opencv鼠标指针左键画图,右键清除.

#按住鼠标左键画图,双击鼠标左键可以清除
import cv2 as cv
import numpy as np 
#创建画布
img=np.zeros((400,400,3),np.uint8)+255
#定义标志位
xys=[]
drawing=False #True画图,False不画图
#定义画图程序
def draw(event,x,y,flag,param):
    global xys,drawing
    if event==cv.EVENT_LBUTTONDOWN: #左键按下
        drawing=True
        xy='(x%s,%s)'%(x,y)
        xys.append([x,y])
    elif event==cv.EVENT_MOUSEMOVE: #鼠标移动
        if drawing==True:
            cv.circle(img,(x,y),2,(255,0,0),-1)
    elif event==cv.EVENT_LBUTTONUP: #左键松开
        drawing=False
    elif event==cv.EVENT_RBUTTONDBLCLK: #双击右键
        img[:]=255
cv.namedWindow('draw_clean')
cv.setMouseCallback('draw_clean',draw)
while(True):
    cv.imshow('draw_clean',img)
    k=cv.waitKey(1)
    if k==27:
        break
cv.destroyAllWindows()