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

90

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.

android
android-widget
drawable
asked on Stack Overflow Nov 2, 2011 by talkol • edited Jan 9, 2013 by paradigmatic

6 Answers

162

Try the following:

Drawable clone = drawable.getConstantState().newDrawable();
answered on Stack Overflow Nov 2, 2011 by Flavio
104

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()

answered on Stack Overflow Aug 30, 2013 by Peter Ajtai • edited Oct 25, 2018 by Epicality
14

This is what works for me.

Drawable clone = drawable.getConstantState().newDrawable().mutate();
answered on Stack Overflow Mar 24, 2017 by Yanru Bi
11

This is my solution, based on this SO question.

The idea is that ImageView gets color filter when user touches it, and color filter is removed when user stops touching it. Only 1 drawable/bitmap is in memory, so no need to waste it. It works as it should.

class PressedEffectStateListDrawable extends StateListDrawable {

    private int selectionColor;

    public PressedEffectStateListDrawable(Drawable drawable, int selectionColor) {
        super();
        this.selectionColor = selectionColor;
        addState(new int[] { android.R.attr.state_pressed }, drawable);
        addState(new int[] {}, drawable);
    }

    @Override
    protected boolean onStateChange(int[] states) {
        boolean isStatePressedInArray = false;
        for (int state : states) {
            if (state == android.R.attr.state_pressed) {
                isStatePressedInArray = true;
            }
        }
        if (isStatePressedInArray) {
            super.setColorFilter(selectionColor, PorterDuff.Mode.MULTIPLY);
        } else {
            super.clearColorFilter();
        }
        return super.onStateChange(states);
    }

    @Override
    public boolean isStateful() {
        return true;
    }
}

usage:

Drawable drawable = new FastBitmapDrawable(bm);
imageView.setImageDrawable(new PressedEffectStateListDrawable(drawable, 0xFF33b5e5));
answered on Stack Overflow Jan 28, 2014 by Malachiasz • edited Apr 25, 2018 by Rahul Sharma
1

I answered a related question here

Basically it seems like StateListDrawables indeed lose their filters. I created a new BitmapDrawale from a altered copy of the Bitmap I originally wanted to use.

answered on Stack Overflow May 13, 2012 by Kuno • edited May 23, 2017 by Community
0
Drawable clone = drawable.mutate().getConstantState().newDrawable().mutate();

in case getConstantState() returns null.

answered on Stack Overflow Dec 6, 2019 by Martin Wang

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