Leap C++ API Reference  0.7.9
Leap::CircleGesture Class Reference

The CircleGesture classes represents a circular finger movement. More...

Inherits Leap::Gesture.

Public Member Functions

Vector center () const
 The center point of the circle within the Leap frame of reference.
 
 CircleGesture ()
 Constructs a new CircleGesture object.
 
 CircleGesture (const Gesture &rhs)
 Constructs a CircleGesture object from an instance of the Gesture class.
 
Vector normal () const
 Returns the normal vector for the circle being traced.
 
Pointable pointable () const
 The finger performing the circle gesture.
 
float progress () const
 The number of times the finger tip has traversed the circle.
 
float radius () const
 The radius of the circle.
 
- Public Member Functions inherited from Leap::Gesture
int64_t duration () const
 The elapsed duration of the recognized movement up to the frame containing this Gesture object, in microseconds.
 
float durationSeconds () const
 The elapsed duration in seconds.
 
Frame frame () const
 The Frame containing this Gesture instance.
 
 Gesture ()
 Constructs a new Gesture object.
 
 Gesture (const Gesture &rhs)
 Constructs a new copy of an Gesture object.
 
HandList hands () const
 The list of hands associated with this Gesture, if any.
 
int32_t id () const
 The gesture ID.
 
bool isValid () const
 Reports whether this Gesture instance represents a valid Gesture.
 
bool operator!= (const Gesture &rhs) const
 Compare Gesture object inequality.
 
bool operator== (const Gesture &rhs) const
 Compare Gesture object equality.
 
PointableList pointables () const
 The list of fingers and tools associated with this Gesture, if any.
 
State state () const
 The gesture state.
 
std::string toString () const
 A string containing a brief, human-readable description of this Gesture.
 
Type type () const
 The gesture type.
 

Static Public Member Functions

static Type classType ()
 The circle gesture type.
 
- Static Public Member Functions inherited from Leap::Gesture
static const Gestureinvalid ()
 Returns an invalid Gesture object.
 

Additional Inherited Members

- Public Types inherited from Leap::Gesture
enum  State { STATE_INVALID = -1, STATE_START = 1, STATE_UPDATE = 2, STATE_STOP = 3 }
 The possible gesture states. More...
 
enum  Type {
  TYPE_INVALID = -1, TYPE_SWIPE = 1, TYPE_CIRCLE = 4, TYPE_SCREEN_TAP = 5,
  TYPE_KEY_TAP = 6
}
 The supported types of gestures. More...
 

Detailed Description

The CircleGesture classes represents a circular finger movement.

A circle movement is recognized when the tip of a finger draws a circle within the Leap field of view.

Leap_Gesture_Circle.png

Important: To use circle gestures in your application, you must enable recognition of the circle gesture. You can enable recognition with:

controller.enableGesture(Gesture::TYPE_CIRCLE);

Circle gestures are continuous. The CircleGesture objects for the gesture have three possible states:

  • State::STATE_START – The circle gesture has just started. The movement has progressed far enough for the recognizer to classify it as a circle.
  • State::STATE_UPDATE – The circle gesture is continuing.
  • State::STATE_STOP – The circle gesture is finished.

You can set the minimum radius and minimum arc length required for a movement to be recognized as a circle using the config attribute of a connected Controller object. Use the following keys to configure circle recognition:

Key string Value type Default value Units
Gesture.Circle.MinRadius float 5.0 mm
Gesture.Circle.MinArc float 1.5*pi radians

The following example demonstrates how to set the circle configuration parameters:

if(controller.config().setFloat("Gesture.Circle.MinRadius", 10.0) &&
controller.config().setFloat("Gesture.Circle.MinArc", .5))
controller.config().save();

Constructor & Destructor Documentation

Leap::CircleGesture::CircleGesture ( )

Constructs a new CircleGesture object.

An uninitialized CircleGesture object is considered invalid. Get valid instances of the CircleGesture class from a Frame object.

Leap::CircleGesture::CircleGesture ( const Gesture rhs)

Constructs a CircleGesture object from an instance of the Gesture class.

Parameters
rhsThe Gesture instance to specialize. This Gesture instance must be a CircleGesture object.

Member Function Documentation

Vector Leap::CircleGesture::center ( ) const

The center point of the circle within the Leap frame of reference.

Returns
Vector The center of the circle in mm from the Leap origin.
static Type Leap::CircleGesture::classType ( )
inlinestatic

The circle gesture type.

Returns
Type The type value designating a circle gesture.
Vector Leap::CircleGesture::normal ( ) const

Returns the normal vector for the circle being traced.

If you draw the circle clockwise, the normal vector points in the same general direction as the pointable object drawing the circle. If you draw the circle counterclockwise, the normal points back toward the pointable. If the angle between the normal and the pointable object drawing the circle is less than 90 degrees, then the circle is clockwise.

std::string clockwiseness; if (circle.pointable().direction().angleTo(circle.normal()) <= PI/4) { clockwiseness = "clockwise"; } else { clockwiseness = "counterclockwise"; }

Returns
Vector the normal vector for the circle being traced
Pointable Leap::CircleGesture::pointable ( ) const

The finger performing the circle gesture.

Returns
Pointable A Pointable object representing the circling finger.
float Leap::CircleGesture::progress ( ) const

The number of times the finger tip has traversed the circle.

Progress is reported as a positive number of the number. For example, a progress value of .5 indicates that the finger has gone halfway around, while a value of 3 indicates that the finger has gone around the the circle three times.

Progress starts where the circle gesture began. Since it the circle must be partially formed before the Leap can recognize it, progress will be greater than zero when a circle gesture first appears in the frame.

Returns
float A positive number indicating the gesture progress.
float Leap::CircleGesture::radius ( ) const

The radius of the circle.

Returns
The circle radius in mm.