@Override
	 public boolean performClick() {
		 boolean result = super.performClick();
		 playSoundEffect(SoundEffectConstants.CLICK);
		 if (mListener != null) {
			 mListener.onShutterButtonClick(this);
		 }
		 return result;
	 }
Hook into the drawable state changing to get changes to isPressed -- the
onPressed listener doesn't always get called when the pressed state
changes.
OCRTest/src/main/java/edu/sfsu/cs/orange/ocr/camera/ShutterButton.java