C / C++ / MFC

HRGN CRegionFromImage::FromFile( const WCHAR* filename, Color color )
{
	HDC hDC = ::GetDC( NULL );
	Graphics g( hDC );

	Bitmap* bitmap = Bitmap::FromFile( filename, FALSE );

	if ( bitmap == NULL ) return NULL;

	Rect rect( 0, 0, bitmap->GetWidth(), bitmap->GetHeight() );
	Region region( rect );
	BitmapData* bitmapdata = new BitmapData;

	bitmap->LockBits( &rect, ImageLockModeRead, PixelFormat32bppARGB, bitmapdata );

	UINT* pixels = (UINT*)bitmapdata->Scan0;

	for ( UINT y = 0; y < bitmap->GetHeight(); y++ )
	{
		for ( UINT x = 0; x < bitmap->GetWidth(); x++ )
		{
			Color pixelcolor( pixels[y * bitmapdata->Stride / 4 + x] );

			if ( color.GetR() == pixelcolor.GetR() && color.GetG() == pixelcolor.GetG() &&
				 color.GetB() == pixelcolor.GetB() )
			{
				Rect xorrect( x, y, 1, 1 );
				region.Xor( xorrect ); // EXCEPTION THROWN HERE!
			}
		}
	}

	bitmap->UnlockBits( bitmapdata );
	delete bitmapdata;

	return region.GetHRGN( &g );
}