从中间扩展和缩小

shrink_to_middle.xml

 

<set xmlns:android="http://schemas.android.com/apk/res/android"> 
    <scale 
        android:interpolator="@android:anim/linear_interpolator" 
        android:fromXScale="1.0" 
        android:toXScale="1.0" 
        android:fromYScale="1.0" 
        android:toYScale="0.0" 
        android:fillAfter="false" 
        android:duration="200" /> 
    <translate 
        android:fromYDelta="0" 
        android:toYDelta="50%" 
        android:duration="200"/> 
</set>

grow_from_middle.xml

<?xml version="1.0" encoding="utf-8"?> 
<set xmlns:android="http://schemas.android.com/apk/res/android"> 
    <scale 
        android:interpolator="@android:anim/linear_interpolator" 
        android:fromXScale="1.0" 
        android:toXScale="1.0" 
        android:fromYScale="0.0" 
        android:toYScale="1.0" 
        android:fillAfter="false" 
        android:startOffset="200" 
        android:duration="200" /> 
    <translate 
        android:fromYDelta="50%" 
        android:toYDelta="0" 
        android:startOffset="200" 
        android:duration="200"/> 
</set>
<?xml version="1.0" encoding="utf-8"?> 
<set xmlns:android="http://schemas.android.com/apk/res/android"> 
    <scale 
        android:interpolator="@android:anim/linear_interpolator" 
        android:fromXScale="1.0" 
        android:toXScale="1.0" 
        android:fromYScale="0.0" 
        android:toYScale="1.0" 
        android:fillAfter="false" 
        android:startOffset="200" 
        android:duration="200" /> 
    <translate 
        android:fromYDelta="50%" 
        android:toYDelta="0" 
        android:startOffset="200" 
        android:duration="200"/> 
</set>