AndroidLogin

Nice Android Login GUI

But animation should be ajust with life cycle of application for example

onDestroy->anime.stop();

to ensure not working in background or something.

To make gradient change every 5 sec. in your main activity onCreate()

RelativeLayout container = (RelativeLayout) findViewById(R.id.container);

       AnimationDrawable anim = (AnimationDrawable) container.getBackground();
       anim.setEnterFadeDuration(5000);
       anim.setExitFadeDuration(5000);

in your onStart()

        if (anim != null && !anim.isRunning())
            anim.start();
            

in Your onDestroy()

        if (anim.isRunning())
            anim.stop();
            

and good luck.