android : Fix touchscreen for reals

Adds proper multitouch tracking for touchscreen

src/android/app/src/main/java/org/citra/citra_emu/NativeLibrary.java

@@ -96,8 +96,9 @@ public final class NativeLibrary {
      * @param x_axis  The value of the x-axis.
      * @param y_axis  The value of the y-axis
      * @param pressed To identify if the touch held down or released.
+     * @return true if the pointer is within the touchscreen
      */
-    public static native void onTouchEvent(float x_axis, float y_axis, boolean pressed);
+    public static native boolean onTouchEvent(float x_axis, float y_axis, boolean pressed);
 
     /**
      * Handles touch movement.

src/android/app/src/main/java/org/citra/citra_emu/overlay/InputOverlay.java

@@ -50,6 +50,8 @@ public final class InputOverlay extends SurfaceView implements OnTouchListener {
 
     private SharedPreferences mPreferences;
 
+    // Stores the ID of the pointer that interacted with the 3DS touchscreen.
+    private int mTouchscreenPointerId = -1;
     /**
      * Constructor
      *
@@ -64,6 +66,9 @@ public final class InputOverlay extends SurfaceView implements OnTouchListener {
             defaultOverlay();
         }
 
+        // Reset 3ds touchscreen pointer ID
+        mTouchscreenPointerId = -1;
+
         // Load the controls.
         refreshControls();
 
@@ -343,18 +348,26 @@ public final class InputOverlay extends SurfaceView implements OnTouchListener {
             switch (event.getAction() & MotionEvent.ACTION_MASK) {
                 case MotionEvent.ACTION_DOWN:
                 case MotionEvent.ACTION_POINTER_DOWN:
-                    NativeLibrary.onTouchEvent(event.getX(pointerIndex), event.getY(pointerIndex), true);
-                    break;
-                case MotionEvent.ACTION_MOVE:
-                    NativeLibrary.onTouchMoved(event.getX(), event.getY());
+                    if (NativeLibrary.onTouchEvent(event.getX(pointerIndex), event.getY(pointerIndex), true)) {
+                        mTouchscreenPointerId = event.getPointerId(pointerIndex);
+                    }
                     break;
                 case MotionEvent.ACTION_UP:
                 case MotionEvent.ACTION_POINTER_UP:
-                    // We dont really care where the touch has been released. We only care whether it has been
-                    // released or not.
-                    NativeLibrary.onTouchEvent(0, 0, false);
+                    if (mTouchscreenPointerId == event.getPointerId(pointerIndex)) {
+                        // We don't really care where the touch has been released. We only care whether it has been
+                        // released or not.
+                        NativeLibrary.onTouchEvent(0, 0, false);
+                        mTouchscreenPointerId = -1;
+                    }
                     break;
             }
+
+            for (int i = 0; i < event.getPointerCount(); i++) {
+                if (mTouchscreenPointerId == event.getPointerId(i)) {
+                    NativeLibrary.onTouchMoved(event.getX(i), event.getY(i));
+                }
+            }
         }
 
         for (InputOverlayDrawableButton button : overlayButtons) {

src/android/app/src/main/jni/emu_window/emu_window.cpp

@@ -81,12 +81,13 @@ void EmuWindow_Android::OnSurfaceChanged(ANativeWindow* surface) {
     render_window = surface;
 }
 
-void EmuWindow_Android::OnTouchEvent(int x, int y, bool pressed) {
+bool EmuWindow_Android::OnTouchEvent(int x, int y, bool pressed) {
     if (pressed) {
-        TouchPressed((unsigned)std::max(x, 0), (unsigned)std::max(y, 0));
-    } else {
-        TouchReleased();
+        return TouchPressed((unsigned)std::max(x, 0), (unsigned)std::max(y, 0));
     }
+
+    TouchReleased();
+    return true;
 }
 
 void EmuWindow_Android::OnTouchMoved(int x, int y) {

src/android/app/src/main/jni/emu_window/emu_window.h

@@ -42,7 +42,7 @@ public:
     void OnSurfaceChanged(ANativeWindow* surface);
 
     /// Handles touch event that occur.(Touched or released)
-    void OnTouchEvent(int x, int y, bool pressed);
+    bool OnTouchEvent(int x, int y, bool pressed);
 
     /// Handles movement of touch pointer
     void OnTouchMoved(int x, int y);

src/android/app/src/main/jni/native.cpp

@@ -351,10 +351,10 @@ jboolean Java_org_citra_citra_1emu_NativeLibrary_onGamePadAxisEvent(JNIEnv* env,
         InputManager::ButtonHandler()->AnalogButtonEvent(axis_id, axis_val));
 }
 
-void Java_org_citra_citra_1emu_NativeLibrary_onTouchEvent(JNIEnv* env,
+jboolean Java_org_citra_citra_1emu_NativeLibrary_onTouchEvent(JNIEnv* env,
                                                           [[maybe_unused]] jclass clazz, jfloat x,
                                                           jfloat y, jboolean pressed) {
-    window->OnTouchEvent((int)x, (int)y, (bool)pressed);
+    return static_cast<jboolean>(window->OnTouchEvent(static_cast<int>(x + 0.5), static_cast<int>(y + 0.5), pressed));
 }
 
 void Java_org_citra_citra_1emu_NativeLibrary_onTouchMoved(JNIEnv* env,

src/android/app/src/main/jni/native.h

@@ -32,7 +32,7 @@ JNIEXPORT jboolean JNICALL Java_org_citra_citra_1emu_NativeLibrary_onGamePadMove
 JNIEXPORT jboolean JNICALL Java_org_citra_citra_1emu_NativeLibrary_onGamePadAxisEvent(
     JNIEnv* env, jclass clazz, jstring j_device, jint axis_id, jfloat axis_val);
 
-JNIEXPORT void JNICALL Java_org_citra_citra_1emu_NativeLibrary_onTouchEvent(JNIEnv* env,
+JNIEXPORT jboolean JNICALL Java_org_citra_citra_1emu_NativeLibrary_onTouchEvent(JNIEnv* env,
                                                                             jclass clazz, jfloat x,
                                                                             jfloat y,
                                                                             jboolean pressed);