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 D

Answer 1

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));