# -*- coding: utf-8 -*- 
# @Time : 2019/2/25 23:45 
# @Author : Mengqi 
# @Function : 
# @File : Trackbar as the Color Palette.py 
# @Software: PyCharm
import cv2
import numpy as np

def nothing(x):
    pass
# Create a black image, a window
img = np.zeros((300,512,3), np.uint8)
cv2.namedWindow('image')

# Create trackbars for clor change
cv2.createTrackbar('R','image',0,255, nothing)
cv2.createTrackbar('G','image',0,255, nothing)
cv2.createTrackbar('B','image',0,255, nothing)

# Create switch for ON/OFF functionality
switch = '0: OFF  \n1: ON'
cv2.createTrackbar(switch,'image',0,1, nothing)

while True:
    cv2.imshow('image', img)
    k = cv2.waitKey(1) & 0xFF
    if k == 27:
        break
    # Get current positions of four trackbars
    r = cv2.getTrackbarPos('R', 'image')
    g = cv2.getTrackbarPos('G', 'image')
    b = cv2.getTrackbarPos('B', 'image')
    s = cv2.getTrackbarPos(switch, 'image')

    if s == 0:
        img[:] = 0
    else:
        img[:] = [b, g, r]
cv2.destroyAllWindows()