opencv学习第6课官方练习实现 Create a Paint application with adjustable colors and brush radius using trackbars

 练习题目来源（网址最下方）：https://docs.opencv.org/4.1.0/d9/dc8/tutorial_py_trackbar.html

import numpy as np 
import cv2 as cv 

brush_color = [80,80,80]
brush_size = 2
drawing = False

# mouse callback function
def draw_circle(event,x,y,flags,param):
	global brush_color,brush_size,drawing
	if event == cv.EVENT_LBUTTONDOWN:
		drawing = True
	elif event == cv.EVENT_MOUSEMOVE:
		if drawing == True:
			cv.circle(img,(x,y),brush_size,brush_color,-1)
	elif event == cv.EVENT_LBUTTONUP:
		drawing = False
		cv.circle(img,(x,y),brush_size,brush_color,-1)


def doChangeColor(x):
	global brush_color
	tem = cv.getTrackbarPos('brush-color','image')
	brush_color = [tem,tem,tem]

def doChangeSize(x):
	global brush_size
	tem = cv.getTrackbarPos('brush-size','image')
	brush_size = tem

img = np.zeros((512,512,3),np.uint8)
cv.namedWindow('image')

cv.createTrackbar('brush-color','image',80,255,doChangeColor)
cv.createTrackbar('brush-size','image',2,5,doChangeSize)

cv.setMouseCallback('image',draw_circle)

while(1):
	cv.imshow('image',img)
	k = cv.waitKey(1) & 0xFF
	if k == 27:
		break

# Destroy all windows that have been created
cv.destroyAllWindows()

参考内容：

https://blog.csdn.net/Ibelievesunshine/article/details/89351928

https://blog.csdn.net/Ibelievesunshine/article/details/89353097