fixes: termux#4281 - Treat Caps Lock as Ctrl on physical keyboard

Author: Workbench

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

@@ -62,6 +62,9 @@ public class TermuxTerminalViewClient extends TermuxTerminalViewClientBase {
     /** Keeping track of the special keys acting as Ctrl and Fn for the soft keyboard and other hardware keys. */
     boolean mVirtualControlKeyDown, mVirtualFnKeyDown;
 
+    /** Keeping track of whether Caps Lock is being treated as Ctrl (physical keyboard remap). */
+    boolean mCapsLockAsCtrl;
+
     private Runnable mShowSoftKeyboardRunnable;
 
     private boolean mShowSoftKeyboardIgnoreOnce;
@@ -322,7 +325,12 @@ private boolean handleVirtualKeys(int keyCode, KeyEvent event, boolean down) {
 
     @Override
     public boolean readControlKey() {
-        return readExtraKeysSpecialButton(SpecialButton.CTRL) || mVirtualControlKeyDown;
+        return readExtraKeysSpecialButton(SpecialButton.CTRL) || mVirtualControlKeyDown || mCapsLockAsCtrl;
+    }
+
+    @Override
+    public void setCapsLockAsCtrl(boolean down) {
+        mCapsLockAsCtrl = down;
     }
 
     @Override

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

@@ -784,6 +784,18 @@ public boolean onKeyDown(int keyCode, KeyEvent event) {
             return true;
         } else if (keyCode == KeyEvent.KEYCODE_LANGUAGE_SWITCH) {
             return super.onKeyDown(keyCode, event);
+        } else if (keyCode == KeyEvent.KEYCODE_ZENKAKU_HANKAKU ||
+                   keyCode == KeyEvent.KEYCODE_HENKAN ||
+                   keyCode == KeyEvent.KEYCODE_MUHENKAN ||
+                   keyCode == KeyEvent.KEYCODE_YEN ||
+                   keyCode == KeyEvent.KEYCODE_RO) {
+            return super.onKeyDown(keyCode, event);
+        } else if (keyCode == KeyEvent.KEYCODE_CAPS_LOCK) {
+            // Treat Caps Lock as Ctrl for physical keyboards where Caps Lock is
+            // remapped to Ctrl at the Android system level. Toggle virtual Ctrl state
+            // on key down and consume the event so it does not toggle Caps Lock LED.
+            mClient.setCapsLockAsCtrl(event.getAction() == KeyEvent.ACTION_DOWN);
+            return true;
         }
 
         final int metaState = event.getMetaState();
@@ -971,6 +983,10 @@ public boolean onKeyUp(int keyCode, KeyEvent event) {
             invalidate();
             return true;
         } else if (event.isSystem()) {
+            if (keyCode == KeyEvent.KEYCODE_CAPS_LOCK) {
+                // Reset the Caps Lock as Ctrl state on key up. (#4281)
+                mClient.setCapsLockAsCtrl(false);
+            }
             // Let system key events through.
             return super.onKeyUp(keyCode, event);
         }

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

@@ -52,6 +52,8 @@ public interface TerminalViewClient {
 
     boolean readControlKey();
 
+    void setCapsLockAsCtrl(boolean down);
+
     boolean readAltKey();
 
     boolean readShiftKey();