python opencv如何实现简易画图板？本篇文章小编给大家分享一下python opencv实现简易画图板代码，小编觉得挺不错的，现在分享给大家供大家参考，有需要的小伙伴们可以来看看。

代码如下：

# -*- coding: utf-8 -*-

"""

Created on Sat May 19 17:34:54 2018

@author: xxx

"""

import cv2 as cv

import numpy as np

def nothing(x):

pass

# 当鼠标按下时变为 True

drawing = False

# 如果 mode 为 True 绘制矩形。按下 'm' 变成绘制曲线

mode = True

ix, iy = -1, -1

#创建回调函数

def draw_circle(event, x, y, flags, param):

r = cv.getTrackbarPos('R', 'image')

g = cv.getTrackbarPos('G', 'image')

b = cv.getTrackbarPos('B', 'image')

color = (b, g, r)

global ix, iy, drawing, mode

# 当按下左键是返回起始位置坐标

if event == cv.EVENT_LBUTTONDOWN:

drawing = True

ix, iy = x, y

# 当鼠标左键按下并移动是绘制图形。event 可以查看移动, flag 查看是否按下

elif event == cv.EVENT_MOUSEMOVE and flags == cv.EVENT_FLAG_LBUTTON:

if drawing == True:

if mode == True:

cv.rectangle(img, (ix, iy), (x, y), color, -1)

else:

# 绘制圆圈，小圆点连在一起就成了线，3代表画笔的粗细

cv.circle(img, (ix, iy), 3, color, -1)

# 下面注释的代码是起始点为圆心，起点到终点为半径

# r = int(np.sqrt((x - ix)**2 + (y - iy)**2))

# cv.circle(img, (x, y), r, (0, 0, 255), -1)

# 当鼠标松开停止绘画

elif event == cv.EVENT_LBUTTONUP:

drawing == False

# if mode == True:

# cv.rectangle(img, (ix, iy), (x, y), (0, 255, 0), -1)

# else:

# cv.circle(img, (x, y), 5, (0, 0, 255), -1)

#创建一幅黑色图形

img = np.zeros((512, 512, 3), np.uint8)

cv.namedWindow('image')

cv.createTrackbar('R', 'image', 0, 255, nothing)

cv.createTrackbar('G', 'image', 0, 255, nothing)

cv.createTrackbar('B', 'image', 0, 255, nothing)

cv.setMouseCallback('image', draw_circle)

while(1):

cv.imshow('image', img)

k = cv.waitKey(1)&0xFF

if k == ord('m'):

mode = not mode

elif k==27:

break

cv.destroyAllWindow()