Python人机交互利用鼠标画图，可随时改变画笔颜色(附代码)

# -*- coding: utf-8 -*-
import cv2
import numpy as np
def nothing(x):
    pass
#赋值命令
drawing=False
mode=True
ix,iy=-1,-1

# 创建回调函数
def draw_circle(event,x,y,flags,param):
    r=cv2.getTrackbarPos('R','image')
    g=cv2.getTrackbarPos('G','image')
    b=cv2.getTrackbarPos('B','image')
    color=(b,g,r)
    global ix,iy,drawing,mode

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

    elif event==cv2.EVENT_MOUSEMOVE and flags==cv2.EVENT_FLAG_LBUTTON:
        if drawing==True:
            if mode==True:
                cv2.rectangle(img,(ix,iy),(x,y),color,-1)
            else:
                cv2.circle(img,(x,y),3,color,-1)
                # r=int(np.sqrt((x-ix)**2+(y-iy)**2))
                # cv2.circle(img,(x,y),r,(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)
img=np.zeros((512,512,3),np.uint8)
cv2.namedWindow('image')
cv2.createTrackbar('R','image',0,255,nothing)
cv2.createTrackbar('G','image',0,255,nothing)
cv2.createTrackbar('B','image',0,255,nothing)
cv2.setMouseCallback('image',draw_circle)

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

运行结果，可改变画笔的颜色，画图。