sample/src/main/res/drawable-nodpi/button_transparent_pressed.xml - platform/external/subsampling-scale-image-view - Gitiles

 <?xml version="1.0" encoding="utf-8"?>
 <shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle">
 	<solid android:color="#770099cc" />
 </shape>
	<?xml version="1.0" encoding="utf-8"?>
	<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle">
	<solid android:color="#770099cc" />
	</shape>