mouse_motion.py

import cv2
import numpy as np
import time

drawing = False # true if mouse is pressed
ix,iy = -1,-1

# mouse callback function
def draw_circle(event,x,y,flags,param):
    global ix,iy,drawing

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

    elif event == cv2.EVENT_MOUSEMOVE:
        if drawing == True:
            cv2.circle(img,(x,y),2,(0,0,255),-1)

    elif event == cv2.EVENT_LBUTTONUP:
        drawing = False
        cv2.circle(img,(x,y),5,(0,0,255),-1)

    # capture time and do whatever you like with time.time() - start
    print(time.time() - start)

img = np.zeros((512,512,3), np.uint8)
cv2.namedWindow('image')
cv2.setMouseCallback('image',draw_circle)
#capture starting time.
start = time.time()

while(1):
    cv2.imshow('image',img)
    k = cv2.waitKey(1) & 0xFF

cv2.destroyAllWindows()