xml
	<shape xmlns:android-"http://schemas.android.com/apk/res/android"
	    android:shape-"oval">
	    <gradient
               android:startColor-"@android:color/white"
               android:endColor-"@android:color/black"
               android:angle-"45"/>
	</shape>

xml
	<rectangle xmlns:android-"http://schemas.android.com/apk/res/android">
	   <gradient
	      android:startColor-"@android:color/white"
	      android:endColor-"android:color/black"
	      android:angle-"135"/>
	</rectangle>

xml
	<shape xmlns:android-"http://schemas.android.com/apk/res/android"
	   android:shape-"rectangle">
	   <gradient
	      android:startColor-"@android:color/white"
	      android:endColor-"@android:color/black"
	      android:angle-"135"/>
	</shape>

xml
	<shape xmlns:android-"http://schemas.android.com/apk/res/android"
	   android:shape-"rectangle">
	   <gradient
	      android:startColor-"@android:color/white"
	      android:endColor-"@android:color/black"
	      android:angle-"98"/>
	</shape>