Android GestureListener gesture, multi-finger Scaling

Note:
1. onDown multi-point events still respond to single-point events
2. triggered when onScroll slides, e1 can only get one point, while e2 can get more points. (I don't know why)
3. Add GestureListener to the view.
You can use the following code:
Public class ViewerInnerTouchListener implements OnTouchListener {

Private GestureDetector gestureDetector;

Public ViewerInnerTouchListener (GAViewer viewer ){
GestureDetector = new GestureDetector (new GestureListener (viewer ));
}

Public boolean onTouch (View v, MotionEvent event ){
GestureDetector. onTouchEvent (event );
Return true;
}

}

SetOnTouchListener (new ViewerInnerTouchListener (this ));

Several methods of GestureListener should be understood
// Triggered when the Touch is down, whether it is touch (including long) or scroll
Public boolean onDown (MotionEvent e ){
Return false;
}

// Triggered when Touch is not sliding
// (Compare with onDown and onLongPress
// OnDown must be triggered immediately as long as Touch down.
Public void onShowPress (MotionEvent e ){
}

// Triggered when Touch is down without moving
// After Touchdown, it will trigger onShowPress before onLongPress after a while without sliding.
Public void onLongPress (MotionEvent e ){
}

// The above two functions are triggered when the touch is down without moving (onScroll) or long-pressed (onLongPress.
/**
* Click very fast (do not slide) Touchup: onDown-> onSingleTapUp-> onSingleTapConfirmed
*
Click a slower (do not slide) Touchup: onDown-> onShowPress-> onSingleTapUp-> onSingleTapConfirmed
* Click longpress. onSingleTapUp is not triggered when onScroll is clicked.
*/
Public boolean onSingleTapUp (MotionEvent e ){
Log. I ("onSingleTapUp", "onSingleTapUp ");
Return false;
}

// Triggered when sliding is reached
Public boolean onScroll (MotionEvent e1, MotionEvent e2, float distanceX,
Float distanceY ){
Return true;
}

// Triggered when up is triggered when a sliding distance is reached.
Public boolean onFling (MotionEvent e1, MotionEvent e2, float velocityX,
Float velocityY ){
Return true;
}