import numpy as np
import cv2 as cv

def nothing(x):
    print(x)

img=np.zeros((300,512,3),np.uint8)
cv.namedWindow('image')

cv.createTrackbar('B','image',0,255,nothing)#i can create multipal in window uniq name,name of window,init vval , last value ,call back function
cv.createTrackbar('G','image',0,255,nothing)
cv.createTrackbar('R','image',0,255,nothing)

switch='0:OFF\n 1: ON'
cv.createTrackbar('switch','image',0,1,nothing)

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

    b=cv.getTrackbarPos('B','image')
    g=cv.getTrackbarPos('G','image')
    r=cv.getTrackbarPos('R','image')
    s=cv.getTrackbarPos('switch','image')


    if s==0:
        img[:]=0
    else:
        img[:]=[b,g,r]


cv.destroyAllWindows()