衡量您在Android中使用onTouchEvent拖了多远？

Question

Is it possible to measure how far someone has dragged their finger on the display using onTouchEvent? Any ideas would be appreciated.

Answer 1

You can use ACTION_DOWN and ACTION_UP to store start and end point that finger touched and calculate the distance that dragged.

For example:

Point p1;
Point p2;

View view = new View(this);

view.setOnTouchListener(new View.OnTouchListener() {
       public boolean onTouch(View v, MotionEvent event) {
         if(event.getAction() == MotionEvent.ACTION_DOWN)
            p1 = new Point((int) event.getX(), (int) event.getY());
         else if(event.getAction() == MotionEvent.ACTION_UP)
            p2 = new Point((int) event.getX(), (int) event.getY());

         return false;
      }
});

and the distance is equal to Math.sqrt(Math.pow(p1.x-p2.x, 2) + Math.pow(p1.y-p2.y, 2)) . And also, if you want to calculate the distance that dragged in any time, you can store the second position if(event.getAction() == MotionEvent.ACTION_MOVE) .