Extraer Contenido Etiquetado de PDF

En este artículo aprenderás cómo extraer contenido etiquetado de un documento PDF usando C#.

El siguiente fragmento de código también funciona con la biblioteca Aspose.PDF.Drawing.

Obtener Contenido PDF Etiquetado

Para obtener el contenido de un documento PDF con texto etiquetado, Aspose.PDF ofrece la propiedad TaggedContent de la clase Document.

El siguiente fragmento de código muestra cómo obtener el contenido de un documento PDF con texto etiquetado:

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void GetTaggedContent()
{
    // 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 Tagged PDF
        Aspose.Pdf.Tagged.ITaggedContent taggedContent = document.TaggedContent;

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

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

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void GetTaggedContent()
{
    // 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;

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

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

Obtener Estructura Raíz

Para obtener la estructura raíz de un documento PDF etiquetado, Aspose.PDF ofrece la propiedad StructTreeRootElement de la interfaz ITaggedContent y StructureElement. El siguiente fragmento de código muestra cómo obtener la estructura raíz de un documento PDF etiquetado:

.NET Core 3.1

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void GetRootStructure()
{
    // Create PDF Document
    using (var document = new Aspose.Pdf.Document())
    {
        // Get Content for work with Tagged PDF
        Aspose.Pdf.Tagged.ITaggedContent taggedContent = document.TaggedContent;

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

        // Properties StructTreeRootElement and RootElement are used for access to
        // StructTreeRoot object of pdf document and to root structure element (Document structure element).
        Aspose.Pdf.LogicalStructure.StructTreeRootElement structTreeRootElement = taggedContent.StructTreeRootElement;
        Aspose.Pdf.LogicalStructure.StructureElement rootElement = taggedContent.RootElement;
    }
}

.NET 8

// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void GetRootStructure()
{
    // Create PDF Document
    using var document = new Aspose.Pdf.Document();

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

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

    // Properties StructTreeRootElement and RootElement are used for access to
    // StructTreeRoot object of pdf document and to root structure element (Document structure element).
    Aspose.Pdf.LogicalStructure.StructTreeRootElement structTreeRootElement = taggedContent.StructTreeRootElement;
    Aspose.Pdf.LogicalStructure.StructureElement rootElement = taggedContent.RootElement;
}

Acceder a Elementos Hijos

Para acceder a los elementos hijos de un documento PDF etiquetado, Aspose.PDF ofrece la clase ElementList. El siguiente fragmento de código muestra cómo acceder a los elementos hijos de un documento PDF etiquetado:

.NET Core 3.1

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

    // Open PDF Document
    using (var document = new Aspose.Pdf.Document(dataDir + "StructureElementsTree.pdf"))
    {
        // Get Content for work with Tagged PDF
        Aspose.Pdf.Tagged.ITaggedContent taggedContent = document.TaggedContent;

        // Access to root element(s)
        Aspose.Pdf.LogicalStructure.ElementList elementList = taggedContent.StructTreeRootElement.ChildElements;

        foreach (Aspose.Pdf.LogicalStructure.Element element in elementList)
        {
            if (element is Aspose.Pdf.LogicalStructure.StructureElement)
            {
                var structureElement = element as Aspose.Pdf.LogicalStructure.StructureElement;

                // Get properties
                string title = structureElement.Title;
                string language = structureElement.Language;
                string actualText = structureElement.ActualText;
                string expansionText = structureElement.ExpansionText;
                string alternativeText = structureElement.AlternativeText;
            }
        }

        // Access to child elements of first element in root element
        elementList = taggedContent.RootElement.ChildElements[1].ChildElements;

        foreach (Aspose.Pdf.LogicalStructure.Element element in elementList)
        {
            if (element is Aspose.Pdf.LogicalStructure.StructureElement)
            {
                var structureElement = element as Aspose.Pdf.LogicalStructure.StructureElement;

                // Set properties
                structureElement.Title = "title";
                structureElement.Language = "fr-FR";
                structureElement.ActualText = "actual text";
                structureElement.ExpansionText = "exp";
                structureElement.AlternativeText = "alt";
            }
        }

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

.NET 8

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

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

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

    // Access to root element(s)
    Aspose.Pdf.LogicalStructure.ElementList elementList = taggedContent.StructTreeRootElement.ChildElements;

    foreach (Aspose.Pdf.LogicalStructure.Element element in elementList)
    {
        if (element is Aspose.Pdf.LogicalStructure.StructureElement)
        {
            var structureElement = element as Aspose.Pdf.LogicalStructure.StructureElement;

            // Get properties
            string title = structureElement.Title;
            string language = structureElement.Language;
            string actualText = structureElement.ActualText;
            string expansionText = structureElement.ExpansionText;
            string alternativeText = structureElement.AlternativeText;
        }
    }

    // Access to child elements of first element in root element
    elementList = taggedContent.RootElement.ChildElements[1].ChildElements;

    foreach (Aspose.Pdf.LogicalStructure.Element element in elementList)
    {
        if (element is Aspose.Pdf.LogicalStructure.StructureElement)
        {
            var structureElement = element as Aspose.Pdf.LogicalStructure.StructureElement;

            // Set properties
            structureElement.Title = "title";
            structureElement.Language = "fr-FR";
            structureElement.ActualText = "actual text";
            structureElement.ExpansionText = "exp";
            structureElement.AlternativeText = "alt";
        }
    }

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

Etiquetado de Imágenes en PDF Existente

Para etiquetar imágenes en un documento PDF existente, Aspose.PDF ofrece el método FindElements de la clase StructureElement. Puedes agregar texto alternativo para figuras usando la propiedad AlternativeText de la clase FigureElement.

El siguiente fragmento de código muestra cómo etiquetar imágenes en un documento PDF existente:

.NET Core 3.1

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

    // Open PDF document
    using (var document1 = new Aspose.Pdf.Document(dataDir + "TH.pdf"))
    {
        // Gets tagged content and root structure element
        Aspose.Pdf.Tagged.ITaggedContent taggedContent = document1.TaggedContent;
        Aspose.Pdf.LogicalStructure.StructureElement rootElement = taggedContent.RootElement;

        // Set title for tagged PDF document
        taggedContent.SetTitle("Document with images");

        foreach (Aspose.Pdf.LogicalStructure.FigureElement figureElement in rootElement.FindElements<Aspose.Pdf.LogicalStructure.FigureElement>(true))
        {
            // Set AlternativeText for Figure
            figureElement.AlternativeText = "Figure alternative text (technique 2)";

            // Create and Set BBox Attribute
            var bboxAttribute = new Aspose.Pdf.LogicalStructure.StructureAttribute(Aspose.Pdf.LogicalStructure.AttributeKey.BBox);
            bboxAttribute.SetRectangleValue(new Aspose.Pdf.Rectangle(0.0, 0.0, 100.0, 100.0));

            Aspose.Pdf.LogicalStructure.StructureAttributes figureLayoutAttributes = figureElement.Attributes.GetAttributes(Aspose.Pdf.LogicalStructure.AttributeOwnerStandard.Layout);
            figureLayoutAttributes.SetAttribute(bboxAttribute);
        }

        // Move Span Element into Paragraph (find wrong span and paragraph in first TD)
        Aspose.Pdf.LogicalStructure.TableElement tableElement = rootElement.FindElements<Aspose.Pdf.LogicalStructure.TableElement>(true)[0];
        Aspose.Pdf.LogicalStructure.SpanElement spanElement = tableElement.FindElements<Aspose.Pdf.LogicalStructure.SpanElement>(true)[0];
        Aspose.Pdf.LogicalStructure.TableTDElement firstTdElement = tableElement.FindElements<Aspose.Pdf.LogicalStructure.TableTDElement>(true)[0];
        Aspose.Pdf.LogicalStructure.ParagraphElement paragraph = firstTdElement.FindElements<Aspose.Pdf.LogicalStructure.ParagraphElement>(true)[0];

        // Move Span Element into Paragraph
        spanElement.ChangeParentElement(paragraph);

        // Save PDF document
        document1.Save(dataDir + "TH_out.pdf");
    }

    // Check PDF/UA Compliance for out document
    using (var document2 = new Aspose.Pdf.Document(dataDir + "TH_out.pdf"))
    {
        bool isPdfUaCompliance = document2.Validate(dataDir + "TH_out.xml", Aspose.Pdf.PdfFormat.PDF_UA_1);
        Console.WriteLine(String.Format("PDF/UA compliance: {0}", isPdfUaCompliance));
    }
}

.NET 8

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

    // Open PDF document
    using var document1 = new Aspose.Pdf.Document(dataDir + "TH.pdf");

    // Gets tagged content and root structure element
    Aspose.Pdf.Tagged.ITaggedContent taggedContent = document1.TaggedContent;
    Aspose.Pdf.LogicalStructure.StructureElement rootElement = taggedContent.RootElement;

    // Set title for tagged PDF document
    taggedContent.SetTitle("Document with images");

    foreach (Aspose.Pdf.LogicalStructure.FigureElement figureElement in rootElement.FindElements<Aspose.Pdf.LogicalStructure.FigureElement>(true))
    {
        // Set AlternativeText for Figure
        figureElement.AlternativeText = "Figure alternative text (technique 2)";

        // Create and Set BBox Attribute
        var bboxAttribute = new Aspose.Pdf.LogicalStructure.StructureAttribute(Aspose.Pdf.LogicalStructure.AttributeKey.BBox);
        bboxAttribute.SetRectangleValue(new Aspose.Pdf.Rectangle(0.0, 0.0, 100.0, 100.0));

        Aspose.Pdf.LogicalStructure.StructureAttributes figureLayoutAttributes = figureElement.Attributes.GetAttributes(Aspose.Pdf.LogicalStructure.AttributeOwnerStandard.Layout);
        figureLayoutAttributes.SetAttribute(bboxAttribute);
    }

    // Move Span Element into Paragraph (find wrong span and paragraph in first TD)
    Aspose.Pdf.LogicalStructure.TableElement tableElement = rootElement.FindElements<Aspose.Pdf.LogicalStructure.TableElement>(true)[0];
    Aspose.Pdf.LogicalStructure.SpanElement spanElement = tableElement.FindElements<Aspose.Pdf.LogicalStructure.SpanElement>(true)[0];
    Aspose.Pdf.LogicalStructure.TableTDElement firstTdElement = tableElement.FindElements<Aspose.Pdf.LogicalStructure.TableTDElement>(true)[0];
    Aspose.Pdf.LogicalStructure.ParagraphElement paragraph = firstTdElement.FindElements<Aspose.Pdf.LogicalStructure.ParagraphElement>(true)[0];

    // Move Span Element into Paragraph
    spanElement.ChangeParentElement(paragraph);

    // Save PDF document
    document1.Save(dataDir + "TH_out.pdf");

    // Check PDF/UA Compliance for out document
    using var document2 = new Aspose.Pdf.Document(dataDir + "TH_out.pdf");

    bool isPdfUaCompliance = document2.Validate(dataDir + "TH_out.pdf", Aspose.Pdf.PdfFormat.PDF_UA_1);
    Console.WriteLine(String.Format("PDF/UA compliance: {0}", isPdfUaCompliance));
}