You need two layers: An ImageView, and a View on top of that with your gradient as android:background. Put these two Views in a FrameLayout:

<FrameLayout
    ... >

    <ImageView
        ...
        android:src="@drawable/trend_donald_sterling" />

    <View
        ...
        android:background="@drawable/trending_gradient_shape"/>


</FrameLayout>

Simply set the alpha value in your gardient.xml:

Your imageView:

android:background="@drawable/trend_donald_sterling"
android:src="@drawable/trending_gradient_shape"

Your gradient xml file:

<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" >

<gradient
    android:angle="90"
    android:endColor="#00ffffff"
    android:startColor="#aa000000"
    android:centerColor="#00ffffff" />

<corners android:radius="0dp" />
</shape>

In the color value, the first two places after # correspond to the alpha value, while the rest are the actual color value in R G B format, two for each.


try using the "foreground" attribute in your imageview

<ImageView
        ...
        android:src="@drawable/trend_donald_sterling"
        android:foreground="@drawable/trending_gradient_shape" />

it worked for me.