test.cs

using System.Drawing;
using System.Text;

public static class WatermarkGenerator
{
    // Create an SVG watermark with centered text and rotation
    public static byte[] CreateSVGWatermark(string text, int rotation, Color color, Font font)
    {
        // Guess the size of the SVG image including rotation
        SizeF size = MeasureTextSize(text, font);

        // Convert font to CSS style
        string fontCssStyle = GetFontCssStyle(font);

        // Convert color to hex
        string colorHex = ColorToHex(color);

        // Generate SVG markup
        string svgMarkup = GenerateSvgMarkup(text, rotation, size, fontCssStyle, colorHex);

        return Encoding.ASCII.GetBytes(svgMarkup);
    }

    private static SizeF MeasureTextSize(string text, Font font)
    {
        using (Graphics graphics = Graphics.FromImage(new Bitmap(1, 1)))
        {
            return graphics.MeasureString(text, font);
        }
    }

    private static string GetFontCssStyle(Font font)
    {
        return $"font-family: {font.FontFamily.Name}; font-size: {font.Size}px; font-weight: {(font.Bold ? "bold" : "normal")};";
    }

    private static string ColorToHex(Color color)
    {
        return $"#{color.R:X2}{color.G:X2}{color.B:X2}";
    }

    private static string GenerateSvgMarkup(string text, int rotation, SizeF size, string fontCssStyle, string colorHex)
    {
        return $@"<svg xmlns='http://www.w3.org/2000/svg' width='{size.Width}' height='{size.Width}' viewBox='0 0 {size.Width} {size.Width}' preserveAspectRatio='none'>
                  <text x='{size.Width / 2}' y='{size.Width / 2}' text-anchor='middle' alignment-baseline='middle' transform='rotate({rotation} {size.Width / 2} {size.Width / 2})' style='{fontCssStyle} fill: {colorHex};'>{text}</text>
                  </svg>";
    }
}