Android activity 透明

<style name="MyThemeTransparent" parent="@android:style/Theme.Black.NoTitleBar.Fullscreen">
        <item name="android:windowBackground">@android:color/transparent</item>
        <item name="android:windowIsTranslucent">true</item>
        <item name="android:windowAnimationStyle">@android:style/Animation.Translucent</item>
    </style>