Is it possible to trigger an event when an element of my scroll view reach a certain position?

Question

I'm using an HorizontalScroll view with android.

I would like to know if technically, it is possible to trigger an event (like changing the text of a textview ) when a specific element of my scrollview reach a certain position (for example when an element become the first visible element starting from the left of the scrollview).

Thanks in advance.

Answer 1

You can do it in this way:

Rect scrollViewBounds = new Rect();
scrollView.getHitRect(scrollViewBounds);

if (yourElementView.getLocalVisibleRect(scrollViewBounds)) {
    // your element (or portion of it) is in visible area
    // you can trigger your event
} else {
    // your element is not in visible area
}