opencv-python-學習筆記四（創建滑動條）

創建跟蹤條與指定窗口綁定

常用函數：

createTrackbar(）創建滑動條且與窗口綁定

cv.createTrackbar(trackbarname,winname,value,count,onChange,userdata)

trackbarname：跟蹤條名稱

winname：綁定窗口名稱

value：初始滑塊位置

count：滑動最大值

onChange：回調函數

userdata：數據，可選

getTrackbarPos() 獲取滑動條數據

cv.getTrackbarPos(trackbarname, winname)

trackbarname：滑動條名稱

winname：窗口名稱

返回值：當前滑動條的位置

綜合示例：

import numpy as np
import cv2 as cv


def nothing(x):
    pass


# Create a black image, a window
img = np.zeros((300, 512, 3), np.uint8)
cv.namedWindow('image')
# create trackbars for color change
cv.createTrackbar('R', 'image', 0, 255, nothing)
cv.createTrackbar('G', 'image', 0, 255, nothing)
cv.createTrackbar('B', 'image', 0, 255, nothing)
while(1):
    cv.imshow('image', img)
    k = cv.waitKey(1) & 0xFF
    if k == 27:
        break
    # get current positions of four trackbars
    r = cv.getTrackbarPos('R', 'image')
    g = cv.getTrackbarPos('G', 'image')
    b = cv.getTrackbarPos('B', 'image')
    # s = cv.getTrackbarPos(switch, 'image')
    img[:] = [b, g, r]
cv.destroyAllWindows()