OpenCV教程-OpenCV鼠标事件

整理：python技术迷

将鼠标用作画笔

import cv2  mouse_events = [j for j in dir(cv2) if 'EVENT' in j]  print(mouse_events)

上面的代码将返回由OpenCV支持的所有鼠标事件的列表。

输出：

['EVENT_FLAG_ALTKEY', 'EVENT_FLAG_CTRLKEY', 'EVENT_FLAG_LBUTTON', 'EVENT_FLAG_MBUTTON', 'EVENT_FLAG_RBUTTON', 'EVENT_FLAG_SHIFTKEY', 'EVENT_LBUTTONDBLCLK', 'EVENT_LBUTTONDOWN', 'EVENT_LBUTTONUP', 'EVENT_MBUTTONDBLCLK', 'EVENT_MBUTTONDOWN', 'EVENT_MBUTTONUP', 'EVENT_MOUSEHWHEEL', 'EVENT_MOUSEMOVE', 'EVENT_MOUSEWHEEL', 'EVENT_RBUTTONDBLCLK', 'EVENT_RBUTTONDOWN', 'EVENT_RBUTTONUP']

画圆

import cv2  import numpy as np  # Creating mouse callback function  def draw_circle(event,x,y,flags,param):      if(event == cv2.EVENT_LBUTTONDBLCLK):              cv2.circle(img,(x,y),100,(255,255, 0),-1)  # Creating a black image, a window and bind the function to window  img = np.zeros((512,512,3), np.uint8)  cv2.namedWindow('image')  cv2.setMouseCallback('image',draw_circle)  while(1):      cv2.imshow('image',img)      if cv2.waitKey(20) & 0xFF == 27:          break  cv2.destroyAllWindows()

在上述代码中，我们首先创建了一个黑色窗口屏幕，其中发生了鼠标事件。当我们在黑色窗口上双击时，它将根据我们在回调函数中定义的内容绘制一个圆。

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绘制矩形和曲线

import cv2  import numpy as np  draw = False # true if the mouse is pressed. Press m to shift into curve mode.  mode = True # if True, draw rectangle.  a,b = -1,-1  # mouse callback function  def draw_circle(event,x,y,flags,param):      global a,b,draw,mode      if(event == cv2.EVENT_LBUTTONDOWN):          draw = True          a,b = x,y      elif (event == cv2.EVENT_MOUSEMOVE):          if draw == True:              if mode == True:                  cv2.rectangle(img,(a,b),(x,y),(0,255,0),-1)              else:                  cv2.circle(img,(x,y),5,(0,0,255),-1)      elif(event == cv2.EVENT_LBUTTONUP):          draw = False          if mode == True:              cv2.rectangle(img,(a,b),(x,y),(0,255,0),-1)          else:              cv2.circle(img,(x,y),5,(0,0,255),-1)  # We bind the keyboard key m to toggle between rectangle and circle.  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 == 27):          break  cv2.destroyAllWindows()

输出

在上面的程序中，我们创建了两个鼠标回调函数。它与OpenCV窗口绑定在一起。在while循环中，我们设置了一个键盘绑定，将键盘键'm'用于在矩形和曲线之间切换。

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