Taking a Leap Forward With JavaFX

Taking A Leap Forward With
JavaFX
Simon Ritter, Oracle Corporation
Gerrit Grunwald, Canoo Engineering AG
Johan Vos, Lodgon
José Pereda, Universidad de Valladolid

The following is intended to outline our general product
direction. It is intended for information purposes only, and
may not be incorporated into any contract. It is not a
commitment to deliver any material, code, or functionality,
and should not be relied upon in making purchasing
decisions. The development, release, and timing of any
features or functionality described for Oracle’s products
remains at the sole discretion of Oracle.

Program Agenda
 The Man Machine Interface
 Leap Motion Controller
 JavaFX Basics and 3D
 Leap Motion Java API
 Demos

The Man Machine Interface

How It All Started

Progress was made…

Multi-touch has become popular

Gaming Has Driven Several Interfaces

Now It’s About Gestures

The Leap Motion Controller

The Basics
 Small device (80 x 30 x 12mm)
 USB connection
– No external power required
 Multiple OS support
– Windows
– Mac OSX
– Linux
 Low cost: $80

The Technology
 Array of infra-red sensors
– Can be susceptible to bright light
 Proprietary motion detection algorithm
– Tracks to 0.01mm resolution
– The secret sauce
 1-2% CPU load
 No GPU requirement

The Details
 The Leap Motion sensor detects hands, fingers and tools
 Data captured as frames continuously
 Listener handles events from frames
 Controller is the connection between device and application
 Gesture recognition must be enabled through the controller

Leap Motion Java API
Co-ordinate System
Right hand Cartesian co-ordinate system

 60cm range
 150 view angle (left/right)
 120 view angle (front/back)
Field Of View

Gestures
 Predefined gestures
– Circle
– Swipe
– Key tap (downward movement: y-axis)
– Screen tap (forward movement: z-axis)
 Turn, twist, tilt, make a fist
– Use motion factors from frame
 Translation, rotation axis, rotation angle, scale factor

JavaFX Basics and 3D

JavaFX: The New Way To Build Java UIs

Scene Graph
 Directed Acyclic Graph
 Parents and children
 Representation of the GUI components

Binding
 Creates a dependency between a property and a
changeable value
 High level API
– Easy to use
– Covers most common situations
 Low level API
– Allows for more complex interactions
– Optimised for fast execution and small footprint

Properties
 Basis for high level binding API
 Concrete types for all primitives, String and Object
– DoubleProperty, StringProperty, etc
 Simple API
– bind / unbind
– bindBidirectional / unbindBidirectional
– isBound

Timeline Based Animations
 Timeline
– Modifies values of variables specified in KeyFrames
 KeyFrame: specifies that a variable should have
– A particular value at a particular time
 KeyValue: Value to be interpolated for an interval

Animated Transitions
 Pre-defined, single-purpose animations
– Fade, Path, Pause, Rotate, Scale, Translate
– Can specify to, from and by values
 Container transitions
– Parallel, sequential
– Can be nested arbitarily
 Transitions and Timelines share ancestary
– A Timeline can be added to a Parallel / Sequential transition

JavaFX And The Third Dimension
 Basic collection of 3D shapes
– Box
– Cylinder
– Sphere
– MeshView (everything else)
 javafx.scene.shape
Shapes

 PhongMaterial
– Way to cover a 3D object in a colour or image
– Uses interpolation to smooth polygon effects
Surfaces

 How to illuminate the scene
 javafx.scene.effect.LightBase
 AmbientLight
– A light source that seems to come from all directions
 PointLight
– An attenuated light source that has a fixed point in space and radiates light
equally away from itself in all directions
Lighting

 Where the scene is viewed from
 PerspectiveCamera
– Field of view is configurable (default is 30°)
 ParallelCamera
– Renders a scene without perspective correction
Cameras

Leap Motion Java API

Interaction Principles
Frame
Application Code
Listener
GUI Node
GUI Node
GUI Node
Controller
Leap
Motion

Basic Approach
 Create Controller
 Register Listener
– Subclass to implement specific functionality
 onFrame callback method in Listener called by Controller
 Or you can use polling
 Frame contains all data
– Hand position, orientation
– Fingers
– Pointer position, orientation

Frame By Frame
 Set of hand and finger tracking data detected at a point in time
 Hand provides:
– Direction of palm
– List of visible Fingers
 Finger (which is a subclass of Pointable) provides:
– Direction
– Tip position and velocity
– Length, width
– Time visible

Handling Gestures
 Enable the gestures you want to use
 Recognised gesture data is added to the Frame
GestureList gl = frame.gestures();
for (int i = 0; i < gl.count(); i++) {
Gesture g = gl.get(i);
if (g.type == TYPE_SWIPE)
SwipeGesture sw = new SwipeGesture(g);
...

Conclusions and More
Information

Conclusions
 Leap Motion adds a great new way to interact with applications
 Java support makes integration with existing applications simple
– Clean, straightforward API
– Simple gesture recognition
 Use your imagination!

Further Information
 www.leapmotion.com
 www.oracle.com/javafx
 jperedadnr.blogspot.co.uk
 blogs.oracle.com/speakjava

Demos

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Taking a Leap Forward With JavaFX

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