【OpenCV-Python】7.OpenCV的响应鼠标事件

7.OpenCV的响应鼠标事件

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前言

  OpenCV可在用户触发鼠标事件时，调用鼠标回调函数完成事件处理。

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一、响应鼠标事件

  鼠标回调函数的基本格式如下：

def mouseCallback(event, x, y, flag, param):... 

mouseCallback为自定义函数名称
event为调用时传递给函数的鼠标事件对象
x和y为出发鼠标事件时，鼠标指针在窗口中的坐标(x,y)
flag为触发鼠标事件时，鼠标拖动或按键盘的操作

1、右键画矩形、左键画圆

img = np.zeros((200,500,3), dtype='uint8') + 255

def draw(event, x, y, flag, param):     # 定义鼠标回调函数
    if event == cv2.EVENT_LBUTTONDBLCLK:                     #双击鼠标左键时画圆
        cv2.circle(img,(x,y),20,(255,0,0),-1)
    elif event == cv2.EVENT_RBUTTONDBLCLK:
        cv2.rectangle(img,(x,y),(x+60,y+30),(0,0,255),-1)    #双击鼠标右键时画矩形
    cv2.imshow("drawing",img)

cv2.namedWindow("drawing")
cv2.setMouseCallback("drawing",draw)    # 为窗口绑定回调函数

while(True):
    cv2.imshow("drawing",img)
    k = cv2.waitKey(1)
    if k == 27:
        break
        
cv2.destroyAllWindows()

2、使用鼠标指针选点绘制多边形

img = np.zeros((576,1024,3), dtype='uint8')+ 255

font = cv2.FONT_HERSHEY_PLAIN
xys = []

def draw(event,x,y,flag,param):
    global xys, img
    if event == cv2.EVENT_LBUTTONUP:
        xy = '(%s,%s)'%(x,y)
        cv2.putText(img,xy,(x,y),font,2,(0,0,0),1,cv2.LINE_AA)
        xys.append([x,y])
        cv2.circle(img,(x,y),5,(0,0,255),-1)
    elif event == cv2.EVENT_RBUTTONUP:
        pts = np.array(xys,np.int32)
        cv2.polylines(img,[pts],True,(0,0,0),2)
        xys = []
    elif event == cv2.EVENT_RBUTTONDBLCLK:
        img = np.zeros((576,1024,3), dtype='uint8')+ 255    #双击鼠标左键时重置图像                        

    cv2.imshow("drawing",img)

cv2.namedWindow("drawing")
cv2.setMouseCallback("drawing",draw)    # 为窗口绑定回调函数
cv2.imshow("drawing",img)
k = cv2.waitKey(0)
if k == 27:
    cv2.destroyAllWindows()

3、按住鼠标左键移动绘图，双击左键清除绘图

img=np.zeros((1200,1320,3), np.uint8) + 255        #创建一幅白色图像
drawing = False

def draw(event,x,y,flag,param):                    #定义鼠标回调函数
    global img,drawing
    
    if event == cv2.EVENT_LBUTTONDOWN:
        drawing = True
    elif event == cv2.EVENT_MOUSEMOVE:
        if drawing == True:
            cv2.circle(img,(x,y),5,(0,0,255),-1)
      elif event == cv2.EVENT_LBUTTONUP:
        drawing = False
    elif event==cv2.EVENT_RBUTTONDBLCLK:
        img=np.zeros((1200,1320,3), np.uint8)+255    #双击鼠标左键时重置图像                        
    cv2.imshow('drawing',img)                        #显示图像

cv2.namedWindow('drawing')                          #命名图像窗口
cv2.setMouseCallback('drawing',draw)                #为窗口绑定回调函数
cv2.imshow('drawing',img)                           #显示图像
cv2.waitKey(0)
cv2.destroyAllWindows()

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总结

  以上内容介绍了OpenCV-Python响应鼠标的三个例子，有关Python、数据科学、人工智能等文章后续会不定期发布，请大家多多关注，一键三连哟(●’◡’●)。