How to obtain the underlying view from a MotionEvent?

Question

My GestureListener class receives a MotionEvent in methods like onSingleTap() or onFling(). Is there a way to determine the underlying view from this event?

Background: I have a LinearLayout which contains many child views. This LinearLayout has a touch listener on it, which calls to a gesture detector. So when the user does a gesture on any child view, the LinearLayout's gesture detector receives a MotionEvent. But the problem is, because there are many children, I need to know exactly which child the user tapped on. But I can't find a method that converts a coordinate to a view. Is there a way to do this?

An ugly solution: The children are added dynamically. So I can keep all the children in a list, then when a MotionEvent comes, I can iterate through the list and see if the point is inside a child. But I don't like this idea. Is there a better way?

score 3 · Answer 1 · answered Aug 11 '11 at 22:45

Are you certain you want the touch listener on the layout? Why not have each view have a touch listener?

Let's assume you have a bunch of switches that require flings to toggle. The switches control a monster. You could have each switch (your View) have a touch listener that passes the switch to the monster. Now the monster can handle each view differently.

Something like this:

brightnessSwitch.setOnTouchListener( new View.OnTouchListener() {
  boolean onTouch(View v, MotionEvent event) {
    monster.toggleBrightness();
    return true;
  });

You could even pass the MotionEvent on to the monster. (Or if you wanted a single type of TouchListeners, you could pass both the view and the event to the monster, but you lose information about which switch is which.)

score 1 · Answer 2 · answered Aug 25 '15 at 20:11

1

If you can, use a ListView or GridView over your base layout (Linear or otherwise) and under your child views.

Then...

int pos = getGridView().pointToPosition((int) me.getX(), (int) me.getY());

View v = getGridView().getChildAt(pos);

You can also listen to the children carefully managing the boolean you return when handling.

answered Aug 25 '15 at 20:11

kandinski

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This gave me nonsensical results when using a `ListView`. The answer here works reliably for me: http://stackoverflow.com/questions/4165765/how-to-get-a-view-from-an-event-coordinates-in-android – aroth Mar 23 '17 at 06:38

score 1 · Answer 3 · answered May 23 '11 at 04:19

1

Since you use an ontouchlistener on your top view group, the LinearLayout, to handle motionevents, if the return value of ontouchlistener is true, the even will not be dispatched to any other targets. So probably you need to use the ugly method. I'm current engaged in this issue and find it really annoying.

Otherwise, set ontouchlistener for each childview as needed.

answered May 23 '11 at 04:19

Neo

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yeah, I guess there is really no other way but the ugly way. Well, as long as it works. Thanks! – wwyt May 23 '11 at 06:29

score -2 · Answer 4 · answered May 23 '11 at 03:40

-2

Give children an id and from the parent view , use parentView.findViewById(R.id.childviewid);

answered May 23 '11 at 03:40

sat

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thank you for the response. But I'm looking for a way to get a view from coordiante. The way you suggested is, actually, for the "ugly solution" I mentioned -- where I keep a list of all the children IDs, then query through all of them to see if a coordinate falls on one of them. – wwyt May 23 '11 at 03:57

How to obtain the underlying view from a MotionEvent?

4 Answers4