rotation and scaling using multi touch in android

Question

i want to rotate and scale the image on multi touch event, i am able to drag, scale the image but i can\'t understand the rotation of image. i am facing problem so please he

Answer 1

   float[] lastEvent = null;
   float d = 0f;
   float newRot = 0f;
   @Override
   public boolean onTouch(View v, MotionEvent event) {
      ImageView view = (ImageView) v;

      // Dump touch event to log
      dumpEvent(event);

      // Handle touch events here...
      switch (event.getAction() & MotionEvent.ACTION_MASK) {
      case MotionEvent.ACTION_DOWN:
         savedMatrix.set(matrix);
     start.set(event.getX(), event.getY());
     if (Constant.TRACE) Log.d(TAG, "mode=DRAG");
     mode = DRAG;
     lastEvent = null;
     break;
  case MotionEvent.ACTION_POINTER_DOWN:
     oldDist = spacing(event);         
     savedMatrix.set(matrix);
     midPoint(mid, event);
     mode = ZOOM;
     if (Constant.TRACE) Log.d(TAG, "mode=ZOOM");

     lastEvent = new float[4];
     lastEvent[0] = event.getX(0);
     lastEvent[1] = event.getX(1);
     lastEvent[2] = event.getY(0);
     lastEvent[3] = event.getY(1);
     d = rotation(event);
     break;
  case MotionEvent.ACTION_UP:
  case MotionEvent.ACTION_POINTER_UP:
     mode = NONE;
     lastEvent = null;
     if (Constant.TRACE) Log.d(TAG, "mode=NONE");         
     break;
  case MotionEvent.ACTION_MOVE:
     if (mode == DRAG) {
        // ...
        matrix.set(savedMatrix);
        matrix.postTranslate(event.getX() - start.x, event.getY() - start.y);
     }
     else if (mode == ZOOM && event.getPointerCount()==2) {
        float newDist = spacing(event);
        if (Constant.TRACE) Log.d(TAG, "Count=" + event.getPointerCount());
        if (Constant.TRACE) Log.d(TAG, "newDist=" + newDist);
        matrix.set(savedMatrix);
        if (newDist > 10f) {              
           float scale = newDist / oldDist;
           matrix.postScale(scale, scale, mid.x, mid.y);
        } 
        if (lastEvent!=null){
            newRot = rotation(event); 
            if (Constant.TRACE) Log.d("Degreeeeeeeeeee", "newRot="+(newRot));
            float r = newRot-d;
            matrix.postRotate(r, imgView.getMeasuredWidth()/2, imgView.getMeasuredHeight()/2);  
        }
     }
     break;
  }

  view.setImageMatrix(matrix);
  return true; // indicate event was handled

}

/** Determine the degree between the first two fingers */
   private float rotation(MotionEvent event) {  
       double delta_x = (event.getX(0) - event.getX(1));
       double delta_y = (event.getY(0) - event.getY(1));
       double radians = Math.atan2(delta_y, delta_x);       
       if (Constant.TRACE) Log.d("Rotation ~~~~~~~~~~~~~~~~~", delta_x+" ## "+delta_y+" ## "+radians+" ## "
                        +Math.toDegrees(radians));
       return (float) Math.toDegrees(radians);
   }

Try this code, but remember some old phone have problem with rotation..