The Controller class is your main interface to the Leap Motion Controller. More...

Inherits com.leapmotion.leap.Interface.

Classes
enum	PolicyFlag
	The supported controller policies. More...

Public Member Functions
boolean	addListener (Listener listener)
	Adds a listener to this Controller.

Config	config ()
	Returns a Config object, which you can use to query the Leap Motion system for configuration information.

	Controller ()
	Constructs a Controller object.

	Controller (Listener listener)
	Constructs a Controller object.

DeviceList	devices ()
	The list of currently attached and recognized Leap Motion controller devices.

void	enableGesture (Gesture.Type type, boolean enable)
	Enables or disables reporting of a specified gesture type.

void	enableGesture (Gesture.Type type)
	Enables or disables reporting of a specified gesture type.

Frame	frame (int history)
	Returns a frame of tracking data from the Leap Motion software.

Frame	frame ()
	Returns a frame of tracking data from the Leap Motion software.

boolean	hasFocus ()
	Reports whether this application is the focused, foreground application.

boolean	isConnected ()
	Reports whether this Controller is connected to the Leap Motion service and the Leap Motion hardware is plugged in.

boolean	isGestureEnabled (Gesture.Type type)
	Reports whether the specified gesture type is enabled.

Controller.PolicyFlag	policyFlags ()
	Gets the active policy settings.

boolean	removeListener (Listener listener)
	Remove a listener from the list of listeners that will receive Leap Motion events.

void	setPolicyFlags (Controller.PolicyFlag flags)
	Requests a change in policy.

Detailed Description

The Controller class is your main interface to the Leap Motion Controller.

Create an instance of this Controller class to access frames of tracking data and configuration information. Frame data can be polled at any time using the Controller::frame() function. Call frame() or frame(0) to get the most recent frame. Set the history parameter to a positive integer to access previous frames. A controller stores up to 60 frames in its frame history.

Polling is an appropriate strategy for applications which already have an intrinsic update loop, such as a game. You can also add an instance of a subclass of Leap::Listener to the controller to handle events as they occur. The Controller dispatches events to the listener upon initialization and exiting, on connection changes, when the application gains and loses the OS input focus, and when a new frame of tracking data is available. When these events occur, the controller object invokes the appropriate callback function defined in your subclass of Listener.

To access frames of tracking data as they become available:

Implement a subclass of the Listener class and override the Listener::onFrame() function.
In your Listener::onFrame() function, call the Controller::frame() function to access the newest frame of tracking data.
To start receiving frames, create a Controller object and add an instance of the Listener subclass to the Controller::addListener() function.

When an instance of a Listener subclass is added to a Controller object, it calls the Listener::onInit() function when the listener is ready for use. When a connection is established between the controller and the Leap Motion software, the controller calls the Listener::onConnect() function. At this point, your application will start receiving frames of data. The controller calls the Listener::onFrame() function each time a new frame is available. If the controller loses its connection with the Leap Motion software or device for any reason, it calls the Listener::onDisconnect() function. If the listener is removed from the controller or the controller is destroyed, it calls the Listener::onExit() function. At that point, unless the listener is added to another controller again, it will no longer receive frames of tracking data.

The Controller object is multithreaded and calls the Listener functions on its own thread, not on an application thread.

Since: 1.0

Constructor & Destructor Documentation

com.leapmotion.leap.Controller.Controller ( )

Constructs a Controller object.

When creating a Controller object, you may optionally pass in a reference to an instance of a subclass of Leap::Listener. Alternatively, you may add a listener using the Controller::addListener() function.

Since: 1.0

com.leapmotion.leap.Controller.Controller ( Listener listener )

Constructs a Controller object.

When creating a Controller object, you may optionally pass in a reference to an instance of a subclass of Leap::Listener. Alternatively, you may add a listener using the Controller::addListener() function.

SampleListener listenerSubclass = new SampleListener();

Controller leapController = new Controller(listenerSubclass);

Parameters

listener An instance of Leap::Listener implementing the callback functions for the Leap Motion events you want to handle in your application.

Since: 1.0

Member Function Documentation

boolean com.leapmotion.leap.Controller.addListener ( Listener listener )

Adds a listener to this Controller.

The Controller dispatches Leap Motion events to each associated listener. The order in which listener callback functions are invoked is arbitrary. If you pass a listener to the Controller's constructor function, it is automatically added to the list and can be removed with the Controller::removeListener() function.

SampleListener listener = new SampleListener();

controller.addListener(listener);

Parameters

listener A subclass of Leap::Listener implementing the callback functions for the Leap Motion events you want to handle in your application.

Returns: Whether or not the listener was successfully added to the list of listeners.

Since: 1.0

Config com.leapmotion.leap.Controller.config ( )

Returns a Config object, which you can use to query the Leap Motion system for configuration information.

controller.config().setFloat("Gesture.Circle.MinRadius", 15f);
controller.config().setFloat("Gesture.Circle.MinArc", 1.7f);
Boolean saved = controller.config().save();

Since: 1.0

DeviceList com.leapmotion.leap.Controller.devices ( )

The list of currently attached and recognized Leap Motion controller devices.

The Device objects in the list describe information such as the range and tracking volume.

DeviceList connectedLeaps = controller.devices();

Currently, the Leap Motion Controller only recognizes a single device at a time.

Since: 1.0

void com.leapmotion.leap.Controller.enableGesture	(	Gesture.Type	type,
		boolean	enable
	)

Enables or disables reporting of a specified gesture type.

By default, all gesture types are disabled. When disabled, gestures of the disabled type are never reported and will not appear in the frame gesture list.

controller.enableGesture(Gesture.Type.TYPE_CIRCLE);

As a performance optimization, only enable recognition for the types of movements that you use in your application.

Parameters

type	The type of gesture to enable or disable. Must be a member of the Gesture::Type enumeration.
enable	True, to enable the specified gesture type; False, to disable.

See Also: Controller::isGestureEnabled()

Since: 1.0

void com.leapmotion.leap.Controller.enableGesture ( Gesture.Type type )

Enables or disables reporting of a specified gesture type.

By default, all gesture types are disabled. When disabled, gestures of the disabled type are never reported and will not appear in the frame gesture list.

controller.enableGesture(Gesture.Type.TYPE_CIRCLE);

As a performance optimization, only enable recognition for the types of movements that you use in your application.

Parameters

type	The type of gesture to enable or disable. Must be a member of the Gesture::Type enumeration.
enable	True, to enable the specified gesture type; False, to disable.

See Also: Controller::isGestureEnabled()

Since: 1.0

Frame com.leapmotion.leap.Controller.frame ( int history )

Returns a frame of tracking data from the Leap Motion software.

Use the optional history parameter to specify which frame to retrieve. Call frame() or frame(0) to access the most recent frame; call frame(1) to access the previous frame, and so on. If you use a history value greater than the number of stored frames, then the controller returns an invalid frame.

        if(controller.isConnected()) //controller is a Controller object
        {
            Frame frame = controller.frame(); //The latest frame
            Frame previous = controller.frame(1); //The previous frame
        }

You can call this function in your Listener implementation to get frames at the Leap Motion frame rate:

class FrameListener extends Listener
{
    public void onFrame(Controller controller)
    {
        Frame frame = controller.frame(); //The latest frame
        Frame previous = controller.frame(1); //The previous frame
        //...
    }
};

Parameters

history The age of the frame to return, counting backwards from the most recent frame (0) into the past and up to the maximum age (59).

Returns: The specified frame; or, if no history parameter is specified, the newest frame. If a frame is not available at the specified history position, an invalid Frame is returned.

Since: 1.0

Frame com.leapmotion.leap.Controller.frame ( )

Returns a frame of tracking data from the Leap Motion software.

Use the optional history parameter to specify which frame to retrieve. Call frame() or frame(0) to access the most recent frame; call frame(1) to access the previous frame, and so on. If you use a history value greater than the number of stored frames, then the controller returns an invalid frame.

        if(controller.isConnected()) //controller is a Controller object
        {
            Frame frame = controller.frame(); //The latest frame
            Frame previous = controller.frame(1); //The previous frame
        }

You can call this function in your Listener implementation to get frames at the Leap Motion frame rate:

class FrameListener extends Listener
{
    public void onFrame(Controller controller)
    {
        Frame frame = controller.frame(); //The latest frame
        Frame previous = controller.frame(1); //The previous frame
        //...
    }
};

Parameters

history The age of the frame to return, counting backwards from the most recent frame (0) into the past and up to the maximum age (59).

Returns: The specified frame; or, if no history parameter is specified, the newest frame. If a frame is not available at the specified history position, an invalid Frame is returned.

Since: 1.0

boolean com.leapmotion.leap.Controller.hasFocus ( )

Reports whether this application is the focused, foreground application.

By default, your application only receives tracking information from the Leap Motion controller when it has the operating system input focus. To receive tracking data when your application is in the background, the background frames policy flag must be set.

if(controller.hasFocus()){
    //perform action that requires application to be focused
}

Returns: True, if application has focus; false otherwise.

See Also: Controller::setPolicyFlags()

Since: 1.0

boolean com.leapmotion.leap.Controller.isConnected ( )

Reports whether this Controller is connected to the Leap Motion service and the Leap Motion hardware is plugged in.

When you first create a Controller object, isConnected() returns false. After the controller finishes initializing and connects to the Leap Motion software and if the Leap Motion hardware is plugged in, isConnected() returns true.

You can either handle the onConnect event using a Listener instance or poll the isConnected() function if you need to wait for your application to be connected to the Leap Motion software before performing some other operation.

if(controller.isConnected()){
    //perform action that requires a connected controller
}

Returns: True, if connected; false otherwise.

Since: 1.0

boolean com.leapmotion.leap.Controller.isGestureEnabled ( Gesture.Type type )

Reports whether the specified gesture type is enabled.

if(!controller.isGestureEnabled(Gesture.Type.TYPE_SWIPE)){
    controller.enableGesture(Gesture.Type.TYPE_SWIPE);
}

Returns: True, if the specified type is enabled; false, otherwise.

See Also: Controller::enableGesture()

Since: 1.0

Controller.PolicyFlag com.leapmotion.leap.Controller.policyFlags ( )

Gets the active policy settings.

Use this function to determine the current policy state. Keep in mind that setting a policy flag is asynchronous, so changes are not effective immediately after calling setPolicyFlag(). In addition, a policy request can be declined by the user. You should always set the policy flags required by your application at startup and check that the policy change request was successful after an appropriate interval.

If the controller object is not connected to the Leap Motion software, then the default policy state is returned.

if (controller.policyFlags() != Controller.PolicyFlag.POLICY_BACKGROUND_FRAMES) {
    controller.setPolicyFlags(Controller.PolicyFlag.POLICY_BACKGROUND_FRAMES);
}

Returns: The current policy flags.

Since: 1.0

boolean com.leapmotion.leap.Controller.removeListener ( Listener listener )

Remove a listener from the list of listeners that will receive Leap Motion events.

A listener must be removed if its lifetime is shorter than the controller to which it is listening.

SampleListener listenerObject = new SampleListener();
leapController.addListener(listenerObject);
// ... much later
leapController.removeListener(listenerObject);

Parameters

listener The listener to remove.

Returns: Whether or not the listener was successfully removed from the list of listeners.

Since: 1.0

void com.leapmotion.leap.Controller.setPolicyFlags ( Controller.PolicyFlag flags )

Requests a change in policy.

A request to change a policy is subject to user approval and a policy can be changed by the user at any time (using the Leap Motion settings dialog). The desired policy flags must be set every time an application runs.

Policy changes are completed asynchronously and, because they are subject to user approval, may not complete successfully. Call Controller::policyFlags() after a suitable interval to test whether the change was accepted.

Currently, the background frames policy is the only policy supported. The background frames policy determines whether an application receives frames of tracking data while in the background. By default, the Leap Motion software only sends tracking data to the foreground application. Only applications that need this ability should request the background frames policy.

At this time, you can use the Leap Motion Settings dialog to globally enable or disable the background frames policy. However, each application that needs tracking data while in the background must also set the policy flag using this function.

This function can be called before the Controller object is connected, but the request will be sent to the Leap Motion software after the Controller connects.

controller.setPolicyFlags(Controller.PolicyFlag.POLICY_BACKGROUND_FRAMES);

Parameters

flags A PolicyFlag value indicating the policies to request.

Since: 1.0

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