[Android] Fixes #2228, reworked touch code

Lets Android take care of which is the primary pointer (the one acting as the
mouse in SDL), reorganized the Java side code as well to make it easier to
understand.

android-project/src/org/libsdl/app/SDLActivity.java

@@ -666,31 +666,48 @@ class SDLSurface extends SurfaceView implements SurfaceHolder.Callback,
     // Touch events
     @Override
     public boolean onTouch(View v, MotionEvent event) {
-             final int touchDevId = event.getDeviceId();
-             final int pointerCount = event.getPointerCount();
-             // touchId, pointerId, action, x, y, pressure
-             int actionPointerIndex = (event.getAction() & MotionEvent.ACTION_POINTER_ID_MASK) >> MotionEvent.ACTION_POINTER_ID_SHIFT; /* API 8: event.getActionIndex(); */
-             int pointerFingerId = event.getPointerId(actionPointerIndex);
-             int action = (event.getAction() & MotionEvent.ACTION_MASK); /* API 8: event.getActionMasked(); */
-
-             float x = event.getX(actionPointerIndex) / mWidth;
-             float y = event.getY(actionPointerIndex) / mHeight;
-             float p = event.getPressure(actionPointerIndex);
-
-             if (action == MotionEvent.ACTION_MOVE && pointerCount > 1) {
-                // TODO send motion to every pointer if its position has
-                // changed since prev event.
-                for (int i = 0; i < pointerCount; i++) {
+        /* Ref: http://developer.android.com/training/gestures/multi.html */
+        final int touchDevId = event.getDeviceId();
+        final int pointerCount = event.getPointerCount();
+        int action = event.getActionMasked();
+        int pointerFingerId;
+        int i = -1;
+        float x,y,p;
+        
+        switch(action) {
+            case MotionEvent.ACTION_MOVE:
+                for (i = 0; i < pointerCount; i++) {
                     pointerFingerId = event.getPointerId(i);
                     x = event.getX(i) / mWidth;
                     y = event.getY(i) / mHeight;
                     p = event.getPressure(i);
                     SDLActivity.onNativeTouch(touchDevId, pointerFingerId, action, x, y, p);
                 }
-             } else {
+                break;
+            
+            case MotionEvent.ACTION_UP:
+            case MotionEvent.ACTION_DOWN:
+                // Primary pointer up/down, the index is always zero
+                i = 0;
+            case MotionEvent.ACTION_POINTER_UP:
+            case MotionEvent.ACTION_POINTER_DOWN:
+                // Non primary pointer up/down
+                if (i == -1) {
+                    i = event.getActionIndex();
+                }
+                
+                pointerFingerId = event.getPointerId(i);
+                x = event.getX(i) / mWidth;
+                y = event.getY(i) / mHeight;
+                p = event.getPressure(i);
                 SDLActivity.onNativeTouch(touchDevId, pointerFingerId, action, x, y, p);
-             }
-      return true;
+                break;
+            
+            default:
+                break;
+        }
+
+        return true;
    } 
 
     // Sensor events

src/video/android/SDL_androidtouch.c

@@ -38,11 +38,8 @@
 #define ACTION_MOVE 2
 #define ACTION_CANCEL 3
 #define ACTION_OUTSIDE 4
-/* The following two are deprecated but it seems they are still emitted (instead the corresponding ACTION_UP/DOWN) as of Android 3.2 */
-#define ACTION_POINTER_1_DOWN 5
-#define ACTION_POINTER_1_UP 6
-
-static SDL_FingerID leftFingerDown = 0;
+#define ACTION_POINTER_DOWN 5
+#define ACTION_POINTER_UP 6
 
 static void Android_GetWindowCoordinates(float x, float y,
                                          int *window_x, int *window_y)
@@ -72,6 +69,7 @@ void Android_OnTouch(int touch_device_id_in, int pointer_finger_id_in, int actio
     SDL_TouchID touchDeviceId = 0;
     SDL_FingerID fingerId = 0;
     int window_x, window_y;
+    static SDL_FingerID pointerFingerID = 0;
 
     if (!Android_Window) {
         return;
@@ -85,22 +83,20 @@ void Android_OnTouch(int touch_device_id_in, int pointer_finger_id_in, int actio
     fingerId = (SDL_FingerID)pointer_finger_id_in;
     switch (action) {
         case ACTION_DOWN:
-        case ACTION_POINTER_1_DOWN:
-            if (!leftFingerDown) {
-                Android_GetWindowCoordinates(x, y, &window_x, &window_y);
-
-                /* send moved event */
-                SDL_SendMouseMotion(NULL, SDL_TOUCH_MOUSEID, 0, window_x, window_y);
-
-                /* send mouse down event */
-                SDL_SendMouseButton(NULL, SDL_TOUCH_MOUSEID, SDL_PRESSED, SDL_BUTTON_LEFT);
-
-                leftFingerDown = fingerId;
-            }
+            /* Primary pointer down */
+            Android_GetWindowCoordinates(x, y, &window_x, &window_y);
+            /* send moved event */
+            SDL_SendMouseMotion(NULL, SDL_TOUCH_MOUSEID, 0, window_x, window_y);
+            /* send mouse down event */
+            SDL_SendMouseButton(NULL, SDL_TOUCH_MOUSEID, SDL_PRESSED, SDL_BUTTON_LEFT);
+            pointerFingerID = fingerId;
+        case ACTION_POINTER_DOWN:
+            /* Non primary pointer down */
             SDL_SendTouch(touchDeviceId, fingerId, SDL_TRUE, x, y, p);
             break;
+            
         case ACTION_MOVE:
-            if (!leftFingerDown) {
+            if (!pointerFingerID) {
                 Android_GetWindowCoordinates(x, y, &window_x, &window_y);
 
                 /* send moved event */
@@ -108,15 +104,17 @@ void Android_OnTouch(int touch_device_id_in, int pointer_finger_id_in, int actio
             }
             SDL_SendTouchMotion(touchDeviceId, fingerId, x, y, p);
             break;
+            
         case ACTION_UP:
-        case ACTION_POINTER_1_UP:
-            if (fingerId == leftFingerDown) {
-                /* send mouse up */
-                SDL_SendMouseButton(NULL, SDL_TOUCH_MOUSEID, SDL_RELEASED, SDL_BUTTON_LEFT);
-                leftFingerDown = 0;
-            }
+            /* Primary pointer up */
+            /* send mouse up */
+            pointerFingerID = (SDL_FingerID) 0;
+            SDL_SendMouseButton(NULL, SDL_TOUCH_MOUSEID, SDL_RELEASED, SDL_BUTTON_LEFT);
+        case ACTION_POINTER_UP:
+            /* Non primary pointer up */
             SDL_SendTouch(touchDeviceId, fingerId, SDL_FALSE, x, y, p);
             break;
+            
         default:
             break;
     }