Leap Motion Java API Reference  0.8.0
com.leapmotion.leap.Listener Class Reference

The Listener class defines a set of callback functions that you can override in a subclass to respond to events dispatched by the Controller object. More...

Public Member Functions

 Listener ()
 Constructs a Listener object.
 
void onConnect (Controller arg0)
 Called when the Controller object connects to the Leap Motion software, or when this Listener object is added to a Controller that is already connected.
 
void onDisconnect (Controller arg0)
 Called when the Controller object disconnects from the Leap Motion software.
 
void onExit (Controller arg0)
 Called when this Listener object is removed from the Controller or the Controller instance is destroyed.
 
void onFocusGained (Controller arg0)
 Called when this application becomes the foreground application.
 
void onFocusLost (Controller arg0)
 Called when this application loses the foreground focus.
 
void onFrame (Controller arg0)
 Called when a new frame of hand and finger tracking data is available.
 
void onInit (Controller arg0)
 Called once, when this Listener object is newly added to a Controller.
 

Detailed Description

The Listener class defines a set of callback functions that you can override in a subclass to respond to events dispatched by the Controller object.

To handle Leap Motion events, create an instance of a Listener subclass and assign it to the Controller instance. The Controller calls the relevant Listener callback function when an event occurs, passing in a reference to itself. You do not have to implement callbacks for events you do not want to handle.

The Controller object calls these Listener functions from a thread created by the Leap Motion library, not the thread used to create or set the Listener instance.

Constructor & Destructor Documentation

com.leapmotion.leap.Listener.Listener ( )

Constructs a Listener object.

Member Function Documentation

void com.leapmotion.leap.Listener.onConnect ( Controller  arg0)

Called when the Controller object connects to the Leap Motion software, or when this Listener object is added to a Controller that is already connected.

public void onConnect (Controller controller){
System.out.println("Connected");
}
Parameters
controllerThe Controller object invoking this callback function.
void com.leapmotion.leap.Listener.onDisconnect ( Controller  arg0)

Called when the Controller object disconnects from the Leap Motion software.

The controller can disconnect when the Leap Motion device is unplugged, the user shuts the Leap Motion software down, or the Leap Motion software encounters an unrecoverable error.

public void onDisconnect (Controller controller){
System.out.println("Disconnected");
}

Note: When you launch a Leap-enabled application in a debugger, the Leap Motion library does not disconnect from the application. This is to allow you to step through code without losing the connection because of time outs.

Parameters
controllerThe Controller object invoking this callback function.
void com.leapmotion.leap.Listener.onExit ( Controller  arg0)

Called when this Listener object is removed from the Controller or the Controller instance is destroyed.

public void onExit (Controller controller){
System.out.println("Exited");
}
Parameters
controllerThe Controller object invoking this callback function.
void com.leapmotion.leap.Listener.onFocusGained ( Controller  arg0)

Called when this application becomes the foreground application.

Only the foreground application receives tracking data from the Leap Motion Controller. This function is only called when the controller object is in a connected state.

public void onFocusGained (Controller controller){
System.out.println("Focus gained");
}
Parameters
controllerThe Controller object invoking this callback function.
void com.leapmotion.leap.Listener.onFocusLost ( Controller  arg0)

Called when this application loses the foreground focus.

Only the foreground application receives tracking data from the Leap Motion Controller. This function is only called when the controller object is in a connected state.

public void onFocusLost (Controller controller){
System.out.println("Focus lost");
}
Parameters
controllerThe Controller object invoking this callback function.
void com.leapmotion.leap.Listener.onFrame ( Controller  arg0)

Called when a new frame of hand and finger tracking data is available.

Access the new frame data using the Controller::frame() function.

public void onFrame (Controller controller){
System.out.println("New Frame");
}

Note, the Controller skips any pending onFrame events while your onFrame handler executes. If your implementation takes too long to return, one or more frames can be skipped. The Controller still inserts the skipped frames into the frame history. You can access recent frames by setting the history parameter when calling the Controller::frame() function. You can determine if any pending onFrame events were skipped by comparing the ID of the most recent frame with the ID of the last received frame.

Parameters
controllerThe Controller object invoking this callback function.
void com.leapmotion.leap.Listener.onInit ( Controller  arg0)

Called once, when this Listener object is newly added to a Controller.

public void onInit (Controller controller){
System.out.println("Initialized");
}
Parameters
controllerThe Controller object invoking this callback function.