【cv笔记1】鼠标事件监听

鼠标事件监听

鼠标事件分类

import cv2
#查看cv2 所有以EVENT开头的预定义变量的名称列表
events=[i for i in dir(cv2) if 'EVENT'in i]
for event in events:
    print(event)

• EVENT_MOUSEMOVE 鼠标移动 Mouse Move
• EVENT_LBUTTONDOWN EVENT_RBUTTONDOWN EVENT_MBUTTONDOWN 鼠标左、右、中键点击
• EVENT_LBUTTONUP EVENT_RBUTTONUP EVENT_MBUTTONUP 鼠标左、右、中键抬起
• EVENT_LBUTTONDBLCLK EVENT_RBUTTONDBLCLK EVENT_MBUTTONDBLCLK 鼠标左、右、中键双击

鼠标事件的回调参数

def onMouse(event, x, y, flags, param):
    #判断事件类型 执行相关操作
    if event == cv2.EVENT_LBUTTONDBLCLK:
       cv2.circle(img, (x, y), 20, (255, 0, 0), -1)

• event 鼠标事件类型， 如上文所述EVENT_MOUSEMOVE等。

• x y鼠标当前在窗口Windows下的x、y坐标

• flags 鼠标事件发生过程值中的一些其他事件标志/状态

  • EVENT_FLAG_LBUTTON EVENT_FLAG_RBUTTON EVENT_FLAG_MBUTTON 左、右、中键正在按下

  • EVENT_FLAG_CTRLKEY EVENT_FLAG_SHIFTKEY EVENT_FLAG_ALTKEY

  CTRL、SHIFT、ALT键正在被按下

• param 用户自定义的参数

检测某两个键子同时按下

def onMouse(event, x, y, flags, param):
    if flags == (cv2.EVENT_FLAG_MBUTTON | cv2.EVENT_FLAG_CTRLKEY):
    #if flags == (cv2.EVENT_FLAG_MBUTTON + cv2.EVENT_FLAG_CTRLKEY)：相同作用
        .......

实例

# 设置鼠标事件回调
cv2.setMouseCallback(windowName,onMouse)  

windowName 指定窗口名 onMouse 回调函数

鼠标 每次双击 在点击处绘制一个圈

import cv2
import numpy as np

def draw_circle(event, x, y, flags, param):
    if event == cv2.EVENT_LBUTTONDBLCLK:
        cv2.circle(img, (x, y), 30, (200, 30, 120), 2)

img = np.zeros((500, 550, 3), np.uint8)
cv2.namedWindow('canvas')

cv2.setMouseCallback('canvas', draw_circle)

while (True):
    cv2.imshow('canvas', img)
    if cv2.waitKey(20) == ord('q'):
        break
cv2.destroyAllWindows()

鼠标按下绘制线条

def draw_circle(event,x,y,flags,param):
    if flags == cv2.EVENT_FLAG_LBUTTON:
        cv2.circle(img,(x,y),3,(0,255,0),-1)

img = np.zeros((500,500,3), np.uint8)
cv2.namedWindow('image')

cv2.setMouseCallback('image',draw_circle)

while(True):
    cv2.imshow('image',img)
    if cv2.waitKey(1) == ord('q'):
        break
cv2.destroyAllWindows()