calibration_data.c

#include <stdio.h>
#include <stdlib.h>
#include "tobii_research_eyetracker.h"

void calibration_data_example(TobiiResearchEyeTracker* eyetracker) {

    /* Save the calibration to file. */
    char* filename = "saved_calibration.bin";
    char* serial_number;

    FILE* f = fopen(filename, "wb");

    TobiiResearchCalibrationData* calibration_data = NULL;
    TobiiResearchStatus status = tobii_research_retrieve_calibration_data(eyetracker, &calibration_data);

    if (status != TOBII_RESEARCH_STATUS_OK)
        return;

    tobii_research_get_serial_number(eyetracker, &serial_number);

    /* None is returned on empty calibration. */
    if (calibration_data->size != 0) {

        printf("Saving calibration to file for eye tracker with serial number %s.\n", serial_number);
        fwrite(calibration_data->data, calibration_data->size, 1, f);
    } else {
        printf("No calibration available for eye tracker with serial number %s.\n", serial_number);
    }

    fclose(f);
    tobii_research_free_calibration_data(calibration_data);



    {
        /* Read the calibration from file. */
        FILE *calibration_file = fopen(filename, "rb" );
        size_t file_size;
        if( !calibration_file ) {
           printf("Calibration file not found!\n");
           return;
        }

        fseek(calibration_file, 0, SEEK_END);
        file_size = (size_t)ftell(calibration_file);

        rewind(calibration_file);

        if(file_size <= 0) {
           printf("Calibration file is empty!\n");
           return;
        };

        TobiiResearchCalibrationData calibration_data_to_write;

        calibration_data_to_write.data = malloc(file_size);
        calibration_data_to_write.size = file_size;

        file_size = fread(calibration_data_to_write.data, calibration_data_to_write.size, 1, calibration_file);

        /* Don't apply empty calibrations. */
        if (file_size > 0) {
            printf("Applying calibration on eye tracker with serial number %s.\n", serial_number);
            tobii_research_apply_calibration_data(eyetracker, &calibration_data_to_write);
        }
        free(calibration_data_to_write.data);
        tobii_research_free_string(serial_number);
        fclose(calibration_file);
    }
}