ControllerΒΆ

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

Inherits Interface.

Public Types

enum  PolicyFlag
 The supported controller policies. More...
 

Public Member Functions

bool addListener (Listener &listener)
 Adds a listener to this Controller. More...
 
BugReport bugReport () const
 
void clearPolicy (PolicyFlag policy) const
 Requests clearing a policy. More...
 
Config config () const
 Returns a Config object, which you can use to query the Leap Motion system for configuration information. More...
 
 Controller (ControllerImplementation *)
 
 Controller ()
 Constructs a Controller object. More...
 
 Controller (Listener &listener)
 Constructs a Controller object. More...
 
DeviceList devices () const
 The list of currently attached and recognized Leap Motion controller devices. More...
 
void enableGesture (Gesture::Type type, bool enable=true) const
 Enables or disables reporting of a specified gesture type. More...
 
FailedDeviceList failedDevices () const
 A list of any Leap Motion hardware devices that are physically connected to the client computer, but are not functioning correctly. More...
 
Frame frame (int history=0) const
 Returns a frame of tracking data from the Leap Motion software. More...
 
bool hasFocus () const
 Reports whether this application is the focused, foreground application. More...
 
ImageList images () const
 The most recent set of images from the Leap Motion cameras. More...
 
bool isConnected () const
 Reports whether this Controller is connected to the Leap Motion service and the Leap Motion hardware is plugged in. More...
 
bool isGestureEnabled (Gesture::Type type) const
 Reports whether the specified gesture type is enabled. More...
 
bool isPaused () const
 Reports whether the Leap Motion service is currently paused. More...
 
bool isPolicySet (PolicyFlag policy) const
 Gets the active setting for a specific policy. More...
 
bool isServiceConnected () const
 Reports whether your application has a connection to the Leap Motion daemon/service. More...
 
int64_t now () const
 Returns a timestamp value as close as possible to the current time. More...
 
PolicyFlag policyFlags () const
 This function has been deprecated. More...
 
ImageList rawImages () const
 
bool removeListener (Listener &listener)
 Remove a listener from the list of listeners that will receive Leap Motion events. More...
 
void setPaused (bool pause)
 Pauses or resumes the Leap Motion service. More...
 
void setPolicy (PolicyFlag policy) const
 Requests setting a policy. More...
 
void setPolicyFlags (PolicyFlag flags) const
 This function has been deprecated. More...
 
virtual ~Controller ()
 

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:

  1. Implement a subclass of the Listener class and override the Listener::onFrame() function.
  2. In your Listener::onFrame() function, call the Controller::frame() function to access the newest frame of tracking data.
  3. 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

Member Enumeration Documentation

enum 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
Enumerator
POLICY_DEFAULT 

The default policy.

Since
1.0
POLICY_BACKGROUND_FRAMES 

Receive background frames.

Since
1.0
POLICY_IMAGES 

Receive images from sensor cameras.

Since
2.1.0
POLICY_OPTIMIZE_HMD 

Optimize the tracking for head-mounted device.

Since
2.1.2
POLICY_ALLOW_PAUSE_RESUME 

Allow pausing and unpausing of the Leap Motion service.

Since
3.0
POLICY_RAW_IMAGES 

Receive raw images.

Constructor & Destructor Documentation

Controller ( ControllerImplementation *  )

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
virtual ~Controller ( )
virtual
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;
Controller leapController = Controller(listenerSubclass);
Parameters
listenerAn 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

bool 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;
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.

Parameters
listenerA 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
BugReport bugReport ( ) const
void clearPolicy ( PolicyFlag  policy) const

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(Leap::Controller::POLICY_OPTIMIZE_HMD);
controller.clearPolicy(Leap::Controller::POLICY_IMAGES);
Parameters
flagsA PolicyFlag value indicating the policy to request.
Since
2.1.6
Config config ( ) const

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

controller.config().setFloat("Gesture.Circle.MinRadius", 15);
controller.config().setFloat("Gesture.Circle.MinArc", 1.7);
bool saved = controller.config().save();
Returns
The Controller's Config object.
Since
1.0
DeviceList devices ( ) const

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.

Leap::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.

Returns
The list of Leap Motion controllers.
Since
1.0
void enableGesture ( Gesture::Type  type,
bool  enable = true 
) const

Enables or disables reporting of a specified gesture type.

controller.enableGesture(Leap::Gesture::TYPE_CIRCLE);
Parameters
typeThe type of gesture to enable or disable. Must be a member of the Gesture::Type enumeration.
enableTrue, to enable the specified gesture type; False, to disable.
See also
Controller::isGestureEnabled()
Deprecated:
3.0
FailedDeviceList failedDevices ( ) const

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.

Leap::FailedDeviceList badDevices = controller.failedDevices();
Since
3.0
Frame frame ( int  history = 0) const

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
{
Leap::Frame frame = controller.frame(); //The latest frame
Leap::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 : Leap::Listener
{
void onFrame(Leap::Controller &controller)
{
Leap::Frame frame = controller.frame(); //The latest frame
Leap::Frame previous = controller.frame(1); //The previous frame
//...
}
};
Parameters
historyThe 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
bool hasFocus ( ) const

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
ImageList images ( ) const

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

Leap::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.

Returns
An ImageList object containing the most recent camera images.
Since
2.2.1
bool isConnected ( ) const

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
bool isGestureEnabled ( Gesture::Type  type) const

Reports whether the specified gesture type is enabled.

Parameters
typeThe type of gesture to check; a member of the Gesture::Type enumeration.
Returns
True, if the specified type is enabled; false, otherwise.
See also
Controller::enableGesture()
Deprecated:
3.0
bool isPaused ( ) const

Reports whether the Leap Motion service is currently paused.

if(controller.isPaused()){
//Display message to user.
}
Returns
True, if the service is paused; false, otherwise.
Since
3.0
bool isPolicySet ( PolicyFlag  policy) const

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.

bool isImagePolicyActive = controller.isPolicySet(Leap::Controller::POLICY_IMAGES);
Parameters
flagsA PolicyFlag value indicating the policy to query.
Returns
A boolean indicating whether the specified policy has been set.
Since
2.1.6
bool isServiceConnected ( ) const

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
int64_t now ( ) const

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
PolicyFlag policyFlags ( ) const

This function has been deprecated.

Use isPolicySet() instead.

Deprecated:
2.1.6
ImageList rawImages ( ) const
bool 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;
leapController.addListener(listenerObject);
// ... much later
leapController.removeListener(listenerObject);
Parameters
listenerThe listener to remove.
Returns
Whether or not the listener was successfully removed from the list of listeners.
Since
1.0
void setPaused ( bool  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.setPaused(true);
Parameters
pauseSet true to pause the service; false to resume.
Since
3.0
void setPolicy ( PolicyFlag  policy) const

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.

Parameters
policyA PolicyFlag value indicating the policy to request.
Since
2.1.6
void setPolicyFlags ( PolicyFlag  flags) const

This function has been deprecated.

Use setPolicy() and clearPolicy() instead.

Deprecated:
2.1.6