Question

In Android, I have a button that contains an image and text. When the button is disabled, the text is automatically grayed out, but the image stays the same. Is it possible to have the image dimmed when the button is disabled without having two separate images?

Answer 1

Finally got it!

I haven’t found a way to do this by setting the image in XML, so have to set it in the code. Here’s what I got that works:

Button btnObjects = (Button)this.findViewById(R.id.button_objects);
Bitmap bm = BitmapFactory.decodeResource(context.getResources(), R.drawable.button_image_objects);
if( <button needs to be disabled> )
{
    btnObjects.setEnabled(false);
    bm = adjustOpacity(bm, 128);
}
else
{
    btnObjects.setEnabled(true);
}
btnObjects.setCompoundDrawablesWithIntrinsicBounds(null, new BitmapDrawable(bm), null, null);

//and here's where the magic happens
private Bitmap adjustOpacity(Bitmap bitmap, int opacity)
{
    //make sure bitmap is mutable (copy of needed)
    Bitmap mutableBitmap = bitmap.isMutable()
                           ? bitmap
                           : bitmap.copy(Bitmap.Config.ARGB_8888, true);

    //draw the bitmap into a canvas
    Canvas canvas = new Canvas(mutableBitmap);

    //create a color with the specified opacity
    int colour = (opacity & 0xFF) << 24;

    //draw the colour over the bitmap using PorterDuff mode DST_IN
    canvas.drawColor(colour, PorterDuff.Mode.DST_IN);

    //now return the adjusted bitmap
    return mutableBitmap;
}