gaze_data.c

#include <stdio.h>
#include <string.h>
#include <inttypes.h>
#include "tobii_research_eyetracker.h"
#include "tobii_research_streams.h"
 
// Define a custom sleep function that's compatible with both windows and linux systems.
// You might want to put functions like this in a common helper file.
#if _WIN32 || _WIN64
#include <windows.h>
static void sleep_ms(int time) {
    Sleep(time);
}
#else
#include <unistd.h>
static void sleep_ms(int time) {
    usleep(time * 1000);
}
#endif
 
 
void gaze_data_callback(TobiiResearchGazeData* gaze_data, void* user_data) {
    memcpy(user_data, gaze_data, sizeof(*gaze_data));
}
 
static void buffer_overflow_notification_callback(TobiiResearchNotification* notification, void* user_data) {
    (void)user_data;
    // Make sure we are handling the correct notification
    if (notification->notification_type == TOBII_RESEARCH_NOTIFICATION_STREAM_BUFFER_OVERFLOW) {
        //notification->value.text contains which streams' buffer is overflowing 
        printf("Buffer overflow occured in %s stream buffer", notification->value.text);
    }
}
 
void gaze_data_example(TobiiResearchEyeTracker* eyetracker) {
 
 
    TobiiResearchGazeData gaze_data;
    char* serial_number = NULL;
    tobii_research_get_serial_number(eyetracker, &serial_number);
 
    printf("Subscribing to gaze data for eye tracker with serial number %s.\n", serial_number);
 
    tobii_research_free_string(serial_number);
 
    // Subscribe to notifications, passing a callback function defined above.  
    TobiiResearchStatus status = tobii_research_subscribe_to_notifications(eyetracker, buffer_overflow_notification_callback, NULL);
 
    if (status != TOBII_RESEARCH_STATUS_OK)
        return;
 
    // Subscribe to gaze stream here. If your code takes to long too process the callback, 
    // the circular buffer will overflow and buffer_overflow_notification_callback will be called.
    // For further information, we refer to our section on "streambufferoverflow".
    status = tobii_research_subscribe_to_gaze_data(eyetracker, gaze_data_callback, &gaze_data);
 
    if (status != TOBII_RESEARCH_STATUS_OK)
        return;
 
    /* Wait while some gaze data is collected. */
    sleep_ms(2000);
 
    status = tobii_research_unsubscribe_from_gaze_data(eyetracker, gaze_data_callback);
    printf("Unsubscribed from gaze data with status %i.\n", status);
 
    printf("Last received gaze package:\n");
    printf("System time stamp: %"  PRId64 "\n", gaze_data.system_time_stamp);
    printf("Device time stamp: %"  PRId64 "\n", gaze_data.device_time_stamp);
    printf("Left eye 2D gaze point on display area: (%f, %f)\n",
            gaze_data.left_eye.gaze_point.position_on_display_area.x,
            gaze_data.left_eye.gaze_point.position_on_display_area.y);
    printf("Right eye 3d gaze origin in user coordinates (%f, %f, %f)\n",
            gaze_data.right_eye.gaze_origin.position_in_user_coordinates.x,
            gaze_data.right_eye.gaze_origin.position_in_user_coordinates.y,
            gaze_data.right_eye.gaze_origin.position_in_user_coordinates.z);
 
    /* Wait while some gaze data is collected. */
    sleep_ms(2000);
    tobii_research_unsubscribe_from_notifications(eyetracker, buffer_overflow_notification_callback);
 
}