矩形框选取图片并保存显示（截图功能）

／／ 矩形框选取显示图片

#include
#include
#include

void mycallback(int event,int x,int y,int flags,void* param);

int main()
{
    IplImage *img=cvLoadImage("/home/eve/Download/ExamplePics/Lena.jpg",1);
   // cvNamedWindow("Lena",1);
     cvShowImage("Lena",img);
     cvSetMouseCallback("Lena",mycallback,img);

    cvWaitKey();
    cvReleaseImage(&img);
    cvDestroyAllWindows();
}

void mycallback(int event,int x,int y,int flags,void* param)
{
    IplImage *img=(IplImage*)param;
    IplImage *src=cvCloneImage(img);
 //   IplImage *dst=cvCloneImage(img);

    static CvPoint lastpoint;
    static CvPoint endpoint;

    if (event ==CV_EVENT_LBUTTONDOWN)
    {
        lastpoint=cvPoint(x,y);
 //       cvShowImage("Lena",src);
    }

    if((event==CV_EVENT_MOUSEMOVE) && (flags & CV_EVENT_FLAG_LBUTTON))
    {
        endpoint=cvPoint(x,y);
        cvDrawRect(src,lastpoint,endpoint,CV_RGB(0,0,255),1,8,0);
        cvShowImage("Lena",src);
    }

    if((event==CV_EVENT_LBUTTONUP))
    {
        endpoint=cvPoint(x,y);
        cvDrawRect(src,lastpoint,endpoint,CV_RGB(0,0,255),1,8,0);
        cvShowImage("Lena",src);

        CvRect rect;

        if(endpoint.x         {
            rect.x=endpoint.x+1;
        }

        else
        {
            rect.x=lastpoint.x+1;
        }

        if(endpoint.y         {
            rect.y=endpoint.y+1;
        }
        else
        {
            rect.y=lastpoint.y+1;
        }

        rect.width=abs(lastpoint.x-endpoint.x)-1;
        rect.height=abs(lastpoint.y-endpoint.y)-1;

        IplImage *dst=cvCreateImage(cvSize(rect.width,rect.height),8,3);
        cvSetImageROI(src,rect);
        dst=cvCloneImage(src);
        cvShowImage("dst",dst);
        cvSaveImage("Part.jpg",dst);

    }
}

／／改进版：矩形框选择图片并保存

void mycallback(int event,int x,int y,int flags,void* param);

int main()
{
    IplImage *img=cvLoadImage("/home/eve/Download/ExamplePics/Lena.jpg",1);
   // cvNamedWindow("Lena",1);
    cvShowImage("Lena",img);

    cvSetMouseCallback("Lena",mycallback,img);

    cvWaitKey();
    cvReleaseImage(&img);
    cvDestroyAllWindows();
}

void mycallback(int event,int x,int y,int flags,void* param)
{
    IplImage *img=(IplImage*)param;
    IplImage *src=cvCloneImage(img);
 //   IplImage *dst=cvCloneImage(img);

    static CvPoint lastpoint;
    static CvPoint endpoint;

    if (event ==CV_EVENT_LBUTTONDOWN)
    {
        lastpoint=cvPoint(x,y);
 //       cvShowImage("Lena",src);

    }

    if((event==CV_EVENT_MOUSEMOVE) && (flags & CV_EVENT_FLAG_LBUTTON))
    {

        endpoint=cvPoint(x,y);
        cvDrawRect(src,lastpoint,endpoint,CV_RGB(0,0,255),1,8,0);
        cvShowImage("Lena",src);

    }

    if((event==CV_EVENT_LBUTTONUP))
    {
        endpoint=cvPoint(x,y);
        cvDrawRect(src,lastpoint,endpoint,CV_RGB(0,0,255),1,8,0);
        cvShowImage("Lena",src);

        CvRect rect;

        if(endpoint.x         {
            rect.x=endpoint.x+1;
        }

        else
        {
            rect.x=lastpoint.x+1;
        }

        if(endpoint.y         {
            rect.y=endpoint.y+1;
        }
        else
        {
            rect.y=lastpoint.y+1;
        }

        rect.width=abs(lastpoint.x-endpoint.x)-1;
        rect.height=abs(lastpoint.y-endpoint.y)-1;

        IplImage *dst=cvCreateImage(cvSize(rect.width,rect.height),8,3);
        cvSetImageROI(src,rect);
        dst=cvCloneImage(src);
        cvShowImage("dst",dst);
        cvSaveImage("Part.jpg",dst);

    }