鼠标操作

一、鼠标操作SetMouseCallback()

#include<opencv2opencv.hpp>
#include<iostream>
#include<vector>
using namespace cv;
using namespace std;

#define WINDOW_NAME "【程序窗口】"

void on_MouseHandle(int event, int x, int y, int flags, void* param);
void DrawRectangle(Mat &img, Rect box);
void ShowHelpText();

Rect g_rectangle;
bool g_bDrawingBox = false; //是否进行绘制
RNG g_rng(12345);

int main(int argc,char** argv) {
    //Mat image1= imread("C:\Users\Nelsoner\Desktop\Camera Roll\05.jpg");
    //Mat image2 = imread("C:\Users\Nelsoner\Desktop\Camera Roll\08.jpg");
    
    g_rectangle = Rect(-1,-1,0,0);
    Mat srcImage(600,800,CV_8UC3),tempImage;
    srcImage.copyTo(tempImage);
    srcImage = Scalar::all(0);

    //设置鼠标操作回掉函数
    namedWindow(WINDOW_NAME);
    setMouseCallback(WINDOW_NAME,on_MouseHandle,(void*)&srcImage);

    //程序主循环，当进行绘制的标识符为真，进行绘制
    while (1) {
        srcImage.copyTo(tempImage);   //复制源图到临时变量
        if (g_bDrawingBox)
            DrawRectangle(tempImage,g_rectangle);
        imshow(WINDOW_NAME,tempImage);
        if (waitKey(10) == 27)   //按下ESC键，程序退出
            break;
    }
    return 0;
}

void on_MouseHandle(int event, int x, int y, int flags, void* param) {
    Mat& image = *(Mat*)param;
    switch (event) {
        //鼠标移动消息
        case EVENT_MOUSEMOVE:
        {
            if (g_bDrawingBox)  //如果是否进行绘制的标识符为真，则记录下长和宽到Rect型变量中
            {
                g_rectangle.width = x - g_rectangle.x;
                g_rectangle.height = y - g_rectangle.y;
            }
        }
        break;

        //左键按下消息
        case EVENT_LBUTTONDOWN:
        {
            g_bDrawingBox = true;
            g_rectangle = Rect(x, y, 0, 0);    //记录起始点
        }
        break;

        //左键抬起消息
        case EVENT_LBUTTONUP:
        {
            g_bDrawingBox = false;   //置标识符为false
            //对宽和高小于0的处理
            if (g_rectangle.width < 0) {
                g_rectangle.x += g_rectangle.width;
                g_rectangle.width *= -1;
            }
            if (g_rectangle.height < 0) {
                g_rectangle.y += g_rectangle.height;
                g_rectangle.height *= -1;
            }
            //调用函数进行绘制
            DrawRectangle(image,g_rectangle);
        }
        break;
    }
}

void DrawRectangle(Mat &img, Rect box)
{
    rectangle(img,box.tl(),box.br(),Scalar(g_rng.uniform(0,255),g_rng.uniform(0,255), g_rng.uniform(0, 255)));
}

效果图：

学习小总结：

1.OpenCV函数中输出图像的内存分配是自动完成的（如果不特别指定的话）

2.使用OpenCV的C++接口时不需要考虑内存释放问题

3.复制运算和拷贝构造函数只复制信息头

4.使用函数clone()或者copyTo()来复制一副图像的矩阵