在OpenCV中利用鼠标绘制矩形和截取图像的矩形区域

程序之一，在OpenCV中利用鼠标绘制矩形

#include <cv.h>
#include <highgui.h>
#include <stdio.h>
#pragma comment( lib, "cv.lib" )
#pragma comment( lib, "cxcore.lib" )
#pragma comment( lib, "highgui.lib" )
IplImage* src = 0;
IplImage* dst = 0;
void on_mouse( int event, int x, int y, int flags, void* ustc)
{
static CvPoint pre_pt = {-1,-1};
static CvPoint cur_pt = {-1,-1};
CvFont font;
cvInitFont(&font, CV_FONT_HERSHEY_SIMPLEX, 0.5, 0.5, 0, 1, CV_AA);
char temp[16];

if( event == CV_EVENT_LBUTTONDOWN )
{
cvCopy(dst,src);
sprintf(temp,"(%d,%d)",x,y);
pre_pt = cvPoint(x,y);
cvPutText(src,temp, pre_pt, &font, cvScalar(0,0, 0, 255));
cvCircle( src, pre_pt, 3,cvScalar(255,0,0,0) ,CV_FILLED, CV_AA, 0 );
cvShowImage( "src", src );
cvCopy(src,dst);
}
else if( event == CV_EVENT_MOUSEMOVE && !(flags & CV_EVENT_FLAG_LBUTTON))
{
cvCopy(dst,src);
sprintf(temp,"(%d,%d)",x,y);
cur_pt = cvPoint(x,y);
cvPutText(src,temp, cur_pt, &font, cvScalar(0,0, 0, 255));
cvShowImage( "src", src );
}
else if( event == CV_EVENT_MOUSEMOVE && (flags & CV_EVENT_FLAG_LBUTTON))
{
cvCopy(dst,src);
sprintf(temp,"(%d,%d)",x,y);
cur_pt = cvPoint(x,y);
cvPutText(src,temp, cur_pt, &font, cvScalar(0,0, 0, 255));
cvRectangle(src, pre_pt, cur_pt, cvScalar(0,255,0,0), 1, 8, 0 );
cvShowImage( "src", src );
}
else if( event == CV_EVENT_LBUTTONUP )
{
sprintf(temp,"(%d,%d)",x,y);
cur_pt = cvPoint(x,y);
cvPutText(src,temp, cur_pt, &font, cvScalar(0,0, 0, 255));
cvCircle( src, cur_pt, 3,cvScalar(255,0,0,0) ,CV_FILLED, CV_AA, 0 );
cvRectangle( src, pre_pt, cur_pt, cvScalar(0,255,0,0), 1, 8, 0 );
cvShowImage( "src", src );
cvCopy(src,dst);
}
}
int main()
{
src=cvLoadImage("lena.jpg",1);
dst=cvCloneImage(src);
cvNamedWindow("src",1);
cvSetMouseCallback( "src", on_mouse, 0 );

cvShowImage("src",src);
cvWaitKey(0);
cvDestroyAllWindows();
cvReleaseImage(&src);
cvReleaseImage(&dst);
return 0;
}

效果图如下