帶標簽的 PDF（也稱為 PDF/UA）是一種包含底層標簽樹（類似于 HTML）的 PDF，用于定義文檔的結(jié)構(gòu)。這些標簽可以幫助屏幕閱讀器瀏覽整個文檔而不會丟失任何信息。本文介紹如何使用Spire.PDF for .NET在 C# 和 VB.NET 中從頭開始創(chuàng)建帶標簽的 PDF 。

Spire.PDF for .NET 是一款獨立 PDF 控件，用于 .NET 程序中創(chuàng)建、編輯和操作 PDF 文檔。使用 Spire.PDF 類庫，開發(fā)人員可以新建一個 PDF 文檔或者對現(xiàn)有的 PDF 文檔進行處理，且無需安裝 Adobe Acrobat。

E-iceblue 功能類庫Spire 系列文檔處理組件均由中國本土團隊研發(fā)，不依賴第三方軟件，不受其他國家的技術(shù)或法律法規(guī)限制，同時適配國產(chǎn)操作系統(tǒng)如中科方德、中標麒麟等，兼容國產(chǎn)文檔處理軟件 WPS（如 .wps/.et/.dps 等格式

Spire.PDF for.net下載   

安裝 Spire.PDF for .NET

 首先，您需要將 Spire.PDF for.NET 包中包含的 DLL 文件作為引用添加到您的 .NET 項目中。

PM> Install-Package Spire.PDF

創(chuàng)建具有豐富元素的標簽 PDF

要在帶標簽的 PDF 文檔中添加結(jié)構(gòu)元素，我們必須首先創(chuàng)建PdfTaggedContent類的對象。然后，使用PdfTaggedContent.StructureTreeRoot.AppendChildElement()方法將元素添加到根。以下是使用 Spire.PDF for .NET 向帶標簽的 PDF 添加“標題”元素的詳細步驟。

• 創(chuàng)建一個PdfDocument對象并使用PdfDocument.Pages.Add()方法向其中添加一個頁面。
• 創(chuàng)建PdfTaggedContent類的對象。
• 使用PdfTaggedContent.SetPdfUA1Identification()方法使文檔符合 PDF/UA 識別。
• 使用PdfTaggedContent.StructureTreeRoot.AppendChildElement()方法將“文檔”元素添加到文檔的根目錄。
• 使用PdfStructureElement.AppendChildElement()方法在“document”元素下添加“heading”元素。
• 使用PdfStructureElement.BeginMarkedContent()方法添加開始標簽，指示標題元素的開始。
• 使用PdfPageBase.Canvas.DrawString()方法在頁面上繪制標題文本。
• 使用PdfStructureElement.BeginMarkedContent()方法添加結(jié)束標簽，這意味著標題元素在此結(jié)束。
• 使用PdfDocument.SaveToFile()方法將文檔保存為 PDF 文件。

 以下代碼片段提供了一個示例，說明如何在 C# 和 VB.NET 中在標記的 PDF 文檔中創(chuàng)建各種元素，包括文檔、標題、段落、圖形和表格。

【C#】

using Spire.Pdf;
using Spire.Pdf.Graphics;
using Spire.Pdf.Interchange.TaggedPdf;
using Spire.Pdf.Tables;
using System.Data;
using System.Drawing;

namespace CreatePDFUA
{
class Program
{
static void Main(string[] args)
{
//Create a PdfDocument object
PdfDocument doc = new PdfDocument();

//Add a page
PdfPageBase page = doc.Pages.Add(PdfPageSize.A4, new PdfMargins(20));

//Set tab order
page.SetTabOrder(TabOrder.Structure);

//Create an object of PdfTaggedContent class
PdfTaggedContent taggedContent = new PdfTaggedContent(doc);

//Set language and title for the document
taggedContent.SetLanguage("en-US");
taggedContent.SetTitle("test");

//Set PDF/UA1 identification
taggedContent.SetPdfUA1Identification();

//Create font and brush
PdfTrueTypeFont font = new PdfTrueTypeFont(new Font("Times New Roman", 14), true);
PdfSolidBrush brush = new PdfSolidBrush(Color.Black);

//Add a "document" element
PdfStructureElement document = taggedContent.StructureTreeRoot.AppendChildElement(PdfStandardStructTypes.Document);

//Add a "heading" element
PdfStructureElement heading1 = document.AppendChildElement(PdfStandardStructTypes.HeadingLevel1);
heading1.BeginMarkedContent(page);
string headingText = "What Is a Tagged PDF?";
page.Canvas.DrawString(headingText, font, brush, new PointF(0, 0));
heading1.EndMarkedContent(page);

//Add a "paragraph" element
PdfStructureElement paragraph = document.AppendChildElement(PdfStandardStructTypes.Paragraph);
paragraph.BeginMarkedContent(page);
string paragraphText = "“Tagged PDF” doesn’t seem like a life-changing term. But for some, it is. For people who are " +
"blind or have low vision and use assistive technology (such as screen readers and connected Braille displays) to " +
"access information, an untagged PDF means they are missing out on information contained in the document because assistive " +
"technology cannot “read” untagged PDFs. Digital accessibility has opened up so many avenues to information that were once " +
"closed to people with visual disabilities, but PDFs often get left out of the equation.";
RectangleF rect = new RectangleF(0, 30, page.Canvas.ClientSize.Width, page.Canvas.ClientSize.Height);
page.Canvas.DrawString(paragraphText, font, brush, rect);
paragraph.EndMarkedContent(page);

//Add a "figure" element to
PdfStructureElement figure = document.AppendChildElement(PdfStandardStructTypes.Figure);
figure.BeginMarkedContent(page);
PdfImage image = PdfImage.FromFile(@"C:\Users\Administrator\Desktop\pdfua.png");
page.Canvas.DrawImage(image, new PointF(0, 150));
figure.EndMarkedContent(page);

//Add a "table" element
PdfStructureElement table = document.AppendChildElement(PdfStandardStructTypes.Table);
table.BeginMarkedContent(page);
PdfTable pdfTable = new PdfTable();
pdfTable.Style.DefaultStyle.Font = font;
DataTable dataTable = new DataTable();
dataTable.Columns.Add("Name");
dataTable.Columns.Add("Age");
dataTable.Columns.Add("Sex");
dataTable.Rows.Add(new string[] { "John", "22", "Male" });
dataTable.Rows.Add(new string[] { "Katty", "25", "Female" });
pdfTable.DataSource = dataTable;
pdfTable.Style.ShowHeader = true;
pdfTable.Draw(page.Canvas, new PointF(0, 280), 300f);
table.EndMarkedContent(page);

//Save the document to file
doc.SaveToFile("CreatePDFUA.pdf");
}
}
}

【VB.NET】

Imports Spire.Pdf
Imports Spire.Pdf.Graphics
Imports Spire.Pdf.Interchange.TaggedPdf
Imports Spire.Pdf.Tables
Imports System.Data
Imports System.Drawing

Namespace CreatePDFUA
Class Program
Shared Sub Main(ByVal args() As String)
'Create a PdfDocument object
Dim doc As PdfDocument = New PdfDocument()

'Add a page
Dim page As PdfPageBase = doc.Pages.Add(PdfPageSize.A4,New PdfMargins(20))

'Set tab order
page.SetTabOrder(TabOrder.Structure)

'Create an object of PdfTaggedContent class
Dim taggedContent As PdfTaggedContent = New PdfTaggedContent(doc)

'Set language and title for the document
taggedContent.SetLanguage("en-US")
taggedContent.SetTitle("test")

'Set PDF/UA1 identification
taggedContent.SetPdfUA1Identification()

'Create font and brush
Dim font As PdfTrueTypeFont = New PdfTrueTypeFont(New Font("Times New Roman",14),True)
Dim brush As PdfSolidBrush = New PdfSolidBrush(Color.Black)

'Add a "document" element
Dim document As PdfStructureElement = taggedContent.StructureTreeRoot.AppendChildElement(PdfStandardStructTypes.Document)

'Add a "heading" element
Dim heading1 As PdfStructureElement = document.AppendChildElement(PdfStandardStructTypes.HeadingLevel1)
heading1.BeginMarkedContent(page)
Dim headingText As String = "What Is a Tagged PDF?"
page.Canvas.DrawString(headingText,font,brush,New PointF(0,0))
heading1.EndMarkedContent(page)

'Add a "paragraph" element
Dim paragraph As PdfStructureElement = document.AppendChildElement(PdfStandardStructTypes.Paragraph)
paragraph.BeginMarkedContent(page)
String paragraphText = "“Tagged PDF” doesn’t seem like a life-changing term. But for some, it is. For people who are " +
"blind or have low vision and use assistive technology (such as screen readers and connected Braille displays) to " +
"access information, an untagged PDF means they are missing out on information contained in the document because assistive " +
"technology cannot “read” untagged PDFs. Digital accessibility has opened up so many avenues to information that were once " +
"closed to people with visual disabilities, but PDFs often get left out of the equation."
Dim rect As RectangleF = New RectangleF(0,30,page.Canvas.ClientSize.Width,page.Canvas.ClientSize.Height)
page.Canvas.DrawString(paragraphText, font, brush, rect)
paragraph.EndMarkedContent(page)

'Add a "figure" element to
Dim figure As PdfStructureElement = document.AppendChildElement(PdfStandardStructTypes.Figure)
figure.BeginMarkedContent(page)
Dim image As PdfImage = PdfImage.FromFile("C:\Users\Administrator\Desktop\pdfua.png")
page.Canvas.DrawImage(image,New PointF(0,150))
figure.EndMarkedContent(page)

'Add a "table" element
Dim table As PdfStructureElement = document.AppendChildElement(PdfStandardStructTypes.Table)
table.BeginMarkedContent(page)
Dim pdfTable As PdfTable = New PdfTable()
pdfTable.Style.DefaultStyle.Font = font
Dim dataTable As DataTable = New DataTable()
dataTable.Columns.Add("Name")
dataTable.Columns.Add("Age")
dataTable.Columns.Add("Sex")
Dim String() As dataTable.Rows.Add(New
{
"John", "22", "Male"
}
)
Dim String() As dataTable.Rows.Add(New
{
"Katty", "25", "Female"
}
)
pdfTable.DataSource = dataTable
pdfTable.Style.ShowHeader = True
pdfTable.Draw(page.Canvas,New PointF(0,280),300f)
table.EndMarkedContent(page)

'Save the document to file
doc.SaveToFile("CreatePDFUA.pdf")
End Sub
End Class
End Namespace

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