Aspose.PDF for .NET是一種高PDF處理和解析API，用于在跨平臺(tái)應(yīng)用程序中執(zhí)行文檔管理和操作任務(wù)。API可以輕松用于生成、修改、轉(zhuǎn)換、渲染、保護(hù)和打印PDF文檔，而無(wú)需使用Adobe Acrobat。此外，API還提供PDF壓縮選項(xiàng)，表格創(chuàng)建和操作，圖形和圖像功能，廣泛的超鏈接功能，印章和水印任務(wù)，擴(kuò)展的安全控制和自定義字體處理。

在接下來(lái)的系列教程中，將為開(kāi)發(fā)者帶來(lái)Aspose.PDF for .NET的一系列使用教程，例如進(jìn)行文檔間的轉(zhuǎn)換，如何標(biāo)記PDF文件，如何使用表單和圖表等等。本文將介紹如何管理PDF文件的頁(yè)眉和頁(yè)腳。

>>Aspose.PDF for .NET更新至最新版v20.11，歡迎下載體驗(yàn)。

在現(xiàn)有的PDF文件中添加文本

要將文本添加到現(xiàn)有的PDF文件中，需要以下步驟：

1. 使用文檔對(duì)象打開(kāi)輸入的PDF。
2. 獲取要向其添加文本的特定頁(yè)面。
3. 使用輸入文本以及其他文本屬性創(chuàng)建一個(gè)TextFragment對(duì)象。從特定頁(yè)面創(chuàng)建的TextBuilder對(duì)象（要向其添加文本）允許您使用AppendText方法將TextFragment對(duì)象添加到頁(yè)面。
4. 調(diào)用Document對(duì)象的Save方法并保存輸出的PDF文件。

添加文字

以下代碼段顯示了如何在現(xiàn)有的PDF文件中添加文本。

// The path to the documents directory.
string dataDir = RunExamples.GetDataDir_AsposePdf_Text();

// Open document
Document pdfDocument = new Document(dataDir + "input.pdf");

// Get particular page
Page pdfPage = (Page)pdfDocument.Pages[1];

// Create text fragment
TextFragment textFragment = new TextFragment("main text");
textFragment.Position = new Position(100, 600);

// Set text properties
textFragment.TextState.FontSize = 12;
textFragment.TextState.Font = FontRepository.FindFont("TimesNewRoman");
textFragment.TextState.BackgroundColor = Aspose.Pdf.Color.FromRgb(System.Drawing.Color.LightGray);
textFragment.TextState.ForegroundColor = Aspose.Pdf.Color.FromRgb(System.Drawing.Color.Red);

// Create TextBuilder object
TextBuilder textBuilder = new TextBuilder(pdfPage);

// Append the text fragment to the PDF page
textBuilder.AppendText(textFragment);
            
dataDir = dataDir + "AddText_out.pdf";

// Save resulting PDF document.
pdfDocument.Save(dataDir);

從流中加載字體

以下代碼片段顯示了在將文本添加到PDF文檔時(shí)如何從Stream對(duì)象加載Font。

// The path to the documents directory.
string dataDir = RunExamples.GetDataDir_AsposePdf_Text();
string fontFile = "";

// Load input PDF file
Document doc = new Document( dataDir + "input.pdf");
// Create text builder object for first page of document
TextBuilder textBuilder = new TextBuilder(doc.Pages[1]);
// Create text fragment with sample string
TextFragment textFragment = new TextFragment("Hello world");

if (fontFile != "")
{
    // Load the TrueType font into stream object
    using (FileStream fontStream = File.OpenRead(fontFile))
    {
        // Set the font name for text string
        textFragment.TextState.Font = FontRepository.OpenFont(fontStream, FontTypes.TTF);
        // Specify the position for Text Fragment
        textFragment.Position = new Position(10, 10);
        // Add the text to TextBuilder so that it can be placed over the PDF file
        textBuilder.AppendText(textFragment);
    }

    dataDir = dataDir + "LoadingFontFromStream_out.pdf";

    // Save resulting PDF document.
    doc.Save(dataDir);
}

使用TextParagraph添加文本

以下代碼段顯示了如何使用TextParagraph類在PDF文檔中添加文本。

// The path to the documents directory.
string dataDir = RunExamples.GetDataDir_AsposePdf_Text();
// Open document
Document doc = new Document();
// Add page to pages collection of Document object
Page page = doc.Pages.Add();
TextBuilder builder = new TextBuilder(page);
// Create text paragraph
TextParagraph paragraph = new TextParagraph();
// Set subsequent lines indent
paragraph.SubsequentLinesIndent = 20;
// Specify the location to add TextParagraph
paragraph.Rectangle = new Aspose.Pdf.Rectangle(100, 300, 200, 700);
// Specify word wraping mode
paragraph.FormattingOptions.WrapMode = TextFormattingOptions.WordWrapMode.ByWords;
// Create text fragment
TextFragment fragment1 = new TextFragment("the quick brown fox jumps over the lazy dog");
fragment1.TextState.Font = FontRepository.FindFont("Times New Roman");
fragment1.TextState.FontSize = 12;
// Add fragment to paragraph
paragraph.AppendLine(fragment1);
// Add paragraph
builder.AppendParagraph(paragraph);

dataDir = dataDir + "AddTextUsingTextParagraph_out.pdf";

// Save resulting PDF document.
doc.Save(dataDir);
            

將超鏈接添加到TextSegment

PDF頁(yè)面可以包含一個(gè)或多個(gè)TextFragment對(duì)象，其中每個(gè)TextFragment對(duì)象可以具有一個(gè)或多個(gè)TextSegment實(shí)例。為了設(shè)置TextSegment的超鏈接，可以在提供Aspose.Pdf.WebHyperlink實(shí)例的對(duì)象時(shí)使用TextSegment類的Hyperlink屬性。請(qǐng)嘗試使用以下代碼段來(lái)滿足此要求。

// The path to the documents directory.
string dataDir = RunExamples.GetDataDir_AsposePdf_Text();
// Create document instance
Document doc = new Document();
// Add page to pages collection of PDF file
Page page1 = doc.Pages.Add();
// Create TextFragment instance
TextFragment tf = new TextFragment("Sample Text Fragment");
// Set horizontal alignment for TextFragment
tf.HorizontalAlignment = Aspose.Pdf.HorizontalAlignment.Right;
// Create a textsegment with sample text
TextSegment segment = new TextSegment(" ... Text Segment 1...");
// Add segment to segments collection of TextFragment
tf.Segments.Add(segment);
// Create a new TextSegment 
segment = new TextSegment("Link to Google");
// Add segment to segments collection of TextFragment
tf.Segments.Add(segment);
// Set hyperlink for TextSegment
segment.Hyperlink = new Aspose.Pdf.WebHyperlink("www.google.com");
// Set forground color for text segment
segment.TextState.ForegroundColor = Aspose.Pdf.Color.Blue;
// Set text formatting as italic
segment.TextState.FontStyle = FontStyles.Italic;
// Create another TextSegment object
segment = new TextSegment("TextSegment without hyperlink");
// Add segment to segments collection of TextFragment
tf.Segments.Add(segment);
// Add TextFragment to paragraphs collection of page object
page1.Paragraphs.Add(tf);

dataDir = dataDir + "AddHyperlinkToTextSegment_out.pdf";

// Save resulting PDF document.
doc.Save(dataDir);
 

使用OTF字體

用于.NET的Aspose.PDF提供了在創(chuàng)建/處理PDF文件內(nèi)容時(shí)使用Custom / TrueType字體的功能，以便使用默認(rèn)系統(tǒng)字體以外的內(nèi)容顯示文件內(nèi)容。從.NET 10.3.0的Aspose.PDF版本開(kāi)始，我們提供了對(duì)Open Type Fonts的支持。

// The path to the documents directory.
string dataDir = RunExamples.GetDataDir_AsposePdf_Text();
// Create new document instance
Document pdfDocument = new Document();
// Add page to pages collection of PDF file
Aspose.Pdf.Page page = pdfDocument.Pages.Add();
// Create TextFragment instnace with sample text
TextFragment fragment = new TextFragment("Sample Text in OTF font");
// Find font inside system font directory
// Fragment.TextState.Font = FontRepository.FindFont("HelveticaNeueLT Pro 45 Lt");
// Or you can even specify the path of OTF font in system directory
fragment.TextState.Font = FontRepository.OpenFont(dataDir + "space age.otf");
// Specify to emend font inside PDF file, so that its displayed properly,
// Even if specific font is not installed/present over target machine
fragment.TextState.Font.IsEmbedded = true;
// Add TextFragment to paragraphs collection of Page instance
page.Paragraphs.Add(fragment);

dataDir = dataDir + "OTFFont_out.pdf";

// Save resulting PDF document.
pdfDocument.Save(dataDir);