import cv2 as cv


def on_change(val):
    pass


if __name__ == '__main__':
    windowName = 'Canny edge detector'
    cv.namedWindow(windowName, cv.WINDOW_NORMAL)
    image = cv.imread("../img/lena.png", cv.IMREAD_COLOR)

    kernelSizes = [(1, 1), (3, 3), (9, 9), (15, 15)]

    blur_t = 'Blur'
    low_threshold_t = 'Low Threshold'
    high_threshold_t = 'High Threshold'
    aperture_size_t = 'Aperture Size'
    cv.createTrackbar(blur_t, windowName, 0, 3, on_change)
    cv.createTrackbar(low_threshold_t, windowName, 0, 300, on_change)
    cv.createTrackbar(high_threshold_t, windowName, 0, 300, on_change)
    cv.createTrackbar(aperture_size_t, windowName, 3, 30, on_change)

    cv.imshow(windowName, image)

    while 1:
        img = image.copy()
        k = cv.waitKey(1) & 0xFF
        if k == 27:
            break

        blur = cv.getTrackbarPos(blur_t, windowName)
        low_threshold = cv.getTrackbarPos(low_threshold_t, windowName)
        high_threshold = cv.getTrackbarPos(high_threshold_t, windowName)
        aperture_size = cv.getTrackbarPos(aperture_size_t, windowName)
        lena_blurred = cv.GaussianBlur(img, kernelSizes[blur], 0, 0)

        edges = cv.Canny(lena_blurred, low_threshold, high_threshold, aperture_size)

        cv.imshow(windowName, edges)

    cv.destroyAllWindows()