试图在 OpenCV 读取的图像上画线，但没有画线答案

【问题标题】：Trying to draw line on the image which is read by OpenCV, but no line is drawn试图在 OpenCV 读取的图像上画线，但没有画线
【发布时间】：2020-02-27 09:01:24
【问题描述】：

我构建了一个简单的代码，通过 openCV 窗口显示图像并使用 setmousecallback 函数，我想在打开的 cv 图像上绘制一条水平线。然而，即使没有错误警报，图像上也没有显示任何线条。我想我犯了错误，但据我所知，我找不到。请告诉我为什么不能在“src”图像上画一条线。

import cv2 
import numpy as np 

x_start, y_start, x_end, y_end = -1,-1,-1,-1
drawing = False

def line_draw(event, x,y, flags, param):

    global x_start, y_start, x_end, y_end, drawing  

    if event == cv2.EVENT_LBUTTONDOWN:
        drawing = True
        x_start, y_start = x,y
        print("up")
    elif event == cv2.EVENT_MOUSEMOVE:
        if drawing == True:
            cv2.line(src,(10,y),(500,y),(255,0,0),1)
            print("move")

    elif event == cv2.EVENT_LBUTTONUP:
        drawing = False
        cv2.line(src,(10,y),(500,y),(255,0,0),1)
        print("up")


src = cv2.imread("d:/sample.jpg")
cv2.namedWindow("image_window")
cv2.imshow("image_window", src)
cv2.setMouseCallback("image_window", line_draw)

cv2.waitKey(0)
cv2.destroyAllWindows()

【问题讨论】：

标签： python opencv events

【解决方案1】：

试试这个：

...
...
    elif event == cv2.EVENT_MOUSEMOVE:
        if drawing == True:
            src = cv2.line(src,(10,y),(500,y),(255,0,0),1)
            print("move")

【讨论】：