How to use the trackbar control in Opencv

1. Trackbarname, winname: the name of the trackbar and the window name in which it is displayed
2. Value: trackbar: current value, which can be set to the default value of 0
3. Count: the minimum value is 0, and the maximum value is count.
4. Callback, userdata: default values of callback functions and callback functions

1. Trackbarname: input parameters, specifically the name of the trackbar
2. Winname: Input parameters, specifically the name of the window where the trackbar is located

使用trackbar滑动实现改变窗帘背景色案例


import cv2
import numpy as np

def callback():
    pass

# 创建窗口
cv2.namedWindow('trackbar',cv2.WINDOW_NORMAL)
cv2.resizeWindow('trackbar',640,360)

# 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((360,640,3),np.uint8)
while 1:
    # 获取当前trackbar的值
    r=cv2.getTrackbarPos('R','trackbar')
    g=cv2.getTrackbarPos('G','trackbar')
    b=cv2.getTrackbarPos('B','trackbar')

    # 改变背景图片颜色
    img[:]=[b,g,r]
    cv2.imshow('trackbar',img)
    
    # 按q键退出
    key=cv2.waitKey(10)
    if key==ord('q'):
        break

cv2.destroyAllWindows()