android PopupWindow 添加下拉展开动画效果

1.两个动画，包括show 和hide

show:

<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>

hide:

<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>

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2.添加动画样式:

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3.添加动画

PopupWindow.setAnimationStyle(R.style.popmenu_animation);