enhancement(LorieView.java): improve input handling

app/src/main/cpp/lorie/activity.c

@@ -26,7 +26,7 @@ extern volatile int conn_fd; // The only variable from shared with X server code
 
 static struct {
     jclass self;
-    jmethodID getInstance, clientConnectedStateChanged;
+    jmethodID getInstance, clientConnectedStateChanged, resetIme;
 } MainActivity = {0};
 
 static struct {
@@ -115,6 +115,7 @@ static void nativeInit(JNIEnv *env, jobject thiz) {
         MainActivity.self = FindClassOrDie(env,  "com/termux/x11/MainActivity");
         MainActivity.getInstance = FindMethodOrDie(env, MainActivity.self, "getInstance", "()Lcom/termux/x11/MainActivity;", JNI_TRUE);
         MainActivity.clientConnectedStateChanged = FindMethodOrDie(env, MainActivity.self, "clientConnectedStateChanged", "()V", JNI_FALSE);
+        MainActivity.resetIme = FindMethodOrDie(env, (*env)->GetObjectClass(env, thiz), "resetIme", "()V", JNI_FALSE);
     }
 
     (*env)->GetJavaVM(env, &vm);
@@ -205,6 +206,9 @@ static int xcallback(int fd, int events, __unused void* data) {
 #endif
                     LorieBuffer_release(buffer);
                 }
+                case EVENT_WINDOW_FOCUS_CHANGED: {
+                    (*env)->CallVoidMethod(env, thiz, MainActivity.resetIme);
+                }
             }
         }
 
@@ -290,6 +294,8 @@ static void sendWindowChange(__unused JNIEnv* env, __unused jobject cls, jint wi
 
 static void sendMouseEvent(__unused JNIEnv* env, __unused jobject cls, jfloat x, jfloat y, jint which_button, jboolean button_down, jboolean relative) {
     if (conn_fd != -1) {
+        if (which_button > 0)
+            (*env)->CallVoidMethod(env, globalThiz, MainActivity.resetIme);
         lorieEvent e = { .mouse = { .t = EVENT_MOUSE, .x = x, .y = y, .detail = which_button, .down = button_down, .relative = relative } };
         write(conn_fd, &e, sizeof(e));
     }
@@ -306,6 +312,7 @@ static void sendStylusEvent(__unused JNIEnv *env, __unused jobject thiz, jfloat
                             jint pressure, jint tilt_x, jint tilt_y,
                             jint orientation, jint buttons, jboolean eraser, jboolean mouse) {
     if (conn_fd != -1) {
+        (*env)->CallVoidMethod(env, globalThiz, MainActivity.resetIme);
         lorieEvent e = { .stylus = { .t = EVENT_STYLUS, .x = x, .y = y, .pressure = pressure, .tilt_x = tilt_x, .tilt_y = tilt_y, .orientation = orientation, .buttons = buttons, .eraser = eraser, .mouse = mouse } };
         write(conn_fd, &e, sizeof(e));
     }
@@ -320,6 +327,7 @@ static void requestStylusEnabled(__unused JNIEnv *env, __unused jclass clazz, jb
 
 static jboolean sendKeyEvent(__unused JNIEnv* env, __unused jobject cls, jint scan_code, jint key_code, jboolean key_down) {
     if (conn_fd != -1) {
+        (*env)->CallVoidMethod(env, globalThiz, MainActivity.resetIme);
         int code = (scan_code) ?: android_to_linux_keycode[key_code];
         log(DEBUG, "Sending key: %d (%d %d %d)", code + 8, scan_code, key_code, key_down);
         lorieEvent e = { .key = { .t = EVENT_KEY, .key = code + 8, .state = key_down } };
@@ -358,7 +366,7 @@ static void sendTextEvent(JNIEnv *env, __unused jobject thiz, jbyteArray text) {
             p += len;
             if (p - (char*) str >= length)
                 break;
-            usleep(30000);
+            usleep(2500);
         }
 
         (*env)->ReleaseByteArrayElements(env, text, str, JNI_ABORT);

app/src/main/cpp/lorie/cmdentrypoint.c

@@ -437,6 +437,13 @@ void lorieSendRootWindowBuffer(LorieBuffer* buffer) {
     }
 }
 
+void DDXNotifyFocusChanged(void) {
+    if (conn_fd != -1) {
+        lorieEvent e = { .type = EVENT_WINDOW_FOCUS_CHANGED };
+        write(conn_fd, &e, sizeof(e));
+    }
+}
+
 JNIEXPORT jobject JNICALL
 Java_com_termux_x11_CmdEntryPoint_getXConnection(JNIEnv *env, __unused jobject cls) {
     int client[2];

app/src/main/cpp/lorie/lorie.h

@@ -104,6 +104,7 @@ typedef enum {
     EVENT_CLIPBOARD_ANNOUNCE,
     EVENT_CLIPBOARD_REQUEST,
     EVENT_CLIPBOARD_SEND,
+    EVENT_WINDOW_FOCUS_CHANGED,
 } eventType;
 
 typedef union {

app/src/main/cpp/patches/xserver.patch

@@ -299,3 +299,23 @@ index f9b7b06d9..f4b2aeddc 100644
 
      /* display is initialized to "0" by main(). It is then set to the display
       * number if specified on the command line. */
++++ b/dix/enterleave.c
+@@ -1540,6 +1540,8 @@ DeviceFocusEvents(DeviceIntPtr dev, WindowPtr from, WindowPtr to, int mode)
+     }
+ }
+
++extern void DDXNotifyFocusChanged(void);
++
+ /**
+  * Figure out if focus events are necessary and send them to the
+  * appropriate windows.
+@@ -1550,6 +1552,9 @@ DeviceFocusEvents(DeviceIntPtr dev, WindowPtr from, WindowPtr to, int mode)
+ void
+ DoFocusEvents(DeviceIntPtr pDev, WindowPtr from, WindowPtr to, int mode)
+ {
++    if (from != to)
++        DDXNotifyFocusChanged();
++
+     if (!IsKeyboardDevice(pDev))
+         return;
+

app/src/main/java/com/termux/x11/LorieView.java

@@ -24,17 +24,18 @@
 import android.view.inputmethod.EditorInfo;
 import android.view.inputmethod.InputConnection;
 import android.view.inputmethod.InputMethodManager;
-import android.view.inputmethod.InputMethodSubtype;
+import android.view.inputmethod.TextSnapshot;
 
 import androidx.annotation.Keep;
 import androidx.annotation.NonNull;
 
 import com.termux.x11.input.InputStub;
 import com.termux.x11.input.TouchInputHandler;
 
-import java.nio.charset.StandardCharsets;
 import java.util.regex.PatternSyntaxException;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
+
 import dalvik.annotation.optimization.CriticalNative;
 import dalvik.annotation.optimization.FastNative;
 
@@ -54,11 +55,77 @@ interface PixelFormat {
     private static boolean clipboardSyncEnabled = false;
     private static boolean hardwareKbdScancodesWorkaround = false;
     private final InputMethodManager mIMM = (InputMethodManager)getContext().getSystemService(Context.INPUT_METHOD_SERVICE);
-    private String mImeLang;
-    private boolean mImeCJK;
-    public boolean enableGboardCJK;
     private Callback mCallback;
     private final Point p = new Point();
+    CharSequence currentComposingText = null;
+    private final InputConnection mConnection = new BaseInputConnection(this, true) {
+        private final MainActivity a = MainActivity.getInstance();
+        private final CharSequence seq = "        ";
+
+        @Override public Editable getEditable() {
+            return null;
+        }
+
+        // Needed to send arrow keys with IME's cursor control feature
+        @Override public CharSequence getTextBeforeCursor(int length, int flags) { return seq; }
+        @Override public CharSequence getTextAfterCursor(int length, int flags) { return seq; }
+        @Override public boolean setComposingRegion(int start, int end) { return true; }
+
+        void sendKey(int k) {
+            LorieView.this.sendKeyEvent(0, k, true);
+            LorieView.this.sendKeyEvent(0, k, false);
+        }
+
+        @Override public boolean deleteSurroundingText(int beforeLength, int afterLength) {
+            for (int i=0; i<beforeLength; i++) sendKey(KeyEvent.KEYCODE_DEL);
+            for (int i=0; i<afterLength; i++) sendKey(KeyEvent.KEYCODE_FORWARD_DEL);
+            return true;
+        }
+
+        /**
+         * X server itself does not provide any way to compose text.
+         * But we can simply send text we want and erase it in the case if user does not need it.
+         *
+         * @noinspection SameReturnValue*/
+        boolean replaceText(CharSequence newText, boolean reuse) {
+            int oldLen = currentComposingText != null ? currentComposingText.length() : 0;
+            int newLen = newText != null ? newText.length() : 0;
+            if (oldLen > 0 && newLen > 0 && (currentComposingText.toString().startsWith(newText.toString())
+                    || newText.toString().startsWith(currentComposingText.toString()))) {
+                for (int i=0; i < oldLen - newLen; i++)
+                    sendKey(KeyEvent.KEYCODE_DEL);
+                for (int i=oldLen; i<newLen; i++)
+                    sendTextEvent(String.valueOf(newText.charAt(i)).getBytes(UTF_8));
+            } else {
+                for (int i = 0; i < oldLen; i++)
+                    sendKey(KeyEvent.KEYCODE_DEL);
+                if (newText != null)
+                    sendTextEvent(newText.toString().getBytes(UTF_8));
+            }
+
+            currentComposingText = reuse ? newText : null;
+
+            if (a.useTermuxEKBarBehaviour && a.mExtraKeys != null)
+                a.mExtraKeys.unsetSpecialKeys();
+            return true;
+        }
+
+        @Override public boolean setComposingText(CharSequence text, int newCursorPosition) {
+            return replaceText(text, true);
+        }
+
+        @Override
+        public boolean commitText(CharSequence text, int newCursorPosition) {
+            return replaceText(text, false);
+        }
+
+        @Override
+        public boolean finishComposingText() {
+            // We do not implement real composing, so no need to finish it.
+            currentComposingText = null;
+            return true;
+        }
+    };
     private final SurfaceHolder.Callback mSurfaceCallback = new SurfaceHolder.Callback() {
         @Override public void surfaceCreated(@NonNull SurfaceHolder holder) {
             holder.setFormat(PixelFormat.BGRA_8888);
@@ -235,8 +302,6 @@ public void reloadPreferences(Prefs p) {
         clipboardSyncEnabled = p.clipboardEnable.get();
         setClipboardSyncEnabled(clipboardSyncEnabled, clipboardSyncEnabled);
         TouchInputHandler.refreshInputDevices();
-        enableGboardCJK = p.enableGboardCJK.get();
-        mIMM.restartInput(this);
     }
 
     // It is used in native code
@@ -252,14 +317,14 @@ void setClipboardText(String text) {
     /** @noinspection unused*/ // It is used in native code
     void requestClipboard() {
         if (!clipboardSyncEnabled) {
-            sendClipboardEvent("".getBytes(StandardCharsets.UTF_8));
+            sendClipboardEvent("".getBytes(UTF_8));
             return;
         }
 
         CharSequence clip = clipboard.getText();
         if (clip != null) {
             String text = String.valueOf(clipboard.getText());
-            sendClipboardEvent(text.getBytes(StandardCharsets.UTF_8));
+            sendClipboardEvent(text.getBytes(UTF_8));
             Log.d("CLIP", "sending clipboard contents: " + text);
         }
     }
@@ -298,67 +363,32 @@ public void onWindowFocusChanged(boolean hasFocus) {
         TouchInputHandler.refreshInputDevices();
     }
 
-    public void checkRestartInput(boolean recheck) {
-        if (!enableGboardCJK)
-            return;
-
-        InputMethodSubtype methodSubtype = mIMM.getCurrentInputMethodSubtype();
-        String languageTag = methodSubtype == null ? null : methodSubtype.getLanguageTag();
-        if (languageTag != null && languageTag.length() >= 2 && !languageTag.substring(0, 2).equals(mImeLang))
-            mIMM.restartInput(this);
-        else if (recheck) { // recheck needed because sometimes requestCursorUpdates() is called too fast, before InputMethodManager detect change in IM subtype
-            MainActivity.handler.postDelayed(() -> checkRestartInput(false), 40);
-        }
-    }
-
     @Override
     public InputConnection onCreateInputConnection(EditorInfo outAttrs) {
-        outAttrs.inputType = InputType.TYPE_CLASS_TEXT | InputType.TYPE_TEXT_FLAG_NO_SUGGESTIONS | InputType.TYPE_TEXT_VARIATION_VISIBLE_PASSWORD;
-
+        outAttrs.inputType = InputType.TYPE_CLASS_TEXT | InputType.TYPE_TEXT_FLAG_NO_SUGGESTIONS | InputType.TYPE_TEXT_VARIATION_NORMAL;
+        outAttrs.actionLabel = "↵";
         // Note that IME_ACTION_NONE cannot be used as that makes it impossible to input newlines using the on-screen
         // keyboard on Android TV (see https://github.com/termux/termux-app/issues/221).
         outAttrs.imeOptions = EditorInfo.IME_FLAG_NO_FULLSCREEN;
+        return mConnection;
+    }
 
-        if (enableGboardCJK) {
-            InputMethodSubtype methodSubtype = mIMM.getCurrentInputMethodSubtype();
-            mImeLang = methodSubtype == null ? null : methodSubtype.getLanguageTag();
-            if (mImeLang != null && mImeLang.length() > 2)
-                mImeLang = mImeLang.substring(0, 2);
-            mImeCJK = mImeLang != null && (mImeLang.equals("zh") || mImeLang.equals("ko") || mImeLang.equals("ja"));
-            outAttrs.inputType = InputType.TYPE_CLASS_TEXT | InputType.TYPE_TEXT_FLAG_NO_SUGGESTIONS |
-                    (mImeCJK ? InputType.TYPE_TEXT_VARIATION_NORMAL : InputType.TYPE_TEXT_VARIATION_VISIBLE_PASSWORD);
-            return new BaseInputConnection(this, false) {
-                // workaround for Gboard
-                // Gboard calls requestCursorUpdates() whenever switching language
-                // check and then restart keyboard in different inputType when needed
-                @Override
-                public Editable getEditable() {
-                    checkRestartInput(true);
-                    return super.getEditable();
-                }
-                @Override
-                public boolean requestCursorUpdates(int cursorUpdateMode) {
-                    checkRestartInput(true);
-                    return super.requestCursorUpdates(cursorUpdateMode);
-                }
+    /**
+     * Unfortunately there is no direct way to focus inside X windows.
+     * As a workaround we will reset IME on X window focus change and any user interaction
+     * with LorieView except sending text (Unicode) and mouse movements.
+     * We must reset IME to get rid of pending composing, autocomplete and other status related stuff.
+     * It is called from native code, not from Java.
+     * @noinspection unused
+     */
+    @Keep void resetIme() {
+        if (currentComposingText == null)
+            return;
 
-                @Override
-                public boolean commitText(CharSequence text, int newCursorPosition) {
-                    boolean result = super.commitText(text, newCursorPosition);
-                    if (mImeCJK)
-                        // suppress Gboard CJK keyboard suggestion
-                        // this workaround does not work well for non-CJK keyboards
-                        // , when typing fast and two keypresses (commitText) are close in time
-                        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU)
-                            mIMM.invalidateInput(LorieView.this);
-                        else
-                            mIMM.restartInput(LorieView.this);
-                    return result;
-                }
-            };
-        } else {
-            return super.onCreateInputConnection(outAttrs);
-        }
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU)
+            mIMM.invalidateInput(this);
+        else
+            mIMM.restartInput(this);
     }
 
     static native boolean renderingInActivity();

app/src/main/java/com/termux/x11/MainActivity.java

@@ -90,7 +90,7 @@ public class MainActivity extends AppCompatActivity implements View.OnApplyWindo
     private static boolean externalKeyboardConnected = false;
     private View.OnKeyListener mLorieKeyListener;
     private boolean filterOutWinKey = false;
-    private boolean useTermuxEKBarBehaviour = false;
+    boolean useTermuxEKBarBehaviour = false;
     private boolean isInPictureInPictureMode = false;
 
     public static Prefs prefs = null;
@@ -232,7 +232,6 @@ else if (SamsungDexUtils.checkDeXEnabled(this))
         onPreferencesChanged("");
 
         toggleExtraKeys(false, false);
-        checkRestartInput();
 
         initStylusAuxButtons();
         initMouseAuxButtons();
@@ -879,15 +878,6 @@ public static boolean isConnected() {
         return LorieView.connected();
     }
 
-    private void checkRestartInput() {
-        // an imperfect workaround for Gboard CJK keyboard in DeX soft keyboard mode
-        // in that particular mode during language switching, InputConnection#requestCursorUpdates() is not called and no signal can be picked up. 
-        // therefore, check to activate CJK keyboard is done upon a keypress.  
-        if (getLorieView().enableGboardCJK && SamsungDexUtils.checkDeXEnabled(this))
-            getLorieView().checkRestartInput(false);
-        handler.postDelayed(this::checkRestartInput, 300);
-    }
-
     public static void getRealMetrics(DisplayMetrics m) {
         if (getInstance() != null &&
                 getInstance().getLorieView() != null &&

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

@@ -84,8 +84,6 @@ E.g. <b>META</b> for <i>META key</i>, \n
     <string name="pref_pauseKeyInterceptingWithEsc">Pause key intercepting with Esc key</string>
     <string name="pref_filterOutWinkey">Filter out intercepted Win (Meta/Mod4) key.</string>
     <string name="pref_filterOutWinkey_summary">Allows you to use Dex shortcuts while intercepting. Requires Accessibility service to work.</string>
-    <string name="pref_enableGboardCJK">Workaround to enable CJK Gboard</string>
-    <string name="pref_enableGboardCJK_summary">May require Android 14 and Gboard 14</string>
 
     <string name="pref_clipboardEnable">Clipboard sharing</string>
     <string name="pref_requestNotificationPermission">Request notification permission</string>

app/src/main/res/xml/preferences.xml

@@ -49,7 +49,6 @@
         <SwitchPreferenceCompat app:key="enableAccessibilityServiceAutomatically" app:defaultValue="false" />
         <SwitchPreferenceCompat app:key="pauseKeyInterceptingWithEsc" app:defaultValue="false" />
         <SwitchPreferenceCompat app:key="filterOutWinkey" app:defaultValue="false" />
-        <SwitchPreferenceCompat app:key="enableGboardCJK" app:defaultValue="false" />
     </PreferenceScreen>
     <PreferenceScreen app:key="other">
         <SwitchPreferenceCompat app:key="clipboardEnable" app:defaultValue="true" />