Using ImageView as background for an Android Layout
I did it thusly using a RelativeLayout as the parent:
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:background="#000000" >
<ImageView
style="@style/BackGroundImageView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="42dp"
tools:ignore="ContentDescription" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center_horizontal"
android:orientation="vertical" >
<!--Rest of widgets......-->
</LinearLayout>
</RelativeLayout>
My Style for it:
<style name="BackGroundImageView">
<item name="android:alpha">0.5</item>
<item name="android:scaleType">fitXY</item>
<item name="android:src">@drawable/img_background</item>
</style>
I used a style, because the alpha setting doesn't work on lower APIs (can't remember what the limit is offhand).