private void callShutterButtonFocus(boolean pressed) {
		 if (mListener != null) {
			 mListener.onShutterButtonFocus(this , pressed);
		 }
	 }
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