MFC与opencv的cvSetMouseCallback用起来感觉很不兼容。

大部分时候，用cvSetMouseCallback也许只是为了获取一个矩形框，或者绘制一个点，或者其它什么简易的图形，通过调用该函数来得到鼠标交互的参数信息。

然而，这么一个简单的要求，在MFC框架中并不是很方便调用。

通过阅读 opencv 官方提供的samples源码，其中在grabcut上面有个GCApplication类，用来控制或者获取绘制信息，我觉得很方便，将其精简一下，如下：

#define GC_BGD 0#define GC_FGD 1#define GC_PR_BGD 2#define GC_PR_FGD 3const Scalar GREEN = Scalar(0,255,0);class GCApp{public:    enum{ NOT_SET = 0, IN_PROCESS = 1, SET = 2 };public:    void mouseClick( int event, int x, int y, int flags, void* param );    void setImageAndWinName( const Mat& _image, const string& _winName);    void reset();    void showImage() const;public:    Rect rect;    uchar rectState;    const Mat* image;    Mat mask;    const string* winName;};void GCApp::reset(){    if( !mask.empty() )        mask.setTo(Scalar::all(GC_BGD));    rectState = NOT_SET;}void GCApp::setImageAndWinName( const Mat& _image, const string& _winName  ){    if( _image.empty() || _winName.empty() )        return;    image = &_image;    winName = &_winName;    mask.create( image->size(), CV_8UC1);    reset();}void GCApp::showImage() const{    if( image->empty() || winName->empty() )        return;    Mat res;    image->copyTo( res );    if( rectState == IN_PROCESS || rectState == SET )        rectangle( res, Point( rect.x, rect.y ), Point(rect.x + rect.width, rect.y + rect.height ), GREEN, 2);    imshow( *winName, res );}void GCApp::mouseClick( int event, int x, int y, int flags, void* ){    switch( event )    {    case CV_EVENT_LBUTTONDOWN: // set rect or GC_BGD(GC_FGD) labels        {            if( rectState == NOT_SET )            {                rectState = IN_PROCESS;                rect = Rect( x, y, 1, 1 );            }            showImage();        }        break;    case CV_EVENT_MOUSEMOVE:        if( rectState == IN_PROCESS )        {            rect = Rect( Point(rect.x, rect.y), Point(x,y) );            showImage();        }        break;    case CV_EVENT_LBUTTONUP:        if( rectState == IN_PROCESS )        {            rect = Rect( Point(rect.x, rect.y), Point(x,y) );            rectState = SET;            showImage();        }        break;    }}

由于cvSetMouseCallback需要回调on_mouse函数，声明一个on_mouse函数，注意，得是 static void

GCApp gcapp;static void on_mouse( int event, int x, int y, int flags, void* param ){    gcapp.mouseClick( event, x, y, flags, param );}

然后，在需要的地方，加上如下的代码，即完成了对鼠标绘制信息的获取，在这里，是针对矩形绘制的获取：

const string winName = "DrawRegion";    cvNamedWindow( winName.c_str(), CV_WINDOW_AUTOSIZE );    cvSetMouseCallback( winName.c_str(), on_mouse, 0 );    gcapp.setImageAndWinName( img, winName );    gcapp.showImage();    for (;;)    {        int c = cvWaitKey(0);        //  ESC 键 结束        if (char(c) == '\x1b' && gcapp.rectState == gcapp.SET)        {            break;        }    }    Rect rect = gcapp.rect;