Titan 2 Elite: physical keyboard fix + streaming scroll-hold

- Only bubble real system keys (isSystem() synthetic letter events
  injected by the Titan 2 keyboard layer now reach the KCM path).
- Latch hardware Shift/Alt from modifier key events; injected letter
  events arrive without meta state. Cleared on keyup, focus loss and
  session attach.
- Consult the kcm alt layer for Alt+<key> (Alt+W -> '1') and send the
  resolved char without the ESC alt-prefix.
- Hold the scroll viewport when the user scrolled up while output is
  streaming; auto-follow resumes on scroll-to-bottom or typing.
- versionCode 1023 / versionName 0.119.0-titan2.1

app/build.gradle

@@ -43,8 +43,8 @@ android {
     defaultConfig {
         minSdkVersion project.properties.minSdkVersion.toInteger()
         targetSdkVersion project.properties.targetSdkVersion.toInteger()
-        versionCode 118
-        versionName "0.118.0"
+        versionCode 1023
+        versionName "0.119.0-titan2.1"
 
         if (appVersionName) versionName = appVersionName
         validateVersionName(versionName)

terminal-view/src/main/java/com/termux/view/TerminalView.java

@@ -68,6 +68,15 @@ public final class TerminalView extends View {
 
     /** The top row of text to display. Ranges from -activeTranscriptRows to 0. */
     int mTopRow;
+
+    /** TITAN2 PATCH: user scrolled away from the bottom; hold the viewport until they return. */
+    boolean mUserScrollLock;
+
+    /** TITAN2 PATCH: latched hardware Shift/Alt state. The Titan 2 keyboard layer re-injects
+     * synthetic key events (FLAG_FROM_SYSTEM) whose letter events often arrive without meta
+     * state, so the modifier state is tracked from the modifier key events themselves. */
+    boolean mHardwareShiftDown;
+    boolean mHardwareAltDown;
     int[] mDefaultSelectors = new int[]{-1,-1,-1,-1};
 
     float mScaleFactor = 1.f;
@@ -290,6 +299,9 @@ public final class TerminalView extends View {
     public boolean attachSession(TerminalSession session) {
         if (session == mTermSession) return false;
         mTopRow = 0;
+        mUserScrollLock = false; // TITAN2 PATCH
+        mHardwareShiftDown = false; // TITAN2 PATCH
+        mHardwareAltDown = false; // TITAN2 PATCH
 
         mTermSession = session;
         mEmulator = null;
@@ -479,6 +491,17 @@ public final class TerminalView extends View {
                 mTopRow -= rowShift;
                 decrementYTextSelectionCursors(rowShift);
             }
+        } else if (mUserScrollLock && mTopRow != 0) {
+            // TITAN2 PATCH: the user scrolled up, so hold the viewport instead of snapping
+            // back to the bottom on every screen update (e.g. while an app streams output).
+            // Keep the same content in view when new lines are appended.
+            int rowShift = mEmulator.getScrollCounter();
+            if (-mTopRow + rowShift > rowsInHistory) {
+                mTopRow = -rowsInHistory;
+            } else {
+                mTopRow -= rowShift;
+            }
+            skipScrolling = true;
         }
 
         if (!skipScrolling && mTopRow != 0) {
@@ -583,6 +606,9 @@ public final class TerminalView extends View {
                 handleKeyCode(up ? KeyEvent.KEYCODE_DPAD_UP : KeyEvent.KEYCODE_DPAD_DOWN, 0);
             } else {
                 mTopRow = Math.min(0, Math.max(-(mEmulator.getScreen().getActiveTranscriptRows()), mTopRow + (up ? -1 : 1)));
+                // TITAN2 PATCH: scrolling away from the bottom pauses auto-follow;
+                // scrolling back to the bottom (mTopRow == 0) resumes it.
+                mUserScrollLock = mTopRow != 0;
                 if (!awakenScrollBars()) invalidate();
             }
         }
@@ -770,6 +796,21 @@ public final class TerminalView extends View {
         if (TERMINAL_VIEW_KEY_LOGGING_ENABLED)
             mClient.logInfo(LOG_TAG, "onKeyDown(keyCode=" + keyCode + ", isSystem()=" + event.isSystem() + ", event=" + event + ")");
         if (mEmulator == null) return true;
+
+        // TITAN2 PATCH: latch hardware Shift/Alt state from the modifier key events
+        // themselves. The synthetic letter events injected by the Titan 2 keyboard layer
+        // are flagged FLAG_FROM_SYSTEM and often arrive without meta state.
+        switch (keyCode) {
+            case KeyEvent.KEYCODE_SHIFT_LEFT:
+            case KeyEvent.KEYCODE_SHIFT_RIGHT:
+                mHardwareShiftDown = true;
+                break;
+            case KeyEvent.KEYCODE_ALT_LEFT:
+            case KeyEvent.KEYCODE_ALT_RIGHT:
+                mHardwareAltDown = true;
+                break;
+        }
+
         if (isSelectingText()) {
             stopTextSelectionMode();
         }
@@ -777,7 +818,11 @@ public final class TerminalView extends View {
         if (mClient.onKeyDown(keyCode, event, mTermSession)) {
             invalidate();
             return true;
-        } else if (event.isSystem() && (!mClient.shouldBackButtonBeMappedToEscape() || keyCode != KeyEvent.KEYCODE_BACK)) {
+        } else if (event.isSystem() && isRealSystemKey(keyCode)
+                && (!mClient.shouldBackButtonBeMappedToEscape() || keyCode != KeyEvent.KEYCODE_BACK)) {
+            // TITAN2 PATCH: only bubble *real* system keys (back, home, volume, ...). The
+            // Titan 2 keyboard layer re-injects letter events with FLAG_FROM_SYSTEM, which
+            // must reach the KCM path below instead of being dropped on the activity.
             return super.onKeyDown(keyCode, event);
         } else if (event.getAction() == KeyEvent.ACTION_MULTIPLE && keyCode == KeyEvent.KEYCODE_UNKNOWN) {
             mTermSession.write(event.getCharacters());
@@ -788,8 +833,9 @@ public final class TerminalView extends View {
 
         final int metaState = event.getMetaState();
         final boolean controlDown = event.isCtrlPressed() || mClient.readControlKey();
-        final boolean leftAltDown = (metaState & KeyEvent.META_ALT_LEFT_ON) != 0 || mClient.readAltKey();
-        final boolean shiftDown = event.isShiftPressed() || mClient.readShiftKey();
+        // TITAN2 PATCH: also use the latched hardware modifier state (injected events lack meta).
+        final boolean leftAltDown = (metaState & KeyEvent.META_ALT_LEFT_ON) != 0 || mClient.readAltKey() || mHardwareAltDown;
+        final boolean shiftDown = event.isShiftPressed() || mClient.readShiftKey() || mHardwareShiftDown;
         final boolean rightAltDownFromEvent = (metaState & KeyEvent.META_ALT_RIGHT_ON) != 0;
 
         int keyMod = 0;
@@ -817,8 +863,19 @@ public final class TerminalView extends View {
         if (mClient.readFnKey()) effectiveMetaState |= KeyEvent.META_FUNCTION_ON;
 
         int result = event.getUnicodeChar(effectiveMetaState);
+        boolean altLayerUsed = false;
+        if (!rightAltDownFromEvent && leftAltDown && result != 0) {
+            // TITAN2 PATCH: consult the kcm alt layer (e.g. Alt+W -> '1' in TitanKey.kcm).
+            // The base lookup above strips left-alt from the meta state, so upstream never
+            // uses the alt layer and instead sends ESC + <char>.
+            int altLayerResult = event.getUnicodeChar(effectiveMetaState | KeyEvent.META_ALT_LEFT_ON | KeyEvent.META_ALT_ON);
+            if (altLayerResult != 0 && altLayerResult != result) {
+                result = altLayerResult;
+                altLayerUsed = true;
+            }
+        }
         if (TERMINAL_VIEW_KEY_LOGGING_ENABLED)
-            mClient.logInfo(LOG_TAG, "KeyEvent#getUnicodeChar(" + effectiveMetaState + ") returned: " + result);
+            mClient.logInfo(LOG_TAG, "KeyEvent#getUnicodeChar(" + effectiveMetaState + ") returned: " + result + (altLayerUsed ? " (kcm alt layer)" : ""));
         if (result == 0) {
             return false;
         }
@@ -835,7 +892,7 @@ public final class TerminalView extends View {
                 if (combinedChar > 0) result = combinedChar;
                 mCombiningAccent = 0;
             }
-            inputCodePoint(event.getDeviceId(), result, controlDown, leftAltDown);
+            inputCodePoint(event.getDeviceId(), result, controlDown, leftAltDown, altLayerUsed);
         }
 
         if (mCombiningAccent != oldCombiningAccent) invalidate();
@@ -844,6 +901,10 @@ public final class TerminalView extends View {
     }
 
     public void inputCodePoint(int eventSource, int codePoint, boolean controlDownFromEvent, boolean leftAltDownFromEvent) {
+        inputCodePoint(eventSource, codePoint, controlDownFromEvent, leftAltDownFromEvent, false);
+    }
+
+    public void inputCodePoint(int eventSource, int codePoint, boolean controlDownFromEvent, boolean leftAltDownFromEvent, boolean altConsumedByKcm) {
         if (TERMINAL_VIEW_KEY_LOGGING_ENABLED) {
             mClient.logInfo(LOG_TAG, "inputCodePoint(eventSource=" + eventSource + ", codePoint=" + codePoint + ", controlDownFromEvent=" + controlDownFromEvent + ", leftAltDownFromEvent="
                 + leftAltDownFromEvent + ")");
@@ -856,7 +917,11 @@ public final class TerminalView extends View {
             mEmulator.setCursorBlinkState(true);
 
         final boolean controlDown = controlDownFromEvent || mClient.readControlKey();
-        final boolean altDown = leftAltDownFromEvent || mClient.readAltKey();
+        // TITAN2 PATCH: if the kcm alt layer already produced the character (altConsumedByKcm),
+        // do not also send the ESC alt-prefix.
+        final boolean altDown = !altConsumedByKcm && (leftAltDownFromEvent || mClient.readAltKey());
+
+        mUserScrollLock = false; // TITAN2 PATCH: input returns the view to the live bottom
 
         if (mClient.onCodePoint(codePoint, controlDown, mTermSession)) return;
 
@@ -921,6 +986,7 @@ public final class TerminalView extends View {
         String code = KeyHandler.getCode(keyCode, keyMod, term.isCursorKeysApplicationMode(), term.isKeypadApplicationMode());
         if (code == null) return false;
         mTermSession.write(code);
+        mUserScrollLock = false; // TITAN2 PATCH: input returns the view to the live bottom
         return true;
     }
 
@@ -956,6 +1022,18 @@ public final class TerminalView extends View {
         if (TERMINAL_VIEW_KEY_LOGGING_ENABLED)
             mClient.logInfo(LOG_TAG, "onKeyUp(keyCode=" + keyCode + ", event=" + event + ")");
 
+        // TITAN2 PATCH: release latched hardware modifier state (see onKeyDown).
+        switch (keyCode) {
+            case KeyEvent.KEYCODE_SHIFT_LEFT:
+            case KeyEvent.KEYCODE_SHIFT_RIGHT:
+                mHardwareShiftDown = false;
+                break;
+            case KeyEvent.KEYCODE_ALT_LEFT:
+            case KeyEvent.KEYCODE_ALT_RIGHT:
+                mHardwareAltDown = false;
+                break;
+        }
+
         // Do not return for KEYCODE_BACK and send it to the client since user may be trying
         // to exit the activity.
         if (mEmulator == null && keyCode != KeyEvent.KEYCODE_BACK) return true;
@@ -971,6 +1049,60 @@ public final class TerminalView extends View {
         return true;
     }
 
+    @Override
+    public void onWindowFocusChanged(boolean hasWindowFocus) {
+        super.onWindowFocusChanged(hasWindowFocus);
+        // TITAN2 PATCH: drop latched hardware modifier state when focus is lost, in case
+        // the keyup was delivered elsewhere (app switch, notification shade, dialog, ...).
+        if (!hasWindowFocus) {
+            mHardwareShiftDown = false;
+            mHardwareAltDown = false;
+        }
+    }
+
+    /**
+     * TITAN2 PATCH: mirror of the @hide {@code KeyEvent.isSystemKey(int)}. Used to tell
+     * real system keys (back, home, volume, ...) apart from the synthetic letter events
+     * that the Titan 2 keyboard layer injects with FLAG_FROM_SYSTEM.
+     */
+    private static boolean isRealSystemKey(int keyCode) {
+        switch (keyCode) {
+            case KeyEvent.KEYCODE_MENU:
+            case KeyEvent.KEYCODE_SOFT_RIGHT:
+            case KeyEvent.KEYCODE_HOME:
+            case KeyEvent.KEYCODE_BACK:
+            case KeyEvent.KEYCODE_CALL:
+            case KeyEvent.KEYCODE_ENDCALL:
+            case KeyEvent.KEYCODE_VOLUME_UP:
+            case KeyEvent.KEYCODE_VOLUME_DOWN:
+            case KeyEvent.KEYCODE_MUTE:
+            case KeyEvent.KEYCODE_HEADSETHOOK:
+            case KeyEvent.KEYCODE_MEDIA_PLAY:
+            case KeyEvent.KEYCODE_MEDIA_PAUSE:
+            case KeyEvent.KEYCODE_MEDIA_PLAY_PAUSE:
+            case KeyEvent.KEYCODE_MEDIA_STOP:
+            case KeyEvent.KEYCODE_MEDIA_NEXT:
+            case KeyEvent.KEYCODE_MEDIA_PREVIOUS:
+            case KeyEvent.KEYCODE_MEDIA_REWIND:
+            case KeyEvent.KEYCODE_MEDIA_RECORD:
+            case KeyEvent.KEYCODE_MEDIA_FAST_FORWARD:
+            case KeyEvent.KEYCODE_CAMERA:
+            case KeyEvent.KEYCODE_FOCUS:
+            case KeyEvent.KEYCODE_SEARCH:
+            case KeyEvent.KEYCODE_BRIGHTNESS_DOWN:
+            case KeyEvent.KEYCODE_BRIGHTNESS_UP:
+            case KeyEvent.KEYCODE_MEDIA_AUDIO_TRACK:
+            case KeyEvent.KEYCODE_SLEEP:
+            case KeyEvent.KEYCODE_WAKEUP:
+            case KeyEvent.KEYCODE_VOICE_ASSIST:
+            case KeyEvent.KEYCODE_ASSIST:
+            case KeyEvent.KEYCODE_APP_SWITCH:
+                return true;
+            default:
+                return false;
+        }
+    }
+
     /**
      * This is called during layout when the size of this view has changed. If you were just added to the view
      * hierarchy, you're called with the old values of 0.
@@ -1000,6 +1132,7 @@ public final class TerminalView extends View {
                 mTerminalCursorBlinkerRunnable.setEmulator(mEmulator);
 
             mTopRow = 0;
+            mUserScrollLock = false; // TITAN2 PATCH
             scrollTo(0, 0);
             invalidate();
         }