Android: using onTouchEvent with a custom view in a custom viewgroup

Question

I have a custom view which I call "Node" that is a child of a custom ViewGroup called "NodeGrid". The "NodeGrid" class more specifically extends RelativeLayout.

I have the following code snippet in my custom view class ("Node"):

private boolean isBeingDragged = false;

@Override
public boolean onTouchEvent(MotionEvent event) {

    if (event.getAction() == MotionEvent.ACTION_DOWN)
    {
        isBeingDragged = true;
    }
    else if (event.getAction() == MotionEvent.ACTION_UP)
    {
        isBeingDragged = false;
    }
    else if (event.getAction() == MotionEvent.ACTION_MOVE)
    {
        if (isBeingDragged)
        {
            float xPosition = event.getX();
            float yPosition = event.getY();

            //change the x and y position here
        }
    }

    return false;
}

The problem:

After having set breakpoints in this code, it seems like onTouchEvent is getting called only for the MotionEvent.ACTION_DOWN case, but not for either of the other two cases ("action up" or "action move"). Does anyone know of anything off hand that could be causing this to happen?

Also (could be related):

Does it matter how the view is added to the ViewGroup? I noticed that in addition to "addView" there are other methods for adding children to a ViewGroup such as "addFocusables" and "addTouchables". Right now I am simply adding the child view to the ViewGroup using "addView".

Answer 1

From the SDK Documentation:

onTouch() - This returns a boolean to indicate whether your listener consumes this event. The important thing is that this event can have multiple actions that follow each other. So, if you return false when the down action event is received, you indicate that you have not consumed the event and are also not interested in subsequent actions from this event. Thus, you will not be called for any other actions within the event, such as a finger gesture, or the eventual up action event.

You need to return true when the ACTION_DOWN event is triggered to indicate that you are interested in the subsequent calls relating to that same event.

HTH