dcanh121 dcanh121 - 3 months ago 14
Android Question

Detect touch event on a view when dragged over from other view

How do I detect the touch event if the user touches on view A and drags to bottom over the view B. I want to detect the touch event in View B.

I added touch listener in view B but doesn't receive events if the user initially touched A and dragged over the B.

enter image description here

Answer

You can use the code bellow to achive your request:

Method to test view bounds (used in code beloow)

    Rect outRect = new Rect();
    int[] location = new int[2];

    private boolean isViewInBounds(View view, int x, int y){
        view.getDrawingRect(outRect);
        view.getLocationOnScreen(location);
        outRect.offset(location[0], location[1]);
        return outRect.contains(x, y);
    }

Testing with two TextView

    final TextView viewA = (TextView)  findViewById(R.id.textView);
    final TextView viewB = (TextView)  findViewById(R.id.textView2);

Setup viewA

The empty OnClickListener is required to keep OnTouchListener active until ACTION_UP

    viewA.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {}
    });

    viewA.setOnTouchListener(new OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            int x = (int)event.getRawX();
            int y = (int)event.getRawY();
            if(event.getAction() == MotionEvent.ACTION_UP){
                if(inViewBounds(viewB, x, y))
                    viewB.dispatchTouchEvent(event);
                else if(isViewInBounds(viewA, x, y)){
                    Log.d(TAG, "onTouch ViewA");
                    //Here goes code to execute on onTouch ViewA
                }
            }
            // Further touch is not handled
            return false;
        }
    });

Setup viewB

This is only required if you also want to press on viewB and drag to viewA

    viewB.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {}
    });

    viewB.setOnTouchListener(new OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            int x = (int)event.getRawX();
            int y = (int)event.getRawY();
            if(event.getAction() == MotionEvent.ACTION_UP){
                if(inViewBounds(viewA, x, y))
                    viewA.dispatchTouchEvent(event);
                else if(isViewInBounds(viewB, x, y)){
                    Log.d(TAG, "onTouch ViewB");
                    //Here goes code to execute on onTouch ViewB
                }
            }
            // Further touch is not handled
            return false;
        }
    });

Regards.

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