本文实例讲述了python基于opencv实现的简单画板功能。分享给大家供大家参考，具体如下：
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import cv2
import numpy as np
drawing = false # true if mouse is pressed
ix,iy = -1,-1
def nothing(x):
pass
# mouse callback function
def draw_circle(event,x,y,flags,param):
global ix,iy,drawing
g = param[0]
b = param[1]
r = param[2]
shape = param[3]
if event == cv2.event_lbuttondown:
drawing = true
ix,iy = x,y
elif event == cv2.event_mousemove:
if drawing == true:
if shape == 0:
cv2.rectangle(img,(ix,iy),(x,y),(g,b,r),-1)
else:
cv2.circle(img,(x,y),5,(g,b,r),-1)
elif event == cv2.event_lbuttonup:
drawing = false
if shape == 0:
cv2.rectangle(img,(ix,iy),(x,y),(g,b,r),-1)
else:
cv2.circle(img,(x,y),5,(g,b,r),-1)
# create a black image, a window
img = np.zeros((300,512,3), np.uint8)
cv2.namedwindow('image')
# create trackbars for color change
cv2.createtrackbar('r','image',0,255,nothing)
cv2.createtrackbar('g','image',0,255,nothing)
cv2.createtrackbar('b','image',0,255,nothing)
# create switch for on/off functionality
switch1 = '0 : off \n1 : on'
switch2 = '0: rectangle \n1: line '
cv2.createtrackbar(switch1, 'image',0,1,nothing)
cv2.createtrackbar(switch2, 'image',0,1,nothing)
while(1):
cv2.imshow('image',img)
k = cv2.waitkey(1) & 0xff
# get current positions of four trackbars
if k == 27:
break
r = cv2.gettrackbarpos('r','image')
g = cv2.gettrackbarpos('g','image')
b = cv2.gettrackbarpos('b','image')
shape = cv2.gettrackbarpos(switch2,'image')
s = cv2.gettrackbarpos(switch1,'image')
if s == 0:
img[:] = 0
else:
if k == 27:
break
cv2.setmousecallback('image',draw_circle,(b,g,r,shape))
cv2.destroyallwindows()
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运行效果：
希望本文所述对大家python程序设计有所帮助。
原文链接：https://blog.csdn.net/xuminnju/article/details/79588161