鼠标事件有下面几种（没有滚轮事件，比较遗憾）：

#define CV_EVENT_MOUSEMOVE 0                   滑动

#define CV_EVENT_LBUTTONDOWN 1           左键点击

#define CV_EVENT_RBUTTONDOWN 2           右键点击

#define CV_EVENT_MBUTTONDOWN 3           中键点击

#define CV_EVENT_LBUTTONUP 4                 左键放开

#define CV_EVENT_RBUTTONUP 5                 右键放开

#define CV_EVENT_MBUTTONUP 6                 中键放开

#define CV_EVENT_LBUTTONDBLCLK 7         左键双击

#define CV_EVENT_RBUTTONDBLCLK 8         右键双击

#define CV_EVENT_MBUTTONDBLCLK 9         中键双击

下面用一个例子来学习一下这个事件：

#include <cv.h>

#include <highgui.h>

CvRect box;

bool draging;

void mouse_callback(int event, int x, int y, int flags, void* param)

{

	IplImage *image = (IplImage*)param;

	switch(event) {

	case CV_EVENT_MOUSEMOVE:

		if(draging) {

			box.width = x - box.x;

			box.height = y - box.y;

			//printf("%d,%d,%d,%d\n", box.x,box.y,box.width,box.height);

		}

	break;

	case CV_EVENT_LBUTTONDOWN:

		draging = true;

		printf("down evt\n");

		box.x = x;

		box.y = y;

		printf("%d,%d,%d,%d\n", box.x,box.y,box.width,box.height);

	break;

	case CV_EVENT_LBUTTONUP:

		draging = false;

		printf("%d,%d,%d,%d\n", box.x,box.y,box.width,box.height);

		box.x = 0;

		box.y = 0;

		box.width = 0;

		box.height  = 0;

		printf("up evt\n");

	break;

	}

}

int main(int argc, char **argv)

{

	const char* window_name = "my mouse";

	box =  cvRect(-1, -1, 0, 0);

	IplImage *image = cvCreateImage(cvSize(200,200), 8, 3);

	cvZero(image);

	cvNamedWindow(window_name);

	cvSetMouseCallback(window_name, mouse_callback, (void *)image);

	cvShowImage(window_name, image);

	while(1) {

		if(draging) {

			cvZero(image);

			cvRectangle(image,cvPoint(box.x,box.y),

				cvPoint(box.x + box.width ,box.y+box.height),

				cvScalar(255,255,0));

			cvShowImage(window_name, image);

		}

		if(cvWaitKey(10) == 27)

			break;

	}

	cvReleaseImage(&image);

	cvDestroyWindow(window_name);

}

这个例子的效果实际上是在鼠标拖动的时候画矩形。核心点就是回调函数了：

cvSetMouseCallback(window_name, mouse_callback, (void *)image);

cvWaitKey是一个非阻塞的过程，所以拖动的时候下面的代码一直会被调用：

			cvZero(image);

			cvRectangle(image,cvPoint(box.x,box.y),

				cvPoint(box.x + box.width ,box.y+box.height),

				cvScalar(255,255,0));

			cvShowImage(window_name, image);

这就是刷新的过程了。

下面是效果图：