python opencv：使用鼠标当做画笔

鼠标事件

import cv2
events=[i for i in dir(cv2) if 'EVENT'in i]
print events

双击画圆圈

import cv2
import numpy as np
# mouse callback function
def draw_circle(event, x, y, flags, param):
    if event == cv2.EVENT_LBUTTONDBLCLK:
        cv2.circle(img, (x, y), 100, (255, 0, 0), -1)
# 创建图像与窗口并将窗口与回调函数绑定
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()

import cv2
import numpy as np
# 当鼠标按下时变为 True
drawing = False
# 如果 mode 为 true 绘制矩形。按下'm' 变成绘制曲线。
mode = True
ix, iy = -1, -1
# 创建回调函数
def draw_circle(event, x, y, flags, param):
    global ix, iy, drawing, mode
# 当按下左键是返回起始位置坐标
    if event == cv2.EVENT_LBUTTONDOWN:
        drawing = True
        ix, iy = x, y
# 当鼠标左键按下并移动是绘制图形。 event 可以查看移动， flag 查看是否按下
    elif event == cv2.EVENT_MOUSEMOVE and flags == cv2.EVENT_FLAG_LBUTTON:
        if drawing == True:
            if mode == True:
                cv2.rectangle(img, (ix, iy), (x, y), (0, 255, 0), -1)
            else:
                # 绘制圆圈，小圆点连在一起就成了线， 3 代表了笔画的粗细
                cv2.circle(img, (x, y), 3, (0, 0, 255), -1)
            # 下面注释掉的代码是起始点为圆心，起点到终点为半径的
            # r=int(np.sqrt((x-ix)**2+(y-iy)**2))
            # cv2.circle(img,(x,y),r,(0,0,255),-1)
            # 当鼠标松开停止绘画。
    elif event == cv2.EVENT_LBUTTONUP:
        drawing == False
        # if mode==True:
        # cv2.rectangle(img,(ix,iy),(x,y),(0,255,0),-1)
        # else:
        # cv2.circle(img,(x,y),5,(0,0,255),-1)
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