Android - How to tell when a specific view has been rendered?

Question

I have a regular button that I want to display a timer on. So imagine the text of the button changes every second as a countdown timer. However, I need this timer to only st

Answer 1

You could create a custom button then implement onFinishInflate() or when you initialize the custom button, set it's visibility to invisible and implement onWindowVisibilityChanged(int). Then when you set the button to visible you start the timer. You could also have it be a start button, which when pressed starts the timer and changes what's needed to behave as a timer button.

http://developer.android.com/reference/android/view/View.html

Answer 2

OnGlobalLayoutListener() is the right place to go. It's guaranteed that it will be called when your button has been layed out ("fully rendered and ready to go on the screen"). For example, in onCreate() you could do:

btn = (Button) findViewById(R.id.bn);   
btn.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {

    @Override
    public void onGlobalLayout() {
        new AsyncTaskTimer.execute();
        // prevent the listener to be called more than once
        btn.getViewTreeObserver().removeOnGlobalLayoutListener(this);
    }
});