OPENCV FOR PYTHON 学习笔记 - 鼠标回调事件

import numpy as np
import cv2 as cv


#鼠标双击画圆
def draw_cycle(event,x,y,flags,param):
    if event == cv.EVENT_LBUTTONDBLCLK:
        cv.circle(img,(x,y),100,(255,0,0),-1)

#当鼠标按下时变为True
drawing = False
#mode 为 True 绘制矩形，按下m 变为绘制曲线
mode = True
ix,iy = -1,-1

'''
鼠标事件回调函数
参数1 event 代表了鼠标的各种操作，详细看一下各个event事件：
    #define CV_EVENT_MOUSEMOVE 0             //滑动
    #define CV_EVENT_LBUTTONDOWN 1           //左键点击
    #define CV_EVENT_RBUTTONDOWN 2           //右键点击
    #define CV_EVENT_MBUTTONDOWN 3           //中键点击
    #define CV_EVENT_LBUTTONUP 4             //左键放开
    #define CV_EVENT_RBUTTONUP 5             //右键放开
    #define CV_EVENT_MBUTTONUP 6             //中键放开
    #define CV_EVENT_LBUTTONDBLCLK 7         //左键双击
    #define CV_EVENT_RBUTTONDBLCLK 8         //右键双击
    #define CV_EVENT_MBUTTONDBLCLK 9         //中键双击
参数2，3 int x,int y，代表鼠标位于窗口的（x，y）坐标位置，即Point(x,y);
参数4 int flags，代表鼠标的拖拽事件，以及键盘鼠标联合事件，共有32种事件：
    flags:
    #define CV_EVENT_FLAG_LBUTTON 1       //左鍵拖曳
    #define CV_EVENT_FLAG_RBUTTON 2       //右鍵拖曳
    #define CV_EVENT_FLAG_MBUTTON 4       //中鍵拖曳
    #define CV_EVENT_FLAG_CTRLKEY 8       //(8~15)按Ctrl不放事件
    #define CV_EVENT_FLAG_SHIFTKEY 16     //(16~31)按Shift不放事件
    #define CV_EVENT_FLAG_ALTKEY 32       //(32~39)按Alt不放事件
'''
def draw_shape(event,x,y,flags,param):
    global ix,iy,drawing,mode
    #按下鼠标左键时，返回起始位置坐标
    if event == cv.EVENT_LBUTTONDOWN:
        drawing = True
        ix,iy = x,y
    #当鼠标左键按下，并且移动时绘制图形
    elif event == cv.EVENT_MOUSEMOVE and flags == cv.EVENT_FLAG_LBUTTON:
        if drawing == True:
            if mode == True:
                cv.rectangle(img,(ix,iy),(x,y),(0,255,0),-1)
            else:
                cv.circle(img,(x,y),3,(0,0,255),-1)
    elif event == cv.EVENT_LBUTTONUP:
        drawing == False

#创建图像和窗口，并将窗口与回调函数绑定
img = np.zeros((512,512,3),np.uint8)
cv.namedWindow('img')
cv.setMouseCallback('img',draw_shape)

while(1):
    cv.imshow('img',img)
    if(cv.waitKey(20)&0xFF == ord('q')):
        break
    elif (cv.waitKey(20)&0xFF == ord('m')):
        mode = not mode
cv.destroyAllWindows()