Building Android UIs with Custom Views

Interaction

So far, it's not really useful as we can't interact with it. To add interaction, we need to override the onTouchEvent() method from the View, as we have seen in previous chapters.

In our own implementation of onTouchEvent, we are mainly interested in the ACTION_DOWN, ACTION_UP, and ACTION_MOVE events. Let's see the implementation we have done:

private float dragX; private float dragY; private boolean dragged; ... @Override public boolean onTouchEvent(MotionEvent event) { switch(event.getAction()) { case MotionEvent.ACTION_DOWN: dragX = event.getX(); dragY = event.getY(); getParent().requestDisallowInterceptTouchEvent(true); dragged = false; return true; case MotionEvent.ACTION_UP: if (!dragged) { // touching inside the channel ...