protected void maybeBuildAndSetGestureDetector(AbstractDraweeController controller) {
    GestureDetector gestureDetector = controller.getGestureDetector();
    if (gestureDetector == null) {
      gestureDetector = GestureDetector.newInstance(mContext);
      controller.setGestureDetector(gestureDetector);
    }
  }
Installs a gesture detector to the given controller.
drawee/src/main/java/com/facebook/drawee/controller/AbstractDraweeControllerBuilder.java