Create Tagged PDF using C#

Creating a Tagged PDF means adding (or creating) certain elements to the document that will enable the document to be validated in accordance with PDF/UA requirements. These elements are called often Structure Elements.

The following code snippet also works with Aspose.PDF.Drawing library.

Creating Tagged PDF (Simple Scenario)

In order to create structure elements in a Tagged PDF Document, Aspose.PDF offers methods to create structure elements using the ITaggedContent interface. Following code snippet shows how to create Tagged PDF which contains 2 elements: header and paragraph.

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void CreateTaggedPdfDocument01()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Create PDF document
    using (var document = new Aspose.Pdf.Document())
    {
        // Get Content for work with TaggedPdf
        Aspose.Pdf.Tagged.ITaggedContent taggedContent = document.TaggedContent;
        var rootElement = taggedContent.RootElement;

        // Set Title and Language for Document
        taggedContent.SetTitle("Tagged Pdf Document");
        taggedContent.SetLanguage("en-US");

        Aspose.Pdf.LogicalStructure.HeaderElement mainHeader = taggedContent.CreateHeaderElement();
        mainHeader.SetText("Main Header");

        Aspose.Pdf.LogicalStructure.ParagraphElement paragraphElement = taggedContent.CreateParagraphElement();
        paragraphElement.SetText("Lorem ipsum dolor sit amet, consectetur adipiscing elit. " +
            "Aenean nec lectus ac sem faucibus imperdiet. Sed ut erat ac magna ullamcorper hendrerit. " +
            "Cras pellentesque libero semper, gravida magna sed, luctus leo. Fusce lectus odio, laoreet" +
            "nec ullamcorper ut, molestie eu elit. Interdum et malesuada fames ac ante ipsum primis in faucibus." +
            "Aliquam lacinia sit amet elit ac consectetur. Donec cursus condimentum ligula, vitae volutpat" +
            "sem tristique eget. Nulla in consectetur massa. Vestibulum vitae lobortis ante. Nulla ullamcorper" +
            "pellentesque justo rhoncus accumsan. Mauris ornare eu odio non lacinia. Aliquam massa leo, rhoncus" +
            "ac iaculis eget, tempus et magna. Sed non consectetur elit. Sed vulputate, quam sed lacinia luctus," +
            "ipsum nibh fringilla purus, vitae posuere risus odio id massa. Cras sed venenatis lacus.");

        rootElement.AppendChild(mainHeader);
        rootElement.AppendChild(paragraphElement);

        // Save Tagged PDF Document
        document.Save(dataDir + "TaggedPdfDocument_out.pdf");
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void CreateTaggedPdfDocument01()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Create PDF Document
    using var document = new Aspose.Pdf.Document();

    // Get Content for work with TaggedPdf
    Aspose.Pdf.Tagged.ITaggedContent taggedContent = document.TaggedContent;
    var rootElement = taggedContent.RootElement;

    // Set Title and Language for Document
    taggedContent.SetTitle("Tagged Pdf Document");
    taggedContent.SetLanguage("en-US");

    Aspose.Pdf.LogicalStructure.HeaderElement mainHeader = taggedContent.CreateHeaderElement();
    mainHeader.SetText("Main Header");

    Aspose.Pdf.LogicalStructure.ParagraphElement paragraphElement = taggedContent.CreateParagraphElement();
    paragraphElement.SetText("Lorem ipsum dolor sit amet, consectetur adipiscing elit. " +
        "Aenean nec lectus ac sem faucibus imperdiet. Sed ut erat ac magna ullamcorper hendrerit. " +
        "Cras pellentesque libero semper, gravida magna sed, luctus leo. Fusce lectus odio, laoreet" +
        "nec ullamcorper ut, molestie eu elit. Interdum et malesuada fames ac ante ipsum primis in faucibus." +
        "Aliquam lacinia sit amet elit ac consectetur. Donec cursus condimentum ligula, vitae volutpat" +
        "sem tristique eget. Nulla in consectetur massa. Vestibulum vitae lobortis ante. Nulla ullamcorper" +
        "pellentesque justo rhoncus accumsan. Mauris ornare eu odio non lacinia. Aliquam massa leo, rhoncus" +
        "ac iaculis eget, tempus et magna. Sed non consectetur elit. Sed vulputate, quam sed lacinia luctus," +
        "ipsum nibh fringilla purus, vitae posuere risus odio id massa. Cras sed venenatis lacus.");

    rootElement.AppendChild(mainHeader);
    rootElement.AppendChild(paragraphElement);

    // Save Tagged PDF Document
    document.Save(dataDir + "TaggedPdfDocument_out.pdf");
}

We will get the following document after creation:

Creating Tagged PDF with nested elements (Creating Structure Elements Tree)

In some cases, we need to create more complex structure, eg. place quotes in paragraph. In order to create structure elements tree we should use AppendChild method. Following code snippet shows how to create structure elements tree of Tagged PDF Document:

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void CreateTaggedPdfDocument02()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Create PDF Document
    using (var document = new Aspose.Pdf.Document())
    {
        // Get Content for work with TaggedPdf
        Aspose.Pdf.Tagged.ITaggedContent taggedContent = document.TaggedContent;
        var rootElement = taggedContent.RootElement;

        // Set Title and Language for Document
        taggedContent.SetTitle("Tagged Pdf Document");
        taggedContent.SetLanguage("en-US");

        Aspose.Pdf.LogicalStructure.HeaderElement header1 = taggedContent.CreateHeaderElement(1);
        header1.SetText("Header Level 1");

        Aspose.Pdf.LogicalStructure.ParagraphElement paragraphWithQuotes = taggedContent.CreateParagraphElement();
        paragraphWithQuotes.StructureTextState.Font = Aspose.Pdf.Text.FontRepository.FindFont("Calibri");
        paragraphWithQuotes.AdjustPosition(new Aspose.Pdf.Tagged.PositionSettings
            {
                Margin = new Aspose.Pdf.MarginInfo(10, 5, 10, 5)
            });

        Aspose.Pdf.LogicalStructure.SpanElement spanElement1 = taggedContent.CreateSpanElement();
        spanElement1.SetText("Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aenean nec lectus ac sem faucibus imperdiet. Sed ut erat ac magna ullamcorper hendrerit. Cras pellentesque libero semper, gravida magna sed, luctus leo. Fusce lectus odio, laoreet nec ullamcorper ut, molestie eu elit. Interdum et malesuada fames ac ante ipsum primis in faucibus. Aliquam lacinia sit amet elit ac consectetur. Donec cursus condimentum ligula, vitae volutpat sem tristique eget. Nulla in consectetur massa. Vestibulum vitae lobortis ante. Nulla ullamcorper pellentesque justo rhoncus accumsan. Mauris ornare eu odio non lacinia. Aliquam massa leo, rhoncus ac iaculis eget, tempus et magna. Sed non consectetur elit. ");

        Aspose.Pdf.LogicalStructure.QuoteElement quoteElement = taggedContent.CreateQuoteElement();
        quoteElement.SetText("Sed vulputate, quam sed lacinia luctus, ipsum nibh fringilla purus, vitae posuere risus odio id massa.");
        quoteElement.StructureTextState.FontStyle = Aspose.Pdf.Text.FontStyles.Bold | Aspose.Pdf.Text.FontStyles.Italic;
        Aspose.Pdf.LogicalStructure.SpanElement spanElement2 = taggedContent.CreateSpanElement();
        spanElement2.SetText(" Sed non consectetur elit.");

        paragraphWithQuotes.AppendChild(spanElement1);
        paragraphWithQuotes.AppendChild(quoteElement);
        paragraphWithQuotes.AppendChild(spanElement2);

        rootElement.AppendChild(header1);
        rootElement.AppendChild(paragraphWithQuotes);

        // Save Tagged PDF Document
        document.Save(dataDir + "TaggedPdfDocument_out.pdf");
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void CreateTaggedPdfDocument02()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Create PDF Document
    using var document = new Aspose.Pdf.Document();

    // Get Content for work with TaggedPdf
    Aspose.Pdf.Tagged.ITaggedContent taggedContent = document.TaggedContent;
    var rootElement = taggedContent.RootElement;

    // Set Title and Language for Document
    taggedContent.SetTitle("Tagged Pdf Document");
    taggedContent.SetLanguage("en-US");

    Aspose.Pdf.LogicalStructure.HeaderElement header1 = taggedContent.CreateHeaderElement(1);
    header1.SetText("Header Level 1");

    Aspose.Pdf.LogicalStructure.ParagraphElement paragraphWithQuotes = taggedContent.CreateParagraphElement();
    paragraphWithQuotes.StructureTextState.Font = Aspose.Pdf.Text.FontRepository.FindFont("Calibri");
    
    paragraphWithQuotes.AdjustPosition(new Aspose.Pdf.Tagged.PositionSettings
        {
            Margin = new Aspose.Pdf.MarginInfo(10, 5, 10, 5)
        });

    Aspose.Pdf.LogicalStructure.SpanElement spanElement1 = taggedContent.CreateSpanElement();
    spanElement1.SetText("Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aenean nec lectus ac sem faucibus imperdiet. Sed ut erat ac magna ullamcorper hendrerit. Cras pellentesque libero semper, gravida magna sed, luctus leo. Fusce lectus odio, laoreet nec ullamcorper ut, molestie eu elit. Interdum et malesuada fames ac ante ipsum primis in faucibus. Aliquam lacinia sit amet elit ac consectetur. Donec cursus condimentum ligula, vitae volutpat sem tristique eget. Nulla in consectetur massa. Vestibulum vitae lobortis ante. Nulla ullamcorper pellentesque justo rhoncus accumsan. Mauris ornare eu odio non lacinia. Aliquam massa leo, rhoncus ac iaculis eget, tempus et magna. Sed non consectetur elit. ");

    Aspose.Pdf.LogicalStructure.QuoteElement quoteElement = taggedContent.CreateQuoteElement();
    quoteElement.SetText("Sed vulputate, quam sed lacinia luctus, ipsum nibh fringilla purus, vitae posuere risus odio id massa.");
    quoteElement.StructureTextState.FontStyle = Aspose.Pdf.Text.FontStyles.Bold | Aspose.Pdf.Text.FontStyles.Italic;
    Aspose.Pdf.LogicalStructure.SpanElement spanElement2 = taggedContent.CreateSpanElement();
    spanElement2.SetText(" Sed non consectetur elit.");

    paragraphWithQuotes.AppendChild(spanElement1);
    paragraphWithQuotes.AppendChild(quoteElement);
    paragraphWithQuotes.AppendChild(spanElement2);

    rootElement.AppendChild(header1);
    rootElement.AppendChild(paragraphWithQuotes);

    // Save Tagged PDF Document
    document.Save(dataDir + "TaggedPdfDocument_out.pdf");
}

We will get the following document after creation:

Styling Text Structure

In order to style the text structure in a Tagged PDF Document, Aspose.PDF offers the Font, FontSize, FontStyle and ForegroundColor properties of the StructureTextState Class. Following code snippet shows how to style text structure in a Tagged PDF Document:

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void AddStyle()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Create PDF Document
    using (var document = new Aspose.Pdf.Document())
    {
        // Get Content for work with TaggedPdf
        Aspose.Pdf.Tagged.ITaggedContent taggedContent = document.TaggedContent;

        // Set Title and Language for Document
        taggedContent.SetTitle("Tagged Pdf Document");
        taggedContent.SetLanguage("en-US");

        Aspose.Pdf.LogicalStructure.ParagraphElement p = taggedContent.CreateParagraphElement();
        taggedContent.RootElement.AppendChild(p);

        p.StructureTextState.FontSize = 18F;
        p.StructureTextState.ForegroundColor = Aspose.Pdf.Color.Red;
        p.StructureTextState.FontStyle = Aspose.Pdf.Text.FontStyles.Italic;

        p.SetText("Red italic text.");

        // Save Tagged PDF Document
        document.Save(dataDir + "StyleTextStructure_out.pdf");
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void AddStyle()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Create PDF Document
    using var document = new Aspose.Pdf.Document();

    // Get Content for work with TaggedPdf
    Aspose.Pdf.Tagged.ITaggedContent taggedContent = document.TaggedContent;

    // Set Title and Language for Document
    taggedContent.SetTitle("Tagged Pdf Document");
    taggedContent.SetLanguage("en-US");

    Aspose.Pdf.LogicalStructure.ParagraphElement p = taggedContent.CreateParagraphElement();
    taggedContent.RootElement.AppendChild(p);

    p.StructureTextState.FontSize = 18F;
    p.StructureTextState.ForegroundColor = Aspose.Pdf.Color.Red;
    p.StructureTextState.FontStyle = Aspose.Pdf.Text.FontStyles.Italic;

    p.SetText("Red italic text.");

    // Save Tagged PDF Document
    document.Save(dataDir + "StyleTextStructure_out.pdf");
}

Illustrating Structure Elements

In order to illustrate structure elements in a Tagged PDF Document, Aspose.PDF offers IllustrationElement class. Following code snippet shows how to illustrate structure elements in a Tagged PDF Document:

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void IllustrateStructureElements()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Create PDF Document
    using (var document = new Aspose.Pdf.Document())
    {
        // Get Content for work with TaggedPdf
        Aspose.Pdf.Tagged.ITaggedContent taggedContent = document.TaggedContent;

        // Set Title and Language for Document
        taggedContent.SetTitle("Tagged Pdf Document");
        taggedContent.SetLanguage("en-US");

        Aspose.Pdf.LogicalStructure.IllustrationElement figure1 = taggedContent.CreateFigureElement();
        taggedContent.RootElement.AppendChild(figure1);
        figure1.AlternativeText = "Figure One";
        figure1.Title = "Image 1";
        figure1.SetTag("Fig1");
        figure1.SetImage(dataDir + "image.png");
        
        // Adjust position
        figure1.AdjustPosition(new Aspose.Pdf.Tagged.PositionSettings
        {
            Margin = new Aspose.Pdf.MarginInfo
            {
                Left = 50,
                Top = 20
            },
        });

        // Save Tagged PDF Document
        document.Save(dataDir + "IllustrationStructureElements_out.pdf");
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void IllustrateStructureElements()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Create PDF Document
    using var document = new Aspose.Pdf.Document();

    // Get Content for work with TaggedPdf
    Aspose.Pdf.Tagged.ITaggedContent taggedContent = document.TaggedContent;

    // Set Title and Language for Document
    taggedContent.SetTitle("Tagged Pdf Document");
    taggedContent.SetLanguage("en-US");

    Aspose.Pdf.LogicalStructure.IllustrationElement figure1 = taggedContent.CreateFigureElement();
    taggedContent.RootElement.AppendChild(figure1);
    figure1.AlternativeText = "Figure One";
    figure1.Title = "Image 1";
    figure1.SetTag("Fig1");
    figure1.SetImage(dataDir + "image.png");
    
    // Adjust position
    figure1.AdjustPosition(new Aspose.Pdf.Tagged.PositionSettings
    {
        Margin = new Aspose.Pdf.MarginInfo
        {
            Left = 50,
            Top = 20
        },
    });

    // Save Tagged PDF Document
    document.Save(dataDir + "IllustrationStructureElements_out.pdf");
}

Validate Tagged PDF

Aspose.PDF for .NET provides the ability to validate a PDF/UA Tagged PDF Document. Validation of PDF/UA standard supports:

• Checks for XObjects.
• Checks for Actions.
• Checks for Optional Content.
• Checks for Embedded Files.
• Checks for Acroform Fields(Validate Natural Language and Alternate Name and Digital Signatures).
• Checks for XFA Form Fields.
• Checks for Security settings.
• Checks for Navigation.
• Checks for Annotations.

The code snippet below shows how to validate the Tagged PDF Document. Corresponding problems will be displayed in the XML log report.

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void ValidateTaggedPdf()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "StructureElements.pdf"))
    {
        bool isValid = document.Validate(dataDir + "StructureElements_log.xml", Aspose.Pdf.PdfFormat.PDF_UA_1);
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void ValidateTaggedPdf()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Open PDF document
    using var document = new Aspose.Pdf.Document(dataDir + "StructureElements.pdf");

    bool isValid = document.Validate(dataDir + "StructureElements_log.xml", Aspose.Pdf.PdfFormat.PDF_UA_1);
}

Adjust position of Text Structure

The following code snippet shows how to adjust Text Structure position in the Tagged PDF document:

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void AdjustPosition()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Create PDF Document
    using (var document = new Aspose.Pdf.Document())
    {
        // Get Content for work with TaggedPdf
        var taggedContent = document.TaggedContent;

        // Set Title and Language for Document
        taggedContent.SetTitle("Tagged Pdf Document");
        taggedContent.SetLanguage("en-US");

        // Create paragraph
        var p = taggedContent.CreateParagraphElement();
        taggedContent.RootElement.AppendChild(p);
        p.SetText("Text.");

        // Adjust position
        p.AdjustPosition(new Aspose.Pdf.Tagged.PositionSettings
        {
            HorizontalAlignment = Aspose.Pdf.HorizontalAlignment.None,
            Margin = new Aspose.Pdf.MarginInfo
            {
                Left = 300,
                Right = 0,
                Top = 20,
                Bottom = 0
            },
            VerticalAlignment = Aspose.Pdf.VerticalAlignment.None,
            IsFirstParagraphInColumn = false,
            IsKeptWithNext = false,
            IsInNewPage = false,
            IsInLineParagraph = false
        });

        // Save Tagged PDF Document
        document.Save(dataDir + "AdjustTextPosition_out.pdf");
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void AdjustPosition()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Create PDF Document
    using var document = new Aspose.Pdf.Document();
    
    // Get Content for work with TaggedPdf
    var taggedContent = document.TaggedContent;

    // Set Title and Language for Document
    taggedContent.SetTitle("Tagged Pdf Document");
    taggedContent.SetLanguage("en-US");

    // Create paragraph
    var p = taggedContent.CreateParagraphElement();
    taggedContent.RootElement.AppendChild(p);
    p.SetText("Text.");

    // Adjust position
    p.AdjustPosition(new Aspose.Pdf.Tagged.PositionSettings
    {
        HorizontalAlignment = Aspose.Pdf.HorizontalAlignment.None,
        Margin = new Aspose.Pdf.MarginInfo
        {
            Left = 300,
            Right = 0,
            Top = 20,
            Bottom = 0
        },
        VerticalAlignment = Aspose.Pdf.VerticalAlignment.None,
        IsFirstParagraphInColumn = false,
        IsKeptWithNext = false,
        IsInNewPage = false,
        IsInLineParagraph = false
    });

    // Save Tagged PDF Document
    document.Save(dataDir + "AdjustTextPosition_out.pdf");
}

Creating Tagged PDF automatically with PDF/UA-1 conversion

Aspose.PDF enables the automatic generation of basic logical structure markup when converting a document to PDF/UA-1. Users may then manually improve upon this basic logical structure, providing additional insights regarding the document contents.

To generate a logical document structure, create an instance of the Aspose.Pdf.AutoTaggingSettings class, set its AutoTaggingSettings.EnableAutoTagging property to true, and assign it to the PdfFormatConversionOptions.AutoTaggingSettings property.

If the document already has logical structure tags, enabling auto-tagging will destroy the existing logical structure and generate a new one.

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void ConvertToPdfUAWithAutomaticTagging()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Open PDF document
    using (Aspose.Pdf.Document document = new Aspose.Pdf.Document(dataDir + "BreakfastMenu.pdf"))
    {
        // Create conversion options
        Aspose.Pdf.PdfFormatConversionOptions options = new Aspose.Pdf.PdfFormatConversionOptions(dataDir + "ConvertToPdfUAWithAutomaticTagging.xml", PdfFormat.PDF_UA_1, ConvertErrorAction.Delete);

        // Create auto-tagging settings
        // Aspose.Pdf.AutoTaggingSettings.Default may be used to set the same settings as given below
        Aspose.Pdf.AutoTaggingSettings autoTaggingSettings = new Aspose.Pdf.AutoTaggingSettings();

        // Enable auto-tagging during the conversion process
        autoTaggingSettings.EnableAutoTagging = true;

        // Use the heading recognition strategy that's optimal for the given document structure
        autoTaggingSettings.HeadingRecognitionStrategy = Aspose.Pdf.HeadingRecognitionStrategy.Auto;

        // Assign auto-tagging settings to be used during the conversion process
        options.AutoTaggingSettings = autoTaggingSettings;

        // During the conversion, the document logical structure will be automatically created
        document.Convert(options);

        // Save PDF document
        document.Save(dataDir + "ConvertToPdfUAWithAutomaticTagging_out.pdf");
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void ConvertToPdfUAWithAutomaticTagging()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Open PDF document
    using Aspose.Pdf.Document document = new Aspose.Pdf.Document(dataDir + "BreakfastMenu.pdf");

    // Create conversion options
    Aspose.Pdf.PdfFormatConversionOptions options = new Aspose.Pdf.PdfFormatConversionOptions(dataDir + "ConvertToPdfUAWithAutomaticTagging.xml", PdfFormat.PDF_UA_1, ConvertErrorAction.Delete);

    // Create auto-tagging settings
    // Aspose.Pdf.AutoTaggingSettings.Default may be used to set the same settings as given below
    Aspose.Pdf.AutoTaggingSettings autoTaggingSettings = new Aspose.Pdf.AutoTaggingSettings
    {
        // Enable auto-tagging during the conversion process
        EnableAutoTagging = true,

        // Use the heading recognition strategy that's optimal for the given document structure
        HeadingRecognitionStrategy = Aspose.Pdf.HeadingRecognitionStrategy.Auto
    };

    // Assign auto-tagging settings to be used during the conversion process
    options.AutoTaggingSettings = autoTaggingSettings;

    // During the conversion, the document logical structure will be automatically created
    document.Convert(options);

    // Save PDF document
    document.Save(dataDir + "ConvertToPdfUAWithAutomaticTagging_out.pdf");
}

Creating Tagged PDF with Form Fields

You can tag interactive form fields in a PDF document to ensure they are included in the logical structure tree for accessibility (PDF/UA). The snippet below demonstrates how to create a form field, register it in the AcroForm, and associate it with a /Form structure element in the structure tree.

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void CreatePdfWithTaggedFormField()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Create PDF document
    using (var document = new Aspose.Pdf.Document())
    {
        document.Pages.Add();
        
        // Get Content for work with TaggedPdf
        Aspose.Pdf.Tagged.ITaggedContent taggedContent = document.TaggedContent;
        Aspose.Pdf.LogicalStructure.StructureElement rootElement = taggedContent.RootElement;

        // Create a visible signature form field (AcroForm)
        var signatureField = new Aspose.Pdf.Forms.SignatureField(document.Pages[1], new Aspose.Pdf.Rectangle(50, 50, 100, 100));
        signatureField.PartialName = "Signature1";
        signatureField.AlternateName = "signature 1";
        
        // Add the signature field to the document's AcroForm
        document.Form.Add(signatureField);

        // Create a /Form structure element in the tag tree
        Aspose.Pdf.LogicalStructure.FormElement form = taggedContent.CreateFormElement();
        form.AlternativeText = "form 1";
        
        // Link the /Form tag to the signature field via an /OBJR reference
        form.Tag(signatureField);
        
        // Add the /Form structure element to the document’s logical structure tree
        rootElement.AppendChild(form);

        // Save PDF document
        document.Save(dataDir + "CreatePdfWithTaggedFormField_out.pdf");
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void CreatePdfWithTaggedFormField()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();

    // Create PDF document
    using var document = new Aspose.Pdf.Document();
    
    document.Pages.Add();
    
    // Get Content for work with TaggedPdf
    Aspose.Pdf.Tagged.ITaggedContent taggedContent = document.TaggedContent;
    Aspose.Pdf.LogicalStructure.StructureElement rootElement = taggedContent.RootElement;

    // Create a visible signature form field (AcroForm)
    var signatureField = new Aspose.Pdf.Forms.SignatureField(document.Pages[1], new Aspose.Pdf.Rectangle(50, 50, 100, 100));
    signatureField.PartialName = "Signature1";
    signatureField.AlternateName = "signature 1";
    
    // Add the signature field to the document's AcroForm
    document.Form.Add(signatureField);

    // Create a /Form structure element in the tag tree
    Aspose.Pdf.LogicalStructure.FormElement form = taggedContent.CreateFormElement();
    form.AlternativeText = "form 1";
    
    // Link the /Form tag to the signature field via an /OBJR reference
    form.Tag(signatureField);
    
    // Add the /Form structure element to the document’s logical structure tree
    rootElement.AppendChild(form);

    // Save PDF document
    document.Save(dataDir + "CreatePdfWithTaggedFormField_out.pdf");
}

Creating Tagged PDF with table of contents (TOC) page

Generate a tagged PDF document with an accessible Table of Contents (TOC) page.

.NET Core 3.1

    // For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
    private static void CreatePdfWithTOCpage()
    {
        // The path to the documents directory
        var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();
    
        // Create PDF document
        using (var doc = new Aspose.Pdf.Document())
        {
            // Get tagged content for the PDF structure
            Aspose.Pdf.Tagged.ITaggedContent content = doc.TaggedContent;
            Aspose.Pdf.LogicalStructure.StructureElement rootElement = content.RootElement;
            content.SetLanguage("en-US");
    
            // Add the table of contents (TOC) page
            Aspose.Pdf.Page tocPage = doc.Pages.Add();
            tocPage.TocInfo = new Aspose.Pdf.TocInfo();
    
            // Create a TOC structure element
            Aspose.Pdf.LogicalStructure.TOCElement tocElement = content.CreateTOCElement();
    
            // Add the TOC element to the document structure tree
            rootElement.AppendChild(tocElement);
    
            // Add a content page
            doc.Pages.Add();
    
            // Create a header element and set its text
            Aspose.Pdf.LogicalStructure.HeaderElement header = content.CreateHeaderElement(1);
            header.SetText("1. Header");
    
            // Add the header to the document structure
            rootElement.AppendChild(header);
    
            // Create a TOC item (TOCI) element
            Aspose.Pdf.LogicalStructure.TOCIElement toci = content.CreateTOCIElement();
    
            // Add the TOCI element to the TOC element
            tocElement.AppendChild(toci);
    
            // Add an entry to the TOC page and link it to the TOCI element
            header.AddEntryToTocPage(tocPage, toci);
    
            // Add a logical reference to the header within the TOCI element
            toci.AddRef(header);
    
            // Save PDF document
            doc.Save(dataDir + "CreatePdfWithTOCpage_out.pdf");
        }
    }

.NET 8

    // For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
    private static void CreatePdfWithTOCpage()
    {
        // The path to the documents directory
        var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();
    
        // Create PDF document
        using var doc = new Aspose.Pdf.Document();
        
        // Get tagged content for the PDF structure
        Aspose.Pdf.Tagged.ITaggedContent content = doc.TaggedContent;
        Aspose.Pdf.LogicalStructure.StructureElement rootElement = content.RootElement;
        content.SetLanguage("en-US");
    
        // Add the table of contents (TOC) page
        Aspose.Pdf.Page tocPage = doc.Pages.Add();
        tocPage.TocInfo = new Aspose.Pdf.TocInfo();
    
        // Create a TOC structure element
        Aspose.Pdf.LogicalStructure.TOCElement tocElement = content.CreateTOCElement();
    
        // Add the TOC element to the document structure tree
        rootElement.AppendChild(tocElement);
    
        // Add a content page
        doc.Pages.Add();
    
        // Create a header element and set its text
        Aspose.Pdf.LogicalStructure.HeaderElement header = content.CreateHeaderElement(1);
        header.SetText("1. Header");
    
        // Add the header to the document structure
        rootElement.AppendChild(header);
    
        // Create a TOC item (TOCI) element
        Aspose.Pdf.LogicalStructure.TOCIElement toci = content.CreateTOCIElement();
    
        // Add the TOCI element to the TOC element
        tocElement.AppendChild(toci);
    
        // Add an entry to the TOC page and link it to the TOCI element
        header.AddEntryToTocPage(tocPage, toci);
    
        // Add a logical reference to the header within the TOCI element
        toci.AddRef(header);
    
        // Save PDF document
        doc.Save(dataDir + "CreatePdfWithTOCpage_out.pdf");
    }

Generate a tagged PDF that includes an accessible table of contents page, which contains a page title and nested sublist.

.NET Core 3.1

    // For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
    private static void CreatePdfWithTOCpageAdvanced()
    {
        // The path to the documents directory
        var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();
    
        // Create PDF document
        using (var doc = new Aspose.Pdf.Document())
        {
            // Get tagged content for the PDF structure
            Aspose.Pdf.Tagged.ITaggedContent content = doc.TaggedContent;
            Aspose.Pdf.LogicalStructure.StructureElement rootElement = content.RootElement;
            content.SetLanguage("en-US");
    
            // Add the table of contents (TOC) page
            Aspose.Pdf.Page tocPage = doc.Pages.Add();
            tocPage.TocInfo = new Aspose.Pdf.TocInfo();
            tocPage.TocInfo.Title = new Aspose.Pdf.Text.TextFragment("Table of Contents");
    
            // Create a TOC structure element
            Aspose.Pdf.LogicalStructure.TOCElement tocElement = content.CreateTOCElement();
    
            // Create a header element for the TOC page title
            Aspose.Pdf.LogicalStructure.HeaderElement headerForTOCpageTitle = content.CreateHeaderElement(1);
            tocElement.LinkTocPageTitleToHeaderElement(tocPage, headerForTOCpageTitle);
    
            // Add the TOC page title header and TOC element to the document structure tree
            rootElement.AppendChild(headerForTOCpageTitle);
            rootElement.AppendChild(tocElement);
    
            // Add a content page
            doc.Pages.Add();
    
            // Create a header element and set its text
            Aspose.Pdf.LogicalStructure.HeaderElement header = content.CreateHeaderElement(1);
            header.SetText("1. Header");
    
            // Add the header to the document structure
            rootElement.AppendChild(header);
    
            // Create a TOC item (TOCI) element
            Aspose.Pdf.LogicalStructure.TOCIElement toci = content.CreateTOCIElement();
    
            // Add the TOCI element to the TOC element
            tocElement.AppendChild(toci);
    
            // Add an entry to the TOC page and link it to the TOCI element
            header.AddEntryToTocPage(tocPage, toci);
    
            // Add a logical reference to the header within the TOCI element
            toci.AddRef(header);
    
            // Create a list element for TOCI subitems
            Aspose.Pdf.LogicalStructure.ListElement listElement = content.CreateListElement();
            for (var i = 1; i <= 3; i++)
            {
                // Create a list item (LI) element
                Aspose.Pdf.LogicalStructure.ListLIElement li = content.CreateListLIElement();
    
                // Add the list item to the list element
                listElement.AppendChild(li);
    
                // Create a sub-header element and set its properties
                Aspose.Pdf.LogicalStructure.HeaderElement subHeader = content.CreateHeaderElement(2);
                subHeader.StructureTextState.FontSize = 14;
                subHeader.Language = "en-US";
                subHeader.SetText($@"1.{i} subheader ");
    
                // Add an entry to the TOC page and link it to the LI element
                subHeader.AddEntryToTocPage(tocPage, li);
    
                // Add a logical reference to the subheader element
                li.AddRef(subHeader);
    
                // Create a paragraph element and set its text and language
                Aspose.Pdf.LogicalStructure.ParagraphElement p = content.CreateParagraphElement();
                p.SetText("Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.");
                p.Language = "en-US";
    
                // Add the sub-header and paragraph to the document structure
                rootElement.AppendChild(subHeader);
                rootElement.AppendChild(p);
            }
    
            // Add the list element as a child to the TOCI element
            toci.AppendChild(listElement);
    
            // --- Additional TOC header example ---
            // Create a second header element (see comments above for header 1)
            Aspose.Pdf.LogicalStructure.HeaderElement header2 = content.CreateHeaderElement(1);
            header2.SetText("2. Header");
            rootElement.AppendChild(header2);
    
            Aspose.Pdf.LogicalStructure.TOCIElement toci2 = content.CreateTOCIElement();
            tocElement.AppendChild(toci2);
    
            header2.AddEntryToTocPage(tocPage, toci2);
            toci2.AddRef(header2);
    
            // Save the PDF document
            doc.Save(dataDir + "CreatePdfWithTOCpageAdvanced_out.pdf");
        }
    }

.NET 8

    // For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
    private static void CreatePdfWithTOCpageAdvanced()
    {
        // The path to the documents directory
        var dataDir = RunExamples.GetDataDir_AsposePdf_WorkingDocuments();
    
        // Create PDF document
        using var doc = new Aspose.Pdf.Document();
        
        // Get tagged content for the PDF structure
        Aspose.Pdf.Tagged.ITaggedContent content = doc.TaggedContent;
        Aspose.Pdf.LogicalStructure.StructureElement rootElement = content.RootElement;
        content.SetLanguage("en-US");
    
        // Add the table of contents (TOC) page
        Aspose.Pdf.Page tocPage = doc.Pages.Add();
        tocPage.TocInfo = new Aspose.Pdf.TocInfo();
        tocPage.TocInfo.Title = new Aspose.Pdf.Text.TextFragment("Table of Contents");
    
        // Create a TOC structure element
        Aspose.Pdf.LogicalStructure.TOCElement tocElement = content.CreateTOCElement();
    
        // Create a header element for the TOC page title
        Aspose.Pdf.LogicalStructure.HeaderElement headerForTOCpageTitle = content.CreateHeaderElement(1);
        tocElement.LinkTocPageTitleToHeaderElement(tocPage, headerForTOCpageTitle);
    
        // Add the TOC page title header and TOC element to the document structure tree
        rootElement.AppendChild(headerForTOCpageTitle);
        rootElement.AppendChild(tocElement);
    
        // Add a content page
        doc.Pages.Add();
    
        // Create a header element and set its text
        Aspose.Pdf.LogicalStructure.HeaderElement header = content.CreateHeaderElement(1);
        header.SetText("1. Header");
    
        // Add the header to the document structure
        rootElement.AppendChild(header);
    
        // Create a TOC item (TOCI) element
        Aspose.Pdf.LogicalStructure.TOCIElement toci = content.CreateTOCIElement();
    
        // Add the TOCI element to the TOC element
        tocElement.AppendChild(toci);
    
        // Add an entry to the TOC page and link it to the TOCI element
        header.AddEntryToTocPage(tocPage, toci);
    
        // Add a logical reference to the header within the TOCI element
        toci.AddRef(header);
    
        // Create a list element for TOCI subitems
        Aspose.Pdf.LogicalStructure.ListElement listElement = content.CreateListElement();
        for (var i = 1; i <= 3; i++)
        {
            // Create a list item (LI) element
            Aspose.Pdf.LogicalStructure.ListLIElement li = content.CreateListLIElement();
    
            // Add the list item to the list element
            listElement.AppendChild(li);
    
            // Create a sub-header element and set its properties
            Aspose.Pdf.LogicalStructure.HeaderElement subHeader = content.CreateHeaderElement(2);
            subHeader.StructureTextState.FontSize = 14;
            subHeader.Language = "en-US";
            subHeader.SetText($@"1.{i} subheader ");
    
            // Add an entry to the TOC page and link it to the LI element
            subHeader.AddEntryToTocPage(tocPage, li);
    
            // Add a logical reference to the subheader element
            li.AddRef(subHeader);
    
            // Create a paragraph element and set its text and language
            Aspose.Pdf.LogicalStructure.ParagraphElement p = content.CreateParagraphElement();
            p.SetText("Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.");
            p.Language = "en-US";
    
            // Add the sub-header and paragraph to the document structure
            rootElement.AppendChild(subHeader);
            rootElement.AppendChild(p);
        }
    
        // Add the list element as a child to the TOCI element
        toci.AppendChild(listElement);
    
        // --- Additional TOC header example ---
        // Create a second header element (see comments above for header 1)
        Aspose.Pdf.LogicalStructure.HeaderElement header2 = content.CreateHeaderElement(1);
        header2.SetText("2. Header");
        rootElement.AppendChild(header2);
    
        Aspose.Pdf.LogicalStructure.TOCIElement toci2 = content.CreateTOCIElement();
        tocElement.AppendChild(toci2);
    
        header2.AddEntryToTocPage(tocPage, toci2);
        toci2.AddRef(header2);
    
        // Save the PDF document
        doc.Save(dataDir + "CreatePdfWithTOCpageAdvanced_out.pdf");
    }