绘制一个没有填充的矩形

DrawMouseEvent.py

# -*- coding: utf-8 -*-
 """
 Created on Sun Jan 5 11:41:39 2014
 @author: duan
 """
 import cv2
 import numpy as np# 当鼠标按下时变为True
 drawing=False
 # 如果mode 为true 绘制矩形。按下'm' 变成绘制曲线。
 mode=True
 ix,iy=-1,-1# 创建回调函数
 def draw_circle(event,x,y,flags,param):
  global ix,iy,drawing,mode
  # 当按下左键是返回起始位置坐标
  if event==cv2.EVENT_LBUTTONDOWN:
   drawing=True
   ix,iy=x,y
  # 当鼠标左键按下并移动是绘制图形。event 可以查看移动，flag 查看是否按下
  elif event==cv2.EVENT_MOUSEMOVE and flags==cv2.EVENT_FLAG_LBUTTON:
   if drawing==True:
    if mode==False:
     # 绘制圆圈，小圆点连在一起就成了线，3 代表了笔画的粗细
     cv2.circle(img,(x,y),3,(0,0,255),-1)
  # 下面注释掉的代码是起始点为圆心，起点到终点为半径的
  # r=int(np.sqrt((x-ix)**2+(y-iy)**2))
  # cv2.circle(img,(x,y),r,(0,0,255),-1)
  # 当鼠标松开停止绘画。
  elif event==cv2.EVENT_LBUTTONUP:
   drawing==False
   if mode==True:
     cv2.rectangle(img,(ix,iy),(x,y),(255,0,0),1) # if mode==True:
  # cv2.rectangle(img,(ix,iy),(x,y),(0,255,0),-1)
  # else:
  # cv2.circle(img,(x,y),5,(0,0,255),-1)img=np.zeros((512,512,3),np.uint8)
 cv2.namedWindow('image')
 cv2.setMouseCallback('image',draw_circle)
 while(1):
  cv2.imshow('image',img)
  k=cv2.waitKey(1)&0xFF
  if k==ord('m'):
   mode=not mode
  elif k==ord('c'):
   #Clear
   img=np.zeros((512,512,3),np.uint8)
  elif k==27:
   break