python利用 opencv實現(xiàn)一個簡易的畫圖板

# -*- coding: utf-8 -*-
"""
Created on Sat May 19 17:34:54 2018

@author: xxx
"""

import cv2 as cv
import numpy as np


def nothing(x):
  pass

# 當鼠標按下時變?yōu)?True
drawing = False
# 如果 mode 為 True 繪制矩形。按下 'm' 變成繪制曲線
mode = True
ix, iy = -1, -1

#創(chuàng)建回調(diào)函數(shù)
def draw_circle(event, x, y, flags, param):
  r = cv.getTrackbarPos('R', 'image')
  g = cv.getTrackbarPos('G', 'image')
  b = cv.getTrackbarPos('B', 'image')
  color = (b, g, r)

  global ix, iy, drawing, mode
  # 當按下左鍵是返回起始位置坐標
  if event == cv.EVENT_LBUTTONDOWN:
    drawing = True
    ix, iy = x, y
#    當鼠標左鍵按下并移動是繪制圖形。event 可以查看移動, flag 查看是否按下
  elif event == cv.EVENT_MOUSEMOVE and flags == cv.EVENT_FLAG_LBUTTON:
    if drawing == True:
      if mode == True:
        cv.rectangle(img, (ix, iy), (x, y), color, -1)
      else:
        # 繪制圓圈，小圓點連在一起就成了線，3代表畫筆的粗細
        cv.circle(img, (ix, iy), 3, color, -1)
        # 下面注釋的代碼是起始點為圓心，起點到終點為半徑
#        r = int(np.sqrt((x - ix)**2 + (y - iy)**2))
#        cv.circle(img, (x, y), r, (0, 0, 255), -1)
#    當鼠標松開停止繪畫
  elif event == cv.EVENT_LBUTTONUP:
      drawing == False
#      if mode == True:
#        cv.rectangle(img, (ix, iy), (x, y), (0, 255, 0), -1)
#      else:
#      cv.circle(img, (x, y), 5, (0, 0, 255), -1)

#創(chuàng)建一幅黑色圖形
img = np.zeros((512, 512, 3), np.uint8)
cv.namedWindow('image')

cv.createTrackbar('R', 'image', 0, 255, nothing)
cv.createTrackbar('G', 'image', 0, 255, nothing)
cv.createTrackbar('B', 'image', 0, 255, nothing)
cv.setMouseCallback('image', draw_circle)

while(1):
  cv.imshow('image', img)
  k = cv.waitKey(1)&0xFF
  if k == ord('m'):
    mode = not mode
  elif k==27:
    break


cv.destroyAllWindow()