Activity with transparent background

Try to set

    getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));

in your activity.

You can also try to do this in a style:

 <style name="AppTheme" parent="@android:style/Theme.Translucent.NoTitleBar">
    <item name="android:windowBackground">@android:color/transparent</item>
    <item name="android:colorBackgroundCacheHint">@null</item>
</style>

Create Style

<style name="MyTransparentTheme" parent="android:Theme.Dialog">
       <item name="android:windowIsTranslucent">true</item>
       <item name="android:windowBackground">@android:color/transparent</item>
       <item name="android:windowContentOverlay">@null</item>
       <item name="android:windowNoTitle">true</item>
       <item name="android:windowIsFloating">true</item>
       <item name="android:backgroundDimEnabled">false</item>

this is manifest:

<activity
            android:name="your package.activity"
            android:theme="@style/MyTransparentTheme">
        </activity>