How to distinguish between drag and click in onTouchEvent()?

Question

I have a custom layout pinch zoom code as a parent and a child layout that handle the click feature. Therefore I use on touch intercept, but the problem is that with this it would not know when to click or drag.

 @Override
    public boolean onInterceptTouchEvent(MotionEvent ev){


    switch (ev.getAction() & MotionEvent.ACTION_MASK) {
        case MotionEvent.ACTION_DOWN:
            startClickTime = System.currentTimeMillis(); //start time when first finger land
            Log.i("Zoom", " actionDown");
            if ( scale > MIN_ZOOM){
                mode = Mode.DRAG;
                startX = ev.getX() - prevDx;
                startY = ev.getY() - prevDy;
            }
            return false; //go to child layout

        case MotionEvent.ACTION_POINTER_DOWN:
            mode = Mode.ZOOM;
            return true;

        case MotionEvent.ACTION_UP:
            long clickDuration = System.currentTimeMillis() - startClickTime;
            mode = Mode.NONE;
            if(clickDuration < MAX_CLICK_DURATION){
                return false;
            }
            else {
                // letting go from drag or zooming
                return true;
            }

        case MotionEvent.ACTION_MOVE:
            clickDuration = System.currentTimeMillis() - startClickTime;
            if (clickDuration > MAX_CLICK_DURATION){
                return true;
            }
            else {
                return false;
            }
    }
    return false;
}

In my child layout for click feature:

switch (motionEvent.getAction() & MotionEvent.ACTION_MASK) {

                case MotionEvent.ACTION_DOWN:
                        // primary finger down
                     return true;

                case MotionEvent.ACTION_POINTER_DOWN:
                        // non-primary finger down
                    return false;

                case MotionEvent.ACTION_CANCEL:
                    return false;

                case MotionEvent.ACTION_UP:
                    // primary finder up
                    Intent intent = new Intent(context, DeviceActivity.class);
                    context.startActivity(intent);
                    return true;

                case MotionEvent.ACTION_POINTER_UP:
                    // non-primary finger up
                    return false;
            }

So is there a way to distinguish drag and click.

score 0 · Answer 1 · answered Jul 08 '16 at 09:20

There are four states in a click and drag events: Started -> Continuing -> Dropped -> Ended

The DragEvent class provides integers representing them:

ACTION_DRAG_STARTED
ACTION_DRAG_ENTERED
ACTION_DRAG_LOCATION
ACTION_DRAG_EXITED
ACTION_DROP
ACTION_DRAG_ENDED

Always remember that a drag operation requires a selected item on the screen (you are picking up something and moving). But in zooming you don't have a selected item, but what you get instead is the view. Using this property you can distinguish between the Drag and Zoom operations.

Do you have any example of how to use it in onInterceptTouchEvent? — Zheng Xian, Jul 11 '16 at 01:42

score 0 · Answer 2 · answered Jul 08 '16 at 09:22

0

Try this:

final GestureDetector gestureDetector = new GestureDetector(new GestureDetector.SimpleOnGestureListener() {
public void onLongPress(MotionEvent e) {
    Log.e("", "Longpress detected");
}
});

public boolean onTouchEvent(MotionEvent event) {
   return gestureDetector.onTouchEvent(event);
};

answered Jul 08 '16 at 09:22

3

Why should the OP "try this code"? A **good answer** will always have an explanation of what was done and why it was done in such a manner, not only for the OP but for future visitors to SO. – B001ᛦ Jul 08 '16 at 09:36

How to distinguish between drag and click in onTouchEvent()?

2 Answers2