学习OpenCV——鼠标事件（画框）

Refer from http://blog.csdn.net/yangtrees/article/details/7573919
[cpp]
view plaincopyprint?

#include "cv.h"
#include "highgui.h"

bool check_line_state=false;
IplImage* workImg;
IplImage* imgshow;
CvRect ROI_rect;

void on_mouse4(int event, int x,int y,int flags,void* param)
{
int thickness=2;
CvPoint p1,p2;
if(event==CV_EVENT_LBUTTONDOWN)
{
//当前鼠标位置（x，y）
ROI_rect.x=x;
ROI_rect.y=y;
check_line_state=true;
}
else if(check_line_state&&event==CV_EVENT_MOUSEMOVE)//鼠标状态
{
cvCopy(workImg,imgshow);//这一步很重要，不断更新显示图像，不然画出的图像如图2所示
p1=cvPoint(ROI_rect.x,ROI_rect.y);
p2=cvPoint(x,y);
cvRectangle(imgshow,p1,p2,CV_RGB(0,255,150),thickness,CV_AA,0);
cvShowImage("image",imgshow);

}
else if(check_line_state&&event==CV_EVENT_LBUTTONUP)
{
check_line_state=false;
cvWaitKey(20);
}
}

int main()
{
workImg=cvLoadImage("D:/Demo.jpg",1);
imgshow=cvCreateImage(cvSize(workImg->width,workImg->height),workImg->depth,workImg->nChannels);
cvCopy(workImg,imgshow);
//cvFlip(imgshow);

ROI_rect.x=ROI_rect.y=0;
cvNamedWindow("image",CV_WINDOW_AUTOSIZE);
cvShowImage("image",imgshow);

cvSetMouseCallback("image",on_mouse4);

cvWaitKey();
cvDestroyWindow("image");
}

图1： 图2：