Setting Gradient Background programmatically

Question

I have an image on which I'm putting a colored overlay, like this (the colors are taken from here):

layout/list_item_view.xml

<View 
    android:id="@+id/image_cover_gradient"
    android:layout_width="fill_parent"
    android:layout_height="80dip"
    android:layout_alignParentTop="true"
    android:layout_marginTop="70dp"
    android:background="@drawable/gradient_blue"        
    />

drawable/gradient_blue.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item>
    <shape>
        <gradient
            android:angle="90"
            android:startColor="@color/CornflowerBlue"
            android:endColor="@color/Transparent"
            android:type="linear" />
    </shape>
</item>
</selector>

This always puts a blue overlay (CornflowerBlue) and it works as expected.

Now I'm trying to do this programatically and followed some stackoverflow answers (such as this), but still can't make it work. Here's my code:

private void setColor(int color){
    View gradientCover = view.findViewById(R.id.image_cover_gradient);
    // this FAILS because it's a StateListDrawable
    //GradientDrawable coverGd = (GradientDrawable) gradientCover.getBackground();
    //coverGd.setColor(color);

    //this doesn't seem to work either (I don't see any effect on the image)
    GradientDrawable drawable = new GradientDrawable(
            Orientation.BOTTOM_TOP, new int[] { color, resources.getColor(R.color.Transparent) 
            });
    StateListDrawable sld = new StateListDrawable();
    sld.addState(new int[] { android.R.attr.startColor, android.R.attr.endColor}, drawable);
    gradientCover.setBackground(sld);
}

get rid of StateListDrawable, all you need is GradientDrawable — pskink
– pskink, Commented Sep 1, 2014 at 14:21
Kotlin code for whom may need it: stackoverflow.com/a/54495750/6247186 — Hamed Jaliliani
– Hamed Jaliliani, Commented Feb 2, 2019 at 17:50

Haji · Accepted Answer · 2014-09-02 08:35:25Z

11

As @pskink suggested - removing the StateListDrawable solved it:

GradientDrawable drawable = new GradientDrawable(
    Orientation.BOTTOM_TOP, new int[] { color, resources.getColor(R.color.Transparent) 
});     
gradientCover.setBackground(drawable);

answered Sep 2, 2014 at 8:35

Haji

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