What is <cvShowImageHWND>

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CV_IMPL void cvShowImageHWND(HWND w_hWnd, const CvArr* arr) { CV_FUNCNAME( "cvShowImageHWND" );

__BEGIN__;

SIZE size = { 0, 0 };
int channels = 0;
void* dst_ptr = 0;
const int channels0 = 3;
int origin = 0;
CvMat stub, dst, *image;
bool changed_size = false;
BITMAPINFO tempbinfo;
HDC hdc = NULL;

if( !arr )
    EXIT;
if( !w_hWnd )
    EXIT;

hdc = GetDC(w_hWnd);

if( CV_IS_IMAGE_HDR( arr ) )
    origin = ((IplImage*)arr)->origin;

CV_CALL( image = cvGetMat( arr, &stub ) );

if ( hdc )
{
        //GetBitmapData
        BITMAP bmp;
        GdiFlush();
        HGDIOBJ h = GetCurrentObject( hdc, OBJ_BITMAP );

        if (h == NULL)
        EXIT;
        if (GetObject(h, sizeof(bmp), &bmp) == 0) //GetObject(): returns size of object, 0 if error
        EXIT;

        channels = bmp.bmBitsPixel/8;
        dst_ptr = bmp.bmBits;
 }

if( size.cx != image->width || size.cy != image->height || channels != channels0 )
{
    changed_size = true;

    uchar buffer[sizeof(BITMAPINFO) + 255*sizeof(RGBQUAD)];
    BITMAPINFO* binfo = (BITMAPINFO*)buffer;

    BOOL bDeleteObj = DeleteObject(GetCurrentObject(hdc, OBJ_BITMAP));
            CV_Assert( FALSE != bDeleteObj );

    size.cx = image->width;
    size.cy = image->height;
    channels = channels0;

    FillBitmapInfo( binfo, size.cx, size.cy, channels*8, 1 );

    SelectObject( hdc, CreateDIBSection( hdc, binfo, DIB_RGB_COLORS, &dst_ptr, 0, 0));
}

cvInitMatHeader( &dst, size.cy, size.cx, CV_8UC3, dst_ptr, (size.cx * channels + 3) & -4 );
cvConvertImage( image, &dst, origin == 0 ? CV_CVTIMG_FLIP : 0 );

// Image stretching to fit the window
RECT rect;
GetClientRect(w_hWnd, &rect);
StretchDIBits( hdc, 0, 0, rect.right, rect.bottom, 0, 0, image->width, image->height, dst_ptr, &tempbinfo, DIB_RGB_COLORS, SRCCOPY );

// ony resize window if needed
InvalidateRect(w_hWnd, 0, 0);

__END__;

}

I found it in <c:\opencv_243\modules\highgui\src\window_w32.cpp>

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