import cv2
import numpy as np

drawing = False # true if mouse is pressed
mode = True # if True, draw rectangle. press 'm' to toggle to curve

ix, iy = -1, -1

# mouse callback function

def draw_shape(event, x, y, flags, param):
    global ix, iy, drawing, mode

    if event == cv2.EVENT_LBUTTONDOWN:
        drawing = True
        ix, iy = x, y

    elif event == cv2.EVENT_MOUSEMOVE:
        if drawing == True:
            if mode == True:
                cv2.rectangle(img, (ix, iy), (x, y), (0, 255, 0), -1)
            else:
                cv2.circle(img, (x, y), 5, (0,0,255), -1)

    elif event == cv2.EVENT_LBUTTONUP:
        drawing = False
        if mode == True:
            cv2.rectangle(img, (ix, iy), (x, y), (0, 255, 0), -1)
        else:
            cv2.circle(img, (x, y), 5, (0,0,255), -1)
# bind this callback to window; in main loop, set keyboard binding 'm'
# to toggle between rect and circle
img = np.zeros((512, 512, 3), np.uint8)
cv2.namedWindow('image')
cv2.setMouseCallback('image', draw_shape)

while(1):
    cv2.imshow('image', img)
    k = cv2.waitKey(1) & 0xFF
    if k == ord('m'):
        mode = not mode
    elif k == 27:
        break
cv2.destroyAllWindows()
