TrackBar控件

createTrackbar(trackbarname,winname,value,count,onChange)

1.创建 TrackBar控件

2.value为 TrackBar控件的默认值

3.count为 TrackBar控件的最大值，最小为0

getTrackbarPos(trackbarname,winname)获取TrackBar当前值

导入相应的库

import cv2
import numpy as np

创建窗口

cv2.namedWindow('trackbar',cv2.WINDOW_NORMAL)
cv2.resizeWindow('mouse',640,360)

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)

获取当前TrackBar的值

    r = cv2.getTrackbarPos('R','trackbar')
    g = cv2.getTrackbarPos('G','trackbar')
    b = cv2.getTrackbarPos('B','trackbar')

改变背影图的颜色

    img[:] = [b,g,r]
    cv2.imshow('trackbar',img)

释放窗口

cv2.destroyAllWindows()

显示结果

完整学习代码

import cv2
import numpy as np
 
# 创建窗口
cv2.namedWindow('trackbar',cv2.WINDOW_NORMAL)
cv2.resizeWindow('mouse',640,360)
#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 & 0XFF == ord('q'):
        break
cv2.destroyAllWindows()