Android: Cloning a drawable in order to make a StateListDrawable with filters

Question

I'm trying to make a general framework function that makes any Drawable become highlighted when pressed/focused/selected/etc.

My function takes a Drawable and returns a StateListDrawable, where the default state is the Drawable itself, and the state for android.R.attr.state_pressed is the same drawable, just with a filter applied using setColorFilter.

My problem is that I can't clone the drawable and make a separate instance of it with the filter applied. Here is what I'm trying to achieve:

StateListDrawable makeHighlightable(Drawable drawable) {     StateListDrawable res = new StateListDrawable();      Drawable clone = drawable.clone(); // how do I do this??      clone.setColorFilter(0xFFFF0000, PorterDuff.Mode.MULTIPLY);     res.addState(new int[] {android.R.attr.state_pressed}, clone);     res.addState(new int[] { }, drawable);     return res; } 

If I don't clone then the filter is obviously applied to both states. I tried playing with mutate() but it doesn't help..

Any ideas?

Update:

The accepted answer indeed clones a drawable. It didn't help me though because my general function fails on a different problem. It seems that when you add a drawable to a StateList, it loses all its filters.

Answer 1

Try the following:

Drawable clone = drawable.getConstantState().newDrawable(); 

Answer 2

If you apply a filter / etc to a drawable created with getConstantState().newDrawable() then all instances of that drawable will be changed as well, since drawables use the constantState as a cache!

So if you color a circle using a color filter and a newDrawable(), you will change the color of all the circles.

If you want to make this drawable updatable without affecting other instances then, then you must mutate that existing constant state.

// To make a drawable use a separate constant state drawable.mutate() 

For a good explanation see:

http://www.curious-creature.org/2009/05/02/drawable-mutations/

http://developer.android.com/reference/android/graphics/drawable/Drawable.html#mutate()