opencv3/python 鼠标响应操作

鼠标回调函数：

def setMouseCallback(
windowName,         #窗口名称
onMouse,            #鼠标响应处理函数
param=None)         #处理函数的ID

event鼠标事件:

event：
EVENT_LBUTTONDBLCLK = 7         左键双击
EVENT_LBUTTONDOWN = 1           左键点击
EVENT_LBUTTONUP = 4             左键释放
EVENT_MBUTTONDBLCLK = 9         中间释放
EVENT_MBUTTONDOWN = 3           中间点击
EVENT_MBUTTONUP = 6             中间释放
EVENT_MOUSEHWHEEL = 11          滚轮事件
EVENT_MOUSEMOVE = 0             滑动
EVENT_MOUSEWHEEL = 10           滚轮事件
EVENT_RBUTTONDBLCLK = 8         右键双击
EVENT_RBUTTONDOWN = 2           右键点击
EVENT_RBUTTONUP = 5             右键释放


flags:
EVENT_FLAG_ALTKEY = 32          按Alt不放事件
EVENT_FLAG_CTRLKEY = 8          按Ctrl不放事件
EVENT_FLAG_LBUTTON = 1          左键拖拽
EVENT_FLAG_MBUTTON = 4          中键拖拽
EVENT_FLAG_RBUTTON = 2          右键拖拽
EVENT_FLAG_SHIFTKEY = 16        按Shift不放事件

示例

在图像上用鼠标点击左键拖拽画一矩形，并输出矩形信息：

import cv2
def draw_rectangle(event,x,y,flags,param):
    global ix, iy
    if event==cv2.EVENT_LBUTTONDOWN:
        ix, iy = x, y
        print("point1:=", x, y)
    elif event==cv2.EVENT_LBUTTONUP:
        print("point2:=", x, y)
        print("width=",x-ix)
        print("height=", y - iy)
        cv2.rectangle(img, (ix, iy), (x, y), (0, 255, 0), 2)

img = cv2.imread("max.png")  #加载图片
cv2.namedWindow('image')
cv2.setMouseCallback('image', draw_rectangle)
while(1):
    cv2.imshow('image', img)
    if cv2.waitKey(20) & 0xFF == 27:
        break
cv2.destroyAllWindows()

输出：

point1:= 254 64
point2:= 708 569
width= 454
height= 505