OpenCV从鼠标回调函数返回值 [英] OpenCV Return value from mouse callback function

问题描述

在OpenCV中，我想将Point(x，y)之类的点位置返回给main()函数，该函数在鼠标回调函数中单击图像.除了设置全局变量之外，还有其他方法吗?

In OpenCV I want to return the point position like Point(x,y) to the main() function that I　click on the image in the mouse callback function . Is there anyway other than setting a global variable?

我不想在on_mouse()函数中编写所有代码.

I don't want to write all the codes inside the on_mouse() function.

谢谢

推荐答案

通过将指向数据的指针作为参数传递给setMouseCallback()，可以避免使用全局变量.同意@berek，只是想在下面显示一个完整的示例，以避免混淆全局变量.

You can avoid using global variables by passing a pointer to your data as a parameter to setMouseCallback(). Agree with @berek, just wanted to show a full example below to avoid confusion about global variables.

using namespace cv; 

void on_mouse( int e, int x, int y, int d, void *ptr )
{
    Point*p = (Point*)ptr;
    p->x = x;
    p->y = y;
}

in main() {
    Point p;
    namedWindow("window");
    Mat image = imread("someimage.jpg");
    imshow(image);


    //pass a pointer to `p` as parameter
    setMouseCallback("window",on_mouse, &p ); 

    // p will update with new mouse-click image coordinates 
    // whenever user clicks on the image window 
}

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