opencv_鼠标事件

#include<opencv2/core/core.hpp>
#include<opencv2/imgproc/imgproc.hpp>
#include<opencv2/highgui/highgui.hpp>
#include<opencv2/opencv.hpp>
#include<iostream>

using namespace cv;
Mat org, dst, img, tmp;
void on_mouse(int event, int x, int y, int flags, void *ustc) {

    static Point pre_pt = (-1, -1);//初始坐标  
    static Point cur_pt = (-1, -1);//实时坐标  
    char temp[16];      //显示的(x,y)字符串
    if (event == CV_EVENT_LBUTTONDOWN) {//左键按下，读取初始坐标，并在图像上该点处划圆  

        org.copyTo(img);
        sprintf(temp, "(%d,%d)", x, y);   //格式化输出
        pre_pt = Point(x, y);
        putText(img, temp, pre_pt, FONT_HERSHEY_SIMPLEX, 0.5, Scalar(0, 0, 0, 255), 1, 8);//在窗口上显示坐标  
        circle(img, pre_pt, 2, Scalar(255, 0, 0, 0), CV_FILLED, CV_AA, 0);//划圆  
        imshow("img", img);
    }
    else if (event == CV_EVENT_MOUSEMOVE && !(flags & CV_EVENT_FLAG_LBUTTON)){//左键没有按下的情况下鼠标移动的处理函数  
        img.copyTo(tmp);
        sprintf(temp, "(%d,%d)", x, y);
        cur_pt = Point(x, y);
        putText(tmp, temp, cur_pt, FONT_HERSHEY_SIMPLEX, 0.5, Scalar(0, 0, 0, 255));//只是实时显示鼠标移动的坐标  
        imshow("img", tmp);
    }
    else if (event == CV_EVENT_MOUSEMOVE && (flags & CV_EVENT_FLAG_LBUTTON)){ //左键按下时，鼠标移动，则在图像上划矩形  
        img.copyTo(tmp);
        sprintf(temp, "(%d,%d)", x, y);
        cur_pt = Point(x, y);
        putText(tmp, temp, cur_pt, FONT_HERSHEY_SIMPLEX, 0.5, Scalar(0, 0, 0, 255));
        rectangle(tmp, pre_pt, cur_pt, Scalar(0, 255, 0, 0), 1, 8, 0);//在临时图像上实时显示鼠标拖动时形成的矩形  
        imshow("img", tmp);
    }
    else if (event == CV_EVENT_LBUTTONUP) {//左键松开，将在图像上划矩形  
        org.copyTo(img);
        sprintf(temp, "(%d,%d)", x, y);
        cur_pt = Point(x, y);
        putText(img, temp, cur_pt, FONT_HERSHEY_SIMPLEX, 0.5, Scalar(0, 0, 0, 255));
        circle(img, pre_pt, 2, Scalar(255, 0, 0, 0), CV_FILLED, CV_AA, 0);
        rectangle(img, pre_pt, cur_pt, Scalar(0, 255, 0, 0), 1, 8, 0);//根据初始点和结束点，将矩形画到img上  
        imshow("img", img);
        img.copyTo(tmp);
        //截取矩形包围的图像，并保存到dst中  
        int width = abs(pre_pt.x - cur_pt.x);
        int height = abs(pre_pt.y - cur_pt.y);
        if (width == 0 || height == 0) {
            printf("width == 0 || height == 0");
            return;
        }
        dst = org(Rect(min(cur_pt.x, pre_pt.x), min(cur_pt.y, pre_pt.y), width, height));
        namedWindow("dst");          //即新建立一个窗口进行输出结果
        imshow("dst", dst);
        waitKey(0);
    }
}
void main() {
    org = imread("1.png");
    org.copyTo(img);
    org.copyTo(tmp);
    namedWindow("img");//定义一个img窗口  
    setMouseCallback("img", on_mouse, 0);//调用回调函数  
    imshow("img", img);
    waitKey(0);
}