView(view, new FrameLayout.LayoutParams(
+            FrameLayout.LayoutParams.MATCH_PARENT, FrameLayout.LayoutParams.MATCH_PARENT));
+        if (Build.VERSION.SDK_INT >= 30) {
+            root.setOnApplyWindowInsetsListener((v, insets) -> {
+                Insets i = insets.getInsets(WindowInsets.Type.systemBars()
+                    | WindowInsets.Type.ime() | WindowInsets.Type.displayCutout());
+                v.setPadding(i.left, i.top, i.right, i.bottom);
+                return WindowInsets.CONSUMED;
+            });
+        } else {
+            root.setFitsSystemWindows(true);
+        }
+        setContentView(root);
+
+        session = ((WhcApp) getApplication()).session();
+        session.setHost(this);
+        applyAppearance();
+        view.attach(session, this);
+        applyFullscreen();
+        view.requestFocus();
+    }
+
+    @Override
+    @SuppressWarnings("deprecation")
+    public void onBackPressed() {
+        moveTaskToBack(true);
+    }
+
+    @Override
+    protected void onDestroy() {
+        if (session != null) session.setHost(null);
+        super.onDestroy();
+    }
+
+    private float dp(float v) {
+        return TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, v, getResources().getDisplayMetrics());
+    }
+
+    private int textPx() {
+        return Math.round(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, textSp,
+            getResources().getDisplayMetrics()));
+    }
+
+    private void applyAppearance() {
+        appearance = Appearance.load(getFilesDir());
+        Properties colors = appearance.colors == null ? new Properties() : appearance.colors;
+        try {
+            TerminalColors.COLOR_SCHEME.updateWith(colors);
+        } catch (IllegalArgumentException e) {
+            Log.w("whc-shell", "bad colors.properties", e);
+            TerminalColors.COLOR_SCHEME.updateWith(new Properties());
+        }
+        session.resetColors();
+        session.setCursorStyle(appearance.cursorStyle);
+        int h = Math.round(dp(appearance.marginHorizontalDp));
+        int v = Math.round(dp(appearance.marginVerticalDp));
+        view.setPadding(h, v, h, v);
+        view.setFont(appearance.typeface, textPx());
+        view.setBlink(appearance.blinkMs);
+    }
+
+    private void applyFullscreen() {
+        if (Build.VERSION.SDK_INT < 30) return;
+        WindowInsetsController c = getWindow().getInsetsController();
+        if (c == null) return;
+        if (fullscreen) {
+            c.setSystemBarsBehavior(WindowInsetsController.BEHAVIOR_SHOW_TRANSIENT_BARS_BY_SWIPE);
+            c.hide(WindowInsets.Type.systemBars());
+        } else {
+            c.show(WindowInsets.Type.systemBars());
+        }
+    }
+
+    private void setClipboard(String text) {
+        ClipboardManager cm = getSystemService(ClipboardManager.class);
+        if (cm != null) cm.setPrimaryClip(ClipData.newPlainText("terminal", text));
+    }
+
+    private void pasteText(String text) {
+        if (text != null && !text.isEmpty() && session.emulator() != null && session.isConnected()) {
+            view.clearSelection();
+            session.emulator().paste(text);
+        }
+    }
+
+    // TermView.Actions
+
+    @Override
+    public void paste() {
+        ClipboardManager cm = getSystemService(ClipboardManager.class);
+        ClipData clip = cm == null ? null : cm.getPrimaryClip();
+        if (clip == null || clip.getItemCount() == 0) return;
+        CharSequence text = clip.getItemAt(0).coerceToText(this);
+        if (text != null) pasteText(text.toString());
+    }
+
+    @Override
+    public void pastePrimary() {
+        if (primary != null) pasteText(primary);
+        else paste();
+    }
+
+    @Override
+    public void copy(String text) {
+        setClipboard(text);
+        view.clearSelection();
+    }
+
+    @Override
+    public void setPrimary(String text) {
+        primary = text;
+    }
+
+    @Override
+    public void zoom(int delta) {
+        textSp = delta == 0 ? DEFAULT_SP : Math.max(MIN_SP, Math.min(MAX_SP, textSp + delta));
+        prefs.edit().putFloat("text_sp", textSp).apply();
+        view.setTextSizePx(textPx());
+    }
+
+    @Override
+    public void toggleFullscreen() {
+        fullscreen = !fullscreen;
+        prefs.edit().putBoolean("fullscreen", fullscreen).apply();
+        applyFullscreen();
+    }
+
+    @Override
+    public void buildMenu(ContextMenu menu, String selection) {
+        if (selection != null)
+            menu.add("复制    Ctrl+Shift+C").setOnMenuItemClickListener(i -> {
+                copy(selection);
+                return true;
+            });
+        menu.add("粘贴    Ctrl+Shift+V").setOnMenuItemClickListener(i -> {
+            paste();
+            return true;
+        });
+        menu.add("全选    Ctrl+Shift+A").setOnMenuItemClickListener(i -> {
+            view.selectAll();
+            return true;
+        });
+        menu.add("放大    Ctrl+Shift+=").setOnMenuItemClickListener(i -> {
+            zoom(1);
+            return true;
+        });
+        menu.add("缩小    Ctrl+Shift+-").setOnMenuItemClickListener(i -> {
+            zoom(-1);
+            return true;
+        });
+        menu.add((fullscreen ? "退出全屏" : "全屏") + "    F11").setOnMenuItemClickListener(i -> {
+            toggleFullscreen();
+            return true;
+        });
+        if (!session.isConnected() && !session.isConnecting())
+            menu.add("重新连接").setOnMenuItemClickListener(i -> {
+                session.connect();
+                return true;
+            });
+    }
+
+    // TermSession.Host
+
+    @Override
+    public void onScreenUpdated() {
+        view.onScreenUpdated();
+    }
+
+    @Override
+    public void onTitleChanged(String title) {
+        setTitle(title == null || title.isEmpty() ? getString(R.string.app_name) : title);
+    }
+
+    @Override
+    public void onCopy(String text) {
+        setClipboard(text);
+    }
+
+    @Override
+    public void onPasteRequest() {
+        paste();
+    }
+
+    @Override
+    public void onBell() {
+    }
+
+    @Override
+    public void onAppearanceSynced() {
+        applyAppearance();
+    }
+
+    @Override
+    public void startSshd(Consumer<Boolean> reply) {
+        try {
+            getPackageManager().getPackageInfo("com.termux", 0);
+        } catch (PackageManager.NameNotFoundException e) {
+            reply.accept(false);
+            return;
+        }
+        if (checkSelfPermission(RUN_COMMAND_PERMISSION) == PackageManager.PERMISSION_GRANTED) {
+            reply.accept(sendRunSshd());
+            return;
+        }
+        if (pendingSshdReply != null) pendingSshdReply.accept(false);
+        pendingSshdReply = reply;
+        requestPermissions(new String[]{RUN_COMMAND_PERMISSION}, REQ_RUN_COMMAND);
+    }
+
+    @Override
+    public void onRequestPermissionsResult(int code, String[] permissions, int[] results) {
+        super.onRequestPermissionsResult(code, permissions, results);
+        if (code != REQ_RUN_COMMAND || pendingSshdReply == null) return;
+        Consumer<Boolean> reply = pendingSshdReply;
+        pendingSshdReply = null;
+        boolean granted = results.length > 0 && results[0] == PackageManager.PERMISSION_GRANTED;
+        if (!granted) Toast.makeText(this, "未授权“在 Termux 中运行命令”，请手动在 Termux 里运行 sshd",
+            Toast.LENGTH_LONG).show();
+        reply.accept(granted && sendRunSshd());
+    }
+
+    private boolean sendRunSshd() {
+        Intent i = new Intent("com.termux.RUN_COMMAND");
+        i.setClassName("com.termux", "com.termux.app.RunCommandService");
+        i.putExtra("com.termux.RUN_COMMAND_PATH", "/data/data/com.termux/files/usr/bin/sshd");
+        i.putExtra("com.termux.RUN_COMMAND_BACKGROUND", true);
+        try {
+            startService(i);
+            return true;
+        } catch (RuntimeException e) {
+            Log.w("whc-shell", "RUN_COMMAND failed", e);
+            return false;
+        }
+    }
+
+    @Override
+    public void askPassword(String message, Consumer<String> reply) {
+        int pad = Math.round(dp(20));
+        LinearLayout box = new LinearLayout(this);
+        box.setOrientation(LinearLayout.VERTICAL);
+        box.setPadding(pad, pad / 2, pad, 0);
+        TextView msg = new TextView(this);
+        msg.setText(message);
+        EditText pw = new EditText(this);
+        pw.setInputType(InputType.TYPE_CLASS_TEXT | InputType.TYPE_TEXT_VARIATION_PASSWORD);
+        pw.setHint("Termux 密码");
+        box.addView(msg);
+        box.addView(pw);
+
+        AtomicBoolean answered = new AtomicBoolean();
+        AlertDialog d = new AlertDialog.Builder(this)
+            .setTitle("登录 Termux")
+            .setView(box)
+            .setPositiveButton("登录", (dlg, w) -> {
+                if (answered.compareAndSet(false, true)) reply.accept(pw.getText().toString());
+            })
+            .setNegativeButton("取消", null)
+            .setOnDismissListener(dlg -> {
+                if (answered.compareAndSet(false, true)) reply.accept(null);
+                view.requestFocus();
+            })
+            .create();
+        pw.setOnEditorActionListener((tv, action, ev) -> {
+            if (answered.compareAndSet(false, true)) reply.accept(pw.getText().toString());
+            d.dismiss();
+            return true;
+        });
+        d.show();
+        pw.requestFocus();
+    }
+
+    @Override
+    public void confirm(String message, Consumer<Boolean> reply) {
+        AtomicBoolean answered = new AtomicBoolean();
+        new AlertDialog.Builder(this)
+            .setMessage(message)
+            .setPositiveButton("信任", (dlg, w) -> {
+                if (answered.compareAndSet(false, true)) reply.accept(true);
+            })
+            .setNegativeButton("拒绝", null)
+            .setOnDismissListener(dlg -> {
+                if (answered.compareAndSet(false, true)) reply.accept(false);
+                view.requestFocus();
+            })
+            .show();
+    }
+}

app/src/main/java/xyz/whcself/whcshell/SshKeys.java

@@ -0,0 +1,69 @@
+package xyz.whcself.whcshell;
+
+import org.bouncycastle.crypto.AsymmetricCipherKeyPair;
+import org.bouncycastle.crypto.generators.Ed25519KeyPairGenerator;
+import org.bouncycastle.crypto.params.Ed25519KeyGenerationParameters;
+import org.bouncycastle.crypto.util.OpenSSHPrivateKeyUtil;
+import org.bouncycastle.crypto.util.OpenSSHPublicKeyUtil;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.security.SecureRandom;
+import java.util.Base64;
+
+/** The client's Ed25519 identity, stored in OpenSSH format in a private directory. */
+final class SshKeys {
+
+    final File privateKey;
+    final File publicKey;
+
+    private SshKeys(File dir) {
+        privateKey = new File(dir, "id_ed25519");
+        publicKey = new File(dir, "id_ed25519.pub");
+    }
+
+    /** Loads the key pair from {@code dir}, generating it first if missing. */
+    static SshKeys ensure(File dir, String comment) throws IOException {
+        SshKeys k = new SshKeys(dir);
+        if (k.privateKey.isFile() && k.publicKey.isFile()) return k;
+        if (!dir.isDirectory() && !dir.mkdirs()) throw new IOException("cannot create " + dir);
+
+        Ed25519KeyPairGenerator gen = new Ed25519KeyPairGenerator();
+        gen.init(new Ed25519KeyGenerationParameters(new SecureRandom()));
+        AsymmetricCipherKeyPair pair = gen.generateKeyPair();
+
+        Base64.Encoder b64 = Base64.getEncoder();
+        String priv = "-----BEGIN OPENSSH PRIVATE KEY-----\n"
+            + Base64.getMimeEncoder(70, new byte[]{'\n'}).encodeToString(
+                OpenSSHPrivateKeyUtil.encodePrivateKey(pair.getPrivate()))
+            + "\n-----END OPENSSH PRIVATE KEY-----\n";
+        String pub = "ssh-ed25519 "
+            + b64.encodeToString(OpenSSHPublicKeyUtil.encodePublicKey(pair.getPublic()))
+            + " " + comment.replaceAll("[^A-Za-z0-9._@-]", "_") + "\n";
+
+        write(k.privateKey, priv);
+        write(k.publicKey, pub);
+        return k;
+    }
+
+    /** The single authorized_keys line, without a trailing newline. */
+    String publicLine() throws IOException {
+        return new String(Files.readAllBytes(publicKey.toPath()), StandardCharsets.UTF_8).trim();
+    }
+
+    private static void write(File f, String s) throws IOException {
+        File tmp = new File(f.getPath() + ".tmp");
+        try (FileOutputStream out = new FileOutputStream(tmp)) {
+            out.write(s.getBytes(StandardCharsets.UTF_8));
+            out.getFD().sync();
+        }
+        tmp.setReadable(false, false);
+        tmp.setReadable(true, true);
+        tmp.setWritable(false, false);
+        tmp.setWritable(true, true);
+        if (!tmp.renameTo(f)) throw new IOException("cannot rename " + tmp);
+    }
+}

app/src/main/java/xyz/whcself/whcshell/TermSession.java

@@ -0,0 +1,508 @@
+package xyz.whcself.whcshell;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.content.pm.PackageManager;
+import android.os.Build;
+import android.os.Handler;
+import android.os.Looper;
+import android.util.Log;
+
+import com.termux.terminal.ByteQueue;
+import com.termux.terminal.TerminalEmulator;
+import com.termux.terminal.TerminalOutput;
+import com.termux.terminal.TerminalSessionClient;
+
+import net.schmizz.sshj.SSHClient;
+import net.schmizz.sshj.common.Buffer;
+import net.schmizz.sshj.connection.channel.direct.Session;
+import net.schmizz.sshj.sftp.FileAttributes;
+import net.schmizz.sshj.sftp.SFTPClient;
+import net.schmizz.sshj.transport.verification.HostKeyVerifier;
+import net.schmizz.sshj.userauth.UserAuthException;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.net.ConnectException;
+import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.security.PublicKey;
+import java.util.Base64;
+import java.util.Collections;
+import java.util.List;
+import java.util.Objects;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Consumer;
+
+/**
+ * A terminal emulator fed by an SSH shell channel to the local Termux sshd.
+ *
+ * All emulator access happens on the main thread; the connection thread only moves bytes.
+ */
+public final class TermSession extends TerminalOutput implements TerminalSessionClient {
+
+    public interface Host {
+        void onScreenUpdated();
+
+        void onTitleChanged(String title);
+
+        void onCopy(String text);
+
+        void onPasteRequest();
+
+        void onBell();
+
+        /** Shows a password prompt; {@code reply} receives null when cancelled. */
+        void askPassword(String message, Consumer<String> reply);
+
+        void confirm(String message, Consumer<Boolean> reply);
+
+        /** Asks Termux to start sshd; {@code reply} receives whether the request was sent. */
+        void startSshd(Consumer<Boolean> reply);
+
+        /** Files under {@link Appearance#dir} changed. */
+        void onAppearanceSynced();
+    }
+
+    private static final String TAG = "whc-shell";
+    private static final int TRANSCRIPT_ROWS = 10000;
+
+    static final String HOST = "127.0.0.1";
+    static final int PORT = 8022;
+
+    private final Context app;
+    private final SharedPreferences prefs;
+    private final Handler main = new Handler(Looper.getMainLooper());
+    private final byte[] drainBuf = new byte[16 * 1024];
+
+    private Host host;
+    private TerminalEmulator emulator;
+    private volatile int cols, rows, cellW, cellH;
+    private Conn conn;
+    private boolean connected;
+    private int cursorStyle = TerminalEmulator.DEFAULT_TERMINAL_CURSOR_STYLE;
+
+    TermSession(Context app) {
+        this.app = app;
+        this.prefs = app.getSharedPreferences("session", Context.MODE_PRIVATE);
+    }
+
+    public void setHost(Host h) {
+        host = h;
+    }
+
+    public TerminalEmulator emulator() {
+        return emulator;
+    }
+
+    public boolean isConnected() {
+        return connected;
+    }
+
+    public boolean isConnecting() {
+        return conn != null && !connected;
+    }
+
+    public void setCursorStyle(int style) {
+        cursorStyle = style;
+        if (emulator != null) emulator.setCursorStyle();
+    }
+
+    /** Re-reads the color scheme into the emulator after {@code TerminalColors.COLOR_SCHEME} changed. */
+    public void resetColors() {
+        if (emulator != null) emulator.mColors.reset();
+    }
+
+    /** Called by the view whenever its size in cells changes; the first call starts the session. */
+    public void resize(int c, int r, int cw, int ch) {
+        cols = c;
+        rows = r;
+        cellW = cw;
+        cellH = ch;
+        if (emulator == null) {
+            emulator = new TerminalEmulator(this, c, r, cw, ch, TRANSCRIPT_ROWS, this);
+            connect();
+        } else {
+            emulator.resize(c, r, cw, ch);
+            if (conn != null) conn.resize(c, r, c * cw, r * ch);
+        }
+    }
+
+    public void connect() {
+        if (emulator == null || conn != null) return;
+        conn = new Conn();
+        conn.start();
+    }
+
+    private void local(String text) {
+        byte[] b = text.getBytes(StandardCharsets.UTF_8);
+        emulator.append(b, b.length);
+        if (host != null) host.onScreenUpdated();
+    }
+
+    private void localFromAnyThread(String text) {
+        main.post(() -> local(text));
+    }
+
+    // TerminalOutput: bytes the user (or the emulator, for replies) sends to the remote side.
+
+    @Override
+    public void write(byte[] data, int offset, int count) {
+        if (conn != null && connected) conn.send(data, offset, count);
+    }
+
+    @Override
+    public void titleChanged(String oldTitle, String newTitle) {
+        if (host != null) host.onTitleChanged(newTitle);
+    }
+
+    @Override
+    public void onCopyTextToClipboard(String text) {
+        if (host != null) host.onCopy(text);
+    }
+
+    @Override
+    public void onPasteTextFromClipboard() {
+        if (host != null) host.onPasteRequest();
+    }
+
+    @Override
+    public void onBell() {
+        if (host != null) host.onBell();
+    }
+
+    @Override
+    public void onColorsChanged() {
+        if (host != null) host.onScreenUpdated();
+    }
+
+    // TerminalSessionClient
+
+    @Override
+    public void onTerminalCursorStateChange(boolean state) {
+    }
+
+    @Override
+    public Integer getTerminalCursorStyle() {
+        return cursorStyle;
+    }
+
+    @Override
+    public void logError(String tag, String message) {
+        Log.e(TAG, tag + ": " + message);
+    }
+
+    @Override
+    public void logWarn(String tag, String message) {
+        Log.w(TAG, tag + ": " + message);
+    }
+
+    @Override
+    public void logInfo(String tag, String message) {
+        Log.i(TAG, tag + ": " + message);
+    }
+
+    @Override
+    public void logDebug(String tag, String message) {
+        Log.d(TAG, tag + ": " + message);
+    }
+
+    @Override
+    public void logVerbose(String tag, String message) {
+        Log.v(TAG, tag + ": " + message);
+    }
+
+    @Override
+    public void logStackTraceWithMessage(String tag, String message, Exception e) {
+        Log.e(TAG, tag + ": " + message, e);
+    }
+
+    @Override
+    public void logStackTrace(String tag, Exception e) {
+        Log.e(TAG, tag, e);
+    }
+
+    /** Termux's Linux user name, e.g. u0_a315. Termux sshd ignores it, but stock sshd would not. */
+    private String termuxUser() {
+        try {
+            int uid = app.getPackageManager().getApplicationInfo("com.termux", 0).uid;
+            return "u" + (uid / 100000) + "_a" + (uid % 100000 - 10000);
+        } catch (PackageManager.NameNotFoundException e) {
+            return "termux";
+        }
+    }
+
+    private <T> T askOnMain(Consumer<Consumer<T>> ask) throws InterruptedException {
+        CountDownLatch done = new CountDownLatch(1);
+        AtomicReference<T> result = new AtomicReference<>();
+        main.post(() -> {
+            if (host == null) {
+                done.countDown();
+                return;
+            }
+            ask.accept(v -> {
+                result.set(v);
+                done.countDown();
+            });
+        });
+        done.await();
+        return result.get();
+    }
+
+    private static String fingerprint(PublicKey key) {
+        try {
+            byte[] blob = new Buffer.PlainBuffer().putPublicKey(key).getCompactData();
+            byte[] d = MessageDigest.getInstance("SHA-256").digest(blob);
+            return "SHA256:" + Base64.getEncoder().withoutPadding().encodeToString(d);
+        } catch (Exception e) {
+            throw new IllegalStateException(e);
+        }
+    }
+
+    private static String describe(Throwable e) {
+        if (e instanceof ConnectException)
+            return "连不上 " + HOST + ":" + PORT + "，请先在 Termux 里运行 sshd";
+        String m = e.getMessage();
+        return m == null || m.isEmpty() ? e.getClass().getSimpleName() : m;
+    }
+
+    private final class Conn extends Thread implements HostKeyVerifier {
+        private final ByteQueue queue = new ByteQueue(64 * 1024);
+        private final AtomicBoolean posted = new AtomicBoolean();
+        private final ExecutorService io = Executors.newSingleThreadExecutor();
+        private volatile SSHClient ssh;
+        private volatile Session.Shell shell;
+        private volatile OutputStream out;
+
+        Conn() {
+            super("ssh-conn");
+            setDaemon(true);
+        }
+
+        @Override
+        public void run() {
+            String err = null;
+            try {
+                session();
+            } catch (Exception e) {
+                Log.w(TAG, "session ended", e);
+                err = describe(e);
+            }
+            queue.close();
+            io.shutdownNow();
+            try {
+                if (ssh != null) ssh.disconnect();
+            } catch (IOException ignored) {
+            }
+            String why = err;
+            main.post(() -> finished(why));
+        }
+
+        private SSHClient open() throws Exception {
+            for (int attempt = 0; ; attempt++) {
+                SSHClient c = new SSHClient();
+                c.setConnectTimeout(5000);
+                c.addHostKeyVerifier(this);
+                try {
+                    c.connect(HOST, PORT);
+                    return c;
+                } catch (ConnectException e) {
+                    c.close();
+                    if (attempt == 0) {
+                        Boolean sent = askOnMain(reply -> host.startSshd(reply));
+                        if (sent == null || !sent) throw e;
+                        localFromAnyThread("\033[2m已请求 Termux 启动 sshd …\033[0m\r\n");
+                    } else if (attempt >= 8) {
+                        throw new IOException("Termux 没有启动 sshd。请在 ~/.termux/termux.properties 里设置 "
+                            + "allow-external-apps = true，或手动在 Termux 里运行 sshd", e);
+                    }
+                    Thread.sleep(500);
+                }
+            }
+        }
+
+        private void session() throws Exception {
+            localFromAnyThread("\033[2m正在连接 Termux (" + HOST + ":" + PORT + ") …\033[0m\r\n");
+            SSHClient c = open();
+            ssh = c;
+            authenticate(c);
+
+            Session s = c.startSession();
+            s.allocatePTY("xterm-256color", cols, rows, cols * cellW, rows * cellH,
+                Collections.emptyMap());
+            Session.Shell sh = s.startShell();
+            shell = sh;
+            out = sh.getOutputStream();
+            main.post(() -> {
+                if (conn == this) connected = true;
+            });
+            Thread sync = new Thread(() -> syncAppearance(c), "ssh-sync");
+            sync.setDaemon(true);
+            sync.start();
+
+            InputStream in = sh.getInputStream();
+            byte[] buf = new byte[8192];
+            int n;
+            while ((n = in.read(buf)) > 0) {
+                if (!queue.write(buf, 0, n)) break;
+                if (posted.compareAndSet(false, true)) main.post(this::drain);
+            }
+        }
+
+        private void drain() {
+            posted.set(false);
+            int n;
+            boolean any = false;
+            while ((n = queue.read(drainBuf, false)) > 0) {
+                emulator.append(drainBuf, n);
+                any = true;
+            }
+            if (any && host != null) host.onScreenUpdated();
+        }
+
+        private void authenticate(SSHClient c) throws Exception {
+            String user = termuxUser();
+            SshKeys keys = SshKeys.ensure(app.getFilesDir(), "whc-shell@" + Build.MODEL);
+            try {
+                c.authPublickey(user, c.loadKeys(keys.privateKey.getPath()));
+                return;
+            } catch (UserAuthException ignored) {
+            }
+            String msg = "首次连接需要 Termux 的登录密码（在 Termux 里用 passwd 设置）。\n"
+                + "成功后会把本机公钥加入 ~/.ssh/authorized_keys，以后自动用密钥登录。";
+            for (int i = 0; i < 3; i++) {
+                String m = msg;
+                String pw = askOnMain(reply -> host.askPassword(m, reply));
+                if (pw == null) throw new IOException("已取消登录");
+                try {
+                    c.authPassword(user, pw);
+                    installKey(c, keys.publicLine());
+                    return;
+                } catch (UserAuthException e) {
+                    msg = "密码不对，请重试。";
+                }
+            }
+            throw new IOException("密码验证失败");
+        }
+
+        private void installKey(SSHClient c, String line) throws IOException {
+            String q = "'" + line.replace("'", "'\\''") + "'";
+            String cmd = "umask 077; mkdir -p ~/.ssh && touch ~/.ssh/authorized_keys && "
+                + "{ grep -qxF " + q + " ~/.ssh/authorized_keys || echo " + q
+                + " >> ~/.ssh/authorized_keys; }";
+            try (Session s = c.startSession()) {
+                Session.Command run = s.exec(cmd);
+                run.join(10, TimeUnit.SECONDS);
+                Integer st = run.getExitStatus();
+                if (st == null || st != 0)
+                    localFromAnyThread("\033[33m公钥写入失败（exit " + st + "），下次仍需密码。\033[0m\r\n");
+                else
+                    localFromAnyThread("\033[2m已写入公钥，以后自动登录。\033[0m\r\n");
+            }
+        }
+
+        /** Mirrors ~/.termux/{font.ttf,colors.properties,termux.properties} when they change. */
+        private void syncAppearance(SSHClient c) {
+            File dir = Appearance.dir(app.getFilesDir());
+            if (!dir.isDirectory() && !dir.mkdirs()) return;
+            boolean changed = false;
+            try (SFTPClient sftp = c.newSFTPClient()) {
+                for (String name : Appearance.FILES) {
+                    String remote = ".termux/" + name;
+                    File local = new File(dir, name);
+                    FileAttributes a = sftp.statExistence(remote);
+                    if (a != null && a.getSize() > 32L << 20) a = null;
+                    String stamp = a == null ? null : a.getSize() + ":" + a.getMtime();
+                    String key = "sync." + name;
+                    if (Objects.equals(stamp, prefs.getString(key, null)) && (a == null) != local.isFile())
+                        continue;
+                    if (a == null) {
+                        if (local.exists() && !local.delete()) continue;
+                    } else {
+                        File part = new File(dir, name + ".part");
+                        sftp.get(remote, part.getPath());
+                        if (!part.renameTo(local)) continue;
+                    }
+                    prefs.edit().putString(key, stamp).apply();
+                    changed = true;
+                }
+            } catch (Exception e) {
+                Log.w(TAG, "appearance sync failed", e);
+            }
+            if (changed) main.post(() -> {
+                if (host != null) host.onAppearanceSynced();
+            });
+        }
+
+        void send(byte[] data, int offset, int count) {
+            byte[] copy = new byte[count];
+            System.arraycopy(data, offset, copy, 0, count);
+            try {
+                io.execute(() -> {
+                    try {
+                        out.write(copy);
+                        out.flush();
+                    } catch (IOException e) {
+                        Log.w(TAG, "write failed", e);
+                    }
+                });
+            } catch (java.util.concurrent.RejectedExecutionException ignored) {
+            }
+        }
+
+        void resize(int c, int r, int w, int h) {
+            if (shell == null) return;
+            try {
+                io.execute(() -> {
+                    try {
+                        shell.changeWindowDimensions(c, r, w, h);
+                    } catch (Exception e) {
+                        Log.w(TAG, "resize failed", e);
+                    }
+                });
+            } catch (java.util.concurrent.RejectedExecutionException ignored) {
+            }
+        }
+
+        // HostKeyVerifier: trust on first use, ask when the key changes.
+
+        @Override
+        public boolean verify(String hostname, int port, PublicKey key) {
+            String k = "hostkey." + hostname + ":" + port;
+            String fp = fingerprint(key);
+            String old = prefs.getString(k, null);
+            if (fp.equals(old)) return true;
+            if (old != null) {
+                String m = "Termux 的主机密钥变了（重装 Termux 或重新生成 ssh_host_* 会这样）。\n\n旧：" + old
+                    + "\n新：" + fp + "\n\n信任新密钥？";
+                Boolean ok;
+                try {
+                    ok = askOnMain(reply -> host.confirm(m, reply));
+                } catch (InterruptedException e) {
+                    return false;
+                }
+                if (ok == null || !ok) return false;
+            }
+            prefs.edit().putString(k, fp).apply();
+            return true;
+        }
+
+        @Override
+        public List<String> findExistingAlgorithms(String hostname, int port) {
+            return Collections.emptyList();
+        }
+    }
+
+    private void finished(String err) {
+        conn = null;
+        connected = false;
+        local("\r\n\033[33m[" + (err == null ? "连接已关闭" : err) + "] 按 Enter 重新连接\033[0m\r\n");
+    }
+}

app/src/main/java/xyz/whcself/whcshell/TermView.java

@@ -0,0 +1,730 @@
+package xyz.whcself.whcshell;
+
+import android.content.Context;
+import android.graphics.Canvas;
+import android.graphics.Typeface;
+import android.os.SystemClock;
+import android.text.Editable;
+import android.text.InputType;
+import android.view.ContextMenu;
+import android.view.GestureDetector;
+import android.view.InputDevice;
+import android.view.KeyCharacterMap;
+import android.view.KeyEvent;
+import android.view.MotionEvent;
+import android.view.PointerIcon;
+import android.view.View;
+import android.view.inputmethod.BaseInputConnection;
+import android.view.inputmethod.EditorInfo;
+import android.view.inputmethod.InputConnection;
+import android.view.inputmethod.InputMethodManager;
+
+import com.termux.terminal.KeyHandler;
+import com.termux.terminal.TerminalBuffer;
+import com.termux.terminal.TerminalEmulator;
+import com.termux.terminal.TerminalRow;
+import com.termux.terminal.TextStyle;
+import com.termux.view.TerminalRenderer;
+
+import java.nio.charset.StandardCharsets;
+
+/** Draws a {@link TermSession} and turns keyboard, IME and pointer input into terminal input. */
+public final class TermView extends View {
+
+    public interface Actions {
+        void paste();
+
+        /** Pastes the last mouse selection (X11-style primary selection), or the clipboard. */
+        void pastePrimary();
+
+        void copy(String text);
+
+        void setPrimary(String text);
+
+        void zoom(int delta);
+
+        void toggleFullscreen();
+
+        /** Fills the right-click / long-press menu. */
+        void buildMenu(ContextMenu menu, String selection);
+    }
+
+    private static final long MULTI_CLICK_MS = 400;
+    private static final String WORD_CHARS = "_-.~/:@%+=?&#$";
+
+    private TermSession session;
+    private Actions actions;
+    private TerminalRenderer renderer;
+    private Typeface typeface = Typeface.MONOSPACE;
+    private int textSizePx = 28;
+    private int topRow;
+    private float scrollAccum;
+    private int combiningAccent;
+    private final GestureDetector gestures;
+    private final KeyEncoder.Modes modes = new KeyEncoder.Modes();
+
+    // Selection, in external buffer coordinates (negative rows are scrollback), inclusive.
+    private boolean selActive;
+    private int selX1, selY1, selX2, selY2;
+    private int anchorX, anchorY, selMode;
+    private boolean selDragging;
+    private long lastClickTime;
+    private int lastClickX = -1, lastClickY, clickCount;
+
+    // Mouse button state as last seen, and whether the current gesture goes to the application.
+    private int mouseButtons;
+    private boolean mouseReporting;
+    private boolean implicitPrimary;
+    private int lastMouseCol = -1, lastMouseRow = -1;
+
+    private int blinkMs;
+    private boolean blinkOn = true;
+    private final Runnable blink = new Runnable() {
+        @Override
+        public void run() {
+            TerminalEmulator e = emulator();
+            if (e == null || blinkMs == 0) return;
+            blinkOn = !blinkOn;
+            e.setCursorBlinkState(blinkOn);
+            invalidate();
+            postDelayed(this, blinkMs);
+        }
+    };
+
+    public TermView(Context context) {
+        super(context);
+        setFocusable(true);
+        setFocusableInTouchMode(true);
+        setPointerIcon(PointerIcon.getSystemIcon(context, PointerIcon.TYPE_TEXT));
+        setOnCreateContextMenuListener((menu, v, info) -> {
+            if (actions != null) actions.buildMenu(menu, selectedText());
+        });
+        gestures = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
+            @Override
+            public boolean onDown(MotionEvent e) {
+                return true;
+            }
+
+            @Override
+            public boolean onScroll(MotionEvent e1, MotionEvent e2, float dx, float dy) {
+                scrollAccum += dy / renderer.getFontLineSpacing();
+                int lines = (int) scrollAccum;
+                if (lines != 0) {
+                    scrollAccum -= lines;
+                    scrollLines(lines, e2);
+                }
+                return true;
+            }
+
+            @Override
+            public boolean onSingleTapUp(MotionEvent e) {
+                clearSelection();
+                showSoftKeyboard();
+                return true;
+            }
+
+            @Override
+            public void onLongPress(MotionEvent e) {
+                if (emulator() == null) return;
+                selMode = 2;
+                anchorX = column(e);
+                anchorY = bufferRow(e);
+                extendSelection(anchorX, anchorY);
+                showContextMenu(e.getX(), e.getY());
+            }
+        });
+    }
+
+    public void attach(TermSession s, Actions a) {
+        session = s;
+        actions = a;
+        updateSize();
+        invalidate();
+    }
+
+    public void setFont(Typeface tf, int px) {
+        typeface = tf;
+        textSizePx = px;
+        renderer = new TerminalRenderer(px, tf);
+        updateSize();
+        invalidate();
+    }
+
+    public void setTextSizePx(int px) {
+        setFont(typeface, px);
+    }
+
+    public void setBlink(int ms) {
+        blinkMs = ms;
+        removeCallbacks(blink);
+        TerminalEmulator e = emulator();
+        if (e != null) {
+            e.setCursorBlinkingEnabled(ms > 0);
+            e.setCursorBlinkState(true);
+        }
+        blinkOn = true;
+        if (ms > 0 && hasWindowFocus()) postDelayed(blink, ms);
+        invalidate();
+    }
+
+    private void restartBlink() {
+        if (blinkMs == 0) return;
+        TerminalEmulator e = emulator();
+        if (e != null) e.setCursorBlinkState(true);
+        blinkOn = true;
+        removeCallbacks(blink);
+        postDelayed(blink, blinkMs);
+    }
+
+    public void showSoftKeyboard() {
+        requestFocus();
+        InputMethodManager imm = getContext().getSystemService(InputMethodManager.class);
+        if (imm != null) imm.showSoftInput(this, 0);
+    }
+
+    /** Called after new output; keeps a scrolled-back view and the selection anchored to the text. */
+    public void onScreenUpdated() {
+        TerminalEmulator e = emulator();
+        if (e == null) return;
+        int scrolled = e.getScrollCounter();
+        e.clearScrollCounter();
+        if (scrolled != 0) {
+            int min = -e.getScreen().getActiveTranscriptRows();
+            if (topRow < 0) topRow = Math.max(topRow - scrolled, min);
+            if (selActive || selDragging) {
+                selY1 -= scrolled;
+                selY2 -= scrolled;
+                anchorY -= scrolled;
+                if (selY1 < min) clearSelection();
+            }
+        }
+        invalidate();
+    }
+
+    private TerminalEmulator emulator() {
+        return session == null ? null : session.emulator();
+    }
+
+    @Override
+    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
+        updateSize();
+    }
+
+    @Override
+    public void setPadding(int left, int top, int right, int bottom) {
+        super.setPadding(left, top, right, bottom);
+        updateSize();
+    }
+
+    private void updateSize() {
+        int w = getWidth() - getPaddingLeft() - getPaddingRight();
+        int h = getHeight() - getPaddingTop() - getPaddingBottom();
+        if (session == null || renderer == null || w <= 0 || h <= 0) return;
+        float cw = renderer.getFontWidth();
+        int ch = renderer.getFontLineSpacing();
+        int cols = Math.max(4, (int) (w / cw));
+        int rows = Math.max(4, (h - renderer.getFontLineSpacingAndAscent()) / ch);
+        TerminalEmulator e = emulator();
+        if (e == null || e.mColumns != cols || e.mRows != rows) {
+            clearSelection();
+            topRow = 0;
+        }
+        session.resize(cols, rows, (int) cw, ch);
+        if (e == null) setBlink(blinkMs);
+    }
+
+    @Override
+    protected void onDraw(Canvas canvas) {
+        TerminalEmulator e = emulator();
+        if (e == null || renderer == null) {
+            canvas.drawColor(0xff000000);
+            return;
+        }
+        canvas.drawColor(e.mColors.mCurrentColors[TextStyle.COLOR_INDEX_BACKGROUND]);
+        canvas.save();
+        canvas.translate(getPaddingLeft(), getPaddingTop());
+        if (selActive) renderer.render(e, canvas, topRow, selY1, selY2, selX1, selX2);
+        else renderer.render(e, canvas, topRow, -1, -1, -1, -1);
+        canvas.restore();
+    }
+
+    @Override
+    public void onWindowFocusChanged(boolean focused) {
+        super.onWindowFocusChanged(focused);
+        TerminalEmulator e = emulator();
+        if (e != null && e.isFocusReportingActive() && session.isConnected())
+            send(focused ? "\033[I" : "\033[O");
+        if (focused) restartBlink();
+        else removeCallbacks(blink);
+    }
+
+    // ---- output helpers
+
+    private void send(String s) {
+        if (session == null || s == null || s.isEmpty()) return;
+        byte[] b = s.getBytes(StandardCharsets.UTF_8);
+        session.write(b, 0, b.length);
+    }
+
+    /** Sends user input: snaps back to the bottom and drops the selection. */
+    private void sendInput(String s) {
+        if (s == null || s.isEmpty()) return;
+        if (topRow != 0) topRow = 0;
+        clearSelection();
+        restartBlink();
+        send(s);
+        invalidate();
+    }
+
+    // ---- geometry
+
+    private int column(MotionEvent ev) {
+        int cols = emulator().mColumns;
+        int c = (int) ((ev.getX() - getPaddingLeft()) / renderer.getFontWidth());
+        return Math.max(0, Math.min(cols - 1, c));
+    }
+
+    /** Visible row, 0-based. */
+    private int row(MotionEvent ev) {
+        int rows = emulator().mRows;
+        int r = (int) Math.floor((ev.getY() - getPaddingTop()) / renderer.getFontLineSpacing());
+        return Math.max(0, Math.min(rows - 1, r));
+    }
+
+    private int bufferRow(MotionEvent ev) {
+        return row(ev) + topRow;
+    }
+
+    // ---- selection
+
+    public String selectedText() {
+        TerminalEmulator e = emulator();
+        if (!selActive || e == null) return null;
+        String s = e.getSelectedText(selX1, selY1, selX2, selY2);
+        return s == null || s.isEmpty() ? null : s;
+    }
+
+    public void clearSelection() {
+        if (selActive || selDragging) {
+            selActive = false;
+            selDragging = false;
+            invalidate();
+        }
+    }
+
+    public void selectAll() {
+        TerminalEmulator e = emulator();
+        if (e == null) return;
+        selActive = true;
+        selX1 = 0;
+        selY1 = -e.getScreen().getActiveTranscriptRows();
+        selX2 = e.mColumns - 1;
+        selY2 = e.mRows - 1;
+        invalidate();
+    }
+
+    private static boolean before(int x1, int y1, int x2, int y2) {
+        return y1 < y2 || (y1 == y2 && x1 <= x2);
+    }
+
+    private int codePointAt(TerminalBuffer screen, int col, int row) {
+        TerminalRow line = screen.allocateFullLineIfNecessary(screen.externalToInternalRow(row));
+        int i = line.findStartOfColumn(col);
+        if (i >= line.getSpaceUsed()) return ' ';
+        return Character.codePointAt(line.mText, i);
+    }
+
+    private static boolean isWordChar(int cp) {
+        return Character.isLetterOrDigit(cp) || WORD_CHARS.indexOf(cp) >= 0;
+    }
+
+    /** Selects from the anchor to (x, y), snapping to words or lines depending on the click count. */
+    private void extendSelection(int x, int y) {
+        TerminalEmulator e = emulator();
+        TerminalBuffer screen = e.getScreen();
+        int cols = e.mColumns;
+        int ax = anchorX, ay = anchorY;
+        int x1, y1, x2, y2;
+        if (before(ax, ay, x, y)) {
+            x1 = ax; y1 = ay; x2 = x; y2 = y;
+        } else {
+            x1 = x; y1 = y; x2 = ax; y2 = ay;
+        }
+        if (selMode == 2) {
+            if (isWordChar(codePointAt(screen, x1, y1)))
+                while (x1 > 0 && isWordChar(codePointAt(screen, x1 - 1, y1))) x1--;
+            if (isWordChar(codePointAt(screen, x2, y2)))
+                while (x2 < cols - 1 && isWordChar(codePointAt(screen, x2 + 1, y2))) x2++;
+        } else if (selMode == 3) {
+            int min = -screen.getActiveTranscriptRows();
+            while (y1 > min && screen.getLineWrap(y1 - 1)) y1--;
+            while (y2 < e.mRows - 1 && screen.getLineWrap(y2)) y2++;
+            x1 = 0;
+            x2 = cols - 1;
+        }
+        selX1 = x1;
+        selY1 = y1;
+        selX2 = x2;
+        selY2 = y2;
+        selActive = true;
+        invalidate();
+    }
+
+    // ---- scrolling
+
+    /** Positive {@code lines} scrolls towards newer output. */
+    private void scrollLines(int lines, MotionEvent ev) {
+        TerminalEmulator e = emulator();
+        if (e == null || lines == 0) return;
+        boolean up = lines < 0;
+        int n = Math.abs(lines);
+        boolean shift = ev != null && (ev.getMetaState() & KeyEvent.META_SHIFT_ON) != 0;
+        if (e.isMouseTrackingActive() && ev != null && !shift) {
+            int col = column(ev) + 1, row = row(ev) + 1;
+            int button = (up ? TerminalEmulator.MOUSE_WHEELUP_BUTTON
+                : TerminalEmulator.MOUSE_WHEELDOWN_BUTTON) | mouseMods(ev);
+            for (int i = 0; i < n; i++) e.sendMouseEvent(button, col, row, true);
+        } else if (e.isAlternateBufferActive() && !shift) {
+            String key = KeyHandler.getCode(up ? KeyEvent.KEYCODE_DPAD_UP : KeyEvent.KEYCODE_DPAD_DOWN,
+                0, e.isCursorKeysApplicationMode(), e.isKeypadApplicationMode());
+            for (int i = 0; i < n; i++) send(key);
+        } else {
+            scrollTranscript(lines);
+        }
+    }
+
+    private void scrollTranscript(int lines) {
+        TerminalEmulator e = emulator();
+        if (e == null) return;
+        int min = -e.getScreen().getActiveTranscriptRows();
+        int t = Math.min(0, Math.max(min, topRow + lines));
+        if (t != topRow) {
+            topRow = t;
+            invalidate();
+        }
+    }
+
+    // ---- pointer input
+
+    @Override
+    public PointerIcon onResolvePointerIcon(MotionEvent event, int pointerIndex) {
+        return PointerIcon.getSystemIcon(getContext(), PointerIcon.TYPE_TEXT);
+    }
+
+    @Override
+    public boolean onGenericMotionEvent(MotionEvent ev) {
+        if (emulator() == null || renderer == null) return super.onGenericMotionEvent(ev);
+        if (ev.getAction() == MotionEvent.ACTION_SCROLL
+            && ev.isFromSource(InputDevice.SOURCE_CLASS_POINTER)) {
+            float v = ev.getAxisValue(MotionEvent.AXIS_VSCROLL);
+            if ((ev.getMetaState() & KeyEvent.META_CTRL_ON) != 0) {
+                if (actions != null && v != 0) actions.zoom(v > 0 ? 1 : -1);
+                return true;
+            }
+            scrollAccum -= v * 3;
+            int lines = (int) scrollAccum;
+            if (lines != 0) {
+                scrollAccum -= lines;
+                scrollLines(lines, ev);
+            }
+            return true;
+        }
+        if (ev.isFromSource(InputDevice.SOURCE_MOUSE)) return onMouse(ev);
+        return super.onGenericMotionEvent(ev);
+    }
+
+    @Override
+    public boolean onTouchEvent(MotionEvent ev) {
+        if (emulator() == null || renderer == null) return true;
+        if (ev.isFromSource(InputDevice.SOURCE_MOUSE)) return onMouse(ev);
+        return gestures.onTouchEvent(ev);
+    }
+
+    private static int mouseMods(MotionEvent ev) {
+        int meta = ev.getMetaState(), m = 0;
+        if ((meta & KeyEvent.META_SHIFT_ON) != 0) m |= 4;
+        if ((meta & KeyEvent.META_ALT_ON) != 0) m |= 8;
+        if ((meta & KeyEvent.META_CTRL_ON) != 0) m |= 16;
+        return m;
+    }
+
+    private static final int[][] BUTTONS = {
+        {MotionEvent.BUTTON_PRIMARY, TerminalEmulator.MOUSE_LEFT_BUTTON},
+        {MotionEvent.BUTTON_TERTIARY, 1},
+        {MotionEvent.BUTTON_SECONDARY, 2},
+    };
+
+    /**
+     * Mouse events arrive through both onTouchEvent and onGenericMotionEvent depending on the
+     * button, so presses and releases are derived from changes in the button state.
+     */
+    private boolean onMouse(MotionEvent ev) {
+        TerminalEmulator e = emulator();
+        int action = ev.getActionMasked();
+        int state = ev.getButtonState()
+            & (MotionEvent.BUTTON_PRIMARY | MotionEvent.BUTTON_SECONDARY | MotionEvent.BUTTON_TERTIARY);
+        // Touchpad taps and injected events can come as DOWN/UP without any button state.
+        if (action == MotionEvent.ACTION_DOWN && state == 0) implicitPrimary = true;
+        if (action == MotionEvent.ACTION_UP || action == MotionEvent.ACTION_CANCEL) implicitPrimary = false;
+        if (implicitPrimary) state |= MotionEvent.BUTTON_PRIMARY;
+        if (action == MotionEvent.ACTION_CANCEL) state = 0;
+        int pressed = state & ~mouseButtons, released = mouseButtons & ~state;
+        int held = mouseButtons;
+        mouseButtons = state;
+        int col = column(ev), row = row(ev);
+        boolean shift = (ev.getMetaState() & KeyEvent.META_SHIFT_ON) != 0;
+        boolean tracking = e.isMouseTrackingActive() && !shift && session.isConnected();
+
+        if (pressed != 0 && held == 0) {
+            mouseReporting = tracking;
+            requestFocus();
+        }
+        boolean report = (held != 0 || pressed != 0) ? mouseReporting : tracking;
+
+        if (report) {
+            int mods = mouseMods(ev);
+            for (int[] b : BUTTONS)
+                if ((released & b[0]) != 0) e.sendMouseEvent(b[1] | mods, col + 1, row + 1, false);
+            for (int[] b : BUTTONS)
+                if ((pressed & b[0]) != 0) e.sendMouseEvent(b[1] | mods, col + 1, row + 1, true);
+            boolean moved = col != lastMouseCol || row != lastMouseRow;
+            if (moved && pressed == 0 && released == 0 && (action == MotionEvent.ACTION_MOVE
+                || action == MotionEvent.ACTION_HOVER_MOVE)) {
+                int b = 3;
+                for (int[] bb : BUTTONS)
+                    if ((state & bb[0]) != 0) {
+                        b = bb[1];
+                        break;
+                    }
+                e.sendMouseEvent((TerminalEmulator.MOUSE_LEFT_BUTTON_MOVED + b) | mods, col + 1, row + 1, true);
+            }
+            lastMouseCol = col;
+            lastMouseRow = row;
+            return true;
+        }
+        lastMouseCol = col;
+        lastMouseRow = row;
+
+        if ((pressed & MotionEvent.BUTTON_PRIMARY) != 0) {
+            long now = SystemClock.uptimeMillis();
+            int y = row + topRow;
+            if (now - lastClickTime < MULTI_CLICK_MS && Math.abs(col - lastClickX) <= 1 && y == lastClickY)
+                clickCount = clickCount % 3 + 1;
+            else
+                clickCount = 1;
+            lastClickTime = now;
+            lastClickX = col;
+            lastClickY = y;
+            clearSelection();
+            selMode = clickCount;
+            anchorX = col;
+            anchorY = y;
+            selDragging = true;
+            if (selMode > 1) extendSelection(col, y);
+        } else if (selDragging && (state & MotionEvent.BUTTON_PRIMARY) != 0
+            && action == MotionEvent.ACTION_MOVE) {
+            float y = ev.getY();
+            if (y < getPaddingTop()) scrollTranscript(-1);
+            else if (y > getHeight() - getPaddingBottom()) scrollTranscript(1);
+            extendSelection(col, row + topRow);
+        }
+        if ((released & MotionEvent.BUTTON_PRIMARY) != 0 && selDragging) {
+            selDragging = false;
+            String s = selectedText();
+            if (s != null && actions != null) actions.setPrimary(s);
+        }
+        if ((pressed & MotionEvent.BUTTON_TERTIARY) != 0 && actions != null) actions.pastePrimary();
+        if ((pressed & MotionEvent.BUTTON_SECONDARY) != 0) showContextMenu(ev.getX(), ev.getY());
+        return true;
+    }
+
+    // ---- keyboard
+
+    @Override
+    public boolean onKeyDown(int keyCode, KeyEvent ev) {
+        if (session == null) return super.onKeyDown(keyCode, ev);
+
+        if (keyCode == KeyEvent.KEYCODE_BACK) {
+            // Mouse right-click and the navigation bar both arrive as BACK; only a real keyboard means Esc.
+            if (ev.isFromSource(InputDevice.SOURCE_MOUSE)) return true;
+            if (isVirtual(ev)) return super.onKeyDown(keyCode, ev);
+            keyCode = KeyEvent.KEYCODE_ESCAPE;
+        }
+
+        if (ev.isMetaPressed()) return super.onKeyDown(keyCode, ev);
+
+        boolean ctrl = ev.isCtrlPressed(), alt = ev.isAltPressed(), shift = ev.isShiftPressed();
+        if (handleShortcut(keyCode, ctrl, alt, shift)) return true;
+
+        if (!session.isConnected()) {
+            if (!session.isConnecting() && (keyCode == KeyEvent.KEYCODE_ENTER
+                || keyCode == KeyEvent.KEYCODE_NUMPAD_ENTER)) {
+                session.connect();
+                return true;
+            }
+            return !KeyEvent.isModifierKey(keyCode) || super.onKeyDown(keyCode, ev);
+        }
+
+        int meta = ev.getMetaState();
+        int text = ev.getUnicodeChar(meta & ~(KeyEvent.META_CTRL_MASK | KeyEvent.META_ALT_MASK));
+        int base = ev.getUnicodeChar(0);
+        if ((text & KeyCharacterMap.COMBINING_ACCENT) != 0) {
+            combiningAccent = text & KeyCharacterMap.COMBINING_ACCENT_MASK;
+            return true;
+        }
+        if (combiningAccent != 0 && text != 0) {
+            int composed = KeyCharacterMap.getDeadChar(combiningAccent, text);
+            combiningAccent = 0;
+            if (composed != 0) text = base = composed;
+        }
+        if ((base & KeyCharacterMap.COMBINING_ACCENT) != 0) base = 0;
+
+        TerminalEmulator e = emulator();
+        modes.cursorApp = e.isCursorKeysApplicationMode();
+        modes.keypadApp = e.isKeypadApplicationMode();
+        modes.kittyFlags = e.getKittyKeyboardFlags();
+        modes.modifyOtherKeys = e.getModifyOtherKeys();
+        int mods = (shift ? KeyEncoder.SHIFT : 0) | (alt ? KeyEncoder.ALT : 0) | (ctrl ? KeyEncoder.CTRL : 0);
+        String out = KeyEncoder.encode(keyCode, base, text, mods, ev.isNumLockOn(), modes);
+        if (out == null) return KeyEvent.isModifierKey(keyCode) ? super.onKeyDown(keyCode, ev) : false;
+        sendInput(out);
+        return true;
+    }
+
+    /** Terminal-level shortcuts that never reach the application. */
+    private boolean handleShortcut(int keyCode, boolean ctrl, boolean alt, boolean shift) {
+        if (actions == null) return false;
+        if (keyCode == KeyEvent.KEYCODE_F11 && !ctrl && !alt && !shift) {
+            actions.toggleFullscreen();
+            return true;
+        }
+        TerminalEmulator e = emulator();
+        if (shift && !ctrl && !alt && e != null && !e.isAlternateBufferActive()) {
+            if (keyCode == KeyEvent.KEYCODE_PAGE_UP) {
+                scrollTranscript(-(e.mRows - 1));
+                return true;
+            } else if (keyCode == KeyEvent.KEYCODE_PAGE_DOWN) {
+                scrollTranscript(e.mRows - 1);
+                return true;
+            }
+        }
+        if (!ctrl || !shift || alt) return false;
+        switch (keyCode) {
+            case KeyEvent.KEYCODE_C: {
+                String s = selectedText();
+                if (s != null) actions.copy(s);
+                return true;
+            }
+            case KeyEvent.KEYCODE_V:
+                actions.paste();
+                return true;
+            case KeyEvent.KEYCODE_A:
+                selectAll();
+                return true;
+            case KeyEvent.KEYCODE_EQUALS:
+            case KeyEvent.KEYCODE_PLUS:
+            case KeyEvent.KEYCODE_NUMPAD_ADD:
+                actions.zoom(1);
+                return true;
+            case KeyEvent.KEYCODE_MINUS:
+            case KeyEvent.KEYCODE_NUMPAD_SUBTRACT:
+                actions.zoom(-1);
+                return true;
+            case KeyEvent.KEYCODE_0:
+            case KeyEvent.KEYCODE_NUMPAD_0:
+                actions.zoom(0);
+                return true;
+            case KeyEvent.KEYCODE_PAGE_UP:
+                if (e != null) scrollTranscript(-(e.mRows - 1));
+                return true;
+            case KeyEvent.KEYCODE_PAGE_DOWN:
+                if (e != null) scrollTranscript(e.mRows - 1);
+                return true;
+            case KeyEvent.KEYCODE_MOVE_HOME:
+                if (e != null) scrollTranscript(-e.getScreen().getActiveTranscriptRows());
+                return true;
+            case KeyEvent.KEYCODE_MOVE_END:
+                scrollTranscript(Integer.MAX_VALUE / 2);
+                return true;
+            default:
+                return false;
+        }
+    }
+
+    @Override
+    public boolean onKeyUp(int keyCode, KeyEvent ev) {
+        if (keyCode == KeyEvent.KEYCODE_BACK && (ev.isFromSource(InputDevice.SOURCE_MOUSE) || !isVirtual(ev)))
+            return true;
+        return super.onKeyUp(keyCode, ev);
+    }
+
+    @Override
+    @SuppressWarnings("deprecation")
+    public boolean onKeyMultiple(int keyCode, int count, KeyEvent ev) {
+        if (keyCode == KeyEvent.KEYCODE_UNKNOWN && ev.getCharacters() != null) {
+            sendInput(ev.getCharacters());
+            return true;
+        }
+        return super.onKeyMultiple(keyCode, count, ev);
+    }
+
+    private static boolean isVirtual(KeyEvent ev) {
+        InputDevice d = ev.getDevice();
+        return d == null || d.isVirtual();
+    }
+
+    // ---- IME
+
+    @Override
+    public boolean onCheckIsTextEditor() {
+        return true;
+    }
+
+    @Override
+    public InputConnection onCreateInputConnection(EditorInfo out) {
+        // A plain text field (not "visible password") so that Chinese IMEs keep their candidate UI.
+        out.inputType = InputType.TYPE_CLASS_TEXT | InputType.TYPE_TEXT_FLAG_NO_SUGGESTIONS;
+        out.imeOptions = EditorInfo.IME_FLAG_NO_FULLSCREEN | EditorInfo.IME_FLAG_NO_EXTRACT_UI
+            | EditorInfo.IME_ACTION_NONE;
+        return new BaseInputConnection(this, true) {
+            @Override
+            public boolean commitText(CharSequence text, int newCursorPosition) {
+                super.commitText(text, newCursorPosition);
+                flush();
+                return true;
+            }
+
+            @Override
+            public boolean finishComposingText() {
+                super.finishComposingText();
+                flush();
+                return true;
+            }
+
+            @Override
+            public boolean deleteSurroundingText(int before, int after) {
+                Editable ed = getEditable();
+                if (ed == null || ed.length() == 0) {
+                    StringBuilder sb = new StringBuilder();
+                    for (int i = 0; i < before; i++) sb.append('\u007f');
+                    for (int i = 0; i < after; i++) sb.append("\033[3~");
+                    if (session != null && session.isConnected()) sendInput(sb.toString());
+                    return true;
+                }
+                return super.deleteSurroundingText(before, after);
+            }
+
+            private void flush() {
+                Editable ed = getEditable();
+                if (ed == null || ed.length() == 0) return;
+                String s = ed.toString().replace('\n', '\r');
+                ed.clear();
+                if (session != null && !session.isConnected()) {
+                    if (s.contains("\r") && !session.isConnecting()) session.connect();
+                    return;
+                }
+                sendInput(s);
+            }
+        };
+    }
+}

app/src/main/java/xyz/whcself/whcshell/WhcApp.java

@@ -0,0 +1,26 @@
+package xyz.whcself.whcshell;
+
+import android.app.Application;
+
+import org.bouncycastle.jce.provider.BouncyCastleProvider;
+
+import java.security.Security;
+
+public final class WhcApp extends Application {
+
+    private TermSession session;
+
+    @Override
+    public void onCreate() {
+        super.onCreate();
+        // Android ships a trimmed "BC" provider without Ed25519/X25519; sshj needs the full one.
+        Security.removeProvider(BouncyCastleProvider.PROVIDER_NAME);
+        Security.insertProviderAt(new BouncyCastleProvider(), 1);
+    }
+
+    /** The session outlives the activity so that configuration changes never drop the connection. */
+    public TermSession session() {
+        if (session == null) session = new TermSession(this);
+        return session;
+    }
+}

app/src/main/res/drawable/ic_launcher_fg.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <!-- ">_" prompt -->
+    <path
+        android:strokeColor="#4EC9B0"
+        android:strokeWidth="6"
+        android:strokeLineCap="round"
+        android:strokeLineJoin="round"
+        android:pathData="M36,40 L50,54 L36,68" />
+    <path
+        android:strokeColor="#D4D4D4"
+        android:strokeWidth="6"
+        android:strokeLineCap="round"
+        android:pathData="M56,68 L74,68" />
+</vector>

app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@android:color/black" />
+    <foreground android:drawable="@drawable/ic_launcher_fg" />
+</adaptive-icon>

app/src/main/res/values/strings.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string name="app_name">WHC Shell</string>
+</resources>

app/src/main/res/values/themes.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <style name="Theme.WhcShell" parent="android:Theme.Material.NoActionBar">
+        <item name="android:windowBackground">@android:color/black</item>
+        <item name="android:statusBarColor">@android:color/black</item>
+        <item name="android:navigationBarColor">@android:color/black</item>
+        <item name="android:windowLightStatusBar">false</item>
+    </style>
+</resources>

app/src/test/java/com/termux/terminal/WhcEmulatorTest.java

@@ -0,0 +1,118 @@
+package com.termux.terminal;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+
+import java.nio.charset.StandardCharsets;
+
+/** Tests for the whc-shell additions to the emulator. */
+public class WhcEmulatorTest {
+
+    private final StringBuilder replies = new StringBuilder();
+    private final TerminalEmulator emu = new TerminalEmulator(new TerminalOutput() {
+        @Override
+        public void write(byte[] data, int offset, int count) {
+            replies.append(new String(data, offset, count, StandardCharsets.UTF_8));
+        }
+
+        @Override
+        public void titleChanged(String oldTitle, String newTitle) {
+        }
+
+        @Override
+        public void onCopyTextToClipboard(String text) {
+        }
+
+        @Override
+        public void onPasteTextFromClipboard() {
+        }
+
+        @Override
+        public void onBell() {
+        }
+
+        @Override
+        public void onColorsChanged() {
+        }
+    }, 80, 24, 10, 20, 100, null);
+
+    private String feed(String s) {
+        replies.setLength(0);
+        byte[] b = s.getBytes(StandardCharsets.UTF_8);
+        emu.append(b, b.length);
+        return replies.toString();
+    }
+
+    @Test
+    public void kittyStack() {
+        assertEquals("\033[?0u", feed("\033[?u"));
+        feed("\033[>1u");
+        assertEquals(1, emu.getKittyKeyboardFlags());
+        assertEquals("\033[?1u", feed("\033[?u"));
+        feed("\033[>31u");
+        assertEquals("unsupported bits are dropped", 1, emu.getKittyKeyboardFlags());
+        feed("\033[<u");
+        assertEquals(1, emu.getKittyKeyboardFlags());
+        feed("\033[<5u");
+        assertEquals(0, emu.getKittyKeyboardFlags());
+        feed("\033[=1;1u");
+        assertEquals(1, emu.getKittyKeyboardFlags());
+        feed("\033[=1;3u");
+        assertEquals(0, emu.getKittyKeyboardFlags());
+        feed("\033[=1;2u");
+        assertEquals(1, emu.getKittyKeyboardFlags());
+        assertEquals("no text is printed", ' ', emu.getScreen().allocateFullLineIfNecessary(0).mText[0]);
+    }
+
+    @Test
+    public void kittyAltScreenHasOwnStack() {
+        feed("\033[>1u");
+        feed("\033[?1049h");
+        assertEquals(0, emu.getKittyKeyboardFlags());
+        feed("\033[>1u");
+        assertEquals(1, emu.getKittyKeyboardFlags());
+        feed("\033[<u");
+        feed("\033[?1049l");
+        assertEquals(1, emu.getKittyKeyboardFlags());
+        feed("\033c");
+        assertEquals(0, emu.getKittyKeyboardFlags());
+    }
+
+    @Test
+    public void modifyOtherKeys() {
+        feed("\033[>4;2m");
+        assertEquals(2, emu.getModifyOtherKeys());
+        feed("\033[>4;1m");
+        assertEquals(1, emu.getModifyOtherKeys());
+        feed("\033[>4m");
+        assertEquals(0, emu.getModifyOtherKeys());
+    }
+
+    @Test
+    public void mouseModes() {
+        feed("\033[?1002h\033[?1006h");
+        replies.setLength(0);
+        emu.sendMouseEvent(35, 5, 6, true);
+        assertEquals("1002 ignores hover", "", replies.toString());
+        emu.sendMouseEvent(32, 5, 6, true);
+        assertEquals("\033[<32;5;6M", replies.toString());
+
+        feed("\033[?1003h");
+        replies.setLength(0);
+        emu.sendMouseEvent(35, 7, 8, true);
+        assertEquals("\033[<35;7;8M", replies.toString());
+        replies.setLength(0);
+        emu.sendMouseEvent(TerminalEmulator.MOUSE_WHEELUP_BUTTON, 1, 1, true);
+        assertEquals("\033[<64;1;1M", replies.toString());
+
+        feed("\033[?1000h");
+        replies.setLength(0);
+        emu.sendMouseEvent(32, 5, 6, true);
+        assertEquals("modes are exclusive", "", replies.toString());
+        assertEquals(false, emu.isMouseHoverTrackingActive());
+
+        feed("\033[?1004h");
+        assertEquals(true, emu.isFocusReportingActive());
+    }
+}

app/src/test/java/xyz/whcself/whcshell/KeyEncoderTest.java

@@ -0,0 +1,106 @@
+package xyz.whcself.whcshell;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+import static xyz.whcself.whcshell.KeyEncoder.ALT;
+import static xyz.whcself.whcshell.KeyEncoder.CTRL;
+import static xyz.whcself.whcshell.KeyEncoder.SHIFT;
+
+import android.view.KeyEvent;
+
+import org.junit.Test;
+
+public class KeyEncoderTest {
+
+    private static KeyEncoder.Modes modes(int kitty, int mok) {
+        KeyEncoder.Modes m = new KeyEncoder.Modes();
+        m.kittyFlags = kitty;
+        m.modifyOtherKeys = mok;
+        return m;
+    }
+
+    private static String key(int code, int base, int text, int mods, KeyEncoder.Modes m) {
+        return KeyEncoder.encode(code, base, text, mods, false, m);
+    }
+
+    @Test
+    public void legacy() {
+        KeyEncoder.Modes m = modes(0, 0);
+        assertEquals("a", key(KeyEvent.KEYCODE_A, 'a', 'a', 0, m));
+        assertEquals("A", key(KeyEvent.KEYCODE_A, 'a', 'A', SHIFT, m));
+        assertEquals("\u0001", key(KeyEvent.KEYCODE_A, 'a', 'a', CTRL, m));
+        assertEquals("\u0001", key(KeyEvent.KEYCODE_A, 'a', 'A', CTRL | SHIFT, m));
+        assertEquals("\033b", key(KeyEvent.KEYCODE_B, 'b', 'b', ALT, m));
+        assertEquals("\033\u0002", key(KeyEvent.KEYCODE_B, 'b', 'b', ALT | CTRL, m));
+        assertEquals("\0", key(KeyEvent.KEYCODE_SPACE, ' ', ' ', CTRL, m));
+        assertEquals(" ", key(KeyEvent.KEYCODE_SPACE, ' ', ' ', SHIFT, m));
+        assertEquals("\033", key(KeyEvent.KEYCODE_ESCAPE, 0, 0, 0, m));
+        assertEquals("\r", key(KeyEvent.KEYCODE_ENTER, 0, 0, 0, m));
+        assertEquals("\r", key(KeyEvent.KEYCODE_ENTER, 0, 0, SHIFT, m));
+        assertEquals("\033\r", key(KeyEvent.KEYCODE_ENTER, 0, 0, ALT, m));
+        assertEquals("\r", key(KeyEvent.KEYCODE_NUMPAD_ENTER, 0, 0, 0, m));
+        assertEquals("\t", key(KeyEvent.KEYCODE_TAB, 0, 0, 0, m));
+        assertEquals("\033[Z", key(KeyEvent.KEYCODE_TAB, 0, 0, SHIFT, m));
+        assertEquals("\u007f", key(KeyEvent.KEYCODE_DEL, 0, 0, 0, m));
+        assertEquals("\b", key(KeyEvent.KEYCODE_DEL, 0, 0, CTRL, m));
+        assertEquals("\033\u007f", key(KeyEvent.KEYCODE_DEL, 0, 0, ALT, m));
+        assertEquals("\033[1;5D", key(KeyEvent.KEYCODE_DPAD_LEFT, 0, 0, CTRL, m));
+        assertEquals("\033[1;3C", key(KeyEvent.KEYCODE_DPAD_RIGHT, 0, 0, ALT, m));
+        assertEquals("\033[3;5~", key(KeyEvent.KEYCODE_FORWARD_DEL, 0, 0, CTRL, m));
+        assertEquals("\033[5;5~", key(KeyEvent.KEYCODE_PAGE_UP, 0, 0, CTRL, m));
+        assertEquals("\033[6~", key(KeyEvent.KEYCODE_PAGE_DOWN, 0, 0, 0, m));
+        assertEquals("\033[1;2P", key(KeyEvent.KEYCODE_F1, 0, 0, SHIFT, m));
+        assertEquals("中", key(KeyEvent.KEYCODE_UNKNOWN, 0, '中', 0, m));
+        assertNull(key(KeyEvent.KEYCODE_SHIFT_LEFT, 0, 0, SHIFT, m));
+    }
+
+    @Test
+    public void cursorApplicationMode() {
+        KeyEncoder.Modes m = modes(0, 0);
+        m.cursorApp = true;
+        assertEquals("\033OA", key(KeyEvent.KEYCODE_DPAD_UP, 0, 0, 0, m));
+        assertEquals("\033[1;5A", key(KeyEvent.KEYCODE_DPAD_UP, 0, 0, CTRL, m));
+    }
+
+    @Test
+    public void kittyDisambiguate() {
+        KeyEncoder.Modes m = modes(1, 0);
+        assertEquals("a", key(KeyEvent.KEYCODE_A, 'a', 'a', 0, m));
+        assertEquals("A", key(KeyEvent.KEYCODE_A, 'a', 'A', SHIFT, m));
+        assertEquals("\033[97;5u", key(KeyEvent.KEYCODE_A, 'a', 'a', CTRL, m));
+        assertEquals("\033[97;6u", key(KeyEvent.KEYCODE_A, 'a', 'A', CTRL | SHIFT, m));
+        assertEquals("\033[98;3u", key(KeyEvent.KEYCODE_B, 'b', 'b', ALT, m));
+        assertEquals("\033[105;5u", key(KeyEvent.KEYCODE_I, 'i', 'i', CTRL, m));
+        assertEquals("\033[32;5u", key(KeyEvent.KEYCODE_SPACE, ' ', ' ', CTRL, m));
+        assertEquals("\033[27u", key(KeyEvent.KEYCODE_ESCAPE, 0, 0, 0, m));
+        assertEquals("\033[27;3u", key(KeyEvent.KEYCODE_ESCAPE, 0, 0, ALT, m));
+        assertEquals("\r", key(KeyEvent.KEYCODE_ENTER, 0, 0, 0, m));
+        assertEquals("\033[13;2u", key(KeyEvent.KEYCODE_ENTER, 0, 0, SHIFT, m));
+        assertEquals("\033[13;5u", key(KeyEvent.KEYCODE_ENTER, 0, 0, CTRL, m));
+        assertEquals("\t", key(KeyEvent.KEYCODE_TAB, 0, 0, 0, m));
+        assertEquals("\033[9;2u", key(KeyEvent.KEYCODE_TAB, 0, 0, SHIFT, m));
+        assertEquals("\u007f", key(KeyEvent.KEYCODE_DEL, 0, 0, 0, m));
+        assertEquals("\033[127;5u", key(KeyEvent.KEYCODE_DEL, 0, 0, CTRL, m));
+        assertEquals("\033[127;3u", key(KeyEvent.KEYCODE_DEL, 0, 0, ALT, m));
+        assertEquals("\033[1;5D", key(KeyEvent.KEYCODE_DPAD_LEFT, 0, 0, CTRL, m));
+        assertEquals("\033[3;5~", key(KeyEvent.KEYCODE_FORWARD_DEL, 0, 0, CTRL, m));
+    }
+
+    @Test
+    public void modifyOtherKeys() {
+        KeyEncoder.Modes m1 = modes(0, 1);
+        assertEquals("\u0001", key(KeyEvent.KEYCODE_A, 'a', 'a', CTRL, m1));
+        assertEquals("\033[27;6;65~", key(KeyEvent.KEYCODE_A, 'a', 'A', CTRL | SHIFT, m1));
+        assertEquals("\033[27;5;49~", key(KeyEvent.KEYCODE_1, '1', '1', CTRL, m1));
+        assertEquals("\033[27;2;13~", key(KeyEvent.KEYCODE_ENTER, 0, 0, SHIFT, m1));
+        assertEquals("\t", key(KeyEvent.KEYCODE_TAB, 0, 0, 0, m1));
+        assertEquals("\033b", key(KeyEvent.KEYCODE_B, 'b', 'b', ALT, m1));
+
+        KeyEncoder.Modes m2 = modes(0, 2);
+        assertEquals("\033[27;5;97~", key(KeyEvent.KEYCODE_A, 'a', 'a', CTRL, m2));
+        assertEquals("\033[27;3;98~", key(KeyEvent.KEYCODE_B, 'b', 'b', ALT, m2));
+        assertEquals("\033[27;5;9~", key(KeyEvent.KEYCODE_TAB, 0, 0, CTRL, m2));
+        assertEquals("\033[27;5;127~", key(KeyEvent.KEYCODE_DEL, 0, 0, CTRL, m2));
+        assertEquals("a", key(KeyEvent.KEYCODE_A, 'a', 'a', 0, m2));
+    }
+}

app/src/test/java/xyz/whcself/whcshell/SshKeysTest.java

@@ -0,0 +1,58 @@
+package xyz.whcself.whcshell;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assume.assumeNotNull;
+
+import net.schmizz.sshj.SSHClient;
+import net.schmizz.sshj.connection.channel.direct.Session;
+import net.schmizz.sshj.transport.verification.PromiscuousVerifier;
+
+import org.bouncycastle.jce.provider.BouncyCastleProvider;
+import org.junit.Test;
+
+import java.io.File;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.security.Security;
+import java.util.concurrent.TimeUnit;
+
+public class SshKeysTest {
+
+    @Test
+    public void generatesOpenSshFiles() throws Exception {
+        File dir = Files.createTempDirectory("whc-keys").toFile();
+        SshKeys k = SshKeys.ensure(dir, "test@host name");
+        String pub = k.publicLine();
+        assertTrue(pub, pub.matches("ssh-ed25519 [A-Za-z0-9+/=]+ test@host_name"));
+        String priv = new String(Files.readAllBytes(k.privateKey.toPath()), StandardCharsets.US_ASCII);
+        assertTrue(priv.startsWith("-----BEGIN OPENSSH PRIVATE KEY-----\n"));
+        assertEquals(pub, SshKeys.ensure(dir, "other").publicLine());
+    }
+
+    /**
+     * Needs an sshd on 127.0.0.1:$WHC_SSHD_PORT whose AuthorizedKeysFile is
+     * $WHC_SSHD_KEYDIR/authorized_keys.
+     */
+    @Test
+    public void logsInWithGeneratedKey() throws Exception {
+        String port = System.getenv("WHC_SSHD_PORT");
+        String dir = System.getenv("WHC_SSHD_KEYDIR");
+        assumeNotNull(port, dir);
+        Security.insertProviderAt(new BouncyCastleProvider(), 1);
+        SshKeys k = SshKeys.ensure(new File(dir), "test");
+        Files.write(new File(dir, "authorized_keys").toPath(),
+            (k.publicLine() + "\n").getBytes(StandardCharsets.US_ASCII));
+        try (SSHClient c = new SSHClient()) {
+            c.addHostKeyVerifier(new PromiscuousVerifier());
+            c.connect("127.0.0.1", Integer.parseInt(port));
+            c.authPublickey(System.getProperty("user.name"), c.loadKeys(k.privateKey.getPath()));
+            try (Session s = c.startSession()) {
+                Session.Command cmd = s.exec("echo whc-ok");
+                String out = new String(cmd.getInputStream().readAllBytes(), StandardCharsets.UTF_8);
+                cmd.join(5, TimeUnit.SECONDS);
+                assertEquals("whc-ok\n", out);
+            }
+        }
+    }
+}

build.gradle

@@ -0,0 +1,3 @@
+plugins {
+    id "com.android.application" version "8.10.1" apply false
+}

gradle.properties

@@ -0,0 +1,3 @@
+org.gradle.jvmargs=-Xmx2g -Dfile.encoding=UTF-8
+android.useAndroidX=true
+android.nonTransitiveRClass=true

settings.gradle

@@ -0,0 +1,18 @@
+pluginManagement {
+    repositories {
+        google()
+        mavenCentral()
+        gradlePluginPortal()
+    }
+}
+
+dependencyResolutionManagement {
+    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
+    repositories {
+        google()
+        mavenCentral()
+    }
+}
+
+rootProject.name = "whc-shell"
+include ":app"

shell.nix

@@ -0,0 +1,27 @@
+{ pkgs ? import <nixpkgs> {
+    config = {
+      allowUnfree = true;
+      android_sdk.accept_license = true;
+    };
+  }
+}:
+
+let
+  buildTools = "35.0.0";
+  android = pkgs.androidenv.composeAndroidPackages {
+    platformVersions = [ "35" ];
+    buildToolsVersions = [ buildTools ];
+    includeEmulator = false;
+    includeSystemImages = false;
+    includeNDK = false;
+  };
+  sdk = "${android.androidsdk}/libexec/android-sdk";
+in
+pkgs.mkShell {
+  packages = [ pkgs.jdk17 pkgs.gradle android.androidsdk pkgs.android-tools ];
+  ANDROID_HOME = sdk;
+  ANDROID_SDK_ROOT = sdk;
+  JAVA_HOME = pkgs.jdk17.home;
+  # The aapt2 that Gradle fetches from Maven is not runnable on NixOS.
+  GRADLE_OPTS = "-Dorg.gradle.project.android.aapt2FromMavenOverride=${sdk}/build-tools/${buildTools}/aapt2";
+}

third_party/Apache-2.0.txt

@@ -0,0 +1,202 @@
+
+                                 Apache License
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+
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+
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third_party/termux-LICENSE.md

@@ -0,0 +1,6 @@
+The `termux/termux-app` repository is released under [GPLv3 only](https://www.gnu.org/licenses/gpl-3.0.html) license.
+
+### Exceptions
+
+- [Terminal Emulator for Android](https://github.com/jackpal/Android-Terminal-Emulator) code is used which is released under [Apache License 2.0](https://www.apache.org/licenses/LICENSE-2.0). Check [`terminal-view`](terminal-view) and [`terminal-emulator`](terminal-emulator) libraries.
+- Check [`termux-shared/LICENSE.md`](termux-shared/LICENSE.md) for `termux-shared` library related exceptions.