• createTrackbar(trackbarname, winname, value, count, onChange)
• 创建TrackBar控件, value为trackbar的默认值,count为bar的最大值,最小为0,onChange是回调函数
• getTrackbarPos(trackbarname,winname)获取TrackBar当前值
  ```python

  trackbar

  import cv2
  import numpy as np

创建窗口

cv2.namedWindow('trackbar', cv2.WINDOW_NORMAL)
cv2.resizeWindow('trackbar', 640, 480)

定义回调函数

def callback(value):
print(value)

创建trackbar

cv2.createTrackbar('R', 'trackbar', 0, 255, callback)
cv2.createTrackbar('G', 'trackbar', 0, 255, callback)
cv2.createTrackbar('B', 'trackbar', 0, 255, callback)

创建一个背景图片

img = np.zeros((480, 640, 3), np.uint8)

while True:

# 获取当前trackbar的值
r = cv2.getTrackbarPos('R', 'trackbar')
g = cv2.getTrackbarPos('G', 'trackbar')
b = cv2.getTrackbarPos('B', 'trackbar')
# 改变背景图颜色
img[:] = [b, g, r]
cv2.imshow('trackbar', img)

key = cv2.waitKey(1)
if key == ord('q'):
    break

cv2.destroyAllWindows()