Python OpenCV实现简易画板：矩形绘制与颜色调节

青禾

发布时间：2026-10-13 | 4人浏览过

原创

本文介绍基于Python和OpenCV实现简易画板的方法。通过处理鼠标左键按下、移动及释放事件，实现矩形和圆形的绘制。利用滚动条动态调节RGB颜色值，支持按“m”键切换绘图模式。代码完整展示了窗口创建、回调函数绑定及主循环逻辑，适合Python初学者理解图形交互原理。

本文分享一个使用Python进行图像处理的简单画板实现示例，供读者参考学习。

Python图像处理功能主要依赖OpenCV的Python接口实现，该语言语法简洁易懂。本案例旨在演示画板涂鸦功能，具体包括绘制矩形和线条，其他功能亦可基于此思路扩展。核心逻辑在于对鼠标事件的处理以及通过滚动条调节颜色。鼠标事件主要涵盖左键按下和释放两个阶段的操作。

import cv2
import numpy as np
# null function
def nothing(x):
  pass
Drawing = False
Mode = True
IX,IY = -1,-1
def drawCircle(Event,X,Y,Flags,Param):
  R = cv2.getTrackbarPos('R','Image')
  G = cv2.getTrackbarPos('G','Image')
  B = cv2.getTrackbarPos('B','Image')
#get color value
  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);
  elif Event == cv2.EVENT_LBUTTONUP:
    Drawing = False
#create image with 3 chanels
Img = np.zeros((660,660,3),np.uint8)
#create window
cv2.namedWindow('Image')
#create track bar, range for 0~255
cv2.createTrackbar('R','Image',0,255,nothing)
cv2.createTrackbar('G','Image',0,255,nothing)
cv2.createTrackbar('B','Image',0,255,nothing)
#set mouse ack
cv2.setMouseCallback('Image',drawCircle)
while(1):
  cv2.imshow('Image',Img)
  k = cv2.waitKey(10)&0xFF
  #switch draw mode
  if k == ord('m'):
    Mode = not Mode
  elif k == 27:
    break
#you must destroy all of sources
cv2.destroyAllWindows()

最终运行效果如下图所示：