2点触摸事件

 private boolean isZoom = false;
 private float oldDist;
    private float spacing(MotionEvent event) {
        float x = event.getX(0) - event.getX(1);
        float y = event.getY(0) - event.getY(1);
        return FloatMath.sqrt(x * x + y * y);
    }
 
 @Override
 public boolean onTouchEvent(MotionEvent event) {
  super.onTouchEvent(event);
  getCurrentInfo();
  
        switch (event.getAction() & MotionEvent.ACTION_MASK) {
        case MotionEvent.ACTION_DOWN:
            break;
        case MotionEvent.ACTION_POINTER_UP:
            isZoom = false;
            break;
        case MotionEvent.ACTION_POINTER_DOWN:
            oldDist = spacing(event);
            isZoom = true;
            break;
        case MotionEvent.ACTION_MOVE:
            if (isZoom) {
                float newDist = spacing(event);

                if (newDist + 10 > oldDist) {
           MapUtil.MapzoomIn();
           setMainMapScale();
                }

                if (newDist + 10 < oldDist) {
           MapUtil.MapzoomOut();
           setMainMapScale();
                }
            }

            break;
        }
  
  return false;
 }