One of the new features ushered in with the Honeycomb release is a new animation system, a set of APIs in a whole new package (android.animation) that makes animating objects and properties much easier than it was before.
“But wait!” you blurt out, nearly projecting a mouthful of coffee onto your keyboard while reading this article, “Isn’t there already an animation system in Android?”
Animation Prior to Honeycomb – Indeed, Android already has animation capabilities: there are several classes and lots of great functionality in the android.view.animation package. For example, you can move, scale, rotate, and fade Views and combine multiple animations together in an AnimationSet object to coordinate them. You can specify animations in a LayoutAnimationController to get automatically staggered animation start times as a container lays out its child views. And you can use one of the many Interpolator implementations like AccelerateInterpolator and Bounce to get natural, nonlinear timing behavior.
But there are a couple of major pieces of functionality lacking in the previous system.
For one thing, you can animate Views… and that’s it. To a great extent, that’s okay. The GUI objects in Android are, after all, Views. So as long as you want to move a Button, or a TextView, or a LinearLayout, or any other GUI object, the animations have you covered. But what if you have some custom drawing in your view that you’d like to animate, like the position of a Drawable, or the translucency of its background color? Then you’re on your own, because the previous animation system only understands how to manipulate View objects.
The previous animations also have a limited scope: you can move, rotate, scale, and fade a View… and that’s it. What about animating the background color of a View? Again, you’re on your own, because the previous animations had a hard-coded set of things they were able to do, and you could not make them do anything else.