android - fade out button

@Matthew_Reid

I got this tip from a wonderful presentation by Eric Burke of square but it works so well I needed to share it.

Android has no standard depressed animation for ImageButton’s so it requires a bit of hacking around to get a similar effect. This can also be used to disable a button (in conjunction with setClickable(false))

First we need to create an AlphaAnimation for our prefered opacity (there is no setAlpha on a view on android versions below 2.3)

/**
     * create a 1 second alpha animation to disable a button
     * @return
     */
    private Animation disabledAnimation() {
        Animation disabledAnim = new AlphaAnimation(0.5f, 0.5f);
        disabledAnim.setDuration(1);
        disabledAnim.setFillEnabled(true);
        disabledAnim.setFillAfter(true);
        return disabledAnim;
    }

Then on the view you want to fade out (either in an OnClickListener or other) start the animation.

v.startAnimation(disabledAnimation());

The reason this works is because we have set the animation duration to 

one second and set fill after to true (keeping the last frame of the animation active after it has finished).

Enjoy :)