学习OpenCV——鼠标事件（画框）

#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：