gesturelib.h

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#pragma once
 
#include "gestureparams.h"
#include "stdint.h"
 
typedef enum event_type {
    // This type of touch event indicates a pointer starting to contact the surface.
    TOUCH_EVENT_DOWN,
    // This type of touch event indicates an update to a pointer already contacting the surface.
    TOUCH_EVENT_MOVE,
    // This type of touch event indicates a pointer already contacting the surface stops contact.
    TOUCH_EVENT_UP
} event_type_t;
 
typedef struct touch_event {
    // This is the type of the touch event; see the enum event_type_t.
    event_type_t type;
    // This is the horizontal position of the touch event; adjust distance values in gestureparams.h to reflect
    // appropriate units used for this.
    float x;
    // This is the vertical position of the touch event; adjust distance values in gestureparams.h to reflect
    // appropriate units used for this.
    float y;
    // This is the time of the touch event in seconds. Timestamps can be relative to any fixed time point, but should be
    // consistent for a single gesture.
    float t;
    // Touch event groups indicate which finger a touch event originates from, ranging from 0 to MAX_TOUCHES. Set this
    // to TOUCH_GROUP_UNDEFINED to let the library assign it automatically.
    unsigned int group;
    // Touch event uids indicate which touch events should be processed as part of the same multi-finger gesture. Touch
    // events that share a uid will be processed into one multi-finger gesture while touch events that do not share a
    // uid will always be processed separately.
    int uid;
} touch_event_t;
 
typedef struct gesture_recognizer {
    // The library uses this flag to track whether a recognizer is enabled.
    char enabled;
    // This is the recognizer function itself.
    void (*recognize)(const touch_event_t*);
    // This is the recognizer initialization function. This function is invoked when a recognizer is added and when the
    // library is initialized.
    void (*init)(void);
} gesture_recognizer_t;
 
// This is the current number of recognizers the library holds. Declared in gesturelib.c
extern int num_recognizers;
// This is the last processed touch event of each group. Indices correspond to groups. Declared in gesturelib.c
extern touch_event_t latest_touch_events[];
 
int init_gesturelib();
 
void process_touch_event(touch_event_t* touch_event);
 
int add_recognizer(void (*recognizer)(const touch_event_t*), void (*init)(void));
 
gesture_recognizer_t remove_recognizer(int recognizer);
 
int enable_recognizer(int recognizer);
 
int disable_recognizer(int recognizer);