Rescale with ratio conserve

gistfile1.cs

        Size Rescale(Size original)
        {
            // Figure out the ratio
            double ratioX = (double)ThumbmailSize.Width / (double)original.Width;
            double ratioY = (double)ThumbmailSize.Height / (double)original.Height;
            // use whichever multiplier is smaller
            double ratio = ratioX < ratioY ? ratioX : ratioY;
            // now we can get the new height and width            
            int newWidth = Convert.ToInt32(original.Width * ratio);
            int newHeight = Convert.ToInt32(original.Height * ratio);
            return new Size(newWidth, newHeight);
        }