Leap.h

/******************************************************************************\
* Copyright (C) 2012-2015 Leap Motion, Inc. All rights reserved.               *
* Leap Motion proprietary and confidential. Not for distribution.              *
* Use subject to the terms of the Leap Motion SDK Agreement available at       *
* https://developer.leapmotion.com/sdk_agreement, or another agreement         *
* between Leap Motion and you, your company or other organization.             *
\******************************************************************************/

#if !defined(__Leap_h__)
#define __Leap_h__

#include "LeapMath.h"
#include <string>
#include <vector>
#include <cstring>

// Define integer types for Visual Studio 2008 and earlier
#if defined(_MSC_VER) && (_MSC_VER < 1600)
typedef __int32 int32_t;
typedef __int64 int64_t;
typedef unsigned __int32 uint32_t;
typedef unsigned __int64 uint64_t;
#else
#include <stdint.h>
#endif

// Define Leap export macros
#if defined(_MSC_VER) // Visual C++
#if LEAP_API_INTERNAL
#define LEAP_EXPORT
#elif LEAP_API_IMPLEMENTATION
#define LEAP_EXPORT __declspec(dllexport)
#else
#define LEAP_EXPORT __declspec(dllimport)
#endif
#define LEAP_EXPORT_CLASS
#define LEAP_EXPORT_PLUGIN __declspec(dllexport)
#elif !defined(SWIG)
#define LEAP_EXPORT __attribute__((visibility("default")))
#define LEAP_EXPORT_CLASS __attribute__((visibility("default")))
#define LEAP_EXPORT_PLUGIN __attribute__((visibility("default")))
#else
#define LEAP_EXPORT
#define LEAP_EXPORT_CLASS
#define LEAP_EXPORT_PLUGIN
#endif

namespace Leap {
  // Interface for internal use only
  class LEAP_EXPORT_CLASS Interface {
  public:
    struct Implementation {
      LEAP_EXPORT virtual ~Implementation() {}
    };
  protected:
    LEAP_EXPORT Interface(void* owner);
    LEAP_EXPORT Interface(Implementation* reference, void* owner);
    LEAP_EXPORT Interface(const Interface& rhs);
    Interface(class SharedObject* object);
    LEAP_EXPORT Interface& operator=(const Interface& rhs);
    LEAP_EXPORT virtual ~Interface();
    template<typename T> T* get() const { return static_cast<T*>(reference()); }
    class SharedObject* m_object;
    LEAP_EXPORT static void deleteCString(const char* cstr);
  private:
    LEAP_EXPORT Implementation* reference() const;
  };
  // Forward declarations for internal use only
  class PointableImplementation;
  class BoneImplementation;
  class FingerImplementation;
  class ToolImplementation;
  class HandImplementation;
  class GestureImplementation;
  class ScreenImplementation;
  class DeviceImplementation;
  class ImageImplementation;
  class InteractionBoxImplementation;
  class BugReportImplementation;
  class FrameImplementation;
  class ControllerImplementation;
  class MaskImplementation;
  class TrackedQuadImplementation;
  template<typename T> class ListBaseImplementation;
  // Forward declarations
  class PointableList;
  class FingerList;
  class ToolList;
  class HandList;
  class GestureList;
  class ImageList;
  class MaskList;
  class Hand;
  class Gesture;
  class Screen;
  class InteractionBox;
  class Frame;
  class Listener;
  /**
   * The Pointable class reports the physical characteristics of a detected finger or tool.
   *
   * Both fingers and tools are classified as Pointable objects. Use the Pointable::isFinger()
   * function to determine whether a Pointable object represents a finger. Use the
   * Pointable::isTool() function to determine whether a Pointable object represents a tool.
   * The Leap Motion software classifies a detected entity as a tool when it is thinner, straighter, and longer
   * than a typical finger.
   *
   * \include Pointable_Get_Basic.txt
   *
   * To provide touch emulation, the Leap Motion software associates a floating touch
   * plane that adapts to the user's finger movement and hand posture. The Leap Motion
   * interprets purposeful movements toward this plane as potential touch points.
   * The Pointable class reports
   * touch state with the touchZone and touchDistance values.
   *
   * Note that Pointable objects can be invalid, which means that they do not contain
   * valid tracking data and do not correspond to a physical entity. Invalid Pointable
   * objects can be the result of asking for a Pointable object using an ID from an
   * earlier frame when no Pointable objects with that ID exist in the current frame.
   * A Pointable object created from the Pointable constructor is also invalid.
   * Test for validity with the Pointable::isValid() function.
   *
   * @since 1.0
   */
  class Pointable : public Interface {
  public:
    /**
     * Defines the values for reporting the state of a Pointable object in relation to
     * an adaptive touch plane.
     * @since 1.0
     */
    enum Zone {
      /**
       * The Pointable object is too far from the plane to be
       * considered hovering or touching.
       * @since 1.0
       */
      ZONE_NONE       = 0,
      /**
       * The Pointable object is close to, but not touching
       * the plane.
       * @since 1.0
       */
      ZONE_HOVERING   = 1,
      /**
       * The Pointable has penetrated the plane.
       * @since 1.0
       */
      ZONE_TOUCHING   = 2,
#ifdef SWIGCSHARP
      // deprecated
      ZONENONE        = ZONE_NONE,
      ZONEHOVERING    = ZONE_HOVERING,
      ZONETOUCHING    = ZONE_TOUCHING,
#endif
    };
    // For internal use only.
    Pointable(PointableImplementation*);
    // For internal use only.
    Pointable(FingerImplementation*);
    // For internal use only.
    Pointable(ToolImplementation*);
    /**
     * Constructs a Pointable object.
     *
     * An uninitialized pointable is considered invalid.
     * Get valid Pointable objects from a Frame or a Hand object.
     *
     * \include Pointable_Pointable.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT Pointable();
    /**
     * A unique ID assigned to this Pointable object, whose value remains the
     * same across consecutive frames while the tracked finger or tool remains
     * visible. If tracking is lost (for example, when a finger is occluded by
     * another finger or when it is withdrawn from the Leap Motion Controller field of view), the
     * Leap Motion software may assign a new ID when it detects the entity in a future frame.
     *
     * \include Pointable_id.txt
     *
     * Use the ID value with the Frame::pointable() function to find this
     * Pointable object in future frames.
     *
     * IDs should be from 1 to 100 (inclusive). If more than 100 objects are tracked
     * an IDs of -1 will be used until an ID in the defined range is available.
     *
     * @returns The ID assigned to this Pointable object.
     * @since 1.0
     */
    LEAP_EXPORT int32_t id() const;
    /**
     * The Frame associated with this Pointable object.
     *
     * \include Pointable_frame.txt
     *
     * @returns The associated Frame object, if available; otherwise,
     * an invalid Frame object is returned.
     * @since 1.0
     */
    LEAP_EXPORT Frame frame() const;
    /**
     * The Hand associated with a finger.
     *
     * \include Pointable_hand.txt
     *
     * Not that in version 2+, tools are not associated with hands. For
     * tools, this function always returns an invalid Hand object.
     *
     * @returns The associated Hand object, if available; otherwise,
     * an invalid Hand object is returned.
     * @since 1.0
     */
    LEAP_EXPORT Hand hand() const;
    /**
     * The tip position in millimeters from the Leap Motion origin.
     *
     * \include Pointable_tipPosition.txt
     *
     * @returns The Vector containing the coordinates of the tip position.
     * @since 1.0
     */
    LEAP_EXPORT Vector tipPosition() const;
    /**
     * The rate of change of the tip position in millimeters/second.
     *
     * \include Pointable_tipVelocity.txt
     *
     * @returns The Vector containing the coordinates of the tip velocity.
     * @since 1.0
     */
    LEAP_EXPORT Vector tipVelocity() const;
    /**
     * The direction in which this finger or tool is pointing.
     *
     * \include Pointable_direction.txt
     *
     * The direction is expressed as a unit vector pointing in the same
     * direction as the tip.
     *
     * \image html images/Leap_Finger_Model.png
     *
     * @returns The Vector pointing in the same direction as the tip of this
     * Pointable object.
     * @since 1.0
     */
    LEAP_EXPORT Vector direction() const;
    /**
     * The estimated width of the finger or tool in millimeters.
     *
     * \include Pointable_width.txt
     *
     * @returns The estimated width of this Pointable object.
     * @since 1.0
     */
    LEAP_EXPORT float width() const;
    /**
     * The estimated length of the finger or tool in millimeters.
     *
     * \include Pointable_length.txt
     *
     * @returns The estimated length of this Pointable object.
     * @since 1.0
     */
    LEAP_EXPORT float length() const;
    /**
     * Whether or not this Pointable is classified as a finger.
     *
     * \include Pointable_Conversion.txt
     *
     * @returns True, if this Pointable is classified as a finger.
     * @since 1.0
     */
    LEAP_EXPORT bool isFinger() const;
    /**
     * Whether or not this Pointable is classified as a tool.
     *
     * \include Pointable_Conversion.txt
     *
     * @returns True, if this Pointable is classified as a tool.
     * @since 1.0
     */
    LEAP_EXPORT bool isTool() const;
    /**
     * Whether or not this Pointable is in an extended posture.
     *
     * A finger is considered extended if it is extended straight from the hand as if
     * pointing. A finger is not extended when it is bent down and curled towards the
     * palm.  Tools are always extended.
     *
     * \include Finger_isExtended.txt
     *
     * @returns True, if the pointable is extended.
     * @since 2.0
     */
    LEAP_EXPORT bool isExtended() const;
    /**
     * Reports whether this is a valid Pointable object.
     *
     * \include Pointable_isValid.txt
     *
     * @returns True, if this Pointable object contains valid tracking data.
     * @since 1.0
     */
    LEAP_EXPORT bool isValid() const;
    /**
     * The current touch zone of this Pointable object.
     *
     * The Leap Motion software computes the touch zone based on a floating touch
     * plane that adapts to the user's finger movement and hand posture. The Leap
     * Motion software interprets purposeful movements toward this plane as potential touch
     * points. When a Pointable moves close to the adaptive touch plane, it enters the
     * "hovering" zone. When a Pointable reaches or passes through the plane, it enters
     * the "touching" zone.
     *
     * The possible states are present in the Zone enum of this class:
     *
     * **Zone.NONE** -- The Pointable is outside the hovering zone.
     *
     * **Zone.HOVERING** -- The Pointable is close to, but not touching the touch plane.
     *
     * **Zone.TOUCHING** -- The Pointable has penetrated the touch plane.
     *
     * The touchDistance value provides a normalized indication of the distance to
     * the touch plane when the Pointable is in the hovering or touching zones.
     *
     * \include Pointable_touchZone.txt
     *
     * @returns The touch zone of this Pointable
     * @since 1.0
     */
    LEAP_EXPORT Zone touchZone() const;
    /**
     * A value proportional to the distance between this Pointable object and the
     * adaptive touch plane.
     *
     * \image html images/Leap_Touch_Plane.png
     *
     * The touch distance is a value in the range [-1, 1]. The value 1.0 indicates the
     * Pointable is at the far edge of the hovering zone. The value 0 indicates the
     * Pointable is just entering the touching zone. A value of -1.0 indicates the
     * Pointable is firmly within the touching zone. Values in between are
     * proportional to the distance from the plane. Thus, the touchDistance of 0.5
     * indicates that the Pointable is halfway into the hovering zone.
     *
     * \include Pointable_touchDistance.txt
     *
     * You can use the touchDistance value to modulate visual feedback given to the
     * user as their fingers close in on a touch target, such as a button.
     *
     * @returns The normalized touch distance of this Pointable object.
     * @since 1.0
     */
    LEAP_EXPORT float touchDistance() const;
    /**
     * The stabilized tip position of this Pointable.
     *
     * Smoothing and stabilization is performed in order to make
     * this value more suitable for interaction with 2D content. The stabilized
     * position lags behind the tip position by a variable amount, depending
     * primarily on the speed of movement.
     *
     * \include Pointable_stabilizedTipPosition.txt
     *
     * @returns A modified tip position of this Pointable object
     * with some additional smoothing and stabilization applied.
     * @since 1.0
     */
    LEAP_EXPORT Vector stabilizedTipPosition() const;
    /**
     * The duration of time this Pointable has been visible to the Leap Motion Controller.
     *
     * \include Pointable_timeVisible.txt
     *
     * @returns The duration (in seconds) that this Pointable has been tracked.
     * @since 1.0
     */
    LEAP_EXPORT float timeVisible() const;
    /**
     * Returns an invalid Pointable object.
     *
     * You can use the instance returned by this function in comparisons testing
     * whether a given Pointable instance is valid or invalid. (You can also use the
     * Pointable::isValid() function.)
     *
     * \include Pointable_invalid.txt
     *
     * @returns The invalid Pointable instance.
     * @since 1.0
     */
    LEAP_EXPORT static const Pointable& invalid();
    /**
     * Compare Pointable object equality.
     *
     * \include Pointable_operator_equals.txt
     *
     * Two Pointable objects are equal if and only if both Pointable objects represent the
     * exact same physical entities in the same frame and both Pointable objects are valid.
     * @since 1.0
     */
    LEAP_EXPORT bool operator==(const Pointable&) const;
    /**
     * Compare Pointable object inequality.
     *
     * \include Pointable_operator_not_equal.txt
     *
     * Two Pointable objects are equal if and only if both Pointable objects represent the
     * exact same physical entities in the same frame and both Pointable objects are valid.
     * @since 1.0
     */
    LEAP_EXPORT bool operator!=(const Pointable&) const;
    /**
     * Writes a brief, human readable description of the Pointable object to an output stream.
     *
     * \include Pointable_operator_stream.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT friend std::ostream& operator<<(std::ostream&, const Pointable&);
    /**
     * A string containing a brief, human readable description of the Pointable object.
     *
     * @returns A description of the Pointable object as a string.
     * @since 1.0
     */
    std::string toString() const {
      const char* cstr = toCString();
      std::string str(cstr);
      deleteCString(cstr);
      return str;
    }
  private:
    LEAP_EXPORT const char* toCString() const;
  };

  /**
   * The Arm class represents the forearm.
   *
   */
  class Arm : public Interface {
  public:
    // For internal use only.
    Arm(HandImplementation*);
    /**
    * Constructs an invalid Arm object.
    *
    * Get valid Arm objects from a Hand object.
    *
    * \include Arm_get.txt
    *
    * @since 2.0.3
    */
    LEAP_EXPORT Arm();
    /**
    * The average width of the arm.
    *
    * \include Arm_width.txt
    *
    * @since 2.0.3
    */
    LEAP_EXPORT float width() const;
    /**
    * The normalized direction in which the arm is pointing (from elbow to wrist).
    *
    * \include Arm_direction.txt
    *
    * @since 2.0.3
    */
    LEAP_EXPORT Vector direction() const;
    /**
     * The orthonormal basis vectors for the Arm bone as a Matrix.
     *
     * Basis vectors specify the orientation of a bone.
     *
     * **xBasis** Perpendicular to the longitudinal axis of the
     *   bone; exits the arm laterally through the sides of the wrist.
     *
     * **yBasis or up vector** Perpendicular to the longitudinal
     *   axis of the bone; exits the top and bottom of the arm. More positive
     *   in the upward direction.
     *
     * **zBasis** Aligned with the longitudinal axis of the arm bone.
     *   More positive toward the wrist.
     *
     * \include Arm_basis.txt
     *
     * The bases provided for the right arm use the right-hand rule; those for
     * the left arm use the left-hand rule. Thus, the positive direction of the
     * x-basis is to the right for the right arm and to the left for the left
     * arm. You can change from right-hand to left-hand rule by multiplying the
     * z basis vector by -1.
     *
     * Note that converting the basis vectors directly into a quaternion
     * representation is not mathematically valid. If you use quaternions,
     * create them from the derived rotation matrix not directly from the bases.
     *
     * @returns The basis of the arm bone as a matrix.
     * @since 2.0.3
     */
    LEAP_EXPORT Matrix basis() const;
    /**
    * The position of the elbow.
    *
    * \include Arm_elbowPosition.txt
    *
    * If not in view, the elbow position is estimated based on typical human
    * anatomical proportions.
    *
    * @since 2.0.3
    */
    LEAP_EXPORT Vector elbowPosition() const;
    /**
    * The position of the wrist.
    *
    * \include Arm_wristPosition.txt
    *
    * Note that the wrist position is not collocated with the end of any bone in
    * the hand. There is a gap of a few centimeters since the carpal bones are
    * not included in the skeleton model.
    *
    * @since 2.0.3
    */
    LEAP_EXPORT Vector wristPosition() const;
    /**
    * The center of the forearm.
    *
    * This location represents the midpoint of the arm between the wrist position
    * and the elbow position.
    *
    * @since 2.1.0
    */
    LEAP_EXPORT Vector center() const;
    /**
    * Reports whether this is a valid Arm object.
    *
    * \include Arm_isValid.txt
    *
    * @returns True, if this Arm object contains valid tracking data.
    * @since 2.0.3
    */
    LEAP_EXPORT bool isValid() const;
    /**
     * Returns an invalid Arm object.
     *
     * \include Arm_invalid.txt
     *
     * @returns The invalid Arm instance.
     * @since 2.0.3
     */
    LEAP_EXPORT static const Arm& invalid();
    /**
    * Compare Arm object equality.
    *
    * \include Arm_operator_equals.txt
    *
    * Two Arm objects are equal if and only if both Arm objects represent the
    * exact same physical arm in the same frame and both Arm objects are valid.
    * @since 2.0.3
    */
    LEAP_EXPORT bool operator==(const Arm&) const;
    /**
    * Compare Arm object inequality.
    *
    * \include Arm_operator_not_equals.txt
    *
    * Two Arm objects are equal if and only if both Arm objects represent the
    * exact same physical arm in the same frame and both Arm objects are valid.
    * @since 2.0.3
    */
    LEAP_EXPORT bool operator!=(const Arm&) const;
    /**
    * Writes a brief, human readable description of the Arm object to an output stream.
    *
    * \include Arm_stream.txt
    *
    * @since 2.0.3
    */
    LEAP_EXPORT friend std::ostream& operator<<(std::ostream&, const Arm&);
    /**
    * A string containing a brief, human readable description of the Arm object.
    *
    * \include Arm_toString.txt
    *
    * @returns A description of the Arm object as a string.
    * @since 2.0.3
    */
    std::string toString() const {
      const char* cstr = toCString();
      std::string str(cstr);
      deleteCString(cstr);
      return str;
    }
  private:
    LEAP_EXPORT const char* toCString() const;
  };

  /**
   * The Bone class represents a tracked bone.
   *
   * All fingers contain 4 bones that make up the anatomy of the finger.
   * Get valid Bone objects from a Finger object.
   *
   * Bones are ordered from base to tip, indexed from 0 to 3.  Additionally, the
   * bone's Type enum may be used to index a specific bone anatomically.
   *
   * \include Bone_iteration.txt
   *
   * The thumb does not have a base metacarpal bone and therefore contains a valid,
   * zero length bone at that location.
   *
   * Note that Bone objects can be invalid, which means that they do not contain
   * valid tracking data and do not correspond to a physical bone. Invalid Bone
   * objects can be the result of asking for a Bone object from an invalid finger,
   * indexing a bone out of range, or constructing a new bone.
   * Test for validity with the Bone::isValid() function.
   * @since 2.0
   */
  class Bone : public Interface {
  public:
    /**
     * Enumerates the names of the bones.
     *
     * Members of this enumeration are returned by Bone::type() to identify a
     * Bone object.
     * @since 2.0
     */
    enum Type {
      TYPE_METACARPAL = 0,   /**< Bone connected to the wrist inside the palm */
      TYPE_PROXIMAL = 1,     /**< Bone connecting to the palm */
      TYPE_INTERMEDIATE = 2, /**< Bone between the tip and the base*/
      TYPE_DISTAL = 3,       /**< Bone at the tip of the finger */
    };
    // For internal use only.
    Bone(BoneImplementation*);
     /**
     * Constructs an invalid Bone object.
     *
     * \include Bone_invalid.txt
     *
     * Get valid Bone objects from a Finger object.
     *
     * @since 2.0
     */
    LEAP_EXPORT Bone();
    /**
     * The base of the bone, closest to the wrist.
     *
     * In anatomical terms, this is the proximal end of the bone.

     * \include Bone_prevJoint.txt
     *
     * @returns The Vector containing the coordinates of the previous joint position.
     * @since 2.0
     */
    LEAP_EXPORT Vector prevJoint() const;
    /**
     * The end of the bone, closest to the finger tip.
     *
     * In anatomical terms, this is the distal end of the bone.
     *
     * \include Bone_nextJoint.txt
     *
     * @returns The Vector containing the coordinates of the next joint position.
     * @since 2.0
     */
    LEAP_EXPORT Vector nextJoint() const;
    /**
     * The midpoint of the bone.
     *
     * \include Bone_center.txt
     *
     * @returns The midpoint in the center of the bone.
     * @since 2.0
     */
    LEAP_EXPORT Vector center() const;
    /**
     * The normalized direction of the bone from base to tip.
     *
     * \include Bone_direction.txt
     *
     * @returns The normalized direction of the bone from base to tip.
     * @since 2.0
     */
    LEAP_EXPORT Vector direction() const;
    /**
     * The estimated length of the bone in millimeters.
     *
     * \include Bone_length.txt
     *
     * @returns The length of the bone in millimeters.
     * @since 2.0
     */
    LEAP_EXPORT float length() const;
    /**
     * The average width of the flesh around the bone in millimeters.
     *
     * \include Bone_width.txt
     *
     * @returns The width of the flesh around the bone in millimeters.
     * @since 2.0
     */
    LEAP_EXPORT float width() const;
    /**
     * The name of this bone.
     *
     * \include Bone_type.txt
     *
     * @returns The anatomical type of this bone as a member of the Bone::Type
     * enumeration.
     * @since 2.0
     */
    LEAP_EXPORT Type type() const;
    /**
     * The orthonormal basis vectors for this Bone as a Matrix.
     *
     * Basis vectors specify the orientation of a bone.
     *
     * **xBasis** Perpendicular to the longitudinal axis of the
     *   bone; exits the sides of the finger.
     *
     * **yBasis or up vector** Perpendicular to the longitudinal
     *   axis of the bone; exits the top and bottom of the finger. More positive
     *   in the upward direction.
     *
     * **zBasis** Aligned with the longitudinal axis of the bone.
     *   More positive toward the base of the finger.
     *
     * The bases provided for the right hand use the right-hand rule; those for
     * the left hand use the left-hand rule. Thus, the positive direction of the
     * x-basis is to the right for the right hand and to the left for the left
     * hand. You can change from right-hand to left-hand rule by multiplying the
     * z basis vector by -1.
     *
     * You can use the basis vectors for such purposes as measuring complex
     * finger poses and skeletal animation.
     *
     * Note that converting the basis vectors directly into a quaternion
     * representation is not mathematically valid. If you use quaternions,
     * create them from the derived rotation matrix not directly from the bases.
     *
     * \include Bone_basis.txt
     *
     * @returns The basis of the bone as a matrix.
     * @since 2.0
     */
    LEAP_EXPORT Matrix basis() const;
    /**
     * Reports whether this is a valid Bone object.
     *
     * \include Bone_isValid.txt
     *
     * @returns True, if this Bone object contains valid tracking data.
     * @since 2.0
     */
    LEAP_EXPORT bool isValid() const;
    /**
     * Returns an invalid Bone object.
     *
     * You can use the instance returned by this function in comparisons testing
     * whether a given Bone instance is valid or invalid. (You can also use the
     * Bone::isValid() function.)
     *
     * \include Bone_invalid.txt
     *
     * @returns The invalid Bone instance.
     * @since 2.0
     */
    LEAP_EXPORT static const Bone& invalid();
    /**
     * Compare Bone object equality.
     *
     * Two Bone objects are equal if and only if both Bone objects represent the
     * exact same physical bone in the same frame and both Bone objects are valid.
     * @since 2.0
     */
    LEAP_EXPORT bool operator==(const Bone&) const;
    /**
     * Compare Bone object inequality.
     *
     * Two Bone objects are equal if and only if both Bone objects represent the
     * exact same physical bone in the same frame and both Bone objects are valid.
     * @since 2.0
     */
    LEAP_EXPORT bool operator!=(const Bone&) const;
    /**
     * Writes a brief, human readable description of the Bone object to an output stream.
     *
     * @since 2.0
     */
    LEAP_EXPORT friend std::ostream& operator<<(std::ostream&, const Bone&);
    /**
     * A string containing a brief, human readable description of the Bone object.
     *
     * \include Bone_toString.txt
     *
     * @returns A description of the Bone object as a string.
     * @since 2.0
     */
    std::string toString() const {
      const char* cstr = toCString();
      std::string str(cstr);
      deleteCString(cstr);
      return str;
    }
  private:
    LEAP_EXPORT const char* toCString() const;
  };

  /**
   * The Finger class represents a tracked finger.
   *
   * Fingers are Pointable objects that the Leap Motion software has classified as a finger.
   * Get valid Finger objects from a Frame or a Hand object.
   *
   * Fingers may be permanently associated to a hand. In this case the angular order of the finger IDs
   * will be invariant. As fingers move in and out of view it is possible for the guessed ID
   * of a finger to be incorrect. Consequently, it may be necessary for finger IDs to be
   * exchanged. All tracked properties, such as velocity, will remain continuous in the API.
   * However, quantities that are derived from the API output (such as a history of positions)
   * will be discontinuous unless they have a corresponding ID exchange.
   *
   * Note that Finger objects can be invalid, which means that they do not contain
   * valid tracking data and do not correspond to a physical finger. Invalid Finger
   * objects can be the result of asking for a Finger object using an ID from an
   * earlier frame when no Finger objects with that ID exist in the current frame.
   * A Finger object created from the Finger constructor is also invalid.
   * Test for validity with the Finger::isValid() function.
   * @since 1.0
   */
  class Finger : public Pointable {
  public:
    /**
     * Deprecated as of version 2.0
     */
    enum Joint {
      JOINT_MCP = 0,
      JOINT_PIP = 1,
      JOINT_DIP = 2,
      JOINT_TIP = 3
    };
    /**
     * Enumerates the names of the fingers.
     *
     * Members of this enumeration are returned by Finger::type() to identify a
     * Finger object.
     * @since 2.0
     */
    enum Type {
      TYPE_THUMB  = 0, /**< The thumb */
      TYPE_INDEX  = 1, /**< The index or fore-finger */
      TYPE_MIDDLE = 2, /**< The middle finger */
      TYPE_RING   = 3, /**< The ring finger */
      TYPE_PINKY  = 4  /**< The pinky or little finger */
    };
    // For internal use only.
    Finger(FingerImplementation*);
    /**
     * Constructs a Finger object.
     *
     * An uninitialized finger is considered invalid.
     * Get valid Finger objects from a Frame or a Hand object.
     * @since 1.0
     */
    LEAP_EXPORT Finger();
    /**
     * If the specified Pointable object represents a finger, creates a copy
     * of it as a Finger object; otherwise, creates an invalid Finger object.
     *
     * \include Finger_Finger.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT explicit Finger(const Pointable&);
    /**
     * Deprecated as of version 2.0
     * Use 'bone' method instead.
     */
    LEAP_EXPORT Vector jointPosition(Joint jointIx) const;

    /**
     * The bone at a given bone index on this finger.
     *
     * \include Bone_iteration.txt
     *
     * @param boneIx An index value from the Bone::Type enumeration identifying the
     * bone of interest.
     * @returns The Bone that has the specified bone type.
     * @since 2.0
     */
    LEAP_EXPORT Bone bone(Bone::Type boneIx) const;

    /**
     * The name of this finger.
     *
     * \include Finger_type.txt
     *
     * @returns The anatomical type of this finger as a member of the Finger::Type
     * enumeration.
     * @since 2.0
     */
    LEAP_EXPORT Type type() const;

    /**
     * Returns an invalid Finger object.
     *
     * You can use the instance returned by this function in comparisons testing
     * whether a given Finger instance is valid or invalid. (You can also use the
     * Finger::isValid() function.)
     *
     * \include Finger_invalid.txt
     *
     * @returns The invalid Finger instance.
     * @since 1.0
     */
    LEAP_EXPORT static const Finger& invalid();

    /**
     * A string containing a brief, human readable description of the Finger object.
     *
     * \include Finger_toString.txt
     *
     * @returns A description of the Finger object as a string.
     * @since 1.0
     */
    std::string toString() const {
      const char* cstr = toCString();
      std::string str(cstr);
      deleteCString(cstr);
      return str;
    }

  private:
    LEAP_EXPORT const char* toCString() const;
  };

  /**
   * The Tool class represents a tracked tool.
   *
   * Tools are Pointable objects that the Leap Motion software has classified as a tool.
   *
   * Get valid Tool objects from a Frame object.
   *
   * \image html images/Leap_Tool.png
   *
   * Note that Tool objects can be invalid, which means that they do not contain
   * valid tracking data and do not correspond to a physical tool. Invalid Tool
   * objects can be the result of asking for a Tool object using an ID from an
   * earlier frame when no Tool objects with that ID exist in the current frame.
   * A Tool object created from the Tool constructor is also invalid.
   * Test for validity with the Tool::isValid() function.
   * @since 1.0
   */
  class Tool : public Pointable {
  public:
    // For internal use only.
    Tool(ToolImplementation*);

    /**
     * Constructs a Tool object.
     *
     * An uninitialized tool is considered invalid.
     * Get valid Tool objects from a Frame object.
     *
     * \include Tool_Tool.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT Tool();

    /**
     * If the specified Pointable object represents a tool, creates a copy
     * of it as a Tool object; otherwise, creates an invalid Tool object.
     *
     * \include Tool_Tool_copy.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT explicit Tool(const Pointable&);

    /**
     * Returns an invalid Tool object.
     *
     * You can use the instance returned by this function in comparisons testing
     * whether a given Tool instance is valid or invalid. (You can also use the
     * Tool::isValid() function.)
     *
     * \include Tool_invalid.txt
     *
     * @returns The invalid Tool instance.
     * @since 1.0
     */
    LEAP_EXPORT static const Tool& invalid();

    /**
     * A string containing a brief, human readable description of the Tool object.
     *
     * @returns A description of the Tool object as a string.
     * @since 1.0
     */
    std::string toString() const {
      const char* cstr = toCString();
      std::string str(cstr);
      deleteCString(cstr);
      return str;
    }

  private:
    LEAP_EXPORT const char* toCString() const;
  };

  /**
   * The Hand class reports the physical characteristics of a detected hand.
   *
   * Hand tracking data includes a palm position and velocity; vectors for
   * the palm normal and direction to the fingers; properties of a sphere fit
   * to the hand; and lists of the attached fingers.
   *
   * Get Hand objects from a Frame object:
   *
   * \include Hand_Get_First.txt
   *
   * Note that Hand objects can be invalid, which means that they do not contain
   * valid tracking data and do not correspond to a physical entity. Invalid Hand
   * objects can be the result of asking for a Hand object using an ID from an
   * earlier frame when no Hand objects with that ID exist in the current frame.
   * A Hand object created from the Hand constructor is also invalid.
   * Test for validity with the Hand::isValid() function.
   * @since 1.0
   */
  class Hand : public Interface {
  public:
    // For internal use only.
    Hand(HandImplementation*);

    /**
     * Constructs a Hand object.
     *
     * An uninitialized hand is considered invalid.
     * Get valid Hand objects from a Frame object.
     *
     * \include Hand_Hand.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT Hand();

    /**
     * A unique ID assigned to this Hand object, whose value remains the same
     * across consecutive frames while the tracked hand remains visible. If
     * tracking is lost (for example, when a hand is occluded by another hand
     * or when it is withdrawn from or reaches the edge of the Leap Motion Controller field of view),
     * the Leap Motion software may assign a new ID when it detects the hand in a future frame.
     *
     * Use the ID value with the Frame::hand() function to find this Hand object
     * in future frames:
     *
     * \include Hand_Get_ID.txt
     *
     * @returns The ID of this hand.
     * @since 1.0
     */
    LEAP_EXPORT int32_t id() const;

    /**
     * The Frame associated with this Hand.
     *
     * \include Hand_frame.txt
     *
     * @returns The associated Frame object, if available; otherwise,
     * an invalid Frame object is returned.
     * @since 1.0
     */
    LEAP_EXPORT Frame frame() const;

    /**
     * The list of Pointable objects detected in this frame
     * that are associated with this hand, given in arbitrary order. The list
     * will always contain 5 fingers.
     *
     * Use PointableList::extended() to remove non-extended fingers from the list.
     *
     * \include Hand_Get_Fingers.txt
     *
     * @returns The PointableList containing all Pointable objects associated with this hand.
     * @since 1.0
     */
    LEAP_EXPORT PointableList pointables() const;

    /**
     * The Pointable object with the specified ID associated with this hand.
     *
     * Use the Hand::pointable() function to retrieve a Pointable object
     * associated with this hand using an ID value obtained from a previous frame.
     * This function always returns a Pointable object, but if no finger
     * with the specified ID is present, an invalid Pointable object is returned.
     *
     * \include Hand_Get_Pointable_ByID.txt
     *
     * Note that the ID values assigned to fingers are based on the hand ID.
     * Hand IDs persist across frames, but only until
     * tracking of that hand is lost. If tracking of the hand is lost and subsequently
     * regained, the new Hand object and its child Finger objects will have a
     * different ID than in an earlier frame.
     *
     * @param id The ID value of a Pointable object from a previous frame.
     * @returns The Pointable object with the matching ID if one exists for this
     * hand in this frame; otherwise, an invalid Pointable object is returned.
     * @since 1.0
     */
    LEAP_EXPORT Pointable pointable(int32_t id) const;

    /**
     * The list of Finger objects detected in this frame that are attached to
     * this hand, given in order from thumb to pinky.  The list cannot be empty.
     *
     * Use PointableList::extended() to remove non-extended fingers from the list.
     *
     * \include Hand_Get_Fingers.txt
     *
     * @returns The FingerList containing all Finger objects attached to this hand.
     * @since 1.0
     */
    LEAP_EXPORT FingerList fingers() const;

    /**
     * The Finger object with the specified ID attached to this hand.
     *
     * Use the Hand::finger() function to retrieve a Finger object attached to
     * this hand using an ID value obtained from a previous frame.
     * This function always returns a Finger object, but if no finger
     * with the specified ID is present, an invalid Finger object is returned.
     *
     * \include Hand_finger.txt
     *
     * Note that ID values persist across frames, but only until tracking of a
     * particular object is lost. If tracking of a finger is lost and subsequently
     * regained, the new Finger object representing that finger may have a
     * different ID than that representing the finger in an earlier frame.
     *
     * @param id The ID value of a Finger object from a previous frame.
     * @returns The Finger object with the matching ID if one exists for this
     * hand in this frame; otherwise, an invalid Finger object is returned.
     * @since 1.0
     */
    LEAP_EXPORT Finger finger(int32_t id) const;

    /*
     * The list of Tool objects detected in this frame that are held by this
     * hand, given in arbitrary order.
     * The list can be empty if no tools held by this hand are detected.
     *
     * \include Hand_tools.txt
     *
     * @returns The ToolList containing all Tool objects held by this hand.
     * @since 1.0
     */
     /**
     * Tools are not associated with hands in version 2+. This list
     * is always empty.
     *
     * @deprecated 2.0
     */
    LEAP_EXPORT ToolList tools() const;

    /*
     * The Tool object with the specified ID held by this hand.
     *
     * Use the Hand::tool() function to retrieve a Tool object held by
     * this hand using an ID value obtained from a previous frame.
     * This function always returns a Tool object, but if no tool
     * with the specified ID is present, an invalid Tool object is returned.
     *
     * \include Hand_tool.txt
     *
     * Note that ID values persist across frames, but only until tracking of a
     * particular object is lost. If tracking of a tool is lost and subsequently
     * regained, the new Tool object representing that tool may have a
     * different ID than that representing the tool in an earlier frame.
     *
     * @param id The ID value of a Tool object from a previous frame.
     * @returns The Tool object with the matching ID if one exists for this
     * hand in this frame; otherwise, an invalid Tool object is returned.
     * @since 1.0
     */
     /**
     * Tools are not associated with hands in version 2+. This function
     * always returns an invalid Tool object.
     *
     * @deprecated 2.0
     */
    LEAP_EXPORT Tool tool(int32_t id) const;

    /**
     * The center position of the palm in millimeters from the Leap Motion Controller origin.
     *
     * \include Hand_palmPosition.txt
     *
     * @returns The Vector representing the coordinates of the palm position.
     * @since 1.0
     */
    LEAP_EXPORT Vector palmPosition() const;

    /**
     * The stabilized palm position of this Hand.
     *
     * Smoothing and stabilization is performed in order to make
     * this value more suitable for interaction with 2D content. The stabilized
     * position lags behind the palm position by a variable amount, depending
     * primarily on the speed of movement.
     *
     * \include Hand_stabilizedPalmPosition.txt
     *
     * @returns A modified palm position of this Hand object
     * with some additional smoothing and stabilization applied.
     * @since 1.0
     */
    LEAP_EXPORT Vector stabilizedPalmPosition() const;

    /**
     * The rate of change of the palm position in millimeters/second.
     *
     * \include Hand_palmVelocity.txt
     *
     * @returns The Vector representing the coordinates of the palm velocity.
     * @since 1.0
     */
    LEAP_EXPORT Vector palmVelocity() const;

    /**
     * The normal vector to the palm. If your hand is flat, this vector will
     * point downward, or "out" of the front surface of your palm.
     *
     * \image html images/Leap_Palm_Vectors.png
     *
     * The direction is expressed as a unit vector pointing in the same
     * direction as the palm normal (that is, a vector orthogonal to the palm).
     *
     * You can use the palm normal vector to compute the roll angle of the palm with
     * respect to the horizontal plane:
     *
     * \include Hand_Get_Angles.txt
     *
     * @returns The Vector normal to the plane formed by the palm.
     * @since 1.0
     */
    LEAP_EXPORT Vector palmNormal() const;

    /**
     * The estimated width of the palm when the hand is in a flat position.
     *
     * \include Hand_palmWidth.txt
     *
     * @returns The width of the palm in millimeters
     * @since 2.0
     */
    LEAP_EXPORT float palmWidth() const;

    /**
     * The direction from the palm position toward the fingers.
     *
     * The direction is expressed as a unit vector pointing in the same
     * direction as the directed line from the palm position to the fingers.
     *
     * You can use the palm direction vector to compute the pitch and yaw angles of the palm with
     * respect to the horizontal plane:
     *
     * \include Hand_Get_Angles.txt
     *
     * @returns The Vector pointing from the palm position toward the fingers.
     * @since 1.0
     */
    LEAP_EXPORT Vector direction() const;

    /**
     * The orientation of the hand as a basis matrix.
     *
     * The basis is defined as follows:
     *
     * **xAxis** Positive in the direction of the pinky
     *
     * **yAxis** Positive above the hand
     *
     * **zAxis** Positive in the direction of the wrist
     *
     * Note: Since the left hand is a mirror of the right hand, the
     * basis matrix will be left-handed for left hands.
     *
     * \include Hand_basis.txt
     *
     * @returns The basis of the hand as a matrix.
     * @since 2.0
     */
    LEAP_EXPORT Matrix basis() const;

    /**
     * The arm to which this hand is attached.
     *
     * If the arm is not completely in view, Arm attributes are estimated based on
     * the attributes of entities that are in view combined with typical human anatomy.
     *
     * \include Arm_get.txt
     *
     * @returns The Arm object for this hand.
     * @since 2.0.3
     */
    LEAP_EXPORT Arm arm() const;

    /**
     * The position of the wrist of this hand.
     *
     * @returns A vector containing the coordinates of the wrist position in millimeters.
     * @since 2.0.3
     */
    LEAP_EXPORT Vector wristPosition() const;

    /**
     * The center of a sphere fit to the curvature of this hand.
     *
     * \include Hand_sphereCenter.txt
     *
     * This sphere is placed roughly as if the hand were holding a ball.
     *
     * \image html images/Leap_Hand_Ball.png
     *
     * @returns The Vector representing the center position of the sphere.
     * @since 1.0
     */
    LEAP_EXPORT Vector sphereCenter() const;

    /**
     * The radius of a sphere fit to the curvature of this hand.
     *
     * This sphere is placed roughly as if the hand were holding a ball. Thus the
     * size of the sphere decreases as the fingers are curled into a fist.
     *
     * \include Hand_sphereRadius.txt
     *
     * @returns The radius of the sphere in millimeters.
     * @since 1.0
     */
    LEAP_EXPORT float sphereRadius() const;

    /**
     * The holding strength of a pinch hand pose.
     *
     * The strength is zero for an open hand, and blends to 1.0 when a pinching
     * hand pose is recognized. Pinching can be done between the thumb
     * and any other finger of the same hand.
     *
     * \include Hand_pinchStrength.txt
     *
     * @returns A float value in the [0..1] range representing the holding strength
     * of the pinch pose.
     * @since 2.0
     */
    LEAP_EXPORT float pinchStrength() const;

    /**
     * The strength of a grab hand pose.
     *
     * The strength is zero for an open hand, and blends to 1.0 when a grabbing hand
     * pose is recognized.
     *
     * \include Hand_grabStrength.txt
     *
     * @returns A float value in the [0..1] range representing the holding strength
     * of the pose.
     * @since 2.0
     */
    LEAP_EXPORT float grabStrength() const;

    /**
     * The change of position of this hand between the current frame and
     * the specified frame.
     *
     * The returned translation vector provides the magnitude and direction of
     * the movement in millimeters.
     *
     * \include Hand_translation.txt
     *
     * If a corresponding Hand object is not found in sinceFrame, or if either
     * this frame or sinceFrame are invalid Frame objects, then this method
     * returns a zero vector.
     *
     * @param sinceFrame The starting frame for computing the translation.
     * @returns A Vector representing the heuristically determined change in
     * hand position between the current frame and that specified in the
     * sinceFrame parameter.
     * @since 1.0
     */
    LEAP_EXPORT Vector translation(const Frame& sinceFrame) const;

    /**
     * The estimated probability that the hand motion between the current
     * frame and the specified frame is intended to be a translating motion.
     *
     * \include Hand_translationProbability.txt
     *
     * If a corresponding Hand object is not found in sinceFrame, or if either
     * this frame or sinceFrame are invalid Frame objects, then this method
     * returns zero.
     *
     * @param sinceFrame The starting frame for computing the translation.
     * @returns A value between 0 and 1 representing the estimated probability
     * that the hand motion between the current frame and the specified frame
     * is intended to be a translating motion.
     * @since 1.0
     */
    LEAP_EXPORT float translationProbability(const Frame& sinceFrame) const;

    /**
     * The axis of rotation derived from the change in orientation of this
     * hand, and any associated fingers, between the current frame
     * and the specified frame.
     *
     * \include Hand_rotationAxis.txt
     *
     * The returned direction vector is normalized.
     *
     * If a corresponding Hand object is not found in sinceFrame, or if either
     * this frame or sinceFrame are invalid Frame objects, then this method
     * returns a zero vector.
     *
     * @param sinceFrame The starting frame for computing the relative rotation.
     * @returns A normalized direction Vector representing the heuristically
     * determined axis of rotational change of the hand between the current
     * frame and that specified in the sinceFrame parameter.
     * @since 1.0
     */
    LEAP_EXPORT Vector rotationAxis(const Frame& sinceFrame) const;

    /**
     * The angle of rotation around the rotation axis derived from the change
     * in orientation of this hand, and any associated fingers,
     * between the current frame and the specified frame.
     *
     * \include Hand_rotationAngle.txt
     *
     * The returned angle is expressed in radians measured clockwise around the
     * rotation axis (using the right-hand rule) between the start and end frames.
     * The value is always between 0 and pi radians (0 and 180 degrees).
     *
     * If a corresponding Hand object is not found in sinceFrame, or if either
     * this frame or sinceFrame are invalid Frame objects, then the angle of
     * rotation is zero.
     *
     * @param sinceFrame The starting frame for computing the relative rotation.
     * @returns A positive value representing the heuristically determined
     * rotational change of the hand between the current frame and that
     * specified in the sinceFrame parameter.
     * @since 1.0
     */
    LEAP_EXPORT float rotationAngle(const Frame& sinceFrame) const;

    /**
     * The angle of rotation around the specified axis derived from the change
     * in orientation of this hand, and any associated fingers,
     * between the current frame and the specified frame.
     *
     * \include Hand_rotationAngle_axis.txt
     *
     * The returned angle is expressed in radians measured clockwise around the
     * rotation axis (using the right-hand rule) between the start and end frames.
     * The value is always between -pi and pi radians (-180 and 180 degrees).
     *
     * If a corresponding Hand object is not found in sinceFrame, or if either
     * this frame or sinceFrame are invalid Frame objects, then the angle of
     * rotation is zero.
     *
     * @param sinceFrame The starting frame for computing the relative rotation.
     * @param axis The axis to measure rotation around.
     * @returns A value representing the heuristically determined rotational
     * change of the hand between the current frame and that specified in the
     * sinceFrame parameter around the specified axis.
     * @since 1.0
     */
    LEAP_EXPORT float rotationAngle(const Frame& sinceFrame, const Vector& axis) const;

    /**
     * The transform matrix expressing the rotation derived from the change
     * in orientation of this hand, and any associated fingers,
     * between the current frame and the specified frame.
     *
     * \include Hand_rotationMatrix.txt
     *
     * If a corresponding Hand object is not found in sinceFrame, or if either
     * this frame or sinceFrame are invalid Frame objects, then this method
     * returns an identity matrix.
     *
     * @param sinceFrame The starting frame for computing the relative rotation.
     * @returns A transformation Matrix representing the heuristically determined
     * rotational change of the hand between the current frame and that specified
     * in the sinceFrame parameter.
     * @since 1.0
     */
    LEAP_EXPORT Matrix rotationMatrix(const Frame& sinceFrame) const;

    /**
     * The estimated probability that the hand motion between the current
     * frame and the specified frame is intended to be a rotating motion.
     *
     * \include Hand_rotationProbability.txt
     *
     * If a corresponding Hand object is not found in sinceFrame, or if either
     * this frame or sinceFrame are invalid Frame objects, then this method
     * returns zero.
     *
     * @param sinceFrame The starting frame for computing the relative rotation.
     * @returns A value between 0 and 1 representing the estimated probability
     * that the hand motion between the current frame and the specified frame
     * is intended to be a rotating motion.
     * @since 1.0
     */
    LEAP_EXPORT float rotationProbability(const Frame& sinceFrame) const;

    /**
     * The scale factor derived from this hand's motion between the current frame
     * and the specified frame.
     *
     * The scale factor is always positive. A value of 1.0 indicates no
     * scaling took place. Values between 0.0 and 1.0 indicate contraction
     * and values greater than 1.0 indicate expansion.
     *
     * \include Hand_scaleFactor.txt
     *
     * The Leap Motion software derives scaling from the relative inward or outward motion of
     * a hand and its associated fingers (independent of translation
     * and rotation).
     *
     * If a corresponding Hand object is not found in sinceFrame, or if either
     * this frame or sinceFrame are invalid Frame objects, then this method
     * returns 1.0.
     *
     * @param sinceFrame The starting frame for computing the relative scaling.
     * @returns A positive value representing the heuristically determined
     * scaling change ratio of the hand between the current frame and that
     * specified in the sinceFrame parameter.
     * @since 1.0
     */
    LEAP_EXPORT float scaleFactor(const Frame& sinceFrame) const;

    /**
     * The estimated probability that the hand motion between the current
     * frame and the specified frame is intended to be a scaling motion.
     *
     * \include Hand_scaleProbability.txt
     *
     * If a corresponding Hand object is not found in sinceFrame, or if either
     * this frame or sinceFrame are invalid Frame objects, then this method
     * returns zero.
     *
     * @param sinceFrame The starting frame for computing the relative scaling.
     * @returns A value between 0 and 1 representing the estimated probability
     * that the hand motion between the current frame and the specified frame
     * is intended to be a scaling motion.
     * @since 1.0
     */
    LEAP_EXPORT float scaleProbability(const Frame& sinceFrame) const;

    /**
     * The duration of time this Hand has been visible to the Leap Motion Controller.
     *
     * \include Hand_timeVisible.txt
     *
     * @returns The duration (in seconds) that this Hand has been tracked.
     * @since 1.0
     */
    LEAP_EXPORT float timeVisible() const;

    /**
     * How confident we are with a given hand pose.
     *
     * The confidence level ranges between 0.0 and 1.0 inclusive.
     *
     * \include Hand_confidence.txt
     *
     * @since 2.0
     */
    LEAP_EXPORT float confidence() const;

    /**
     * Identifies whether this Hand is a left hand.
     *
     * \include Hand_isLeft.txt
     *
     * @returns True if the hand is identified as a left hand.
     * @since 2.0
     */
    LEAP_EXPORT bool isLeft() const;

    /**
     * Identifies whether this Hand is a right hand.
     *
     * \include Hand_isRight.txt
     *
     * @returns True if the hand is identified as a right hand.
     * @since 2.0
     */
    LEAP_EXPORT bool isRight() const;

    /**
     * Reports whether this is a valid Hand object.
     *
     * \include Hand_isValid.txt
     *
     * @returns True, if this Hand object contains valid tracking data.
     * @since 1.0
     */
    LEAP_EXPORT bool isValid() const;

    /**
     * Returns an invalid Hand object.
     *
     * \include Hand_invalid.txt
     *
     * You can use the instance returned by this function in comparisons testing
     * whether a given Hand instance is valid or invalid. (You can also use the
     * Hand::isValid() function.)
     *
     * @returns The invalid Hand instance.
     * @since 1.0
     */
    LEAP_EXPORT static const Hand& invalid();

    /**
     * Compare Hand object equality.
     *
     * \include Hand_operator_equals.txt
     *
     * Two Hand objects are equal if and only if both Hand objects represent the
     * exact same physical hand in the same frame and both Hand objects are valid.
     * @since 1.0
     */
    LEAP_EXPORT bool operator==(const Hand&) const;

    /**
     * Compare Hand object inequality.
     *
     * \include Hand_operator_not_equals.txt
     *
     * Two Hand objects are equal if and only if both Hand objects represent the
     * exact same physical hand in the same frame and both Hand objects are valid.
     * @since 1.0
     */
    LEAP_EXPORT bool operator!=(const Hand&) const;

    /**
     * Writes a brief, human readable description of the Hand object to an output stream.
     *
     * \include Hand_operator_stream.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT friend std::ostream& operator<<(std::ostream&, const Hand&);

    /**
     * A string containing a brief, human readable description of the Hand object.
     *
     * @returns A description of the Hand as a string.
     * @since 1.0
     */
    std::string toString() const {
      const char* cstr = toCString();
      std::string str(cstr);
      deleteCString(cstr);
      return str;
    }

  private:
    LEAP_EXPORT const char* toCString() const;
  };

  /**
   * The Gesture class represents a recognized movement by the user.
   *
   * The Leap Motion Controller watches the activity within its field of view for certain movement
   * patterns typical of a user gesture or command. For example, a movement from side to
   * side with the hand can indicate a swipe gesture, while a finger poking forward
   * can indicate a screen tap gesture.
   *
   * When the Leap Motion software recognizes a gesture, it assigns an ID and adds a
   * Gesture object to the frame gesture list. For continuous gestures, which
   * occur over many frames, the Leap Motion software updates the gesture by adding
   * a Gesture object having the same ID and updated properties in each
   * subsequent frame.
   *
   * **Important:** Recognition for each type of gesture must be enabled using the
   * Controller::enableGesture() function; otherwise **no gestures are recognized or
   * reported**.
   *
   * \include Gesture_Feature_enable.txt
   *
   * Subclasses of Gesture define the properties for the specific movement patterns
   * recognized by the Leap Motion software.
   *
   * The Gesture subclasses include:
   *
   * **CircleGesture** -- A circular movement by a finger.
   *
   * **SwipeGesture** -- A straight line movement by the hand with fingers extended.
   *
   * **ScreenTapGesture** -- A forward tapping movement by a finger.
   *
   * **KeyTapGesture** -- A downward tapping movement by a finger.
   *
   * Circle and swipe gestures are continuous and these objects can have a
   * state of start, update, and stop.
   *
   * The screen tap gesture is a discrete gesture. The Leap Motion software only creates a single
   * ScreenTapGesture object for each tap and it always has a stop state.
   *
   * Get valid Gesture instances from a Frame object. You can get a list of gestures
   * with the Frame::gestures() method. You can get a list of gestures since a
   * specified frame with the `Frame::gestures(const Frame&)` method. You can also
   * use the `Frame::gesture()` method to find a gesture in the current frame using
   * an ID value obtained in a previous frame.
   *
   * Gesture objects can be invalid. For example, when you get a gesture by ID
   * using `Frame::gesture()`, and there is no gesture with that ID in the current
   * frame, then `gesture()` returns an Invalid Gesture object (rather than a null
   * value). Always check object validity in situations where a gesture might be
   * invalid.
   *
   * The following keys can be used with the Config class to configure the gesture
   * recognizer:
   *
   * \table
   * ====================================  ========== ============= =======
   * Key string                            Value type Default value Units
   * ====================================  ========== ============= =======
   * Gesture.Circle.MinRadius              float      5.0           mm
   * Gesture.Circle.MinArc                 float      1.5 * pi      radians
   * Gesture.Swipe.MinLength               float      150           mm
   * Gesture.Swipe.MinVelocity             float      1000          mm/s
   * Gesture.KeyTap.MinDownVelocity        float      50            mm/s
   * Gesture.KeyTap.HistorySeconds         float      0.1           s
   * Gesture.KeyTap.MinDistance            float      3.0           mm
   * Gesture.ScreenTap.MinForwardVelocity  float      50            mm/s
   * Gesture.ScreenTap.HistorySeconds      float      0.1           s
   * Gesture.ScreenTap.MinDistance         float      5.0           mm
   * ====================================  ========== ============= =======
   * \endtable
   *
   * @since 1.0
   */
  class Gesture : public Interface {
  public:
    // For internal use only.
    Gesture(GestureImplementation*);

    /**
     * The supported types of gestures.
     * @since 1.0
     */
    enum Type {
      /**
       * An invalid type.
       * @since 1.0
       */
      TYPE_INVALID    = -1,
      /**
       * A straight line movement by the hand with fingers extended.
       * @since 1.0
       */
      TYPE_SWIPE      = 1,
      /**
       * A circular movement by a finger.
       * @since 1.0
       */
      TYPE_CIRCLE     = 4,
      /**
       * A forward tapping movement by a finger.
       * @since 1.0
       */
      TYPE_SCREEN_TAP = 5,
      /**
       * A downward tapping movement by a finger.
       * @since 1.0
       */
      TYPE_KEY_TAP    = 6,
#ifdef SWIGCSHARP
      // deprecated
      TYPEINVALID     = TYPE_INVALID,
      TYPESWIPE       = TYPE_SWIPE,
      TYPECIRCLE      = TYPE_CIRCLE,
      TYPESCREENTAP   = TYPE_SCREEN_TAP,
      TYPEKEYTAP      = TYPE_KEY_TAP,
#endif
    };

    /**
     * The possible gesture states.
     * @since 1.0
     */
    enum State {
      /**
       * An invalid state
       * @since 1.0
       */
      STATE_INVALID = -1,
      /**
       * The gesture is starting. Just enough has happened to recognize it.
       * @since 1.0
       */
      STATE_START   = 1,
      /**
       * The gesture is in progress. (Note: not all gestures have updates).
       * @since 1.0
       */
      STATE_UPDATE  = 2,
      /**
       * The gesture has completed or stopped.
       * @since 1.0
       */
      STATE_STOP    = 3,
#ifdef SWIGCSHARP
      // deprecated
      STATEINVALID  = STATE_INVALID,
      STATESTART    = STATE_START,
      STATEUPDATE   = STATE_UPDATE,
      STATESTOP     = STATE_STOP,
#endif
    };

    /**
     * Constructs a new Gesture object.
     *
     * An uninitialized Gesture object is considered invalid. Get valid instances
     * of the Gesture class, which will be one of the Gesture subclasses, from a
     * Frame object.
     * @since 1.0
     */
    LEAP_EXPORT Gesture();

    /**
     * Constructs a new copy of an Gesture object.
     *
     * \include Gesture_Gesture_copy.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT Gesture(const Gesture& rhs);

    /**
     * The gesture type.
     *
     * \include Gesture_type.txt
     *
     * @returns Gesture::Type A value from the Gesture::Type enumeration.
     * @since 1.0
     */
    LEAP_EXPORT Type type() const;

    /**
     * The gesture state.
     *
     * Recognized movements occur over time and have a beginning, a middle,
     * and an end. The 'state()' attribute reports where in that sequence this
     * Gesture object falls.
     *
     * \include Gesture_state.txt
     *
     * @returns Gesture::State A value from the Gesture::State enumeration.
     * @since 1.0
     */
    LEAP_EXPORT State state() const;

    /**
     * The gesture ID.
     *
     * All Gesture objects belonging to the same recognized movement share the
     * same ID value. Use the ID value with the Frame::gesture() method to
     * find updates related to this Gesture object in subsequent frames.
     *
     * \include Gesture_id.txt
     *
     * @returns int32_t the ID of this Gesture.
     * @since 1.0
     */
    LEAP_EXPORT int32_t id() const;

    /**
     * The elapsed duration of the recognized movement up to the
     * frame containing this Gesture object, in microseconds.
     *
     * \include Gesture_duration.txt
     *
     * The duration reported for the first Gesture in the sequence (with the
     * STATE_START state) will typically be a small positive number since
     * the movement must progress far enough for the Leap Motion software to recognize it as
     * an intentional gesture.
     *
     * @return int64_t the elapsed duration in microseconds.
     * @since 1.0
     */
    LEAP_EXPORT int64_t duration() const;

    /**
     * The elapsed duration in seconds.
     *
     * \include Gesture_durationSeconds.txt
     *
     * @see duration()
     * @return float the elapsed duration in seconds.
     * @since 1.0
     */
    LEAP_EXPORT float durationSeconds() const;

    /**
     * The Frame containing this Gesture instance.
     *
     * \include Gesture_frame.txt
     _
     * @return Frame The parent Frame object.
     * @since 1.0
     */
    LEAP_EXPORT Frame frame() const;

    /**
     * The list of hands associated with this Gesture, if any.
     *
     * \include Gesture_hands.txt
     *
     * If no hands are related to this gesture, the list is empty.
     *
     * @return HandList the list of related Hand objects.
     * @since 1.0
     */
    LEAP_EXPORT HandList hands() const;

    /**
     * The list of fingers and tools associated with this Gesture, if any.
     *
     * If no Pointable objects are related to this gesture, the list is empty.
     *
     * \include Gesture_pointables.txt
     *
     * @return PointableList the list of related Pointable objects.
     * @since 1.0
     */
    LEAP_EXPORT PointableList pointables() const;

    /**
     * Reports whether this Gesture instance represents a valid Gesture.
     *
     * An invalid Gesture object does not represent a snapshot of a recognized
     * movement. Invalid Gesture objects are returned when a valid object cannot
     * be provided. For example, when you get an gesture by ID
     * using Frame::gesture(), and there is no gesture with that ID in the current
     * frame, then gesture() returns an Invalid Gesture object (rather than a null
     * value). Always check object validity in situations where an gesture might be
     * invalid.
     *
     * \include Gesture_isValid.txt
     *
     * @returns bool True, if this is a valid Gesture instance; false, otherwise.
     * @since 1.0
     */
    LEAP_EXPORT bool isValid() const;

    /**
     * Compare Gesture object equality.
     *
     * \include Gesture_operator_equals.txt
     *
     * Two Gestures are equal if they represent the same snapshot of the same
     * recognized movement.
     * @since 1.0
     */
    LEAP_EXPORT bool operator==(const Gesture& rhs) const;

    /**
     * Compare Gesture object inequality.
     *
     * \include Gesture_operator_not_equals.txt
     *
     * Two Gestures are equal only if they represent the same snapshot of the same
     * recognized movement.
     * @since 1.0
     */
    LEAP_EXPORT bool operator!=(const Gesture& rhs) const;

    /**
     * A string containing a brief, human-readable description of this
     * Gesture.
     *
     * \include Gesture_toString.txt
     *
     * @since 1.0
     */
    std::string toString() const {
      const char* cstr = toCString();
      std::string str(cstr);
      deleteCString(cstr);
      return str;
    }

    /**
     * Returns an invalid Gesture object.
     *
     * You can use the instance returned by this function in comparisons testing
     * whether a given Gesture instance is valid or invalid. (You can also use the
     * Gesture::isValid() function.)
     *
     * \include Gesture_invalid.txt
     *
     * @returns The invalid Gesture instance.
     * @since 1.0
     */
    LEAP_EXPORT static const Gesture& invalid();

  private:
    LEAP_EXPORT const char* toCString() const;
  };

  /**
   * The SwipeGesture class represents a swiping motion a finger or tool.
   *
   * \image html images/Leap_Gesture_Swipe.png
   *
   * SwipeGesture objects are generated for each visible finger or tool.
   * Swipe gestures are continuous; a gesture object with the same
   * ID value will appear in each frame while the gesture continues.
   *
   * **Important:** To use swipe gestures in your application, you must enable
   * recognition of the swipe gesture. You can enable recognition with:
   *
   * \include Gesture_Swipe_Enable.txt
   *
   * You can set the minimum length and velocity required for a movement
   * to be recognized as a swipe using the config attribute of a connected
   * Controller object. Use the following keys to configure swipe recognition:
   *
   * \table
   * ====================================  ========== ============= =======
   * Key string                            Value type Default value Units
   * ====================================  ========== ============= =======
   * Gesture.Swipe.MinLength               float      150           mm
   * Gesture.Swipe.MinVelocity             float      1000          mm/s
   * ====================================  ========== ============= =======
   * \endtable
   *
   * The following example demonstrates how to set the swipe configuration
   * parameters:
   *
   * \include Gesture_Swipe_Params.txt
   *
   * The Controller object must be connected to the Leap Motion service/daemon
   * before setting the configuration parameters.
   *
   * @since 1.0
   */
  class SwipeGesture : public Gesture
  {
  public:
    /**
     * The swipe gesture type.
     *
     * \include SwipeGesture_classType.txt
     *
     * @returns Type The type value designating a swipe gesture.
     * @since 1.0
     */
    static Type classType() { return TYPE_SWIPE; }

    LEAP_EXPORT SwipeGesture();

    /**
     * Constructs a SwipeGesture object from an instance of the Gesture class.
     *
     * \include SwipeGesture_SwipeGesture.txt
     *
     * @param rhs The Gesture instance to specialize. This Gesture instance must
     * be a SwipeGesture object.
     * @since 1.0
     */
    LEAP_EXPORT SwipeGesture(const Gesture& rhs);

    /**
     * The position where the swipe began.
     *
     * \include SwipeGesture_startPosition.txt
     *
     * @returns Vector The starting position within the Leap Motion frame of
     * reference, in mm.
     * @since 1.0
     */
    LEAP_EXPORT Vector startPosition() const;

    /**
     * The current position of the swipe.
     *
     * \include SwipeGesture_position.txt
     *
     * @returns Vector The current swipe position within the Leap Motion frame of
     * reference, in mm.
     * @since 1.0
     */
    LEAP_EXPORT Vector position() const;

    /**
     * The unit direction vector parallel to the swipe motion.
     *
     * \include SwipeGesture_direction.txt
     *
     * You can compare the components of the vector to classify the swipe as
     * appropriate for your application. For example, if you are using swipes
     * for two dimensional scrolling, you can compare the x and y values to
     * determine if the swipe is primarily horizontal or vertical.
     *
     * @returns Vector The unit direction vector representing the swipe
     * motion.
     * @since 1.0
     */
    LEAP_EXPORT Vector direction() const;

    /**
     * The swipe speed in mm/second.
     *
     * \include SwipeGesture_speed.txt
     *
     * @returns float The speed of the finger performing the swipe gesture in
     * millimeters per second.
     * @since 1.0
     */
    LEAP_EXPORT float speed() const;

    /**
     * The finger performing the swipe gesture.
     *
     * \include SwipeGesture_pointable.txt
     *
     * @returns Pointable A Pointable object representing the swiping finger.
     * @since 1.0
     */
    LEAP_EXPORT Pointable pointable() const;
  };

  /**
   * 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 Motion Controller field of view.
   *
   * \image html images/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:
   *
   * \include Gesture_Circle_Enable.txt
   *
   * 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:
   *
   * \table
   * ====================================  ========== ============= =======
   * Key string                            Value type Default value Units
   * ====================================  ========== ============= =======
   * Gesture.Circle.MinRadius              float      5.0           mm
   * Gesture.Circle.MinArc                 float      1.5 * pi      radians
   * ====================================  ========== ============= =======
   * \endtable
   *
   * The following example demonstrates how to set the circle configuration
   * parameters:
   *
   * \include Gesture_Circle_Params.txt
   *
   * The Controller object must be connected to the Leap Motion service/daemon
   * before setting the configuration parameters.
   *
   * @since 1.0
   */
  class CircleGesture : public Gesture
  {
  public:
    /**
     * The circle gesture type.
     *
     * \include CircleGesture_classType.txt
     *
     * @returns Type The type value designating a circle gesture.
     * @since 1.0
     */
    static Type classType() { return TYPE_CIRCLE; }

    /**
     * Constructs a new CircleGesture object.
     *
     * An uninitialized CircleGesture object is considered invalid. Get valid instances
     * of the CircleGesture class from a Frame object.
     * @since 1.0
     */
    LEAP_EXPORT CircleGesture();

    /**
     * Constructs a CircleGesture object from an instance of the Gesture class.
     *
     * \include CircleGesture_CircleGesture.txt
     *
     * @param rhs The Gesture instance to specialize. This Gesture instance must
     * be a CircleGesture object.
     * @since 1.0
     */
    LEAP_EXPORT CircleGesture(const Gesture& rhs);

    /**
     * The center point of the circle within the Leap Motion frame of reference.
     *
     * \include CircleGesture_center.txt
     * @returns Vector The center of the circle in mm from the Leap Motion origin.
     * @since 1.0
     */
    LEAP_EXPORT Vector center() 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.
     *
     * \include Gesture_Circle_Direction.txt
     *
     * @return Vector the normal vector for the circle being traced
     * @since 1.0
     */
    LEAP_EXPORT Vector normal() 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.
     *
     * \include CircleGesture_progress.txt
     *
     * Progress starts where the circle gesture began. Since the circle
     * must be partially formed before the Leap Motion software 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.
     * @since 1.0
     */
    LEAP_EXPORT float progress() const;

    /**
     * The radius of the circle.
     *
     * \include CircleGesture_radius.txt
     *
     * @returns The circle radius in mm.
     * @since 1.0
     */
    LEAP_EXPORT float radius() const;

    /**
     * The finger performing the circle gesture.
     *
     * \include CircleGesture_pointable.txt
     *
     * @returns Pointable A Pointable object representing the circling finger.
     * @since 1.0
     */
    LEAP_EXPORT Pointable pointable() const;
  };

  /**
   * The ScreenTapGesture class represents a tapping gesture by a finger or tool.
   *
   * A screen tap gesture is recognized when the tip of a finger pokes forward
   * and then springs back to approximately the original position, as if
   * tapping a vertical screen. The tapping finger must pause briefly before beginning the tap.
   *
   * \image html images/Leap_Gesture_Tap2.png
   *
   * **Important:** To use screen tap gestures in your application, you must enable
   * recognition of the screen tap gesture. You can enable recognition with:
   *
   * \include Gesture_ScreenTap_Enable.txt
   *
   * ScreenTap gestures are discrete. The ScreenTapGesture object representing a tap always
   * has the state, STATE_STOP. Only one ScreenTapGesture object is created for each
   * screen tap gesture recognized.
   *
   * You can set the minimum finger movement and velocity required for a movement
   * to be recognized as a screen tap as well as adjust the detection window for
   * evaluating the movement using the config attribute of a connected
   * Controller object. Use the following keys to configure screen tap recognition:
   *
   * \table
   * ====================================  ========== ============= =======
   * Key string                            Value type Default value Units
   * ====================================  ========== ============= =======
   * Gesture.ScreenTap.MinForwardVelocity  float      50            mm/s
   * Gesture.ScreenTap.HistorySeconds      float      0.1           s
   * Gesture.ScreenTap.MinDistance         float      5.0           mm
   * ====================================  ========== ============= =======
   * \endtable
   *
   * The following example demonstrates how to set the screen tap configuration
   * parameters:
   *
   * \include Gesture_ScreenTap_Params.txt
   *
   * The Controller object must be connected to the Leap Motion service/daemon
   * before setting the configuration parameters.
   *
   * @since 1.0
   */
  class ScreenTapGesture : public Gesture
  {
  public:
    /**
     * The screen tap gesture type.
     *
     * \include ScreenTapGesture_classType.txt
     *
     * @returns Type The type value designating a screen tap gesture.
     * @since 1.0
     */
    static Type classType() { return TYPE_SCREEN_TAP; }

    /**
     * Constructs a new ScreenTapGesture object.
     *
     * An uninitialized ScreenTapGesture object is considered invalid. Get valid instances
     * of the ScreenTapGesture class from a Frame object.
     * @since 1.0
     */
    LEAP_EXPORT ScreenTapGesture();

    /**
     * Constructs a ScreenTapGesture object from an instance of the Gesture class.
     *
     * \include ScreenTapGesture_ScreenTapGesture.txt
     *
     * @param rhs The Gesture instance to specialize. This Gesture instance must
     * be a ScreenTapGesture object.
     * @since 1.0
     */
    LEAP_EXPORT ScreenTapGesture(const Gesture& rhs);

    /**
     * The position where the screen tap is registered.
     *
     * \include ScreenTapGesture_position.txt
     *
     * @return Vector A Vector containing the coordinates of screen tap location.
     * @since 1.0
     */
    LEAP_EXPORT Vector position() const;

    /**
     * The direction of finger tip motion.
     *
     * \include ScreenTapGesture_direction.txt
     *
     * @returns Vector A unit direction vector.
     * @since 1.0
     */
    LEAP_EXPORT Vector direction() const;

    /**
     * The progress value is always 1.0 for a screen tap gesture.
     *
     * @returns float The value 1.0.
     * @since 1.0
     */
    LEAP_EXPORT float progress() const;

    /**
     * The finger performing the screen tap gesture.
     *
     * \include ScreenTapGesture_pointable.txt
     *
     * @returns Pointable A Pointable object representing the tapping finger.
     * @since 1.0
     */
    LEAP_EXPORT Pointable pointable() const;
  };

  /**
   * The KeyTapGesture class represents a tapping gesture by a finger or tool.
   *
   * A key tap gesture is recognized when the tip of a finger rotates down toward the
   * palm and then springs back to approximately the original position, as if
   * tapping. The tapping finger must pause briefly before beginning the tap.
   *
   * \image html images/Leap_Gesture_Tap.png
   *
   * **Important:** To use key tap gestures in your application, you must enable
   * recognition of the key tap gesture. You can enable recognition with:
   *
   * \include Gesture_KeyTap_Enable.txt
   *
   * Key tap gestures are discrete. The KeyTapGesture object representing a tap always
   * has the state, STATE_STOP. Only one KeyTapGesture object is created for each
   * key tap gesture recognized.
   *
   * You can set the minimum finger movement and velocity required for a movement
   * to be recognized as a key tap as well as adjust the detection window for
   * evaluating the movement using the config attribute of a connected
   * Controller object. Use the following configuration keys to configure key tap
   * recognition:
   *
   * \table
   * ====================================  ========== ============= =======
   * Key string                            Value type Default value Units
   * ====================================  ========== ============= =======
   * Gesture.KeyTap.MinDownVelocity        float      50            mm/s
   * Gesture.KeyTap.HistorySeconds         float      0.1           s
   * Gesture.KeyTap.MinDistance            float      3.0           mm
   * ====================================  ========== ============= =======
   * \endtable
   *
   * The following example demonstrates how to set the key tap configuration
   * parameters:
   *
   * \include Gesture_KeyTap_Params.txt
   *
   * The Controller object must be connected to the Leap Motion service/daemon
   * before setting the configuration parameters.
   *
   * @since 1.0
   */
  class KeyTapGesture : public Gesture
  {
  public:
    /**
     * The key tap gesture type.
     *
     * \include KeyTapGesture_classType.txt
     *
     * @returns Type The type value designating a key tap gesture.
     * @since 1.0
     */
    static Type classType() { return TYPE_KEY_TAP; }

    /**
     * Constructs a new KeyTapGesture object.
     *
     * An uninitialized KeyTapGesture object is considered invalid. Get valid instances
     * of the KeyTapGesture class from a Frame object.
     * @since 1.0
     */
    LEAP_EXPORT KeyTapGesture();

    /**
     * Constructs a KeyTapGesture object from an instance of the Gesture class.
     *
     * \include KeyTapGesture_KeyTapGesture.txt
     *
     * @param rhs The Gesture instance to specialize. This Gesture instance must
     * be a KeyTapGesture object.
     * @since 1.0
     */
    LEAP_EXPORT KeyTapGesture(const Gesture& rhs);

    /**
     * The position where the key tap is registered.
     *
     * \include KeyTapGesture_position.txt
     *
     * @return Vector A Vector containing the coordinates of tap location.
     * @since 1.0
     */
    LEAP_EXPORT Vector position() const;

    /**
     * The direction of finger tip motion.
     *
     * \include KeyTapGesture_direction.txt
     *
     * @returns Vector A unit direction vector if the finger tip is moving;
     * otherwise, a zero-vector.
     * @since 1.0
     */
    LEAP_EXPORT Vector direction() const;

    /**
     * The progress value is always 1.0 for a key tap gesture.
     *
     * @returns float The value 1.0.
     * @since 1.0
     */
    LEAP_EXPORT float progress() const;

    /**
     * The finger performing the key tap gesture.
     *
     * \include KeyTapGesture_pointable.txt
     *
     * @returns Pointable A Pointable object representing the tapping finger.
     * @since 1.0
     */
    LEAP_EXPORT Pointable pointable() const;
  };

  /*
   * Deprecated as of version 1.2.
   */
  class Screen : public Interface {
  public:
    // For internal use only.
    Screen(ScreenImplementation*);

    LEAP_EXPORT Screen();

    LEAP_EXPORT int32_t id() const;

    LEAP_EXPORT Vector intersect(const Pointable& pointable, bool normalize, float clampRatio = 1.0f) const;

    LEAP_EXPORT Vector intersect(const Vector& position, const Vector& direction, bool normalize, float clampRatio = 1.0f) const;

    LEAP_EXPORT Vector project(const Vector& position, bool normalize, float clampRatio = 1.0f) const;

    LEAP_EXPORT Vector horizontalAxis() const;

    LEAP_EXPORT Vector verticalAxis() const;

    LEAP_EXPORT Vector bottomLeftCorner() const;

    LEAP_EXPORT Vector normal() const;

    LEAP_EXPORT int widthPixels() const;

    LEAP_EXPORT int heightPixels() const;

    LEAP_EXPORT float distanceToPoint(const Vector& point) const;

    LEAP_EXPORT bool isValid() const;

    LEAP_EXPORT static const Screen& invalid();

    LEAP_EXPORT bool operator==(const Screen&) const;

    LEAP_EXPORT bool operator!=(const Screen&) const;

    LEAP_EXPORT friend std::ostream& operator<<(std::ostream&, const Screen&);

    std::string toString() const {
      const char* cstr = toCString();
      std::string str(cstr);
      deleteCString(cstr);
      return str;
    }

  private:
    LEAP_EXPORT const char* toCString() const;
  };

  /**
   * The Device class represents a physically connected device.
   *
   * The Device class contains information related to a particular connected
   * device such as device id, field of view relative to the device,
   * and the position and orientation of the device in relative coordinates.
   *
   * The position and orientation describe the alignment of the device relative to the user.
   * The alignment relative to the user is only descriptive. Aligning devices to users
   * provides consistency in the parameters that describe user interactions.
   *
   * Note that Device objects can be invalid, which means that they do not contain
   * valid device information and do not correspond to a physical device.
   * Test for validity with the Device::isValid() function.
   * @since 1.0
   */
  class Device : public Interface {
  public:

  /**
   * The available types of Leap Motion controllers.
   * @since 1.2
   */
    enum Type
    {
    /**
     * A standalone USB peripheral. The original Leap Motion controller device.
     * @since 1.2
     */
      TYPE_PERIPHERAL = 1,
    /**
     * A controller embedded in a keyboard.
     * @since 1.2
     */
      TYPE_LAPTOP,
    /**
     * A controller embedded in a laptop computer.
     * @since 1.2
     */
      TYPE_KEYBOARD
    };

    // For internal use only.
    Device(DeviceImplementation*);

    /**
     * Constructs a Device object.
     *
     * An uninitialized device is considered invalid.
     * Get valid Device objects from a DeviceList object obtained using the
     * Controller::devices() method.
     *
     * \include Device_Device.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT Device();

    /**
     * The angle of view along the x axis of this device.
     *
     * \image html images/Leap_horizontalViewAngle.png
     *
     * The Leap Motion controller scans a region in the shape of an inverted pyramid
     * centered at the device's center and extending upwards. The horizontalViewAngle
     * reports the view angle along the long dimension of the device.
     *
     * \include Device_horizontalViewAngle.txt
     *
     * @returns The horizontal angle of view in radians.
     * @since 1.0
     */
    LEAP_EXPORT float horizontalViewAngle() const;

    /**
     * The angle of view along the z axis of this device.
     *
     * \image html images/Leap_verticalViewAngle.png
     *
     * The Leap Motion controller scans a region in the shape of an inverted pyramid
     * centered at the device's center and extending upwards. The verticalViewAngle
     * reports the view angle along the short dimension of the device.
     *
     * \include Device_verticalViewAngle.txt
     *
     * @returns The vertical angle of view in radians.
     * @since 1.0
     */
    LEAP_EXPORT float verticalViewAngle() const;

    /**
     * The maximum reliable tracking range from the center of this device.
     *
     * The range reports the maximum recommended distance from the device center
     * for which tracking is expected to be reliable. This distance is not a hard limit.
     * Tracking may be still be functional above this distance or begin to degrade slightly
     * before this distance depending on calibration and extreme environmental conditions.
     *
     * \include Device_range.txt
     *
     * @returns The recommended maximum range of the device in mm.
     * @since 1.0
     */
    LEAP_EXPORT float range() const;

    /**
     * The distance between the center points of the stereo sensors.
     *
     * The baseline value, together with the maximum resolution, influence the
     * maximum range.
     *
     * @returns The separation distance between the center of each sensor, in mm.
     * @since 2.2.5
     */
    LEAP_EXPORT float baseline() const;

    /**
     * The distance to the nearest edge of the Leap Motion controller's view volume.
     *
     * The view volume is an axis-aligned, inverted pyramid centered on the device origin
     * and extending upward to the range limit. The walls of the pyramid are described
     * by the horizontalViewAngle and verticalViewAngle and the roof by the range.
     * This function estimates the distance between the specified input position and the
     * nearest wall or roof of the view volume.
     *
     * \include Device_distanceToBoundary.txt
     *
     * @param position The point to use for the distance calculation.
     * @returns The distance in millimeters from the input position to the nearest boundary.
     * @since 1.0
     */
    LEAP_EXPORT float distanceToBoundary(const Vector& position) const;

    /**
     * Reports whether this device is embedded in another computer or computer
     * peripheral.
     *
     * @returns True, if this device is embedded in a laptop, keyboard, or other computer
     * component; false, if this device is a standalone controller.
     * @since 1.2
     */
    LEAP_EXPORT bool isEmbedded() const;

    /**
     * Reports whether this device is streaming data to your application.
     *
     * Currently only one controller can provide data at a time.
     * @since 1.2
     */
    LEAP_EXPORT bool isStreaming() const;

    // primarily for the image API
    /**
     * Deprecated. Always reports false.
     *
     * @since 2.1
     * @deprecated 2.1.1
     */
    LEAP_EXPORT bool isFlipped() const;

    /**
     * The device type.
     *
     * Use the device type value in the (rare) circumstances that you
     * have an application feature which relies on a particular type of device.
     * Current types of device include the original Leap Motion peripheral,
     * keyboard-embedded controllers, and laptop-embedded controllers.
     *
     * @returns The physical device type as a member of the DeviceType enumeration.
     * @since 1.2
     */
    LEAP_EXPORT Type type() const;

    /**
     * An alphanumeric serial number unique to each device.
     *
     * Consumer device serial numbers consist of 2 letters followed by 11 digits.
     *
     * When using multiple devices, the serial number provides an unambiguous
     * identifier for each device.
     * @since 2.2.2
     */
    std::string serialNumber() const {
      const char* cstr = serialNumberCString();
      std::string str(cstr);
      deleteCString(cstr);
      return str;
    }

    /*
     * This API is experimental and not currently intended for external use.
     * Position and orientation can only be manually configured via a config file.
     * This API and the config file may change in the future or be removed entirely.
     *
     * The position of the center of the device in global coordinates (currently defined
     * in the configuration file).
     * @since 2.2.2
     */
    LEAP_EXPORT Vector position() const;

    /*
     * This API is experimental and not currently intended for external use.
     * Position and orientation can only be manually configured via a config file.
     * This API and the config file may change in the future or be removed entirely.
     *
     * The orientation of the device is described by a right-handed basis:
     * xBasis : Unit vector along baseline axis between camera centers
     * yBasis : Unit vector in the direction of the center of view of both cameras
     * zBasis : The completion of the right-handed basis (perpendicular to the
     *          x and y vectors)
     *
     * In the case of a peripheral device, the z-basis vector points
     * out from the green-status-LED side of the device. When multiple-device
     * tracking is enabled, automatic coordinate system orientation is disabled.
     *
     * \image html images/Leap_Axes.png
     *
     * @since 2.2.2
    */
    LEAP_EXPORT Matrix orientation() const;

    /**
     * Reports whether this is a valid Device object.
     *
     * \include Device_isValid.txt
     *
     * @returns True, if this Device object contains valid data.
     * @since 1.0
     */
    LEAP_EXPORT bool isValid() const;

    /**
     * Returns an invalid Device object.
     *
     * You can use the instance returned by this function in comparisons testing
     * whether a given Device instance is valid or invalid. (You can also use the
     * Device::isValid() function.)
     *
     * \include Device_invalid.txt
     *
     * @returns The invalid Device instance.
     * @since 1.0
     */
    LEAP_EXPORT static const Device& invalid();

    /**
     * Compare Device object equality.
     *
     * \include Device_operator_equals.txt
     *
     * Two Device objects are equal if and only if both Device objects represent the
     * exact same Device and both Devices are valid.
     * @since 1.0
     */
    LEAP_EXPORT bool operator==(const Device&) const;

    /**
     * Compare Device object inequality.
     *
     * \include Device_operator_not_equals.txt
     *
     * Two Device objects are equal if and only if both Device objects represent the
     * exact same Device and both Devices are valid.
     * @since 1.0
     */
    LEAP_EXPORT bool operator!=(const Device&) const;

    /**
     * Writes a brief, human readable description of the Device object.
     *
     * \include Device_operator_stream.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT friend std::ostream& operator<<(std::ostream&, const Device&);

    /**
     * A string containing a brief, human readable description of the Device object.
     *
     * @returns A description of the Device as a string.
     * @since 1.0
     */
    std::string toString() const {
      const char* cstr = toCString();
      std::string str(cstr);
      deleteCString(cstr);
      return str;
    }

  private:
    LEAP_EXPORT const char* toCString() const;
    LEAP_EXPORT const char* serialNumberCString() const;
  };

  /**
   * The Image class represents a single image from one of the Leap Motion cameras.
   *
   * In addition to image data, the Image object provides a distortion map for correcting
   * lens distortion.
   *
   * \include Image_raw.txt
   *
   * Note that Image objects can be invalid, which means that they do not contain
   * valid image data. Get valid Image objects from Frame::frames(). Test for
   * validity with the Image::isValid() function.
   * @since 2.1.0
   */
  class Image : public Interface {
  public:

    // For internal use only.
    Image(ImageImplementation*);

    /**
     * Constructs a Image object.
     *
     * An uninitialized image is considered invalid.
     * Get valid Image objects from a ImageList object obtained from the
     * Frame::images() method.
     *
     *
     * @since 2.1.0
     */
    LEAP_EXPORT Image();

    /**
     * The image sequence ID.
     *
     * \include Image_sequenceId.txt
     *
     * @since 2.2.1
     */
    LEAP_EXPORT int64_t sequenceId() const;

    /**
     * The image ID.
     *
     * Images with ID of 0 are from the left camera; those with an ID of 1 are from the
     * right camera (with the device in its standard operating position with the
     * green LED facing the operator).
     *
     * @since 2.1.0
     */
    LEAP_EXPORT int32_t id() const;

    /**
     * The image data.
     *
     * The image data is a set of 8-bit intensity values. The buffer is
     * ``Image::width() * Image::height() * Image::bytesPerPixel()`` bytes long.
     *
     * \include Image_data_1.txt
     *
     * @return The array of unsigned char containing the sensor brightness values.
     * @since 2.1.0
     */
    LEAP_EXPORT const unsigned char* data() const;

    /**
     * The distortion calibration map for this image.
     *
     * The calibration map is a 64x64 grid of points. Each point is defined by
     * a pair of 32-bit floating point values. Each point in the map
     * represents a ray projected into the camera. The value of
     * a grid point defines the pixel in the image data containing the brightness
     * value produced by the light entering along the corresponding ray. By
     * interpolating between grid data points, you can find the brightness value
     * for any projected ray. Grid values that fall outside the range [0..1] do
     * not correspond to a value in the image data and those points should be ignored.
     *
     * \include Image_distortion_1.txt
     *
     * The calibration map can be used to render an undistorted image as well as to
     * find the true angle from the camera to a feature in the raw image. The
     * distortion map itself is designed to be used with GLSL shader programs.
     * In non-realtime contexts, it may be more convenient to use the Image::rectify()
     * and Image::warp() functions.
     *
     * If using shaders is not possible, you can use the distortion map directly.
     * This can be faster than using the ``warp()`` function, if carefully optimized:
     *
     * \include Image_distortion_using.txt
     *
     * Distortion is caused by the lens geometry as well as imperfections in the
     * lens and sensor window. The calibration map is created by the calibration
     * process run for each device at the factory (and which can be rerun by the
     * user).
     *
     * Note, in a future release, there may be two distortion maps per image;
     * one containing the horizontal values and the other containing the vertical values.
     *
     * @returns The float array containing the camera lens distortion map.
     * @since 2.1.0
     */
    LEAP_EXPORT const float* distortion() const;

    /*
     * Do not call this version of data(). It is intended only as a helper for C#,
     * Java, and other languages. Use the primary version of data() which returns a
     * pointer.
     *
     * @since 2.1.0
     */
    void data(unsigned char* dst) const {
      const unsigned char* src = data();
      memcpy(dst, src, width() * height() * bytesPerPixel() * sizeof(unsigned char));
    }

    /*
     * Do not call this version of distortion(). It is intended only as a helper for C#,
     * Java, and other languages. Use the primary version of distortion() which returns
     * a pointer.
     *
     * @since 2.1.0
     */
    void distortion(float* dst) const {
      const float* src = distortion();
      memcpy(dst, src, distortionWidth() * distortionHeight() * sizeof(float));
    }

    /* Do not call dataPointer(). It is intended only as a helper for C#.
     *
     * @since 2.2.7
     */
    void* dataPointer() const {
      return (void*) data();
    }

    /* Do not call distortionPointer(). It is intended only as a helper for C#.
     *
     * @since 2.2.7
     */
    void* distortionPointer() const {
      return (void*) distortion();
    }

    /**
     * The image width.
     *
     * \include Image_image_width_1.txt
     *
     * @since 2.1.0
     */
    LEAP_EXPORT int width() const;

    /**
     * The image height.
     *
     * \include Image_image_height_1.txt
     *
     * @since 2.1.0
     */
    LEAP_EXPORT int height() const;

    /**
     * The number of bytes per pixel.
     *
     * Use this value along with ``Image::width()`` and ``Image:::height()``
     * to calculate the size of the data buffer.
     *
     * \include Image_bytesPerPixel.txt
     *
     * @since 2.2.0
     */
    LEAP_EXPORT int bytesPerPixel() const;

    /**
     * Enumerates the possible image formats.
     *
     * The Image::format() function returns an item from the FormatType enumeration.
     * @since 2.2.0
     */
    enum FormatType {
      INFRARED = 0
    };

    /**
     * The image format.
     *
     * \include Image_format.txt
     *
     * @since 2.2.0
     */
    LEAP_EXPORT FormatType format() const;

    /**
     * The stride of the distortion map.
     *
     * Since each point on the 64x64 element distortion map has two values in the
     * buffer, the stride is 2 times the size of the grid. (Stride is currently fixed
     * at 2 * 64 = 128).
     *
     * \include Image_distortion_width_1.txt
     *
     * @since 2.1.0
     */
    LEAP_EXPORT int distortionWidth() const;

    /**
     * The distortion map height.
     *
     * Currently fixed at 64.
     *
     * \include Image_distortion_height_1.txt
     *
     * @since 2.1.0
     */
    LEAP_EXPORT int distortionHeight() const;

    /**
     * The horizontal ray offset.
     *
     * Used to convert between normalized coordinates in the range [0..1] and the
     * ray slope range [-4..4].
     *
     * \include Image_ray_factors_1.txt
     *
     * @since 2.1.0
     */
    LEAP_EXPORT float rayOffsetX() const;

    /**
     * The vertical ray offset.
     *
     * Used to convert between normalized coordinates in the range [0..1] and the
     * ray slope range [-4..4].
     *
     * \include Image_ray_factors_2.txt
     *
     * @since 2.1.0
     */
    LEAP_EXPORT float rayOffsetY() const;

    /**
     * The horizontal ray scale factor.
     *
     * Used to convert between normalized coordinates in the range [0..1] and the
     * ray slope range [-4..4].
     *
     * \include Image_ray_factors_1.txt
     *
     * @since 2.1.0
     */
    LEAP_EXPORT float rayScaleX() const;

    /**
     * The vertical ray scale factor.
     *
     * Used to convert between normalized coordinates in the range [0..1] and the
     * ray slope range [-4..4].
     *
     * \include Image_ray_factors_2.txt
     *
     * @since 2.1.0
     */
    LEAP_EXPORT float rayScaleY() const;

    /**
     * Provides the corrected camera ray intercepting the specified point on the image.
     *
     * Given a point on the image, ``rectify()`` corrects for camera distortion
     * and returns the true direction from the camera to the source of that image point
     * within the Leap Motion field of view.
     *
     * This direction vector has an x and y component [x, y, 0], with the third element
     * always zero. Note that this vector uses the 2D camera coordinate system
     * where the x-axis parallels the longer (typically horizontal) dimension and
     * the y-axis parallels the shorter (vertical) dimension. The camera coordinate
     * system does not correlate to the 3D Leap Motion coordinate system.
     *
     * \include Image_rectify_1.txt
     *
     * @param uv A Vector containing the position of a pixel in the image.
     * @returns A Vector containing the ray direction (the z-component of the vector is always 0).
     * @since 2.1.0
     */
    LEAP_EXPORT Vector rectify(const Vector& uv) const; // returns a vector (x, y, 0). The z-component is ignored

    /**
     * Provides the point in the image corresponding to a ray projecting
     * from the camera.
     *
     * Given a ray projected from the camera in the specified direction, ``warp()``
     * corrects for camera distortion and returns the corresponding pixel
     * coordinates in the image.
     *
     * The ray direction is specified in relationship to the camera. The first
     * vector element corresponds to the "horizontal" view angle; the second
     * corresponds to the "vertical" view angle.
     *
     * \include Image_warp_1.txt
     *
     * The ``warp()`` function returns pixel coordinates outside of the image bounds
     * if you project a ray toward a point for which there is no recorded data.
     *
     * ``warp()`` is typically not fast enough for realtime distortion correction.
     * For better performance, use a shader program exectued on a GPU.
     *
     * @param xy A Vector containing the ray direction.
     * @returns A Vector containing the pixel coordinates [x, y, 0] (with z always zero).
     * @since 2.1.0
     */
    LEAP_EXPORT Vector warp(const Vector& xy) const; // returns vector (u, v, 0). The z-component is ignored

    /**
     * Returns a timestamp indicating when this frame began being captured on the device.
     * 
     * @since 2.2.7
     */
    LEAP_EXPORT int64_t timestamp() const;
   
    /**
     * Reports whether this Image instance contains valid data.
     *
     * @returns true, if and only if the image is valid.
     * @since 2.1.0
     */
    LEAP_EXPORT bool isValid() const;

    /**
     * Returns an invalid Image object.
     *
     * You can use the instance returned by this function in comparisons testing
     * whether a given Image instance is valid or invalid. (You can also use the
     * Image::isValid() function.)
     *
     * @returns The invalid Image instance.
     * @since 2.1.0
     */
    LEAP_EXPORT static const Image& invalid();

    /**
     * Compare Image object equality.
     *
     * Two Image objects are equal if and only if both Image objects represent the
     * exact same Image and both Images are valid.
     * @since 2.1.0
     */
    LEAP_EXPORT bool operator==(const Image&) const;

    /**
     * Compare Image object inequality.
     *
     *
     * Two Image objects are equal if and only if both Image objects represent the
     * exact same Image and both Images are valid.
     * @since 2.1.0
     */
    LEAP_EXPORT bool operator!=(const Image&) const;

    /**
     * Writes a brief, human readable description of the Image object.
     *
     * @since 2.1.0
     */
    LEAP_EXPORT friend std::ostream& operator<<(std::ostream&, const Image&);

    /**
     * A string containing a brief, human readable description of the Image object.
     *
     * @returns A description of the Image as a string.
     * @since 2.1.0
     */
    std::string toString() const {
      const char* cstr = toCString();
      std::string str(cstr);
      deleteCString(cstr);
      return str;
    }

  private:
    LEAP_EXPORT const char* toCString() const;
  };

  /**
  * Note: This class is an experimental API for internal use only. It may be
  * removed without warning.
  *
  * A bitmap mask defining areas of an image in which a finger or part of a hand
  * is in front of the tracked quad. The mask is a subset of the camera image
  * containing a the region including the quad. Pixels in the mask representing
  * the hand have the value 255. Pixels in the rest of the mask have the value 0.
  *
  * Two masks are provided for every Leap Motion frame. The mask with the id of
  * 0 is for the left image. The right image has id 1.
  *
  * The mask corresponds to the uncorrected image from the camera sensor. If you
  * correct the image for distortion before displaying it, you should also correct
  * the mask.
  *
  * @since 2.2.6
  */
  class Mask : public Interface {
  public:

    // For internal use only.
    Mask(MaskImplementation*);

    /**
    * Constructs a new Mask object. Do not use. Get Mask objects from TrackedQuad.
    * \include Mask_constructor_controller.txt
    * \include Mask_constructor_frame.txt
    * @since 2.2.6
    */
    LEAP_EXPORT Mask();

    /**
    * An id value based on the sequence in which the mask is produced. Corresponds
    * to the Image sequence id.
    * \include Mask_sequenceId.txt
    * @since 2.2.6
    */
    LEAP_EXPORT int64_t sequenceId() const;

    /**
    * An id indicating whether the mask goes with the left (0) or right (1) image.
    * \include Mask_id.txt
    * @since 2.2.6
    */
    LEAP_EXPORT int32_t id() const;

    /**
    * The pixels of the mask.
    *
    * Pixels with the value of 255 represent areas of the image where a finger
    * or part of a hand is in front of the quad. The rest of the mask has the
    * value 0.
    * \include Mask_data.txt
    * @since 2.2.6
    */
    LEAP_EXPORT const unsigned char* data() const;

    void data(unsigned char* dst) const {
      const unsigned char* src = data();
      memcpy(dst, src, width() * height() * sizeof(unsigned char));
    }

    void* dataPointer() const {
      return (void*) data();
    }

    /**
    * The width of the mask in Image pixels.
    * \include Mask_width.txt
    * @since 2.2.6
    */
    LEAP_EXPORT int width() const;

    /**
    * The height of the mask in Image pixels.
    * \include Mask_height.txt
    * @since 2.2.6
    */
    LEAP_EXPORT int height() const;

    /**
    * The offset of the mask from the left edge of the Image in pixels.
    * \include Mask_offsetX.txt
    * @since 2.2.6
    */
    LEAP_EXPORT int offsetX() const;

    /**
    * The offset of the mask from the top edge of the Image in pixels.
    * \include Mask_offsetY.txt
    * @since 2.2.6
    */
    LEAP_EXPORT int offsetY() const;

    /**
    * Reports whether this is a valid Mask object.
    * @since 2.2.6
    */
    LEAP_EXPORT bool isValid() const;

    /** An invalid Mask object.
    * @since 2.2.6
    */
    LEAP_EXPORT static const Mask& invalid();

    /** Compares two Mask objects for equality.
    * @since 2.2.6
    */
    LEAP_EXPORT bool operator==(const Mask&) const;

    /** Compares two Mask objects for inequality.
    * @since 2.2.6
    */
    LEAP_EXPORT bool operator!=(const Mask&) const;

    /** Writes a brief, human readable description of the Mask object.
    * @since 2.2.6
    */
    LEAP_EXPORT friend std::ostream& operator<<(std::ostream&, const Mask&);

    std::string toString() const {
      const char* cstr = toCString();
      std::string str(cstr);
      deleteCString(cstr);
      return str;
    }

  private:
    LEAP_EXPORT const char* toCString() const;
  };

  // For internal use only.
  template<typename L, typename T>
  class ConstListIterator {
  public:
    ConstListIterator<L,T>() : m_list(0), m_index(-1) {}
    ConstListIterator<L,T>(const L& list, int index) : m_list(&list), m_index(index) {}

    const T operator*() const { return (*m_list)[m_index]; }
    const ConstListIterator<L,T> operator++(int) { ConstListIterator<L,T> ip(*this); ++m_index; return ip; }
    const ConstListIterator<L,T>& operator++() { ++m_index; return *this; }
    bool operator!=(const ConstListIterator<L,T>& rhs) const { return m_index != rhs.m_index; }
    bool operator==(const ConstListIterator<L,T>& rhs) const { return m_index == rhs.m_index; }

    typedef std::ptrdiff_t difference_type;
    typedef T value_type;
    typedef const T* pointer;
    typedef const T& reference;
    typedef std::forward_iterator_tag iterator_category;

  private:
    const L* m_list;
    int m_index;
  };

  /**
   * The PointableList class represents a list of Pointable objects.
   *
   * Pointable objects include entities that can be pointed, such as fingers and tools.
   *
   * Get a PointableList object by calling Frame::pointables() or Hand::pointables().
   *
   * \include PointableList_PointableList.txt
   *
   * @since 1.0
   */
  class PointableList : public Interface {
  public:
    // For internal use only.
    PointableList(const ListBaseImplementation<Pointable>&);

    /**
     * Constructs an empty list of pointable entities.
     * @since 1.0
     */
    LEAP_EXPORT PointableList();

    /**
     * Returns the number of pointable entities in this list.
     *
     * \include PointableList_count.txt
     *
     * @returns The number of pointable entities in this list.
     * @since 1.0
     */
    LEAP_EXPORT int count() const;

    /**
     * Reports whether the list is empty.
     *
     * \include PointableList_isEmpty.txt
     *
     * @returns True, if the list has no members.
     * @since 1.0
     */
    LEAP_EXPORT bool isEmpty() const;

    /**
     * Access a list member by its position in the list.
     *
     * \include PointableList_operator_index.txt
     *
     * @param index The zero-based list position index.
     * @returns The Pointable object at the specified index.
     * @since 1.0
     */
    LEAP_EXPORT Pointable operator[](int index) const;

    /**
     * Appends the members of the specified PointableList to this PointableList.
     * @param other A PointableList object containing Pointable objects
     * to append to the end of this PointableList.
     * @since 1.0
     */
    LEAP_EXPORT PointableList& append(const PointableList& other);

    /**
     * Appends the members of the specified FingerList to this PointableList.
     * @param other A FingerList object containing Finger objects
     * to append to the end of this PointableList.
     * @since 1.0
     */
    LEAP_EXPORT PointableList& append(const FingerList& other);

    /**
     * Appends the members of the specified ToolList to this PointableList.
     * @param other A ToolList object containing Tool objects
     * to append to the end of this PointableList.
     * @since 1.0
     */
    LEAP_EXPORT PointableList& append(const ToolList& other);

    /**
     * The member of the list that is farthest to the left within the standard
     * Leap Motion frame of reference (i.e has the smallest X coordinate).
     *
     * \include PointableList_leftmost.txt
     *
     * @returns The leftmost pointable, or invalid if list is empty.
     * @since 1.0
     */
    LEAP_EXPORT Pointable leftmost() const;

    /**
     * The member of the list that is farthest to the right within the standard
     * Leap Motion frame of reference (i.e has the largest X coordinate).
     *
     * \include PointableList_rightmost.txt
     *
     * @returns The rightmost pointable, or invalid if list is empty.
     * @since 1.0
     */
    LEAP_EXPORT Pointable rightmost() const;


    /**
     * The member of the list that is farthest to the front within the standard
     * Leap Motion frame of reference (i.e has the smallest Z coordinate).
     *
     * \include PointableList_frontmost.txt
     *
     * @returns The frontmost pointable, or invalid if list is empty.
     * @since 1.0
     */
    LEAP_EXPORT Pointable frontmost() const;

    /**
     * Returns a new list containing those members of the current list that are
     * extended. This includes all tools and any fingers whose isExtended() function is true.
     *
     * @returns The list of tools and extended fingers from the current list.
     * @since 2.0
     */
    LEAP_EXPORT PointableList extended() const;

    /**
     * A C++ iterator type for PointableList objects.
     *
     * \include PointableList_iterator.txt
     *
     * @since 1.0
     */
    typedef ConstListIterator<PointableList, Pointable> const_iterator;

    /**
     * The C++ iterator set to the beginning of this PointableList.
     *
     * \include PointableList_begin.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT const_iterator begin() const;

    /**
     * The C++ iterator set to the end of this PointableList.
     *
     * \include PointableList_end.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT const_iterator end() const;
  };

  /**
   * The FingerList class represents a list of Finger objects.
   *
   * Get a FingerList object by calling Frame::fingers().
   *
   * \include FingerList_FingerList.txt
   *
   * @since 1.0
   */
  class FingerList : public Interface {
  public:
    // For internal use only.
    FingerList(const ListBaseImplementation<Finger>&);

    /**
     * Constructs an empty list of fingers.
     * @since 1.0
     */
    LEAP_EXPORT FingerList();

    /**
     * Returns the number of fingers in this list.
     *
     * \include FingerList_count.txt
     *
     * @returns The number of fingers in this list.
     * @since 1.0
     */
    LEAP_EXPORT int count() const;

    /**
     * Reports whether the list is empty.
     *
     * \include FingerList_isEmpty.txt
     *
     * @returns True, if the list has no members.
     * @since 1.0
     */
    LEAP_EXPORT bool isEmpty() const;

    /**
     * Access a list member by its position in the list.
     *
     * \include FingerList_index.txt
     *
     * @param index The zero-based list position index.
     * @returns The Finger object at the specified index.
     * @since 1.0
     */
    LEAP_EXPORT Finger operator[](int index) const;

    /**
     * Appends the members of the specified FingerList to this FingerList.
     * @param other A FingerList object containing Finger objects
     * to append to the end of this FingerList.
     * @since 1.0
     */
    LEAP_EXPORT FingerList& append(const FingerList& other);

    /**
     * The member of the list that is farthest to the left within the standard
     * Leap Motion frame of reference (i.e has the smallest X coordinate).
     *
     * \include FingerList_leftmost.txt
     *
     * @returns The leftmost finger, or invalid if list is empty.
     * @since 1.0
     */
    LEAP_EXPORT Finger leftmost() const;

    /**
     * The member of the list that is farthest to the right within the standard
     * Leap Motion frame of reference (i.e has the largest X coordinate).
     *
     * \include FingerList_rightmost.txt
     *
     * @returns The rightmost finger, or invalid if list is empty.
     * @since 1.0
     */
    LEAP_EXPORT Finger rightmost() const;

    /**
     * The member of the list that is farthest to the front within the standard
     * Leap Motion frame of reference (i.e has the smallest Z coordinate).
     *
     * \include FingerList_frontmost.txt
     *
     * @returns The frontmost finger, or invalid if list is empty.
     * @since 1.0
     */
    LEAP_EXPORT Finger frontmost() const;

    /**
     * Returns a new list containing those fingers in the current list that are
     * extended.
     *
     * \include FingerList_extended.txt
     *
     * @returns The list of extended fingers from the current list.
     * @since 2.0
     */
    LEAP_EXPORT FingerList extended() const;

    /**
     * Returns a list containing fingers from the current list of a given finger type by
     * modifying the existing list.
     *
     * \include FingerList_fingerType.txt
     *
    * @returns The list of matching fingers from the current list.
     * @since 2.0
     */
    LEAP_EXPORT FingerList fingerType(Finger::Type type) const;

    /**
     * A C++ iterator type for FingerList objects.
     *
     * \include FingerList_iterator.txt
     *
     * @since 1.0
     */
    typedef ConstListIterator<FingerList, Finger> const_iterator;

    /**
     * The C++ iterator set to the beginning of this FingerList.
     *
     * \include FingerList_begin.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT const_iterator begin() const;

    /**
     * The C++ iterator set to the end of this FingerList.
     *
     * \include FingerList_end.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT const_iterator end() const;
  };

  /**
   * The ToolList class represents a list of Tool objects.
   *
   * Get a ToolList object by calling Frame::tools().
   *
   * \include ToolList_ToolList.txt
   *
   * @since 1.0
   */
  class ToolList : public Interface {
  public:
    // For internal use only.
    ToolList(const ListBaseImplementation<Tool>&);

    /**
     * Constructs an empty list of tools.
     * @since 1.0
     */
    LEAP_EXPORT ToolList();

    /**
     * Returns the number of tools in this list.
     *
     * \include ToolList_count.txt
     *
     * @returns The number of tools in this list.
     * @since 1.0
     */
    LEAP_EXPORT int count() const;

    /**
     * Reports whether the list is empty.
     *
     * \include ToolList_isEmpty.txt
     *
     * @returns True, if the list has no members.
     * @since 1.0
     */
    LEAP_EXPORT bool isEmpty() const;

    /**
     * Access a list member by its position in the list.
     *
     * \include ToolList_operator_index.txt
     *
     * @param index The zero-based list position index.
     * @returns The Tool object at the specified index.
     * @since 1.0
     */
    LEAP_EXPORT Tool operator[](int index) const;

    /**
     * Appends the members of the specified ToolList to this ToolList.
     * @param other A ToolList object containing Tool objects
     * to append to the end of this ToolList.
     * @since 1.0
     */
    LEAP_EXPORT ToolList& append(const ToolList& other);

    /**
     * The member of the list that is farthest to the left within the standard
     * Leap Motion frame of reference (i.e has the smallest X coordinate).
     *
     * \include ToolList_leftmost.txt
     *
     * @returns The leftmost tool, or invalid if list is empty.
     * @since 1.0
     */
    LEAP_EXPORT Tool leftmost() const;

    /**
     * The member of the list that is farthest to the right within the standard
     * Leap Motion frame of reference (i.e has the largest X coordinate).
     *
     * \include ToolList_rightmost.txt
     *
     * @returns The rightmost tool, or invalid if list is empty.
     * @since 1.0
     */
    LEAP_EXPORT Tool rightmost() const;

    /**
     * The member of the list that is farthest to the front within the standard
     * Leap Motion frame of reference (i.e has the smallest Z coordinate).
     *
     * \include ToolList_frontmost.txt
     *
     * @returns The frontmost tool, or invalid if list is empty.
     * @since 1.0
     */
    LEAP_EXPORT Tool frontmost() const;

    /**
     * A C++ iterator type for ToolList objects.
     *
     * \include ToolList_iterator.txt
     *
     * @since 1.0
     */
    typedef ConstListIterator<ToolList, Tool> const_iterator;

    /**
     * The C++ iterator set to the beginning of this ToolList.
     *
     * \include ToolList_begin.txt
     * @since 1.0
     */
    LEAP_EXPORT const_iterator begin() const;

    /**
     * The C++ iterator set to the end of this ToolList.
     *
     * \include ToolList_end.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT const_iterator end() const;
  };

  /**
   * The HandList class represents a list of Hand objects.
   *
   * Get a HandList object by calling Frame::hands().
   *
   * \include HandList_HandList.txt
   *
   * @since 1.0
   */
  class HandList : public Interface {
  public:
    // For internal use only.
    HandList(const ListBaseImplementation<Hand>&);

    /**
     * Constructs an empty list of hands.
     * @since 1.0
     */
    LEAP_EXPORT HandList();

    /**
     * Returns the number of hands in this list.
     *
     * \include HandList_count.txt
     * @returns The number of hands in this list.
     * @since 1.0
     */
    LEAP_EXPORT int count() const;

    /**
     * Reports whether the list is empty.
     *
     * \include HandList_isEmpty.txt
     *
     * @returns True, if the list has no members.
     * @since 1.0
     */
    LEAP_EXPORT bool isEmpty() const;

    /**
     * Access a list member by its position in the list.
     *
     * \include HandList_operator_index.txt
     *
     * @param index The zero-based list position index.
     * @returns The Hand object at the specified index.
     * @since 1.0
     */
    LEAP_EXPORT Hand operator[](int index) const;

    /**
     * Appends the members of the specified HandList to this HandList.
     * @param other A HandList object containing Hand objects
     * to append to the end of this HandList.
     */
    LEAP_EXPORT HandList& append(const HandList& other);

    /**
     * The member of the list that is farthest to the left within the standard
     * Leap Motion frame of reference (i.e has the smallest X coordinate).
     *
     * Note: to determine whether a hand is the left hand, use the Hand::isLeft() function.
     *
     * \include HandList_leftmost.txt
     *
     * @returns The leftmost hand, or invalid if list is empty.
     * @since 1.0
     */
    LEAP_EXPORT Hand leftmost() const;

    /**
     * The member of the list that is farthest to the right within the standard
     * Leap Motion frame of reference (i.e has the largest X coordinate).
     *
     * Note: to determine whether a hand is the right hand, use the Hand::isRight() function.
     *
     * \include HandList_rightmost.txt
     *
     * @returns The rightmost hand, or invalid if list is empty.
     * @since 1.0
     */
    LEAP_EXPORT Hand rightmost() const;

    /**
     * The member of the list that is farthest to the front within the standard
     * Leap Motion frame of reference (i.e has the smallest Z coordinate).
     *
     * \include HandList_frontmost.txt
     *
     * @returns The frontmost hand, or invalid if list is empty.
     * @since 1.0
     */
    LEAP_EXPORT Hand frontmost() const;

    /**
     * A C++ iterator type for this HandList objects.
     *
     * \include HandList_iterator.txt
     *
     * @since 1.0
     */
    typedef ConstListIterator<HandList, Hand> const_iterator;

    /**
     * The C++ iterator set to the beginning of this HandList.
     *
     * \include HandList_begin.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT const_iterator begin() const;

    /**
     * The C++ iterator set to the end of this HandList.
     *
     * \include HandList_end.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT const_iterator end() const;
  };

  /**
   * The GestureList class represents a list of Gesture objects.
   *
   * Get a GestureList object from a Frame object.
   * @since 1.0
   */
  class GestureList : public Interface {
  public:
    // For internal use only.
    GestureList(const ListBaseImplementation<Gesture>&);

    /**
     * Constructs an empty gesture list.
     * @since 1.0
     */
    LEAP_EXPORT GestureList();

    /**
     * The length of this list.
     *
     * \include GestureList_count.txt
     *
     * @returns The number of gestures in this list.
     * @since 1.0
     */
    LEAP_EXPORT int count() const;

    /**
     * Reports whether the list is empty.
     *
     * \include GestureList_isEmpty.txt
     *
     * @returns True, if the list has no members.
     * @since 1.0
     */
    LEAP_EXPORT bool isEmpty() const;

    /**
     * Access a list member by its position in the list.
     *
     * \include GestureList_operator_index.txt
     *
     * @param index The zero-based list position index.
     * @returns The Gesture object at the specified index.
     * @since 1.0
     */
    LEAP_EXPORT Gesture operator[](int index) const;

    /**
     * Appends the members of the specified GestureList to this GestureList.
     * @param other A GestureList object containing Gesture objects
     * to append to the end of this GestureList.
     * @since 1.0
     */
    LEAP_EXPORT GestureList& append(const GestureList& other);

    /**
     * A C++ iterator type for GestureList objects.
     *
     * \include GestureList_iterator.txt
     * @since 1.0
     */
    typedef ConstListIterator<GestureList, Gesture> const_iterator;

    /**
     * The C++ iterator set to the beginning of this GestureList.
     *
     * \include GestureList_begin.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT const_iterator begin() const;

    /**
     * The C++ iterator set to the end of this GestureList.
     *
     * \include GestureList_end.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT const_iterator end() const;
  };

  /*
   * Deprecated as of version 1.2.
   */
  class ScreenList : public Interface {
  public:
    // For internal use only.
    ScreenList(const ListBaseImplementation<Screen>&);

    LEAP_EXPORT ScreenList();

    LEAP_EXPORT int count() const;

    LEAP_EXPORT bool isEmpty() const;

    LEAP_EXPORT Screen operator[](int index) const;

    typedef ConstListIterator<ScreenList, Screen> const_iterator;

    LEAP_EXPORT const_iterator begin() const;

    LEAP_EXPORT const_iterator end() const;

    LEAP_EXPORT Screen closestScreenHit(const Pointable& pointable) const;

    LEAP_EXPORT Screen closestScreenHit(const Vector& position, const Vector& direction) const;

    LEAP_EXPORT Screen closestScreen(const Vector& position) const;
  };

  /**
   * The DeviceList class represents a list of Device objects.
   *
   * Get a DeviceList object by calling Controller::devices().
   * @since 1.0
   */
  class DeviceList : public Interface {
  public:
    // For internal use only.
    DeviceList(const ListBaseImplementation<Device>&);

    /**
     * Constructs an empty list of devices.
     * @since 1.0
     */
    LEAP_EXPORT DeviceList();

    /**
     * Returns the number of devices in this list.
     * @returns The number of devices in this list.
     * @since 1.0
     */
    LEAP_EXPORT int count() const;

    /**
     * Reports whether the list is empty.
     *
     * \include DeviceList_isEmpty.txt
     *
     * @returns True, if the list has no members.
     * @since 1.0
     */
    LEAP_EXPORT bool isEmpty() const;

    /**
     * Access a list member by its position in the list.
     * @param index The zero-based list position index.
     * @returns The Device object at the specified index.
     * @since 1.0
     */
    LEAP_EXPORT Device operator[](int index) const;

    /**
     * Appends the members of the specified DeviceList to this DeviceList.
     * @param other A DeviceList object containing Device objects
     * to append to the end of this DeviceList.
     * @since 1.0
     */
    LEAP_EXPORT DeviceList& append(const DeviceList& other);

    /**
     * A C++ iterator type for this DeviceList objects.
     * @since 1.0
     */
    typedef ConstListIterator<DeviceList, Device> const_iterator;

    /**
     * The C++ iterator set to the beginning of this DeviceList.
     * @since 1.0
     */
    LEAP_EXPORT const_iterator begin() const;

    /**
     * The C++ iterator set to the end of this DeviceList.
     * @since 1.0
     */
    LEAP_EXPORT const_iterator end() const;
  };

  /**
   * The ImageList class represents a list of Image objects.
   *
   * Get the ImageList object associated with the a Frame of tracking data
   * by calling Frame::images(). Get the most recent set of images, which can be
   * newer than the images used to create the current frame, by calling
   * Controller::images().
   *
   * @since 2.1.0
   */
  class ImageList : public Interface {
  public:
    // For internal use only.
    ImageList(const ListBaseImplementation<Image>&);

    /**
     * Constructs an empty list of images.
     * @since 2.1.0
     */
    LEAP_EXPORT ImageList();

    /**
     * The number of images in this list.
     *
     * @returns The number of images in this list.
     * @since 2.1.0
     */
    LEAP_EXPORT int count() const;

    /**
     * Reports whether the list is empty.
     *
     * \include ImageList_isEmpty.txt
     *
     * @returns True, if the list has no members.
     * @since 2.1.0
     */
    LEAP_EXPORT bool isEmpty() const;

    /**
     * Access a list member by its position in the list.
     * @param index The zero-based list position index.
     * @returns The Image object at the specified index.
     * @since 2.1.0
     */
    LEAP_EXPORT Image operator[](int index) const;

    /**
     * Appends the members of the specified ImageList to this ImageList.
     * @param other A ImageList object containing Image objects
     * to append to the end of this ImageList.
     * @since 2.1.0
     */
    LEAP_EXPORT ImageList& append(const ImageList& other);

    /**
     * A C++ iterator type for this ImageList objects.
     * @since 2.1.0
     */
    typedef ConstListIterator<ImageList, Image> const_iterator;

    /**
     * The C++ iterator set to the beginning of this ImageList.
     * @since 2.1.0
     */
    LEAP_EXPORT const_iterator begin() const;

    /**
     * The C++ iterator set to the end of this ImageList.
     * @since 2.1.0
     */
    LEAP_EXPORT const_iterator end() const;
  };

  /**
  * Note: This class is an experimental API for internal use only. It may be
  * removed without warning.
  *
  * Represents a quad-like object tracked by the Leap Motion sensors.
  *
  * Only one quad can be tracked. Once a supported quad is tracked, the state
  * of that quad will be updated for each frame of Leap Motion tracking data.
  *
  * A TrackedQuad object represents the state of the quad at one moment in time.
  * Get a new object from subsequent frames to get the latest state information.
  * @since 2.2.6
  */
  class TrackedQuad : public Interface {
  public:

    // For internal use only.
    TrackedQuad(TrackedQuadImplementation*);

    /**
    * Constructs a new TrackedQuad object. Do not use. Get valid TrackedQuads
    * from a Controller or Frame object.
    * \include TrackedQuad_constructor_controller.txt
    * \include TrackedQuad_constructor_frame.txt
    * @since 2.2.6
    */
    LEAP_EXPORT TrackedQuad();

    /**
    * The physical width of the quad display area in millimeters.
    * \include TrackedQuad_width.txt
    * @since 2.2.6
    */
    LEAP_EXPORT float width() const;

    /**
    * The physical height of the quad display area in millimeters.
    * \include TrackedQuad_height.txt
    * @since 2.2.6
    */
    LEAP_EXPORT float height() const;

    /**
    * The horizontal resolution of the quad display area in pixels.
    * This value is set in a configuration file. It is not determined dynamically.
    * \include TrackedQuad_resolutionX.txt
    * @since 2.2.6
    */
    LEAP_EXPORT int resolutionX() const;

    /**
    * The vertical resolution of the quad display area in pixels.
    * This value is set in a configuration file. It is not determined dynamically.
    * \include TrackedQuad_resolutionY.txt
    * @since 2.2.6
    */
    LEAP_EXPORT int resolutionY() const;

    /**
    * Reports whether the quad is currently detected within the Leap Motion
    * field of view.
    * \include TrackedQuad_visible.txt
    * @since 2.2.6
    */
    LEAP_EXPORT bool visible() const;

    /**
    * The orientation of the quad within the Leap Motion frame of reference.
    * \include TrackedQuad_orientation.txt
    * @since 2.2.6
    */
    LEAP_EXPORT Matrix orientation() const;

    /**
    * The position of the center of the quad display area within the Leap
    * Motion frame of reference. In millimeters.
    * \include TrackedQuad_position.txt
    * @since 2.2.6
    */
    LEAP_EXPORT Vector position() const;

    /**
    * The list of masks for the current set of images. A mask is a bitmap
    * indicating which pixels in the image contain fingers or part of the hand
    * in front of the quad.
    *
    * The mask at index 0 corresponds to the left image; that with index 1, to
    * the right image.
    * \include TrackedQuad_masks.txt
    * @since 2.2.6
    */
    LEAP_EXPORT MaskList masks() const;

    /**
    * The images from which the state of this TrackedQuad was derived.
    * These are the same image objects that you can get from the Controller
    * or Frame object from which you got this TrackedQuad.
    * \include TrackedQuad_images.txt
    * @since 2.2.6
    */
    LEAP_EXPORT ImageList images() const;

    /**
    * Reports whether this is a valid object.
    * \include TrackedQuad_isValid.txt
    * @since 2.2.6
    */
    LEAP_EXPORT bool isValid() const;

    /**
    * An invalid object.
    * @since 2.2.6
    */
    LEAP_EXPORT static const TrackedQuad& invalid();

    /**
    * Compares quad objects for equality.
    * @since 2.2.6
    */
    LEAP_EXPORT bool operator==(const TrackedQuad&) const;

    /**
    * Compares quad objects for inequality.
    * @since 2.2.6
    */
    LEAP_EXPORT bool operator!=(const TrackedQuad&) const;

    /**
    * Provides a brief, human-readable description of this quad.
    * @since 2.2.6
    */
    LEAP_EXPORT friend std::ostream& operator<<(std::ostream&, const TrackedQuad&);

    std::string toString() const {
      const char* cstr = toCString();
      std::string str(cstr);
      deleteCString(cstr);
      return str;
    }

  private:
    LEAP_EXPORT const char* toCString() const;
  };

  /**
  * Note: This class is an experimental API for internal use only. It may be
  * removed without warning.
  *
  * A list containing Mask objects.
  * @since 2.2.6
  */
  class MaskList : public Interface {
  public:
    // For internal use only.
    MaskList(const ListBaseImplementation<Mask>&);

    /**
    * Constructs an empty list for Mask objects.
    * @since 2.2.6
    */
    LEAP_EXPORT MaskList();

    /**
    * The number of masks in this list.
    * @since 2.2.6
    */
    LEAP_EXPORT int count() const;

    /**
    * Reports whether this list is empty.
    * @since 2.2.6
    */
    LEAP_EXPORT bool isEmpty() const;

    /**
    * The MaskList supports array indexing.
    * @since 2.2.6
    */
    LEAP_EXPORT Mask operator[](int index) const;

    /**
    * Appends the contents of another list of masks to this one.
    * @since 2.2.6
    */
    LEAP_EXPORT MaskList& append(const MaskList& other);

    typedef ConstListIterator<MaskList, Mask> const_iterator;

    /**
    * A list iterator set to the beginning of the list.
    * @since 2.2.6
    */
    LEAP_EXPORT const_iterator begin() const;

    /**
    * A list iterator set to the end of the list.
    * @since 2.2.6
    */
    LEAP_EXPORT const_iterator end() const;
  };

  /**
   * The InteractionBox class represents a box-shaped region completely
   * within the field of view of the Leap Motion controller.
   *
   * The interaction box is an axis-aligned rectangular prism and provides normalized
   * coordinates for hands, fingers, and tools within this box. The InteractionBox class
   * can make it easier to map positions in the Leap Motion coordinate system to 2D or
   * 3D coordinate systems used for application drawing.
   *
   * \image html images/Leap_InteractionBox.png
   *
   * The InteractionBox region is defined by a center and dimensions along the x, y,
   * and z axes.
   *
   * Get an InteractionBox object from a Frame object.
   * @since 1.0
   */
  class InteractionBox : public Interface {
  public:
    // For internal use only.
    InteractionBox(InteractionBoxImplementation*);

    LEAP_EXPORT InteractionBox();

    /**
     * Normalizes the coordinates of a point using the interaction box.
     *
     * \include InteractionBox_normalizePoint.txt
     *
     * Coordinates from the Leap Motion frame of reference (millimeters) are converted
     * to a range of [0..1] such that the minimum value of the InteractionBox maps to 0
     * and the maximum value of the InteractionBox maps to 1.
     *
     * @param position The input position in device coordinates.
     * @param clamp Whether or not to limit the output value to the range [0,1] when the
     * input position is outside the InteractionBox. Defaults to true.
     * @returns The normalized position.
     * @since 1.0
     */
    LEAP_EXPORT Vector normalizePoint(const Vector& position, bool clamp = true) const;

    /**
     * Converts a position defined by normalized InteractionBox coordinates into device
     * coordinates in millimeters.
     *
     * \include InteractionBox_denormalizePoint.txt
     *
     * This function performs the inverse of normalizePoint().
     *
     * @param normalizedPosition The input position in InteractionBox coordinates.
     * @returns The corresponding denormalized position in device coordinates.
     * @since 1.0
     */
    LEAP_EXPORT Vector denormalizePoint(const Vector& normalizedPosition) const;

    /**
     * The center of the InteractionBox in device coordinates (millimeters). This point
     * is equidistant from all sides of the box.
     *
     * \include InteractionBox_center.txt
     *
     * @returns The InteractionBox center in device coordinates.
     * @since 1.0
     */
    LEAP_EXPORT Vector center() const;

    /**
     * The width of the InteractionBox in millimeters, measured along the x-axis.
     *
     * \include InteractionBox_width.txt
     *
     * @returns The InteractionBox width in millimeters.
     * @since 1.0
     */
    LEAP_EXPORT float width() const;

    /**
     * The height of the InteractionBox in millimeters, measured along the y-axis.
     *
     * \include InteractionBox_height.txt
     *
     * @returns The InteractionBox height in millimeters.
     * @since 1.0
     */
    LEAP_EXPORT float height() const;

    /**
     * The depth of the InteractionBox in millimeters, measured along the z-axis.
     *
     * \include InteractionBox_depth.txt
     *
     * @returns The InteractionBox depth in millimeters.
     * @since 1.0
     */
    LEAP_EXPORT float depth() const;

    /**
     * Reports whether this is a valid InteractionBox object.
     *
     * \include InteractionBox_isValid.txt
     *
     * @returns True, if this InteractionBox object contains valid data.
     * @since 1.0
     */
    LEAP_EXPORT bool isValid() const;

    /**
     * Returns an invalid InteractionBox object.
     *
     * You can use the instance returned by this function in comparisons testing
     * whether a given InteractionBox instance is valid or invalid. (You can also use the
     * InteractionBox::isValid() function.)
     *
     * \include InteractionBox_invalid.txt
     *
     * @returns The invalid InteractionBox instance.
     * @since 1.0
     */
    LEAP_EXPORT static const InteractionBox& invalid();

    /**
     * Compare InteractionBox object equality.
     *
     * \include InteractionBox_operator_equals.txt
     *
     * Two InteractionBox objects are equal if and only if both InteractionBox objects represent the
     * exact same InteractionBox and both InteractionBoxes are valid.
     * @since 1.0
     */
    LEAP_EXPORT bool operator==(const InteractionBox&) const;

    /**
     * Compare InteractionBox object inequality.
     *
     * \include InteractionBox_operator_not_equals.txt
     *
     * Two InteractionBox objects are equal if and only if both InteractionBox objects represent the
     * exact same InteractionBox and both InteractionBoxes are valid.
     * @since 1.0
     */
    LEAP_EXPORT bool operator!=(const InteractionBox&) const;

    /**
     * Writes a brief, human readable description of the InteractionBox object.
     *
     * \include InteractionBox_operator_stream.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT friend std::ostream& operator<<(std::ostream&, const InteractionBox&);

    /**
     * A string containing a brief, human readable description of the InteractionBox object.
     *
     * @returns A description of the InteractionBox as a string.
     * @since 1.0
     */
    std::string toString() const {
      const char* cstr = toCString();
      std::string str(cstr);
      deleteCString(cstr);
      return str;
    }

  private:
    LEAP_EXPORT const char* toCString() const;
  };

  /**
   * The Frame class represents a set of hand and finger tracking data detected
   * in a single frame.
   *
   * The Leap Motion software detects hands, fingers and tools within the tracking area, reporting
   * their positions, orientations, gestures, and motions in frames at the Leap Motion frame rate.
   *
   * Access Frame objects through an instance of the Controller class:
   *
   * \include Controller_Frame_1.txt
   *
   * Implement a Listener subclass to receive a callback event when a new Frame is available.
   * @since 1.0
   */
  class Frame : public Interface {
  public:
    // For internal use only.
    Frame(FrameImplementation*);

    /**
     * Constructs a Frame object.
     *
     * Frame instances created with this constructor are invalid.
     * Get valid Frame objects by calling the Controller::frame() function.
     *
     * \include Frame_Frame.txt
     *
     * The only time you should use this constructor is before deserializing
     * serialized frame data. Call ``Frame::deserialize(string)`` to recreate
     * a saved Frame.
     *
     * @since 1.0
     */
    LEAP_EXPORT Frame();

    /**
     * A unique ID for this Frame.
     *
     * Consecutive frames processed by the Leap Motion software have consecutive
     * increasing values. You can use the frame ID to avoid processing the same
     * Frame object twice:
     *
     * \include Frame_Duplicate.txt
     *
     * As well as to make sure that your application processes every frame:
     *
     * \include Frame_Skipped.txt
     *
     * @returns The frame ID.
     * @since 1.0
     */
    LEAP_EXPORT int64_t id() const;

    /**
     * The frame capture time in microseconds elapsed since an arbitrary point in 
     * time in the past.
     *
     * Use Controller::now() to calculate the age of the frame.
     *
     * \include Frame_timestamp.txt
     *
     * @returns The timestamp in microseconds.
     * @since 1.0
     */
    LEAP_EXPORT int64_t timestamp() const;

    /**
     * The list of Hand objects detected in this frame, given in arbitrary order.
     * The list can be empty if no hands are detected.
     *
     * \include Frame_hands.txt
     *
     * @returns The HandList containing all Hand objects detected in this frame.
     * @since 1.0
     */
    LEAP_EXPORT HandList hands() const;

    /**
     * The Hand object with the specified ID in this frame.
     *
     * Use the Frame::hand() function to retrieve the Hand object from
     * this frame using an ID value obtained from a previous frame.
     * This function always returns a Hand object, but if no hand
     * with the specified ID is present, an invalid Hand object is returned.
     *
     * \include Frame_hand.txt
     *
     * Note that ID values persist across frames, but only until tracking of a
     * particular object is lost. If tracking of a hand is lost and subsequently
     * regained, the new Hand object representing that physical hand may have
     * a different ID than that representing the physical hand in an earlier frame.
     *
     * @param id The ID value of a Hand object from a previous frame.
     * @returns The Hand object with the matching ID if one exists in this frame;
     * otherwise, an invalid Hand object is returned.
     * @since 1.0
     */
    LEAP_EXPORT Hand hand(int32_t id) const;

    /**
     * The list of Pointable objects (fingers and tools) detected in this frame,
     * given in arbitrary order. The list can be empty if no fingers or tools are detected.
     *
     * Use PointableList::extended() to remove non-extended fingers from the list.
     *
     * \include Frame_pointables.txt
     *
     * @returns The PointableList containing all Pointable objects detected in this frame.
     * @since 1.0
     */
    LEAP_EXPORT PointableList pointables() const;

    /**
     * The Pointable object with the specified ID in this frame.
     *
     * Use the Frame::pointable() function to retrieve the Pointable object from
     * this frame using an ID value obtained from a previous frame.
     * This function always returns a Pointable object, but if no finger or tool
     * with the specified ID is present, an invalid Pointable object is returned.
     *
     * \include Frame_pointable.txt
     *
     * Note that ID values persist across frames, but only until tracking of a
     * particular object is lost. If tracking of a finger or tool is lost and subsequently
     * regained, the new Pointable object representing that finger or tool may have
     * a different ID than that representing the finger or tool in an earlier frame.
     *
     * @param id The ID value of a Pointable object from a previous frame.
     * @returns The Pointable object with the matching ID if one exists in this frame;
     * otherwise, an invalid Pointable object is returned.
     * @since 1.0
     */
    LEAP_EXPORT Pointable pointable(int32_t id) const;

    /**
     * The list of Finger objects detected in this frame, given in arbitrary order.
     * The list can be empty if no fingers are detected.
     *
     * Use PointableList::extended() to remove non-extended fingers from the list.
     *
     * \include Frame_fingers.txt
     *
     * @returns The FingerList containing all Finger objects detected in this frame.
     * @since 1.0
     */
    LEAP_EXPORT FingerList fingers() const;

    /**
     * The Finger object with the specified ID in this frame.
     *
     * Use the Frame::finger() function to retrieve the Finger object from
     * this frame using an ID value obtained from a previous frame.
     * This function always returns a Finger object, but if no finger
     * with the specified ID is present, an invalid Finger object is returned.
     *
     * \include Frame_finger.txt
     *
     * Note that ID values persist across frames, but only until tracking of a
     * particular object is lost. If tracking of a finger is lost and subsequently
     * regained, the new Finger object representing that physical finger may have
     * a different ID than that representing the finger in an earlier frame.
     *
     * @param id The ID value of a Finger object from a previous frame.
     * @returns The Finger object with the matching ID if one exists in this frame;
     * otherwise, an invalid Finger object is returned.
     * @since 1.0
     */
    LEAP_EXPORT Finger finger(int32_t id) const;

    /**
     * The list of Tool objects detected in this frame, given in arbitrary order.
     * The list can be empty if no tools are detected.
     *
     * \include Frame_tools.txt
     *
     * @returns The ToolList containing all Tool objects detected in this frame.
     * @since 1.0
     */
    LEAP_EXPORT ToolList tools() const;

    /**
     * The Tool object with the specified ID in this frame.
     *
     * Use the Frame::tool() function to retrieve the Tool object from
     * this frame using an ID value obtained from a previous frame.
     * This function always returns a Tool object, but if no tool
     * with the specified ID is present, an invalid Tool object is returned.
     *
     * \include Frame_tool.txt
     *
     * Note that ID values persist across frames, but only until tracking of a
     * particular object is lost. If tracking of a tool is lost and subsequently
     * regained, the new Tool object representing that tool may have a
     * different ID than that representing the tool in an earlier frame.
     *
     * @param id The ID value of a Tool object from a previous frame.
     * @returns The Tool object with the matching ID if one exists in this frame;
     * otherwise, an invalid Tool object is returned.
     * @since 1.0
     */
    LEAP_EXPORT Tool tool(int32_t id) const;

    /**
     * The Gesture object with the specified ID in this frame.
     *
     * Use the Frame::gesture() function to return a Gesture object in this
     * frame using an ID obtained in an earlier frame. The function always
     * returns a Gesture object, but if there was no update for the gesture in
     * this frame, then an invalid Gesture object is returned.
     *
     * \include Frame_gesture.txt
     *
     * All Gesture objects representing the same recognized movement share the
     * same ID.
     * @param id The ID of an Gesture object from a previous frame.
     * @returns The Gesture object in the frame with the specified ID if one
     * exists; Otherwise, an Invalid Gesture object.
     * @since 1.0
     */
    LEAP_EXPORT Gesture gesture(int32_t id) const;

    /**
     * The gestures recognized or continuing in this frame.
     *
     * \include Frame_gestures_now.txt
     *
     * Circle and swipe gestures are updated every frame. Tap gestures
     * only appear in the list  for a single frame.
     *
     * @return GestureList the list of gestures.
     * @since 1.0
     */
    LEAP_EXPORT GestureList gestures() const;

    /**
     * Returns a GestureList containing all gestures that have occurred since
     * the specified frame.
     *
     * \include Frame_gestures_since.txt
     *
     * @param sinceFrame An earlier Frame object. The starting frame must
     * still be in the frame history cache, which has a default length of
     * 60 frames.
     * @return GestureList The list of the Gesture objects that have occurred
     * since the specified frame.
     * @since 1.0
     */
    LEAP_EXPORT GestureList gestures(const Frame& sinceFrame) const;

    /**
     * The list of images from the Leap Motion cameras.
     *
     * @return An ImageList object containing the camera images analyzed to create this Frame.
     * @since 2.1
     */
    LEAP_EXPORT ImageList images() const;

    /**
     * The change of position derived from the overall linear motion between
     * the current frame and the specified frame.
     *
     * The returned translation vector provides the magnitude and direction of
     * the movement in millimeters.
     *
     * \include Frame_translation.txt
     *
     * The Leap Motion software derives frame translation from the linear motion of
     * all objects detected in the field of view.
     *
     * If either this frame or sinceFrame is an invalid Frame object, then this
     * method returns a zero vector.
     *
     * @param sinceFrame The starting frame for computing the relative translation.
     * @returns A Vector representing the heuristically determined change in
     * position of all objects between the current frame and that specified
     * in the sinceFrame parameter.
     * @since 1.0
     */
    LEAP_EXPORT Vector translation(const Frame& sinceFrame) const;

    /**
     * The estimated probability that the overall motion between the current
     * frame and the specified frame is intended to be a translating motion.
     *
     * \include Frame_translationProbability.txt
     *
     * If either this frame or sinceFrame is an invalid Frame object, then this
     * method returns zero.
     *
     * @param sinceFrame The starting frame for computing the translation.
     * @returns A value between 0 and 1 representing the estimated probability
     * that the overall motion between the current frame and the specified frame
     * is intended to be a translating motion.
     * @since 1.0
     */
    LEAP_EXPORT float translationProbability(const Frame& sinceFrame) const;

    /**
     * The axis of rotation derived from the overall rotational motion between
     * the current frame and the specified frame.
     *
     * The returned direction vector is normalized.
     *
     * \include Frame_rotationAxis.txt
     *
     * The Leap Motion software derives frame rotation from the relative change in position and
     * orientation of all objects detected in the field of view.
     *
     * If either this frame or sinceFrame is an invalid Frame object, or if no
     * rotation is detected between the two frames, a zero vector is returned.
     *
     * @param sinceFrame The starting frame for computing the relative rotation.
     * @returns A normalized direction Vector representing the axis of the
     * heuristically determined rotational change between the current frame
     * and that specified in the sinceFrame parameter.
     * @since 1.0
     */
    LEAP_EXPORT Vector rotationAxis(const Frame& sinceFrame) const;

    /**
     * The angle of rotation around the rotation axis derived from the overall
     * rotational motion between the current frame and the specified frame.
     *
     * The returned angle is expressed in radians measured clockwise around the
     * rotation axis (using the right-hand rule) between the start and end frames.
     * The value is always between 0 and pi radians (0 and 180 degrees).
     *
     * \include Frame_rotationAngle.txt
     *
     * The Leap Motion software derives frame rotation from the relative change in position and
     * orientation of all objects detected in the field of view.
     *
     * If either this frame or sinceFrame is an invalid Frame object, then the
     * angle of rotation is zero.
     *
     * @param sinceFrame The starting frame for computing the relative rotation.
     * @returns A positive value containing the heuristically determined
     * rotational change between the current frame and that specified in the
     * sinceFrame parameter.
     * @since 1.0
     */
    LEAP_EXPORT float rotationAngle(const Frame& sinceFrame) const;

    /**
     * The angle of rotation around the specified axis derived from the overall
     * rotational motion between the current frame and the specified frame.
     *
     * The returned angle is expressed in radians measured clockwise around the
     * rotation axis (using the right-hand rule) between the start and end frames.
     * The value is always between -pi and pi radians (-180 and 180 degrees).
     *
     * \include Frame_rotationAngle_axis.txt
     *
     * The Leap Motion software derives frame rotation from the relative change in position and
     * orientation of all objects detected in the field of view.
     *
     * If either this frame or sinceFrame is an invalid Frame object, then the
     * angle of rotation is zero.
     *
     * @param sinceFrame The starting frame for computing the relative rotation.
     * @param axis The axis to measure rotation around.
     * @returns A value containing the heuristically determined rotational
     * change between the current frame and that specified in the sinceFrame
     * parameter around the given axis.
     * @since 1.0
     */
    LEAP_EXPORT float rotationAngle(const Frame& sinceFrame, const Vector& axis) const;

    /**
     * The transform matrix expressing the rotation derived from the overall
     * rotational motion between the current frame and the specified frame.
     *
     * \include Frame_rotationMatrix.txt
     *
     * The Leap Motion software derives frame rotation from the relative change in position and
     * orientation of all objects detected in the field of view.
     *
     * If either this frame or sinceFrame is an invalid Frame object, then this
     * method returns an identity matrix.
     *
     * @param sinceFrame The starting frame for computing the relative rotation.
     * @returns A transformation Matrix containing the heuristically determined
     * rotational change between the current frame and that specified in the
     * sinceFrame parameter.
     * @since 1.0
     */
    LEAP_EXPORT Matrix rotationMatrix(const Frame& sinceFrame) const;

    /**
     * The estimated probability that the overall motion between the current
     * frame and the specified frame is intended to be a rotating motion.
     *
     * \include Frame_rotationProbability.txt
     *
     * If either this frame or sinceFrame is an invalid Frame object, then this
     * method returns zero.
     *
     * @param sinceFrame The starting frame for computing the relative rotation.
     * @returns A value between 0 and 1 representing the estimated probability
     * that the overall motion between the current frame and the specified frame
     * is intended to be a rotating motion.
     * @since 1.0
     */
    LEAP_EXPORT float rotationProbability(const Frame& sinceFrame) const;

    /**
     * The scale factor derived from the overall motion between the current frame
     * and the specified frame.
     *
     * The scale factor is always positive. A value of 1.0 indicates no
     * scaling took place. Values between 0.0 and 1.0 indicate contraction
     * and values greater than 1.0 indicate expansion.
     *
     * \include Frame_scaleFactor.txt
     *
     * The Leap Motion software derives scaling from the relative inward or outward motion of
     * all objects detected in the field of view (independent of translation
     * and rotation).
     *
     * If either this frame or sinceFrame is an invalid Frame object, then this
     * method returns 1.0.
     *
     * @param sinceFrame The starting frame for computing the relative scaling.
     * @returns A positive value representing the heuristically determined
     * scaling change ratio between the current frame and that specified in the
     * sinceFrame parameter.
     * @since 1.0
     */
    LEAP_EXPORT float scaleFactor(const Frame& sinceFrame) const;

    /**
     * The estimated probability that the overall motion between the current
     * frame and the specified frame is intended to be a scaling motion.
     *
     * \include Frame_scaleProbability.txt
     *
     * If either this frame or sinceFrame is an invalid Frame object, then this
     * method returns zero.
     *
     * @param sinceFrame The starting frame for computing the relative scaling.
     * @returns A value between 0 and 1 representing the estimated probability
     * that the overall motion between the current frame and the specified frame
     * is intended to be a scaling motion.
     * @since 1.0
     */
    LEAP_EXPORT float scaleProbability(const Frame& sinceFrame) const;

    /**
     * The current InteractionBox for the frame. See the InteractionBox class
     * documentation for more details on how this class should be used.
     *
     * \include Frame_interactionBox.txt
     *
     * @returns The current InteractionBox object.
     * @since 1.0
     */
    LEAP_EXPORT InteractionBox interactionBox() const;

    /**
     * The instantaneous framerate.
     *
     * The rate at which the Leap Motion software is providing frames of data
     * (in frames per second). The framerate can fluctuate depending on available computing
     * resources, activity within the device field of view, software tracking settings,
     * and other factors.
     *
     * \include Frame_currentFramesPerSecond.txt
     *
     * @returns An estimate of frames per second of the Leap Motion Controller.
     * @since 1.0
     */
    LEAP_EXPORT float currentFramesPerSecond() const;

    /**
     * Reports whether this Frame instance is valid.
     *
     * A valid Frame is one generated by the Leap::Controller object that contains
     * tracking data for all detected entities. An invalid Frame contains no
     * actual tracking data, but you can call its functions without risk of a
     * null pointer exception. The invalid Frame mechanism makes it more
     * convenient to track individual data across the frame history. For example,
     * you can invoke:
     *
     * \include Frame_Valid_Chain.txt
     *
     * for an arbitrary Frame history value, "n", without first checking whether
     * frame(n) returned a null object. (You should still check that the
     * returned Finger instance is valid.)
     *
     * @returns True, if this is a valid Frame object; false otherwise.
     * @since 1.0
     */
    LEAP_EXPORT bool isValid() const;

    /**
     * Returns an invalid Frame object.
     *
     * You can use the instance returned by this function in comparisons testing
     * whether a given Frame instance is valid or invalid. (You can also use the
     * Frame::isValid() function.)
     *
     * \include Frame_Invalid_Demo.txt
     *
     * @returns The invalid Frame instance.
     * @since 1.0
     */
    LEAP_EXPORT static const Frame& invalid();

    /**
     * Compare Frame object equality.
     *
     * \include Frame_operator_equals.txt
     *
     * Two Frame objects are equal if and only if both Frame objects represent
     * the exact same frame of tracking data and both Frame objects are valid.
     * @since 1.0
     */
    LEAP_EXPORT bool operator==(const Frame&) const;

    /**
     * Compare Frame object inequality.
     *
     * \include Frame_operator_not_equals.txt
     *
     * Two Frame objects are equal if and only if both Frame objects represent
     * the exact same frame of tracking data and both Frame objects are valid.
     * @since 1.0
     */
    LEAP_EXPORT bool operator!=(const Frame&) const;

    /**
     * Writes a brief, human readable description of the Frame object to an output stream.
     *
     * \include Frame_operator_stream.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT friend std::ostream& operator<<(std::ostream&, const Frame&);

    /**
     * Note: This class is an experimental API for internal use only. It may be
     * removed without warning.
     *
     * Returns information about the currently detected quad in the scene.
     *
     * \include Frame_trackedQuad.txt
     * If no quad is being tracked, then an invalid TrackedQuad is returned.
     * @since 2.2.6
     **/
    LEAP_EXPORT TrackedQuad trackedQuad() const;

    /**
     * Encodes this Frame object as a byte string.
     *
     * \include Frame_serialize.txt
     *
     * @returns The serialized string encoding the data for this frame.
     * @since 2.1.0
     */
    std::string serialize() const {
      size_t length = 0;
      const char* cstr = serializeCString(length);
      std::string str(cstr, length);
      deleteCString(cstr);
      return str;
    }

    /**
     * Decodes a byte string to replace the properties of this Frame.
     *
     * A Controller object must be instantiated for this function to succeed, but
     * it does not need to be connected. To extract gestures from the deserialized
     * frame, you must enable the appropriate gestures first.
     *
     * Any existing data in the frame is
     * destroyed. If you have references to
     * child objects (hands, fingers, etc.), these are preserved as long as the
     * references remain in scope.
     *
     * \include Frame_deserialize.txt
     *
     * **Note:** The behavior when calling functions which take
     * another Frame object as a parameter is undefined when either frame has
     * been deserialized. For example, calling ``gestures(sinceFrame)`` on a
     * deserialized frame or with a deserialized frame as parameter (or both)
     * does not necessarily return all gestures that occurred between the two
     * frames. Motion functions, like ``scaleFactor(startFrame)``, are more
     * likely to return reasonable results, but could return anomalous values
     * in some cases.
     *
     * @param str A std:string object containing the serialized bytes of a frame.
     *
     * @since 2.1.0
     */
    void deserialize(const std::string& str) {
      deserializeCString(str.data(), str.length());
    }

    /*
     * Do not call this version of serialize(). It is intended only as
     * a helper for C#, Java, and other language bindings.
     */
    void serialize(unsigned char* ptr) const {
      size_t length;
      const unsigned char* cstr = reinterpret_cast<const unsigned char*>(serializeCString(length));
      memcpy(ptr, cstr, length * sizeof(unsigned char));
    }

    /*
     * Do not call serializeLength(). It is intended only as a helper for
     * C#, Java, and other language bindings. To get the length of the
     * serialized byte array, use serialize().length()
     */
    int serializeLength() const {
      size_t length = 0;
      serializeCString(length);
      return static_cast<int>(length);
    }

    /*
     * Do not call this version of deserialize(). It is intended only as
     * a helper for C#, Java, and other language bindings.
     */
    void deserialize(const unsigned char* ptr, int length) {
      deserializeCString(reinterpret_cast<const char*>(ptr), static_cast<size_t>(length));
    }

    /**
     * A string containing a brief, human readable description of the Frame object.
     *
     * @returns A description of the Frame as a string.
     * @since 1.0
     */
    std::string toString() const {
      const char* cstr = toCString();
      std::string str(cstr);
      deleteCString(cstr);
      return str;
    }

  private:
    LEAP_EXPORT const char* toCString() const;
    LEAP_EXPORT const char* serializeCString(size_t& length) const;
    LEAP_EXPORT void deserializeCString(const char* str, size_t length);
  };

  /* For internal use only. */
  class BugReport : public Interface {
  public:
    // For internal use only
    BugReport(BugReportImplementation*);

    LEAP_EXPORT BugReport();

    /* Starts recording data. The recording ends when endRecording() is called
    * or after 10 seconds. The recording is saved to the local hard drive. */
    LEAP_EXPORT bool beginRecording();
    /* Ends the recording. */
    LEAP_EXPORT void endRecording();

    /* True while recording is in progress. */
    LEAP_EXPORT bool isActive() const;
    /* Progress as a fraction of the maximum recording length (i.e. 10 seconds).
    * The range of the progress value is [0..1]. */
    LEAP_EXPORT float progress() const;
    /* The recording duration in seconds. */
    LEAP_EXPORT float duration() const;
  };

  /**
   * The Config class provides access to Leap Motion system configuration information.
   *
   * You can get and set gesture configuration parameters using the Config object
   * obtained from a connected Controller object. The key strings required to
   * identify a configuration parameter include:
   *
   * \table
   * ====================================  ========== ============= =======
   * Key string                            Value type Default value Units
   * ====================================  ========== ============= =======
   * Gesture.Circle.MinRadius              float      5.0           mm
   * Gesture.Circle.MinArc                 float      1.5 * pi      radians
   * Gesture.Swipe.MinLength               float      150           mm
   * Gesture.Swipe.MinVelocity             float      1000          mm/s
   * Gesture.KeyTap.MinDownVelocity        float      50            mm/s
   * Gesture.KeyTap.HistorySeconds         float      0.1           s
   * Gesture.KeyTap.MinDistance            float      3.0           mm
   * Gesture.ScreenTap.MinForwardVelocity  float      50            mm/s
   * Gesture.ScreenTap.HistorySeconds      float      0.1           s
   * Gesture.ScreenTap.MinDistance         float      5.0           mm
   * ====================================  ========== ============= =======
   * \endtable
   *
   * After setting a configuration value, you must call the Config::save() method
   * to commit the changes. You can save after the Controller has connected to
   * the Leap Motion service/daemon. In other words, after the Controller
   * has dispatched the serviceConnected or connected events or
   * Controller::isConnected is true. The configuration value changes are
   * not persistent; your application needs to set the values every time it runs.
   *
   * @see CircleGesture
   * @see KeyTapGesture
   * @see ScreenTapGesture
   * @see SwipeGesture
   * @since 1.0
   */
  class Config : public Interface {
  public:
    /**
     * Constructs a Config object.
     * Do not create your own Config objects. Get a Config object using
     * the Controller::config() function.
     *
     * \include Config_Constructor.txt
     *
     * @since 1.0
     */
    LEAP_EXPORT Config();

    /**
     * Enumerates the possible data types for configuration values.
     *
     * The Config::type() function returns an item from the ValueType enumeration.
     * @since 1.0
     */
    enum ValueType {
      /**
       * The data type is unknown.
       * @since 1.0
       */
      TYPE_UNKNOWN = 0,
      /**
       * A boolean value.
       * @since 1.0
       */
      TYPE_BOOLEAN = 1,
      /**
       * A 32-bit integer.
       * @since 1.0
       */
      TYPE_INT32   = 2,
      /**
       * A floating-point number.
       * @since 1.0
       */
      TYPE_FLOAT   = 6,
      /**
       * A string of characters.
       * @since 1.0
       */
      TYPE_STRING  = 8,
#ifdef SWIGCSHARP
      // deprecated
      TYPEUNKNOWN  = TYPE_UNKNOWN,
      TYPEBOOLEAN  = TYPE_BOOLEAN,
      TYPEINT32    = TYPE_INT32,
      TYPEFLOAT    = TYPE_FLOAT,
      TYPESTRING   = TYPE_STRING,
#endif
    };

    /**
     * Reports the natural data type for the value related to the specified key.
     *
     * \include Config_type.txt
     *
     * @param key The key for the looking up the value in the configuration dictionary.
     * @returns The native data type of the value, that is, the type that does not
     * require a data conversion.
     * @since 1.0
     */
    ValueType type(const std::string& key) const {
      return typeCString(key.c_str());
    }

    /**
     * Gets the boolean representation for the specified key.
     *
     * \include Config_getBool.txt
     *
     * @since 1.0
     */
    bool getBool(const std::string& key) const {
      return getBoolCString(key.c_str());
    }

    /** Sets the boolean representation for the specified key.
     *
     * \include Config_setBool.txt
     *
     * @returns true on success, false on failure.
     * @since 1.0
     */
    bool setBool(const std::string& key, bool value) {
      return setBoolCString(key.c_str(), value);
    }

    /**
     * Gets the 32-bit integer representation for the specified key.
     *
     * \include Config_getInt32.txt
     *
     * @since 1.0
     */
    int32_t getInt32(const std::string& key) const {
      return getInt32CString(key.c_str());
    }

    /** Sets the 32-bit integer representation for the specified key.
     *
     * \include Config_setInt32.txt
     *
     * @returns true on success, false on failure.
     * @since 1.0
     */
    bool setInt32(const std::string& key, int32_t value) {
      return setInt32CString(key.c_str(), value);
    }

    /**
     * Gets the floating point representation for the specified key.
     *
     * \include Config_getFloat.txt
     *
     * @since 1.0
     */
    float getFloat(const std::string& key) const {
      return getFloatCString(key.c_str());
    }

    /** Sets the floating point representation for the specified key.
     *
     * \include Config_setFloat.txt
     *
     * @returns true on success, false on failure.
     * @since 1.0
     */
    bool setFloat(const std::string& key, float value) {
      return setFloatCString(key.c_str(), value);
    }

    /**
     * Gets the string representation for the specified key.
     *
     * \include Config_getString.txt
     *
     * @since 1.0
     */
    std::string getString(const std::string& key) const {
      const char* cstr = getStringCString(key.c_str());
      std::string str(cstr);
      deleteCString(cstr);
      return str;
    }

    /** Sets the string representation for the specified key.
     *
     * \include Config_setString.txt
     *
     * @returns true on success, false on failure.
     * @since 1.0
     */
    bool setString(const std::string& key, const std::string& value) {
      return setStringCString(key.c_str(), value.c_str());
    }

    /**
     * Saves the current state of the config.
     *
     * Call ``save()`` after making a set of configuration changes. The
     * ``save()`` function transfers the configuration changes to the Leap Motion
     * service. You can save after the Controller has connected to
     * the Leap Motion service/daemon. In other words, after the Controller
     * has dispatched the serviceConnected or connected events or
     * Controller::isConnected is true. The configuration value changes are not persistent; your
     * application must set the values every time it runs.
     *
     * \include Config_save.txt
     *
     * @returns true on success, false on failure.
     * @since 1.0
     */
    LEAP_EXPORT bool save();
  private:
    LEAP_EXPORT ValueType typeCString(const char* key) const;
    LEAP_EXPORT bool getBoolCString(const char* key) const;
    LEAP_EXPORT bool setBoolCString(const char* key, bool value);
    LEAP_EXPORT int32_t getInt32CString(const char* key) const;
    LEAP_EXPORT bool setInt32CString(const char* key, int32_t value);
    LEAP_EXPORT float getFloatCString(const char* key) const;
    LEAP_EXPORT bool setFloatCString(const char* key, float value);
    LEAP_EXPORT const char* getStringCString(const char* key) const;
    LEAP_EXPORT bool setStringCString(const char* key, const char* value);
  };

  /**
   * 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
   */
  class LEAP_EXPORT_CLASS Controller : public Interface {
  public:
    // For internal use only.
    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
     */
    LEAP_EXPORT Controller();
    LEAP_EXPORT virtual ~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.
     *
     * \include Controller_Controller.txt
     *
     * @param 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
     */
    LEAP_EXPORT Controller(Listener& listener);

    /**
     * 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.
     *
     * \include Controller_isConnected.txt
     * @returns True, if connected; false otherwise.
     * @since 1.0
     */
    LEAP_EXPORT bool isConnected() 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
     */
    LEAP_EXPORT bool isServiceConnected() 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.
     *
     * \include Controller_hasFocus.txt
     *
     * @returns True, if application has focus; false otherwise.
     *
     * @see Controller::setPolicyFlags()
     * @since 1.0
     */
    LEAP_EXPORT bool hasFocus() const;

    /**
     * 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 which 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.
     *
     * Some policies can be denied if the user has disabled the feature on
     * their Leap Motion control panel.
     *
     * @since 1.0
     */
    enum PolicyFlag {
      /**
       * The default policy.
       * @since 1.0
       */
      POLICY_DEFAULT = 0,
      /**
       * Receive background frames.
       * @since 1.0
       */
      POLICY_BACKGROUND_FRAMES = (1 << 0),

      /**
       * Receive raw images from sensor cameras.
       * @since 2.1.0
       */
      POLICY_IMAGES = (1 << 1),

      /**
       * Optimize the tracking for head-mounted device.
       * @since 2.1.2
       */
      POLICY_OPTIMIZE_HMD = (1 << 2),

#ifdef SWIGCSHARP
      // deprecated
      POLICYDEFAULT = POLICY_DEFAULT,
      POLICYBACKGROUNDFRAMES = POLICY_BACKGROUND_FRAMES,
#endif
    };

    /**
     * This function has been deprecated. Use isPolicySet() instead.
     * @deprecated 2.1.6
     */
    LEAP_EXPORT PolicyFlag policyFlags() const;

    /**
     * This function has been deprecated. Use setPolicy() and clearPolicy() instead.
     * @deprecated 2.1.6
     */
    LEAP_EXPORT void setPolicyFlags(PolicyFlag flags) 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.
     *
     * \include Controller_setPolicy.txt
     *
     * @param policy A PolicyFlag value indicating the policy to request.
     * @since 2.1.6
     */
    LEAP_EXPORT void setPolicy(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.
     *
     * \include Controller_clearPolicy.txt
     *
     * @param flags A PolicyFlag value indicating the policy to request.
     * @since 2.1.6
     */
    LEAP_EXPORT void clearPolicy(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.
     *
     * \include Controller_isPolicySet.txt
     *
     * @param flags A PolicyFlag value indicating the policy to query.
     * @returns A boolean indicating whether the specified policy has been set.
     * @since 2.1.6
     */
    LEAP_EXPORT bool isPolicySet(PolicyFlag policy) const;

    /**
     * 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.
     *
     * \include Controller_addListener.txt
     *
     * 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.
     *
     * @param 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
     */
    LEAP_EXPORT bool addListener(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.
     *
     * \include Controller_removeListener.txt
     *
     * @param listener The listener to remove.
     * @returns Whether or not the listener was successfully removed from the
     * list of listeners.
     * @since 1.0
     */
    LEAP_EXPORT bool removeListener(Listener& listener);

    /**
     * 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.
     *
     * \include Controller_Frame_1.txt
     *
     * You can call this function in your Listener implementation to get frames at the
     * Leap Motion frame rate:
     *
     * \include Controller_Listener_onFrame.txt

     * @param 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
     */
    LEAP_EXPORT Frame frame(int history = 0) const;

    /**
     * The most recent set of images from the Leap Motion cameras.
     *
     * \include Controller_images.txt
     *
     * 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
     */
    LEAP_EXPORT ImageList images() const;

    /**
     * Returns a Config object, which you can use to query the Leap Motion system for
     * configuration information.
     *
     * \include Controller_config.txt
     *
     * @returns The Controller's Config object.
     * @since 1.0
     */
    LEAP_EXPORT Config config() 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.
     *
     * \include Controller_devices.txt
     *
     * 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
     */
    LEAP_EXPORT DeviceList devices() const;

    /*
     * Deprecated as of version 1.2.
     */
    LEAP_EXPORT ScreenList locatedScreens() const;

    /* For internal use only. */
    LEAP_EXPORT BugReport bugReport() const;

    /**
     * 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.
     *
     * \include Controller_enableGesture.txt
     *
     * As a performance optimization, only enable recognition for the types
     * of movements that you use in your application.
     *
     * @param type The type of gesture to enable or disable. Must be a
     * member of the Gesture::Type enumeration.
     * @param enable True, to enable the specified gesture type; False,
     * to disable.
     * @see Controller::isGestureEnabled()
     * @since 1.0
     */
    LEAP_EXPORT void enableGesture(Gesture::Type type, bool enable = true) const;

    /**
     * Reports whether the specified gesture type is enabled.
     *
     * \include Controller_isGestureEnabled.txt
     *
     * @param type The type of gesture to check; a member of the Gesture::Type enumeration.
     * @returns True, if the specified type is enabled; false, otherwise.
     * @see Controller::enableGesture()
     * @since 1.0
     */
    LEAP_EXPORT bool isGestureEnabled(Gesture::Type type) const;

    /**
     * Note: This class is an experimental API for internal use only. It may be
     * removed without warning.
     *
     * Returns information about the currently detected quad in the scene.
     *
     * \include Controller_trackedQuad.txt
     * If no quad is being tracked, then an invalid TrackedQuad is returned.
     * @since 2.2.6
     **/
    LEAP_EXPORT TrackedQuad trackedQuad() 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
     **/
    LEAP_EXPORT int64_t now() const;
  };

  /**
   * 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.
   * @since 1.0
   */
  class LEAP_EXPORT_CLASS Listener {
  public:
    /**
     * Constructs a Listener object.
     * @since 1.0
     */
    LEAP_EXPORT Listener() {}

    /**
     * Destroys this Listener object.
     */
    LEAP_EXPORT virtual ~Listener() {}

    /**
     * Called once, when this Listener object is newly added to a Controller.
     *
     * \include Listener_onInit.txt
     *
     * @param controller The Controller object invoking this callback function.
     * @since 1.0
     */
    LEAP_EXPORT virtual void onInit(const Controller&) {}

    /**
     * Called when the Controller object connects to the Leap Motion software and
     * the Leap Motion hardware device is plugged in,
     * or when this Listener object is added to a Controller that is already connected.
     *
     * When this callback is invoked, Controller::isServiceConnected is true,
     * Controller::devices() is not empty, and, for at least one of the Device objects in the list,
     * Device::isStreaming() is true.
     *
     * \include Listener_onConnect.txt
     *
     * @param controller The Controller object invoking this callback function.
     * @since 1.0
     */
    LEAP_EXPORT virtual void onConnect(const Controller&) {}

    /**
     * Called when the Controller object disconnects from the Leap Motion software or
     * the Leap Motion hardware is unplugged.
     * 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.
     *
     * \include Listener_onDisconnect.txt
     *
     * 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.
     *
     * @param controller The Controller object invoking this callback function.
     * @since 1.0
     */
    LEAP_EXPORT virtual void onDisconnect(const Controller&) {}

    /**
     * Called when this Listener object is removed from the Controller
     * or the Controller instance is destroyed.
     *
     * \include Listener_onExit.txt
     *
     * @param controller The Controller object invoking this callback function.
     * @since 1.0
     */
    LEAP_EXPORT virtual void onExit(const Controller&) {}

    /**
     * Called when a new frame of hand and finger tracking data is available.
     * Access the new frame data using the Controller::frame() function.
     *
     * \include Listener_onFrame.txt
     *
     * 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.
     *
     * @param controller The Controller object invoking this callback function.
     * @since 1.0
     */
    LEAP_EXPORT virtual void onFrame(const Controller&) {}

    /**
     * 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.
     *
     * \include Listener_onFocusGained.txt
     *
     * @param controller The Controller object invoking this callback function.
     * @since 1.0
     */
    LEAP_EXPORT virtual void onFocusGained(const Controller&) {}

    /**
     * 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.
     *
     * \include Listener_onFocusLost.txt
     *
     * @param controller The Controller object invoking this callback function.
     * @since 1.0
     */
    LEAP_EXPORT virtual void onFocusLost(const Controller&) {}

    // onServiceConnect/onServiceDisconnect are for connection established/lost.
    // in normal course of events onServiceConnect will get called once after onInit
    // and onServiceDisconnect will not get called. disconnect notification only happens
    // if service stops running or something else bad happens to disconnect controller from service.
    /**
     * Called when the Leap Motion daemon/service connects to your application Controller.
     *
     * \include Listener_onServiceConnect.txt
     *
     * @param controller The Controller object invoking this callback function.
     * @since 1.2
     */
    LEAP_EXPORT virtual void onServiceConnect(const Controller&) {}
    /**
     * Called if the Leap Motion daemon/service disconnects from your application Controller.
     *
     * Normally, this callback is not invoked. It is only called if some external event
     * or problem shuts down the service or otherwise interrupts the connection.
     *
     * \include Listener_onServiceDisconnect.txt
     *
     * @param controller The Controller object invoking this callback function.
     * @since 1.2
     */
    LEAP_EXPORT virtual void onServiceDisconnect(const Controller&) {}

    /**
     * Called when a Leap Motion controller plugged in, unplugged, or the device changes state.
     *
     * State changes include changes in frame rate and entering or leaving "robust" mode.
     * Note that there is currently no way to query whether a device is in robust mode.
     * You can use Frame::currentFramerate() to get the framerate.
     *
     * \include Listener_onDeviceChange.txt
     *
     * @param controller The Controller object invoking this callback function.
     * @since 1.2
     */
    LEAP_EXPORT virtual void onDeviceChange(const Controller&) {}

    /**
     * Called when new images are available.
     * Access the new frame data using the Controller::images() function.
     *
     * \include Listener_onImages.txt
     *
     * @param controller The Controller object invoking this callback function.
     * @since 2.2.1
     */
    LEAP_EXPORT virtual void onImages(const Controller&) {}

  };
}

#endif // __Leap_h__