OpenCV_Python 之 鼠标当笔和trackbar

鼠标事件的返回值

在鼠标左键双击之处画圆圈的代码

import cv2
from cv2 import EVENT_LBUTTONUP
import numpy as np
# 鼠标左键双击之处画个圈圈
def draw_circle(event,x,y,flags,param): #不知道flags和param参数意义
    if event == cv2.EVENT_LBUTTONDBLCLK: #left botton double click
        cv2.circle(img,(x,y),100,(255,0,0),-1)

img = np.zeros((512,512,3),np.uint8)
cv2.namedWindow('image')
cv2.setMouseCallback('image',draw_circle) #鼠标响应

while(1):
    cv2.imshow('image',img)
    if cv2.waitKey(20) & 0xff == 27:
        break
cv2.destroyAllWindows()

Trackbar 滑动条
首先设立一个窗口,然后把trackbar放在窗口里
cv2.createTrackbar('滑动条名称`,windows,origin_value,maximun,function)
其中function为响应函数，可以设置一个什么都不做的函数。

返回滑动条的值num = cv2.getTrackbarPos(滑动条名称，windows)

以下代码为按下左键画图：

#按住鼠标左键来绘制图像，松开回到原点。点击键盘m更改绘图模式（圈圈或rectangle）
drawing = False  #鼠标按下时为True
mode = True  # 1为cycle，0为rec
ix,iy = -1,-1

def nothing():
    pass

cv2.namedWindow("image")
cv2.createTrackbar('R',"image",0,255,nothing)
cv2.createTrackbar('G',"image",0,255,nothing)
cv2.createTrackbar('B',"image",0,255,nothing)

def draw_picture(event,x,y,flags,param):
    global ix,iy,drawing,mode #if edit value in function , use global
    r = cv2.getTrackbarPos("R","image")
    g = cv2.getTrackbarPos("G","image")
    b = cv2.getTrackbarPos("B","image")

    if event == cv2.EVENT_LBUTTONDOWN:
        drawing = True
        ix,iy = x,y #rectangle 要用到
    elif event == cv2.EVENT_MOUSEMOVE and flags == cv2.EVENT_FLAG_LBUTTON: #event看鼠标是否移动，flags看是否按下
        if drawing == True:
            if mode == True:
                cv2.circle(img,(x,y),3,(b,g,r),-1)
            else:
                cv2.rectangle(img,(ix,iy),(x,y),(b,g,r),-1)
    elif event == cv2.EVENT_LBUTTONUP:
        drawing = False

img = np.zeros((512,512,3),np.uint8)
cv2.setMouseCallback("image",draw_picture)
while(1):
    cv2.imshow("image",img)
    k = cv2.waitKey(1)&0xff
    if k ==ord('m'):
        mode = not mode
    elif k ==27:
        break