Android Tutorial

Android Tutorial 147

Defining and Using Tweened Animation Resources

Tweened animation features include scaling, fading, rotation, and

translation. These actions can be applied simultaneously or

sequentially and might use different interpolators. Tweened

animation sequences are not tied to a specific graphic file, so you

can write one sequence and then use it for a variety of different

graphics. For example, you can make moon, star, and diamond

graphics all pulse using a single scaling sequence, or you can make

them spin using a rotate sequence.

Graphic animation sequences can be stored as specially formatted

XML files in the /res/anim directory and are compiled into the

application binary at build time.

Here’s an example of a simple animation resource file

/res/anim/spin.xml that defines a simple rotate operation—rotating

the target graphic counterclockwise four times in place, taking 10

seconds to complete:

<?xml version=”1.0” encoding=”utf-8” ?>
<set xmlns:android=”http://schemas.android.com/apk/res/android”
android:shareInterpolator=”false”>

If we go back to the example of a BitmapDrawable earlier, we can

now add some animation simply by adding the following code to