Create PDF/A-4 Documents for Long-Term Archiving in C#

using Syncfusion.Pdf;
using Syncfusion.Pdf.Graphics;

//Create a new document with the PDF/A-4 standard.
PdfDocument document = new PdfDocument(PdfConformanceLevel.Pdf_A4);

//Add a page to the document.
PdfPage page = document.Pages.Add();

//Create the PDF graphics for the page.
PdfGraphics graphics = page.Graphics;

//Load the TrueType font from the local file.
FileStream fontStream = new FileStream("../../../arial.ttf", FileMode.Open, FileAccess.Read);
PdfFont font = new PdfTrueTypeFont(fontStream, 14);

//Draw the text.
graphics.DrawString("Hello World!!!", font, PdfBrushes.Black, new Syncfusion.Drawing.PointF(0, 0));

//Create the stream object.
FileStream stream = new FileStream("output.pdf",FileMode.Create);

//Save the document into the memory stream.
document.Save(stream);

//Close the document.
document.Close(true);

using Syncfusion.Pdf;
using Syncfusion.Pdf.Interactive;
using Syncfusion.Drawing;
using Syncfusion.Pdf.Graphics;

//Create a new PDF document. 
PdfDocument document = new PdfDocument(PdfConformanceLevel.Pdf_A4E);

//Create a new page. 
PdfPage page = document.Pages.Add(); 
FileStream inputStream = new FileStream("../../../box.u3d", FileMode.Open, FileAccess.Read);

//Create a new PDF 3D annotation. 
Pdf3DAnnotation pdf3dAnnotation = new Pdf3DAnnotation(new RectangleF(10, 50, 300, 150), inputStream);

//Handle the activation of the 3D annotation. 
Pdf3DActivation activation = new Pdf3DActivation(); 
activation.ActivationMode = Pdf3DActivationMode.PageOpen; 
activation.ShowToolbar = true; 
pdf3dAnnotation.Activation = activation; 
pdf3dAnnotation.Appearance.Normal.Graphics.DrawRectangle(PdfBrushes.Red, new RectangleF(10, 50, 300, 150));

//Add annotation to page. 
page.Annotations.Add(pdf3dAnnotation);

//Save the document into the stream. 
FileStream stream = new FileStream("sample.pdf",FileMode.Create); 
document.Save(stream);

//Close the document. 
document.Close(true);

using Syncfusion.Pdf;
using Syncfusion.Pdf.Interactive;
using Syncfusion.Drawing;
using Syncfusion.Pdf.Graphics;

//Create a new PDF document. 
PdfDocument document = new PdfDocument(PdfConformanceLevel.Pdf_A4F);

//Create a new page. 
PdfPage page = document.Pages.Add(); 
page.Graphics.DrawRectangle(PdfBrushes.Red, new RectangleF(10, 50, 300, 150)); 
FileStream data = new FileStream("../../../input.txt", FileMode.Open);

//Create an attachment.
PdfAttachment attachment = new PdfAttachment(@"Input.txt", data); 
attachment.Relationship = PdfAttachmentRelationship.Alternative; 
attachment.ModificationDate = DateTime.Now; 
attachment.Description = "Input.txt"; 
attachment.MimeType = "application/txt";

//Add the attachment to the document. 
document.Attachments.Add(attachment);

//Save the document into the stream. 
FileStream stream = new FileStream("sample.pdf",FileMode.Create); 
document.Save(stream);

//Close the document. 
document.Close(true);

using SkiaSharp;
using Syncfusion.Pdf;
using Syncfusion.Pdf.Graphics;
using Syncfusion.Pdf.Parsing;

FileStream docStream = new FileStream(@"../../../invoice.pdf", FileMode.Open, FileAccess.Read);

PdfLoadedDocument loadedDocument = new PdfLoadedDocument(docStream);

//Sample level font event handling. 
loadedDocument.SubstituteFont += LoadedDocument_SubstituteFont;

//Convert the loaded document to PDF/A document. 
loadedDocument.ConvertToPDFA(PdfConformanceLevel.Pdf_A4E); 
FileStream stream = new FileStream("output.pdf",FileMode.Create);

//Save the document. 
loadedDocument.Save(stream);


//Close the document. 
loadedDocument.Close(true);


static void LoadedDocument_SubstituteFont(object sender, PdfFontEventArgs args)
{
  //Get the font name. 
  string fontName = args.FontName.Split(',')[0];

  //Get the font style. 
  PdfFontStyle fontStyle = args.FontStyle; 
  SKFontStyle sKFontStyle = SKFontStyle.Normal;

  if (fontStyle != PdfFontStyle.Regular)
  {
    if (fontStyle == PdfFontStyle.Bold)
    {
       sKFontStyle = SKFontStyle.Bold;
    }
    else if (fontStyle == PdfFontStyle.Italic)
    {
        sKFontStyle = SKFontStyle.Italic;
    }
    else if (fontStyle == (PdfFontStyle.Italic | PdfFontStyle.Bold))
    {
        sKFontStyle = SKFontStyle.BoldItalic;
    }
  }

  SKTypeface typeface = SKTypeface.FromFamilyName(fontName, sKFontStyle); 
  SKStreamAsset typeFaceStream = typeface.OpenStream(); 
  MemoryStream memoryStream = null;

  if (typeFaceStream != null && typeFaceStream.Length > 0)
  {
    //Create the fontData from the type face stream. 
    byte[] fontData = new byte[typeFaceStream.Length - 1]; 
    typeFaceStream.Read(fontData, typeFaceStream.Length); 
    typeFaceStream.Dispose();

    //Create the new memory stream from the font data. 
    memoryStream = new MemoryStream(fontData);
  }

  //Set the font stream to the event args. 
  args.FontStream = memoryStream;
}