在PDF中替换文本

以下代码片段也适用于Aspose.PDF.Drawing库。

在PDF文档的所有页面中替换文本

为了在PDF文档的所有页面中替换文本，您首先需要使用TextFragmentAbsorber找到您想要替换的特定短语。之后，您需要遍历所有TextFragments以替换文本并更改任何其他属性。完成后，您只需使用Document对象的Save方法保存输出PDF。以下代码片段向您展示了如何在PDF文档的所有页面中替换文本。

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

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "ReplaceTextAll.pdf"))
    {
        // Create TextAbsorber object to find all instances of the input search phrase
        var absorber = new Aspose.Pdf.Text.TextFragmentAbsorber("text");

        // Accept the absorber for all the pages
        document.Pages.Accept(absorber);

        // Get the extracted text fragments
        var textFragmentCollection = absorber.TextFragments;

        // Loop through the fragments
        foreach (var textFragment in textFragmentCollection)
        {
            // Update text and other properties
            textFragment.Text = "TEXT";
            textFragment.TextState.Font = Aspose.Pdf.Text.FontRepository.FindFont("Verdana");
            textFragment.TextState.FontSize = 22;
            textFragment.TextState.ForegroundColor = Aspose.Pdf.Color.FromRgb(System.Drawing.Color.Blue);
            textFragment.TextState.BackgroundColor = Aspose.Pdf.Color.FromRgb(System.Drawing.Color.Green);
        }

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

在特定页面区域中替换文本

为了在特定页面区域中替换文本，首先，我们需要实例化TextFragmentAbsorber对象，使用TextSearchOptions.Rectangle属性指定页面区域，然后遍历所有TextFragments以替换文本。一旦这些操作完成，我们只需使用Document对象的Save方法保存输出PDF。以下代码片段向您展示了如何在PDF文档的特定页面区域中替换文本。

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

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "programaticallyproducedpdf.pdf"))
    {
        // instantiate TextFragment Absorber object
        var absorber = new Aspose.Pdf.Text.TextFragmentAbsorber();

        // search text within page bound
        absorber.TextSearchOptions.LimitToPageBounds = true;

        // specify the page region for TextSearch Options
        absorber.TextSearchOptions.Rectangle = new Aspose.Pdf.Rectangle(100, 100, 200, 200);

        // search text from first page of PDF file
        document.Pages[1].Accept(absorber);

        // iterate through individual TextFragment
        foreach (var textFragment in absorber.TextFragments)
        {
            // update text to blank characters
            textFragment.Text = "";
        }

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

基于正则表达式替换文本

如果您想根据正则表达式替换某些短语，您首先需要使用TextFragmentAbsorber找到所有匹配该特定正则表达式的短语。您需要将正则表达式作为参数传递给TextFragmentAbsorber构造函数。您还需要创建TextSearchOptions对象，以指定是否使用正则表达式。一旦您在TextFragments中获得匹配的短语，您需要遍历所有短语并根据需要进行更新。最后，您需要使用Document对象的Save方法保存更新后的PDF。以下代码片段向您展示了如何基于正则表达式替换文本。

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

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

        // Create TextAbsorber object to find all the phrases matching the regular expression
        var absorber = new Aspose.Pdf.Text.TextFragmentAbsorber("\\d{4}-\\d{4}"); // Like 1999-2000

        // Set text search option to specify regular expression usage
        absorber.TextSearchOptions = new Aspose.Pdf.Text.TextSearchOptions(true);

        // Accept the absorber for a single page
        document.Pages[1].Accept(absorber);

        // Get the extracted text fragments
        var collection = absorber.TextFragments;

        // Loop through the fragments
        foreach (var textFragment in collection)
        {
            // Update text and other properties
            textFragment.Text = "New Phrase";
            // Set to an instance of an object.
            textFragment.TextState.Font = Aspose.Pdf.Text.FontRepository.FindFont("Verdana");
            textFragment.TextState.FontSize = 22;
            textFragment.TextState.ForegroundColor = Aspose.Pdf.Color.FromRgb(System.Drawing.Color.Blue);
            textFragment.TextState.BackgroundColor = Aspose.Pdf.Color.FromRgb(System.Drawing.Color.Green);
        }

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

替换现有PDF文件中的字体

Aspose.PDF for .NET支持在PDF文档中替换文本的功能。然而，有时您只需要替换PDF文档中使用的字体。因此，替换的不是文本，而是使用的字体。TextFragmentAbsorber构造函数的一个重载接受TextEditOptions对象作为参数，我们可以使用TextEditOptions.FontReplace枚举中的RemoveUnusedFonts值来满足我们的需求。以下代码片段展示了如何在PDF文档中替换字体。

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

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "ReplaceTextPage.pdf"))
    {
        // Create text edit options
        var options = new Aspose.Pdf.Text.TextEditOptions(Aspose.Pdf.Text.TextEditOptions.FontReplace.RemoveUnusedFonts);

        // Search text fragments and set edit option as remove unused fonts
        var absorber = new Aspose.Pdf.Text.TextFragmentAbsorber(options);

        // Accept the absorber for all the pages
        document.Pages.Accept(absorber);

        // Traverse through all the TextFragments
        foreach (var textFragment in absorber.TextFragments)
        {
            // If the font name is ArialMT, replace font name with Arial
            if (textFragment.TextState.Font.FontName == "Arial,Bold")
            {
                textFragment.TextState.Font = Aspose.Pdf.Text.FontRepository.FindFont("Arial");
            }
        }

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

文本替换应自动重新排列页面内容

Aspose.PDF for .NET支持在PDF文件中搜索和替换文本的功能。然而，最近一些客户在文本替换时遇到了问题，当特定的TextFragment被较小的内容替换时，结果PDF中显示了一些额外的空格；或者在TextFragment被某个较长字符串替换时，单词与现有页面内容重叠。因此，需求是引入一种机制，一旦PDF文档中的文本被替换，内容应重新排列。

为了满足上述情况，Aspose.PDF for .NET进行了增强，以确保在PDF文件中替换文本时不会出现此类问题。以下代码片段展示了如何在PDF文件中替换文本，并且页面内容应自动重新排列。

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

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "ExtractTextPage.pdf"))
    {
        // Create TextFragment Absorber object with regular expression
        var absorber = new Aspose.Pdf.Text.TextFragmentAbsorber("[TextFragmentAbsorber,companyname,Textbox,50]");
        document.Pages.Accept(absorber);

        // Replace each TextFragment
        foreach (var textFragment in absorber.TextFragments)
        {
            // Set font of text fragment being replaced
            textFragment.TextState.Font = Aspose.Pdf.Text.FontRepository.FindFont("Arial");
            // Set font size
            textFragment.TextState.FontSize = 12;
            textFragment.TextState.ForegroundColor = Aspose.Pdf.Color.Navy;
            // Replace the text with larger string than placeholder
            textFragment.Text = "This is a Larger String for the Testing of this issue";
        }

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

在PDF创建期间呈现可替换符号

可替换符号是文本字符串中的特殊符号，可以在运行时用相应的内容替换。目前，Aspose.PDF命名空间的新文档对象模型支持的可替换符号有$P、$p、\n、\r。$p和$P用于处理运行时的页面编号。$p被替换为当前Paragraph类所在页面的页码。$P被替换为文档中的总页数。当将TextFragment添加到PDF文档的段落集合时，它不支持文本中的换行符。然而，为了添加带有换行符的文本，请使用带有TextParagraph的TextFragment：

  • 在TextFragment中使用\r\n或Environment.NewLine，而不是单个\n。
  • 创建一个TextParagraph对象。它将添加带有换行的文本。
  • 使用TextParagraph.AppendLine添加TextFragment。
  • 使用TextBuilder.AppendParagraph添加TextParagraph。
// For complete examples and data files, visit https://github.com/aspose-pdf/Aspose.PDF-for-.NET
private static void RenderingReplaceableSymbols()
{
    // The path to the documents directory
    var dataDir = RunExamples.GetDataDir_AsposePdf_Text();

    // Create PDF document
    using (var document = new Aspose.Pdf.Document())
    {
        var page = document.Pages.Add();

        // Initialize new TextFragment with text containing required newline markers
        Aspose.Pdf.Text.TextFragment textFragment = new Aspose.Pdf.Text.TextFragment("Applicant Name: " + Environment.NewLine + " Joe Smoe");

        // Set text fragment properties if necessary
        textFragment.TextState.FontSize = 12;
        textFragment.TextState.Font = Aspose.Pdf.Text.FontRepository.FindFont("TimesNewRoman");
        textFragment.TextState.BackgroundColor = Aspose.Pdf.Color.LightGray;
        textFragment.TextState.ForegroundColor = Aspose.Pdf.Color.Red;

        // Create TextParagraph object
        var par = new Aspose.Pdf.Text.TextParagraph();

        // Add new TextFragment to paragraph
        par.AppendLine(textFragment);

        // Set paragraph position
        par.Position = new Aspose.Pdf.Text.Position(100, 600);

        // Create TextBuilder object
        var textBuilder = new Aspose.Pdf.Text.TextBuilder(page);

        // Add the TextParagraph using TextBuilder
        textBuilder.AppendParagraph(par);

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

页眉/页脚区域中的可替换符号

可替换符号也可以放置在PDF文件的页眉/页脚部分。请查看以下代码片段，了解如何在页脚部分添加可替换符号的详细信息。

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

    // Create PDF document
    using (var document = new Aspose.Pdf.Document())
    {
        var page = document.Pages.Add();

        // Create margin info
        var marginInfo = new Aspose.Pdf.MarginInfo();
        marginInfo.Top = 90;
        marginInfo.Bottom = 50;
        marginInfo.Left = 50;
        marginInfo.Right = 50;
        // Assign the marginInfo instance to Margin property of sec1.PageInfo
        page.PageInfo.Margin = marginInfo;

        var headerFooterFirst = new Aspose.Pdf.HeaderFooter();
        page.Header = headerFooterFirst;
        headerFooterFirst.Margin.Left = 50;
        headerFooterFirst.Margin.Right = 50;

        // Instantiate a Text paragraph that will store the content to show as header
        var fragment1 = new Aspose.Pdf.Text.TextFragment("report title");
        fragment1.TextState.Font = Aspose.Pdf.Text.FontRepository.FindFont("Arial");
        fragment1.TextState.FontSize = 16;
        fragment1.TextState.ForegroundColor = Aspose.Pdf.Color.Black;
        fragment1.TextState.FontStyle = Aspose.Pdf.Text.FontStyles.Bold;
        fragment1.TextState.HorizontalAlignment = Aspose.Pdf.HorizontalAlignment.Center;
        fragment1.TextState.LineSpacing = 5f;
        headerFooterFirst.Paragraphs.Add(fragment1);

        var fragment2 = new Aspose.Pdf.Text.TextFragment("Report_Name");
        fragment2.TextState.Font = Aspose.Pdf.Text.FontRepository.FindFont("Arial");
        fragment2.TextState.ForegroundColor = Aspose.Pdf.Color.Black;
        fragment2.TextState.HorizontalAlignment = Aspose.Pdf.HorizontalAlignment.Center;
        fragment2.TextState.LineSpacing = 5f;
        fragment2.TextState.FontSize = 12;
        headerFooterFirst.Paragraphs.Add(fragment2);

        // Create a HeaderFooter object for the section
        var headerFooterFoot = new Aspose.Pdf.HeaderFooter();

        // Set the HeaderFooter object to odd & even footer
        page.Footer = headerFooterFoot;
        headerFooterFoot.Margin.Left = 50;
        headerFooterFoot.Margin.Right = 50;

        // Add a text paragraph containing current page number of total number of pages
        var fragment3 = new Aspose.Pdf.Text.TextFragment("Generated on test date");
        var fragment4 = new Aspose.Pdf.Text.TextFragment("report name ");
        var fragment5 = new Aspose.Pdf.Text.TextFragment("Page $p of $P");

        // Instantiate a table object
        var table2 = new Aspose.Pdf.Table();

        // Add the table in paragraphs collection of the desired section
        headerFooterFoot.Paragraphs.Add(table2);

        // Set with column widths of the table
        table2.ColumnWidths = "165 172 165";

        // Create rows in the table and then cells in the rows
        var row3 = table2.Rows.Add();

        row3.Cells.Add();
        row3.Cells.Add();
        row3.Cells.Add();

        // Set the vertical allignment of the text as center alligned
        row3.Cells[0].Alignment = Aspose.Pdf.HorizontalAlignment.Left;
        row3.Cells[1].Alignment = Aspose.Pdf.HorizontalAlignment.Center;
        row3.Cells[2].Alignment = Aspose.Pdf.HorizontalAlignment.Right;

        row3.Cells[0].Paragraphs.Add(fragment3);
        row3.Cells[1].Paragraphs.Add(fragment4);
        row3.Cells[2].Paragraphs.Add(fragment5);

        // Sec1.Paragraphs.Add(New Text("Aspose.Total for Java is a compilation of every Java component offered by Aspose. It is compiled on a#$NL" + "daily basis to ensure it contains the most up to date versions of each of our Java components. #$NL " + "Using Aspose.Total for Java developers can create a wide range of applications. #$NL #$NL #$NP" + "Aspose.Total for Java is a compilation of every Java component offered by Aspose. It is compiled on a#$NL" + "daily basis to ensure it contains the most up to date versions of each of our Java components. #$NL " + "Using Aspose.Total for Java developers can create a wide range of applications. #$NL #$NL #$NP" + "Aspose.Total for Java is a compilation of every Java component offered by Aspose. It is compiled on a#$NL" + "daily basis to ensure it contains the most up to date versions of each of our Java components. #$NL " + "Using Aspose.Total for Java developers can create a wide range of applications. #$NL #$NL"))
        var table = new Aspose.Pdf.Table();

        table.ColumnWidths = "33% 33% 34%";
        table.DefaultCellPadding = new Aspose.Pdf.MarginInfo();
        table.DefaultCellPadding.Top = 10;
        table.DefaultCellPadding.Bottom = 10;

        // Add the table in paragraphs collection of the desired section
        page.Paragraphs.Add(table);

        // Set default cell border using BorderInfo object
        table.DefaultCellBorder = new Aspose.Pdf.BorderInfo(Aspose.Pdf.BorderSide.All, 0.1f);

        // Set table border using another customized BorderInfo object
        table.Border = new Aspose.Pdf.BorderInfo(Aspose.Pdf.BorderSide.All, 1f);

        table.RepeatingRowsCount = 1;

        // Create rows in the table and then cells in the rows
        var row1 = table.Rows.Add();

        row1.Cells.Add("col1");
        row1.Cells.Add("col2");
        row1.Cells.Add("col3");
        const string CRLF = "\r\n";
        for (int i = 0; i <= 10; i++)
        {
            var row = table.Rows.Add();
            row.IsRowBroken = true;
            for (int c = 0; c <= 2; c++)
            {
                Aspose.Pdf.Cell c1;
                if (c == 2)
                {
                    c1 = row.Cells.Add("Aspose.Total for Java is a compilation of every Java component offered by Aspose. It is compiled on a" + CRLF + "daily basis to ensure it contains the most up to date versions of each of our Java components. " + CRLF + "daily basis to ensure it contains the most up to date versions of each of our Java components. " + CRLF + "Using Aspose.Total for Java developers can create a wide range of applications.");
                }
                else
                {
                    c1 = row.Cells.Add("item1" + c);
                }
                c1.Margin = new Aspose.Pdf.MarginInfo();
                c1.Margin.Left = 30;
                c1.Margin.Top = 10;
                c1.Margin.Bottom = 10;
            }
        }

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

从PDF文件中删除未使用的字体

Aspose.PDF for .NET支持在创建PDF文档时嵌入字体的功能，以及在现有PDF文件中嵌入字体的能力。从Aspose.PDF for .NET 7.3.0开始，它还允许您从PDF文档中删除重复或未使用的字体。

要替换字体，请使用以下方法：

  1. 调用TextFragmentAbsorber类。
  2. 调用TextFragmentAbsorber类的TextEditOptions.FontReplace.RemoveUnusedFonts参数。（这将删除在字体替换过程中变为未使用的字体）。
  3. 为每个文本片段单独设置字体。

以下代码片段替换所有文档页面的所有文本片段的字体，并删除未使用的字体。

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

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "ReplaceTextPage.pdf"))
    {
        var options = new Aspose.Pdf.Text.TextEditOptions(Aspose.Pdf.Text.TextEditOptions.FontReplace.RemoveUnusedFonts);
        var absorber = new Aspose.Pdf.Text.TextFragmentAbsorber();
        document.Pages.Accept(absorber);

        // Iterate through all the TextFragments
        foreach (var textFragment in absorber.TextFragments)
        {
            textFragment.TextState.Font = Aspose.Pdf.Text.FontRepository.FindFont("Arial, Bold");
        }

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

从PDF文档中删除所有文本

使用操作符删除所有文本

在某些文本操作中，您需要从PDF文档中删除所有文本，为此，您通常需要将找到的文本设置为空字符串。关键是，改变多个文本片段的文本会引发许多检查和文本位置调整操作。这些操作在文本编辑场景中是必不可少的。困难在于，您无法确定在循环处理的情况下将删除多少文本片段。

因此，我们建议在从PDF页面删除所有文本的场景中使用另一种方法。请考虑以下代码片段，它的工作速度非常快。

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

    // Open PDF document
    using (var document = new Aspose.Pdf.Document(dataDir + "RemoveAllText.pdf"))
    {
        // Loop through all pages of PDF Document
        for (int i = 1; i <= document.Pages.Count; i++)
        {
            var page = document.Pages[i];
            var operatorSelector = new Aspose.Pdf.OperatorSelector(new Aspose.Pdf.Operators.TextShowOperator());
            // Select all text on the page
            page.Contents.Accept(operatorSelector);
            // Delete all text
            page.Contents.Delete(operatorSelector.Selected);
        }
        // Save PDF document
        document.Save(dataDir + "RemoveAllText_out.pdf", Aspose.Pdf.SaveFormat.Pdf);
    }
}
使用 C# 在 PDF 中格式化文本 使用 C# 在 PDF 中旋转文本