How to set transparency of a background image Android xml file

Question

I have put an image in as the background of my android application with the following line of code:

 android:background="@drawable/background" 

I now want to make it transparent by 40% but how is this possible within the xml file? My exm file is shown below:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@drawable/background" android:alpha="0.6" android:orientation="vertical" android:padding="30dp" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context=".SecondActivity" >  <TextView     android:id="@+id/textView1"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:paddingBottom="5dp"     android:text="Welcome"     android:textColor="#292421"     android:textSize="17sp"     android:textStyle="bold" />  <TextView     android:id="@+id/TextView01"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:gravity="center_vertical"     android:text="This Android application is used to track and record the movements of a person throughout the university of ulster, Magee Campus. The tracking phase of the application can only be initiated whilst within the campus and off campus tracking is unavailable at this moment in time."     android:textColor="#292421"     android:textSize="17sp" />  <LinearLayout     android:layout_width="match_parent"     android:layout_height="wrap_content" >      <Button         android:id="@+id/button1"         android:layout_width="fill_parent"         android:layout_height="match_parent"         android:layout_marginTop="85dp"         android:layout_weight="1"         android:background="#E6E6FA"         android:onClick="tracking"         android:text="@string/tracking_service" />      <LinearLayout         android:layout_width="wrap_content"         android:layout_height="match_parent"         android:padding="20dp" >      </LinearLayout>      <Button         android:id="@+id/button2"         android:layout_width="fill_parent"         android:layout_height="match_parent"         android:layout_marginTop="85dp"         android:layout_weight="1"         android:background="#E6E6FA"         android:onClick="help"         android:text="Help" />  </LinearLayout> 

Answer 1

You can set the alpha property:

android:alpha="0.4" 

via code :

yourView.setAlpha(0.5f); 

only the background :

yourView.getBackground().setAlpha(120);  // here the value is an integer not float 

Answer 2

If you have set an image as background then

 android:alpha="0.x" 

will cause entire screen (child views) to fade. Instead you can make use of

android:backgroundTint="#80FFFFFF" android:backgroundTintMode="src_over" 

to fade only the background image without affecting the child views.