Receiving gestures

In order to receive information and updates about gestures that the controller can recognize for us, we must first politely inform our trusty controller of our desires in the onInit callback:

void Listener::onInit(const Leap::Controller &controller) {
    controller.enableGesture(Leap::Gesture::TYPE_SCREEN_TAP);
    controller.enableGesture(Leap::Gesture::TYPE_SWIPE);
}

And thus for the remainder of the controller's existence it shall diligently try its utmost to notify us when it believes someone has swiped their fingers through the air in a deliberate fashion.

How are we to be notified? When our onFrame callback retrieves a Frame we can ask it if there are any gestures taking place in that frame. Leap::Frame::gestures() returns a Leap::GestureList that contains a list of generic Leap::Gesture instances. A type of Leap::Gesture can be determined, and a suitable subclass with type-specific augmentations can then be constructed:

Leap::GestureList gestures = controller.frame...