Text Extraction

Text Extraction

Aspose.PDF FOSS for .NET provides several mechanisms for extracting text from PDF pages. TextFragmentAbsorber is the primary tool — it scans page content and returns structured TextFragment objects with position, font, and style information.

Basic text extraction

TextAbsorber extracts all text from a page or document as a single string.

using var doc = Document.Open(pdfBytes);

var absorber = new TextAbsorber();
doc.Pages[1].Accept(absorber);

string pageText = absorber.Text;

Extracting text fragments

TextFragmentAbsorber provides structured results. Each TextFragment includes the extracted text, its position on the page, and font details.

using var doc = Document.Open(pdfBytes);

var absorber = new TextFragmentAbsorber();
doc.Pages[1].Accept(absorber);

foreach (var fragment in absorber.TextFragments)
{
    Console.WriteLine($"Text: {fragment.Text}");
    Console.WriteLine($"Position: ({fragment.Position.XIndent}, {fragment.Position.YIndent})");
    Console.WriteLine($"Font: {fragment.TextState.Font.FontName}");
}

Searching with regular expressions

Pass a regex pattern to TextFragmentAbsorber to find specific text.

var absorber = new TextFragmentAbsorber(@"\d{3}-\d{2}-\d{4}");
doc.Pages.Accept(absorber);  // Search all pages

foreach (var fragment in absorber.TextFragments)
{
    Console.WriteLine($"Found: {fragment.Text}");
}

Text segments

Each TextFragment may contain multiple TextSegment objects when the text spans different font runs.

foreach (var fragment in absorber.TextFragments)
{
    foreach (var segment in fragment.Segments)
    {
        Console.WriteLine($"Segment: {segment.Text}, Font: {segment.TextState.Font.FontName}");
    }
}

Font management

FontRepository provides methods to find and load fonts.

var font = FontRepository.FindFont("Helvetica");

Building text paragraphs

TextParagraph allows constructing multi-line text blocks for insertion into a page.

var paragraph = new TextParagraph();
paragraph.AppendLine(new TextFragment("First line"));
paragraph.AppendLine(new TextFragment("Second line"));

Tips and Best Practices

• Use TextFragmentAbsorber when you need position and font data; use TextAbsorber for plain-text extraction.
• Accept the absorber on a single page for faster results, or on doc.Pages to search the entire document.
• Regular expression search is case-sensitive by default — use (?i) prefix for case-insensitive matching.
• Check TextState.Font.IsEmbedded to determine whether a font is embedded in the PDF.
• For large documents, process pages one at a time to manage memory usage.

Common Issues

FAQ

Can I extract text from a specific region of a page?

Yes. Set TextFragmentAbsorber.TextSearchOptions.Rectangle to limit the search to a specific area of the page.

Does text extraction preserve reading order?

The library returns text in content-stream order. For multi-column layouts, you may need to sort fragments by position.

Can I extract text from all pages at once?

Yes. Call doc.Pages.Accept(absorber) to search every page in the document.

API Reference Summary

See Also

• Aspose.PDF for .NET Enterprise Product