android PopupWindow 添加下拉展开动画效果

1.两个动画，包括show 和hide

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
android:fillAfter="true"
android:fillEnabled="true" >

<scale
android:duration="200"
android:fromXScale="1.0"
android:fromYScale="0.0"
android:interpolator="@android:anim/accelerate_decelerate_interpolator"
android:pivotX="50%"
android:pivotY="0%"
android:toXScale="1.0"
android:toYScale="1.0" >
</scale>

<alpha
android:duration="180"
android:fromAlpha="0.0"
android:toAlpha="1.0" />

</set>

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
android:fillEnabled="true"
android:fillAfter="true">

<scale
android:duration="200"
android:fromXScale="1.0"
android:fromYScale="1.0"
android:interpolator="@android:anim/accelerate_interpolator"
android:pivotX="50%"
android:pivotY="0%"
android:toXScale="1.0"
android:toYScale="0.0" >
</scale>

<alpha
android:duration="180"
android:fromAlpha="1.0"
android:toAlpha="0.0" />

</set>

2.添加动画样式:

<style name="popmenu_animation" parent="android:Animation">
<item name="android:windowEnterAnimation">@anim/popumenu_animation_show</item>
<item name="android:windowExitAnimation">@anim/popumenu_animation_hide</item>
</style>

3.添加动画

PopupWindow.setAnimationStyle(R.style.popmenu_animation);