external_signal.c

#include <stdio.h>
#include <inttypes.h>
#include "tobii_research_eyetracker.h"
#include "tobii_research_streams.h"

#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 external_signal_callback(TobiiResearchExternalSignalData* external_signal_data, void* user_data) {
    (void)(user_data); // Is NULL, see subscription call
    printf("External signal: device time stamp %" PRId64 ", value %i \n",
            external_signal_data->device_time_stamp, external_signal_data->value);
}

void external_signal_example(TobiiResearchEyeTracker* eyetracker) {
    char* serial_number;
    tobii_research_get_serial_number(eyetracker, &serial_number);

    printf("Subscribing to external signal for eye tracker with serial number %s.\n", serial_number);

    tobii_research_free_string(serial_number);

    tobii_research_subscribe_to_external_signal_data(eyetracker, external_signal_callback, NULL);

    /* Wait for external signal. */
    sleep_ms(2000);

    tobii_research_unsubscribe_from_external_signal_data(eyetracker, external_signal_callback);
    printf("Unsubscribed from external signal.");

}