Android MotionEvent.getActionIndex() and MultiTouch

Question

I am trying to get the pointer id whene the event MotionEvent.ACTION_MOVE happens.

I am doing it by calling event.getActionIndex() but it always returns 0 for the second, the third, the forth and the fifth finger.

i am using Gingerbread 2.3.3 on Galaxy S I9000

here is my code

switch (event.getActionMasked()) {
case MotionEvent.ACTION_MOVE: {
    Log.d("D","  getActionIndex()="+event.getActionIndex());
    };break;
}

This is the debug results

05-02 19:20:08.628: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=1
05-02 19:20:08.781: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=1
05-02 19:20:08.820: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=1
05-02 19:20:08.914: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=1
05-02 19:20:09.070: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=2
05-02 19:20:09.187: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=2
05-02 19:20:09.324: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=2
05-02 19:20:09.460: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=2
05-02 19:20:09.523: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=2
05-02 19:20:09.542: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=2
05-02 19:20:09.679: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=3
05-02 19:20:09.703: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=3
05-02 19:20:09.847: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=3
05-02 19:20:10.117: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=3
05-02 19:20:10.261: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=4
05-02 19:20:10.281: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=4
05-02 19:20:10.304: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=4
05-02 19:20:10.371: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=4
05-02 19:20:10.410: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=4
05-02 19:20:10.433: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=4
05-02 19:20:10.519: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=4
05-02 19:20:10.558: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=4
05-02 19:20:10.613: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=3
05-02 19:20:10.640: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=2
05-02 19:20:10.656: DEBUG/D(4534): getActionIndex()=0  getPointerCount()=1

Triangle

Answer 1

I am using 3 methods to delegate the responsibility of the mouse events. It works fine on my 2.3 HTC Desire S. it is able to capture multiple touch events.

public void processMouseMove(int mouseX, int mouseY, int pid)
public void processMouseDown(int mouseX, int mouseY, int pid)
public void processMouseUp(int mouseX, int mouseY, int pid)


public boolean onTouch(View v, MotionEvent event) { 
    int p = event.getActionIndex();
    switch(event.getActionMasked()){
        case MotionEvent.ACTION_DOWN:
        case MotionEvent.ACTION_POINTER_DOWN:
            processMouseDown((int)event.getX(p), (int)event.getY(p), event.getPointerId(p));                
        break;              
        case MotionEvent.ACTION_POINTER_UP:                 
        case MotionEvent.ACTION_UP:
            processMouseUp((int)event.getX(p), (int)event.getY(p), event.getPointerId(p));
            break;
        case MotionEvent.ACTION_MOVE:
            final int historySize = event.getHistorySize();
            final int pointerCount = event.getPointerCount();
            for (int h = 0; h < historySize; h++) {
                 for (int p1 = 0; p1 < pointerCount; p1++) {
                    processMouseMove((int)event.getHistoricalX(p1, h), (int)event.getHistoricalY(p1, h), event.getPointerId(p1));
                 }
            }
            for (int p1 = 0; p1 < event.getPointerCount(); p1++) {

                processMouseMove((int)event.getX(p1), (int)event.getY(p1), event.getPointerId(p1));
            }
    }
    return true;
}

Lives

Answer 2

I am using this code to dump events, and it works pretty well.

/** Show an event in the LogCat view, for debugging */
private void dumpEvent(MotionEvent event) {
   String names[] = { "DOWN" , "UP" , "MOVE" , "CANCEL" , "OUTSIDE" ,
      "POINTER_DOWN" , "POINTER_UP" , "7?" , "8?" , "9?" };
   StringBuilder sb = new StringBuilder();
   int action = event.getAction();
   int actionCode = action & MotionEvent.ACTION_MASK;
   sb.append("event ACTION_" ).append(names[actionCode]);
   if (actionCode == MotionEvent.ACTION_POINTER_DOWN
         || actionCode == MotionEvent.ACTION_POINTER_UP) {
      sb.append("(pid " ).append(
      action >> MotionEvent.ACTION_POINTER_ID_SHIFT);
      sb.append(")" );
   }
   sb.append("[" );
   for (int i = 0; i < event.getPointerCount(); i++) {
      sb.append("#" ).append(i);
      sb.append("(pid " ).append(event.getPointerId(i));
      sb.append(")=" ).append((int) event.getX(i));
      sb.append("," ).append((int) event.getY(i));
      if (i + 1 < event.getPointerCount())
         sb.append(";" );
   }
   sb.append("]" );
   Log.d(TAG, sb.toString());
}

I got it off this ZDNET article, so I can't take credit for it. I am running on Android 3.0, but the example code was originally written for earlier versions of Android, so it should work for you too.

It looks like you need to call getPointerId rather than getActionIndex.

Perverse

The code is from here – Perverse

Thank you Jim, i used the code you provided me, and it works pretty well except it does not provide the pointer id causing the ACTION_MOVE event, this is what i got (05-02 20:15:38.863: DEBUG/MTView(5033): event ACTION_MOVE[#0(pid 0)=61,52;#1(pid 1)=265,360]), and (05-02 20:15:38.878: DEBUG/MTView(5033): event ACTION_MOVE[#0(pid 0)=61,52;#1(pid 1)=256,368]), given that i moved my second finger and those two events are consecutive. Thank you vey much Jim. – Triangle

You're welcome, and yeah, it doesn't tell you which finger caused the event. It just tells you the current position of each finger. You can, of course, infer which finger caused it if you compare the current positions to the previous positions. – Perverse

Yes, i think i should compare the positions. – Triangle

Answer 3

Use MotionEventCompat.

// get pointer index from the event object

int pointerIndex = MotionEventCompat.getActionIndex(event);

// get masked (not specific to a pointer) action

int maskedAction = MotionEventCompat.getActionMasked(event);

Immobility