Do you need a high-speed solution to find and replace text in a bunch of PDF files using C#? No need to worry because this article provides a powerful mechanism to find and replace text in PDF files within a few simple steps. Let’s find out how it works.
The find and replace option makes it possible to replace a particular piece of text in a document in one go. This way, you do not have to locate and update each occurrence of the text in the whole document manually. So let’s see how to find and replace text in a PDF in C#. You can also use the same guidelines and the provided code samples to replace text in a batch of PDF files.
- C# Library to Find and Replace Text in PDF
- Find and Replace Text in PDF using C#
- Replace Text in a Particular Page in PDF
- Replace Text in PDF Page Region
- Find and Replace Text in PDF using Regex
C# Library to Find and Replace Text in PDF
To find and replace text in PDF files, we will use Aspose.PDF for .NET. It is a C# class library that provides basic as well as advanced PDF manipulation features for .NET applications. The library also lets you find and replace text in PDF files in different ways with high accuracy and speed.
You can either download the library’s DLL or install it using NuGet.
PM> Install-Package Aspose.PDF
Find and Replace Text in PDF using C#
The following are steps to find and replace text in a PDF document.
- Use Document class to load the PDF document using its path.
- Create an instance of TextFragmentAbsorber class and provide the search phrase to its constructor.
- Accept the text absorber for all the pages of the PDF using Document.Pages.Accept(TextFragmentAbsorber).
- Get the extracted text fragments into TextFragmentCollection object.
- Loop through the found TextFragmentCollection and replace text in each fragment.
- Save updated PDF document using Document.Save(String) method.
C# Code to Replace Text in a PDF
The following code sample shows how to find and replace text in PDF using C#.
| // Open document | |
| Document pdfDocument = new Document("Document.pdf"); | |
| // Create TextAbsorber object to find all instances of the input search phrase | |
| TextFragmentAbsorber textFragmentAbsorber = new TextFragmentAbsorber("text"); | |
| // Accept the absorber for all the pages | |
| pdfDocument.Pages.Accept(textFragmentAbsorber); | |
| // Get the extracted text fragments | |
| TextFragmentCollection textFragmentCollection = textFragmentAbsorber.TextFragments; | |
| // Loop through the fragments | |
| foreach (TextFragment textFragment in textFragmentCollection) | |
| { | |
| // Update text and other properties | |
| textFragment.Text = "TEXT"; | |
| textFragment.TextState.Font = 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 resulting PDF document. | |
| pdfDocument.Save("updated-document.pdf"); |
C# Replace Text in a Particular PDF Page
The following are steps to find and replace text on a particular page in a PDF document.
- Use Document class to load the PDF document using its path.
- Create an instance of TextFragmentAbsorber class and provide the search phrase to its constructor.
- Accept the text absorber for the desired page using [Document.Pages1.Accept(TextFragmentAbsorber)]12.
- Loop through the found TextFragmentAbsorber.TextFragments collection and replace text in each fragment.
- Save updated PDF document using Document.Save(String) method.
The following code sample shows how to find and replace text on a particular page of the PDF using C#.
| // Open document | |
| Document pdfDocument = new Document("Document.pdf"); | |
| // Create TextAbsorber object to find all instances of the input search phrase | |
| TextFragmentAbsorber textFragmentAbsorber = new TextFragmentAbsorber("text"); | |
| // Accept the absorber for desired | |
| pdfDocument.Pages[1].Accept(textFragmentAbsorber); | |
| // Get the extracted text fragments | |
| TextFragmentCollection textFragmentCollection = textFragmentAbsorber.TextFragments; | |
| // Loop through the fragments | |
| foreach (TextFragment textFragment in textFragmentCollection) | |
| { | |
| // Update text and other properties | |
| textFragment.Text = "TEXT"; | |
| textFragment.TextState.Font = 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 resulting PDF document. | |
| pdfDocument.Save("updated-document.pdf"); |
Find and Replace Text in PDF Page Region
You can also find and replace text in a particular region of the page in a PDF document. The following steps show how to define a particular region and then replace text within it.
- Use Document class to load the PDF document using its path.
- Create an instance of TextFragmentAbsorber class and provide the search phrase to its constructor.
- Accept the text absorber for the desired page using Document.Pages[0].Accept(TextFragmentAbsorber).
- Define the page region using the Rectangle class.
- Loop through the TextFragmentAbsorber.TextFragments collection and replace text in each fragment.
- Save updated PDF document using Document.Save(String) method.
The following code sample shows how to find and replace text in a particular page region in a PDF using C#.
| // load PDF file | |
| Document pdf = new Document("Document.pdf"); | |
| // instantiate TextFragment Absorber object | |
| TextFragmentAbsorber TextFragmentAbsorberAddress = new TextFragmentAbsorber(); | |
| // search text within page bound | |
| TextFragmentAbsorberAddress.TextSearchOptions.LimitToPageBounds = true; | |
| // specify the page region for TextSearch Options | |
| TextFragmentAbsorberAddress.TextSearchOptions.Rectangle = new Rectangle(100, 100, 200, 200); | |
| // search text from first page of PDF file | |
| pdf.Pages[1].Accept(TextFragmentAbsorberAddress); | |
| // iterate through individual TextFragment | |
| foreach (TextFragment tf in TextFragmentAbsorberAddress.TextFragments) | |
| { | |
| // update text to blank characters | |
| tf.Text = ""; | |
| } | |
| // save updated PDF file after text replace | |
| pdf.Save("output.pdf"); |
C# Replace Text in PDF with Regex
You can also use regular expressions to find and replace the text occurrences matching a particular pattern. For this, you only need to provide a regular expression instead of the plain search phrase and use TextSearchOptions. The following are the steps to do so.
- Use Document class to load the PDF document using its path.
- Create an instance of TextFragmentAbsorber class and provide the search phrase to its constructor.
- Create an instance of TextSearchOptions class and pass true to its constructor to enable the regex-based search.
- Assign the TextSearchOptions object to TextFragmentAbsorber.TextSearchOptions property.
- Accept the text absorber for the desired page using Document.Pages[0].Accept(TextFragmentAbsorber).
- Define the page region using the Rectangle class.
- Loop through the TextFragmentAbsorber.TextFragments collection and replace text in each fragment.
- Save updated PDF document using Document.Save(String) method.
The following code sample shows how to find and replace text in a PDF using regular expressions in C#.
| // Open document | |
| Document pdfDocument = new Document("Document.pdf"); | |
| // Create TextAbsorber object to find all the phrases matching the regular expression | |
| TextFragmentAbsorber textFragmentAbsorber = new TextFragmentAbsorber("\\d{4}-\\d{4}"); // Like 1999-2000 | |
| // Set text search option to specify regular expression usage | |
| TextSearchOptions textSearchOptions = new TextSearchOptions(true); | |
| textFragmentAbsorber.TextSearchOptions = textSearchOptions; | |
| // Accept the absorber for a single page | |
| pdfDocument.Pages[1].Accept(textFragmentAbsorber); | |
| // Get the extracted text fragments | |
| TextFragmentCollection textFragmentCollection = textFragmentAbsorber.TextFragments; | |
| // Loop through the fragments | |
| foreach (TextFragment textFragment in textFragmentCollection) | |
| { | |
| // Update text and other properties | |
| textFragment.Text = "New Phrase"; | |
| // Set to an instance of an object. | |
| textFragment.TextState.Font = 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 | |
| pdfDocument.Save("output.pdf"); |
Free C# Library to Replace Text in PDF
You can get a free temporary license and replace text in PDF files without any limitations.
Explore C# PDF Library
You can explore more advanced features of the C# PDF library using the documentation.
Conclusion
PDF automation is widely adopted these days to manipulate PDF documents from within the web or desktop applications. This article covered a useful PDF automation feature of finding and replacing text in PDF in C#. The step-by-step guide and code samples have shown how to find and replace text in a whole PDF, a particular page in PDF, or a page region.