Material Login GUI
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.