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androidbackgroundgradientdrawable

Changing gradient background colors on Android at runtime

I'm experimenting with Drawable backgrounds and have had no problems so far.

I'm now trying to change the gradient background color at runtime.

Unfortunately, there's no API to change it at runtime, it seems. Not even by trying to mutate() the drawable, as explained here: Drawable mutations

The sample XML looks like this. It works, as expected.

<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <gradient
        android:startColor="#330000FF"
        android:endColor="#110000FF"
        android:angle="90"/>
</shape>

Sadly, I want a list with various colors, and they'd have to be programatically altered at runtime.

Is there another way to create this gradient background at runtime? Perhaps even not using XML altogether?

Solution

  • Yes! Found a way!

    Had to forget about XML, but here's how I did it:

    On my getView() overloaded function (ListAdapter) I just had to:

        int h = v.getHeight();
    ShapeDrawable mDrawable = new ShapeDrawable(new RectShape());
    mDrawable.getPaint().setShader(new LinearGradient(0, 0, 0, h, Color.parseColor("#330000FF"), Color.parseColor("#110000FF"), Shader.TileMode.REPEAT));
    v.setBackgroundDrawable(mDrawable);

    And that gave me the same result as the XML background above. Now I can programmatically set the background color.