ControllerΒΆ

Methods:

class com::leapmotion::leap::Controller

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:

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

Public Functions

boolean 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);

The Controller does not keep a strong reference to the Listener instance. Ensure that you maintain a reference until the listener is removed from the controller.

Return
Whether or not the listener was successfully added to the list of listeners.
Since
1.0
Parameters
  • listener -

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

void clearPolicy(Controller.PolicyFlag policy)

Requests clearing a policy.

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

controller.clearPolicy(Controller.PolicyFlag.POLICY_OPTIMIZE_HMD);

Since
2.1.6
Parameters
  • flags -

    A PolicyFlag value indicating the policy to request.

Config 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", 2f);
boolean saved = controller.config().save();

Return
The Controller‘s Config object.
Since
1.0

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

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);

Since
1.0
Parameters
  • listener -

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

DeviceList 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 allows a single active device at a time, however there may be multiple devices physically attached and listed here. Any active device(s) are guaranteed to be listed first, however order is not determined beyond that.

Return
The list of Leap Motion controllers.
Since
1.0

void enableGesture(Gesture.Type type, boolean enable)

Enables or disables reporting of a specified gesture type. 

controller.enableGesture(Gesture.Type.TYPE_CIRCLE);

See
Controller::isGestureEnabled()
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.

void enableGesture(Gesture.Type type)

Enables or disables reporting of a specified gesture type. 

controller.enableGesture(Gesture.Type.TYPE_CIRCLE);

See
Controller::isGestureEnabled()
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.

FailedDeviceList failedDevices()

A list of any Leap Motion hardware devices that are physically connected to the client computer, but are not functioning correctly.

The list contains FailedDevice objects containing the pnpID and the reason for failure. No other device information is available.

FailedDeviceList badDevices = controller.failedDevices();

Since
3.0

Frame 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
        //...
    }
}

Return
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
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).

Frame 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
        //...
    }
}

Return
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
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).

boolean 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
}

Return
True, if application has focus; false otherwise.
See
Controller::setPolicyFlags()
Since
1.0

ImageList images()

The most recent set of images from the Leap Motion cameras. 

ImageList images = controller.images();

Depending on timing and the current processing frame rate, the images obtained with this function can be newer than images obtained from the current frame of tracking data.

Return
An ImageList object containing the most recent camera images.
Since
2.2.1

boolean 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
}
Return
True, if connected; false otherwise.
Since
1.0

boolean 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);
}

Return
True, if the specified type is enabled; false, otherwise.
See
Controller::enableGesture()
Parameters
  • type -

    The type of gesture to check; a member of the Gesture::Type enumeration.

boolean isPaused()

Reports whether the Leap Motion service is currently paused. 

if(controller.isPaused()){
    //Display message to user.
}

Return
True, if the service is paused; false, otherwise.
Since
3.0

boolean isPolicySet(Controller.PolicyFlag policy)

Gets the active setting for a specific policy.

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 state for the selected policy is returned.

boolean isImagePolicySet = controller.isPolicySet(Controller.PolicyFlag.POLICY_IMAGES);

Return
A boolean indicating whether the specified policy has been set.
Since
2.1.6
Parameters
  • flags -

    A PolicyFlag value indicating the policy to query.

boolean isServiceConnected()

Reports whether your application has a connection to the Leap Motion daemon/service.

Can be true even if the Leap Motion hardware is not available.

Since
1.2

long now()

Returns a timestamp value as close as possible to the current time.

Values are in microseconds, as with all the other timestamp values.

Since
2.2.7

Controller.PolicyFlag policyFlags()

This function has been deprecated.

Use isPolicySet() instead.

boolean 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();
controller.addListener(listenerObject);

// ... much later
controller.removeListener(listenerObject);

Return
Whether or not the listener was successfully removed from the list of listeners.
Since
1.0
Parameters
  • listener -

    The listener to remove.

void setPaused(boolean pause)

Pauses or resumes the Leap Motion service.

When the service is paused no applications receive tracking data and the service itself uses minimal CPU time.

Before changing the state of the service, you must set the POLICY_ALLOW_PAUSE_RESUME using the Controller::setPolicy() function. Policies must be set every time the application is run.

controller.setPolicy(Controller.PolicyFlag.POLICY_ALLOW_PAUSE_RESUME);
controller.setPaused(true);

Since
3.0
Parameters
  • pause -

    Set true to pause the service; false to resume.

void setPolicy(Controller.PolicyFlag policy)

Requests setting a 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 or system compatibility checks, may not complete successfully. Call Controller::isPolicySet() after a suitable interval to test whether the change was accepted.

controller.setPolicy(Controller.PolicyFlag.POLICY_ALLOW_PAUSE_RESUME);
controller.setPolicy(Controller.PolicyFlag.POLICY_BACKGROUND_FRAMES);
controller.setPolicy(Controller.PolicyFlag.POLICY_IMAGES);
controller.setPolicy(Controller.PolicyFlag.POLICY_OPTIMIZE_HMD);

Since
2.1.6
Parameters
  • policy -

    A PolicyFlag value indicating the policy to request.

void setPolicyFlags(Controller.PolicyFlag flags)

This function has been deprecated.

Use setPolicy() and clearPolicy() instead.

class PolicyFlag

The supported controller policies.

The supported policy flags are:

POLICY_BACKGROUND_FRAMES requests that your application receives frames when it is not the foreground application for user input.

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. The “Allow Background Apps” checkbox must be enabled in the Leap Motion Control Panel or this policy will be denied.

POLICY_IMAGES request that your application receives images from the device cameras. The “Allow Images” checkbox must be enabled in the Leap Motion Control Panel or this policy will be denied.

The images policy determines whether an application receives image data from the Leap Motion sensors with each frame of data. By default, this data is not sent. Only applications that use the image data should request this policy.

POLICY_OPTIMIZE_HMD request that the tracking be optimized for head-mounted tracking.

The optimize HMD policy improves tracking in situations where the Leap Motion hardware is attached to a head-mounted display. This policy is not granted for devices that cannot be mounted to an HMD, such as Leap Motion controllers embedded in a laptop or keyboard.

POLICY_ALLOW_PAUSE_RESUME request that the application be allowed to pause and unpause the Leap Motion service.

Some policies can be denied if the user has disabled the feature on their Leap Motion control panel.

Since
1.0