opencv for python

# -*- coding: utf-8 -*-
import cv2
import numpy as np
r,b,g=0,0,0
def nothing(x):            #滑动条的位置，通常默认为pass
pass

def draw_circle(event,x,y,flags,param):
if event==cv2.EVENT_LBUTTONDBLCLK:
cv2.circle(img1,(x,y),10,(b,g,r),-1)

# 创建一副黑色图像
img=np.zeros((250,512,3),np.uint8)
img1=np.zeros((250,512,3),np.uint8)

cv2.namedWindow('image')
cv2.namedWindow('win')

cv2.createTrackbar('R','image',0,255,nothing)    #创建滑动条    ，滑动条名称，显示窗口名称，范围，回调函数
cv2.createTrackbar('G','image',0,255,nothing)
cv2.createTrackbar('B','image',0,255,nothing)

cv2.setMouseCallback('win',draw_circle)
while(1):
cv2.imshow('win',img1)
cv2.imshow('image',img)
if cv2.waitKey(20)&0xFF==27:
break
r=cv2.getTrackbarPos('R','image')
g=cv2.getTrackbarPos('G','image')
b=cv2.getTrackbarPos('B','image')
img[:]=[b,g,r]
cv2.destroyAllWindows()