Android invalidateDrawable() not working

I have a bunch of drawables in a custom view. I want the user to be able to press on one or multiple drawables and it changes colors. Currently, each drawable is just a StateListDrawable with two states: state_pressed and not pressed. Every time I press a drawable, setState returns true so I'm assuming that it is actually changed, but I don't see the drawable image change. Is invalidateDrawable not doing anything? What am I doing wrong? How can I redraw the one drawable when pressed without needing call customView.invalidate() and redrawing the whole thing each time? I was doing that originally but found that my app ran very slowly/inefficiently. Thanks!

The flow:

Custom View (contains set of our custom class - TouchKey)
- Custom class TouchKey containing drawable and info
- Upon press or release, custom class finds which drawable to change

Here's code for a button touch within TouchKey class (MyTouch is a custom class tracking all the touches on the android device):

public void pressed(MyTouch touch) {
    boolean successfulStateChange = this.drawable.setState(new int[]{android.
                                                           R.attr.state_pressed});
    this.customView.invalidateDrawable(drawable);
}

public void released(MyTouch touch) {
    boolean successfulStateChange = this.drawable.setState(new int[]{-android.
                                                           R.attr.state_pressed});
    this.customView.invalidateDrawable(drawable);
}

How my StateListDrawable is being drawn in my custom view:

public class CustomView extends View {

    private TreeMap<Integer, TouchKey> keymap;

    /* Initialization Code Stuff Here - call drawKey */

    // StateListDrawable Creation
    private StateListDrawable drawKey(Canvas canvas, int bounds_l, 
                                  int bounds_t, int bounds_r, int bounds_b) 
        throws Resources.NotFoundException, XmlPullParserException, IOException {

        StateListDrawable key = new StateListDrawable();
        key.addState(new int[]{android.R.attr.state_pressed}, 
                     ContextCompat.getDrawable(mContext, R.drawable.key_pressed));
        key.addState(new int[]{-android.R.attr.state_pressed}, 
                     ContextCompat.getDrawable(mContext, R.drawable.key_released));    

        key.setBounds(bound_l, bounds_t, bounds_r, bounds_b);
        key.draw(canvas);

        return key;
    }
}

I was doing that originally but found that my app ran very slowly/inefficiently

If do it so you have a big advantages in some place in your code, or (I suppose) doesn't scale images before drawing. So try to find a logic on your code that have a huge advantage on system. Because View.invalidate() so fast method.

Other 0,02$ :

I suppose that you develop something like a keyboard. For this case you need invalidate just region of your canvas.

View.invalidate(new Rect(0, 0, 49, 49));