implement AddCcittG4 image to pdf to use with BitMiracle.LibTiff

[username77]

/// <summary>
/// Adds a CCITT Group 4 (fax) encoded 1bpp image stream as a PDF image XObject (CCITTFaxDecode).
/// This is ideal for monochrome scanned TIFF pages that are already CCITT G4 compressed.
/// </summary>
/// <param name="ccittG4Data">
/// Raw CCITT Group 4 (T.6) compressed bytes (NOT decoded bitmap pixels, NOT wrapped in TIFF).
/// </param>
/// <param name="width">Image width in pixels (Columns).</param>
/// <param name="height">Image height in pixels (Rows).</param>
/// <param name="placementRectangle">
/// Placement rectangle in user space. If default, uses (0,0,width,height).
/// </param>
/// <param name="blackIs1">
/// Set to true if 1 bits represent black (common for bilevel scans).
/// If the result looks inverted, pass false.
/// </param>
public AddedImage AddCcittG4(byte[] ccittG4Data, int width, int height, PdfRectangle placementRectangle = default, bool blackIs1 = true)
{
    if (ccittG4Data is null) throw new ArgumentNullException(nameof(ccittG4Data));
    if (width <= 0) throw new ArgumentOutOfRangeException(nameof(width));
    if (height <= 0) throw new ArgumentOutOfRangeException(nameof(height));

    if (placementRectangle.Equals(default(PdfRectangle)))
    {
        placementRectangle = new PdfRectangle(0, 0, width, height);
    }

    // DecodeParms for CCITTFaxDecode:
    // K = -1 => Group 4 (T.6)
    // Columns/Rows = image dimensions
    // BlackIs1 controls polarity (optional but useful)
    var decodeParms = new Dictionary<NameToken, IToken>

{
{ NameToken.Create("K"), new NumericToken(-1) },
{ NameToken.Create("Columns"), new NumericToken(width) },
{ NameToken.Create("Rows"), new NumericToken(height) },
{ NameToken.Create("BlackIs1"), blackIs1 ? BooleanToken.True : BooleanToken.False }
// You can add these if needed for odd inputs:
// { NameToken.Create("EndOfLine"), BooleanToken.False },
// { NameToken.Create("EncodedByteAlign"), BooleanToken.False },
// { NameToken.Create("EndOfBlock"), BooleanToken.True }
};

    var imgDictionary = new Dictionary<NameToken, IToken>

{
{ NameToken.Type, NameToken.Xobject },
{ NameToken.Subtype, NameToken.Image },
{ NameToken.Width, new NumericToken(width) },
{ NameToken.Height, new NumericToken(height) },
{ NameToken.ColorSpace, NameToken.Devicegray },
{ NameToken.BitsPerComponent, new NumericToken(1) },
{ NameToken.Filter, NameToken.Create("CCITTFaxDecode") },
{ NameToken.DecodeParms, new DictionaryToken(decodeParms) },
{ NameToken.Length, new NumericToken(ccittG4Data.Length) }
};

    // IMPORTANT: Do NOT recompress. ccittG4Data is already compressed with CCITT Group 4.
    var reference = documentBuilder.AddImage(new DictionaryToken(imgDictionary), ccittG4Data);

    var resources = pageDictionary.GetOrCreateDict(NameToken.Resources);
    var xObjects = resources.GetOrCreateDict(NameToken.Xobject);

    var key = NameToken.Create(xobjectsNames.NewName());
    xObjects[key] = reference;

    currentStream.Add(Push.Value);
    currentStream.Add(new ModifyCurrentTransformationMatrix(new[]
    {
placementRectangle.Width, 0,
0, placementRectangle.Height,
placementRectangle.BottomLeft.X, placementRectangle.BottomLeft.Y

}));
currentStream.Add(new InvokeNamedXObject(key));
currentStream.Add(Pop.Value);

    return new AddedImage(reference.Data, width, height);
}