PdfPig

Use PdfDocumentBuilder to create new PDF files.

Key requirements:

• Use builder.AddPage(PageSize) to add pages.
• Font Registration: You must register fonts with the PdfDocumentBuilder (e.g., using AddStandard14Font) before using them in page.AddText. This prevents duplication and allows pages to share font resources.
• Supported fonts include Standard 14 fonts and TrueType fonts (.ttf).

Limitations: Document creation does not support editing forms, changing annotations/metadata, or adding/removing text with existing fonts.

PdfDocumentBuilder builder = new PdfDocumentBuilder();

PdfPageBuilder page = builder.AddPage(PageSize.A4);

// Fonts must be registered with the document builder prior to use to prevent duplication.
PdfDocumentBuilder.AddedFont font = builder.AddStandard14Font(Standard14Font.Helvetica);

page.AddText("Hello World!", 12, new PdfPoint(25, 700), font);

byte[] documentBytes = builder.Build();

File.WriteAllBytes(@"C:\git\newPdf.pdf", documentBytes);

Use PdfDocumentBuilder to construct a new PDF. You can add standard 14 fonts (like Helvetica) or register TrueType (.ttf) fonts to support non-ASCII characters.

Note on Coordinates: PDF coordinates run from the bottom-left of the page upwards. The Y coordinate of the top of the page is higher than 0.

using System.IO;
using UglyToad.PdfPig.Content;
using UglyToad.PdfPig.Core;
using UglyToad.PdfPig.Fonts.Standard14Fonts;
using UglyToad.PdfPig.Writer;

public static class Program
{
    public static void Main()
    {
        PdfDocumentBuilder builder = new PdfDocumentBuilder();

        PdfDocumentBuilder.AddedFont helvetica = builder.AddStandard14Font(Standard14Font.Helvetica);
        PdfDocumentBuilder.AddedFont helveticaBold = builder.AddStandard14Font(Standard14Font.HelveticaBold);

        PdfPageBuilder page = builder.AddPage(PageSize.A4);

        PdfPoint closeToTop = new PdfPoint(15, page.PageSize.Top - 25);

        page.AddText("My first PDF document!", 12, closeToTop, helvetica);
        page.AddText("Hello World!", 10, closeToTop.Translate(0, -15), helveticaBold);

        File.WriteAllBytes(@"C:\temp\file.pdf", builder.Build());
    }
}

Using TrueType Fonts:

PdfDocumentBuilder builder = new PdfDocumentBuilder();
byte[] robotoBytes = File.ReadAllBytes(@"C:\fonts\roboto.ttf");
PdfDocumentBuilder.AddedFont roboto = builder.AddTrueTypeFont(robotoBytes);

The PdfDocument class provides access to various internal structures including AcroForms, XMP metadata, bookmarks, and embedded files.

using System;
using System.Collections.Generic;
using System.Xml.Linq;
using UglyToad.PdfPig;
using UglyToad.PdfPig.AcroForms;
using UglyToad.PdfPig.AcroForms.Fields;
using UglyToad.PdfPig.Content;
using UglyToad.PdfPig.Outline;

public static class Program
{
    public static void Main()
    {
        using (PdfDocument document = PdfDocument.Open(@"C:\temp\file.pdf"))
        {
            Console.WriteLine($"Document has {document.NumberOfPages} pages.");

            if (document.TryGetForm(out AcroForm form))
            {
                foreach (AcroFieldBase field in form.GetFieldsForPage(1))
                {
                    switch (field)
                    {
                        case AcroCheckboxField cb:
                            if (cb.IsChecked)
                            {
                                Console.WriteLine($"Checkbox was checked: {cb.Information.MappingName}.");
                            }
                            break;
                    }
                }
            }

            if (document.TryGetXmpMetadata(out XmpMetadata metadata))
            {
                XDocument xmp = metadata.GetXDocument();
            }
            
            if (document.TryGetBookmarks(out Bookmarks bookmarks))
            {
                Console.WriteLine($"Document contained bookmarks with {bookmarks.Roots.Count} root nodes.");
            }

            Console.WriteLine($"Document uses version {document.Version} of the PDF specification.");

            if (document.Advanced.TryGetEmbeddedFiles(out IReadOnlyList<EmbeddedFile> embeddedFiles))
            {
                Console.WriteLine($"Document contains {embeddedFiles.Count} embedded files.");
            }
        }
    }
}

For complex extraction, you can combine several layout analysis tools to identify words, segment them into blocks, and determine reading order. This process can be used to create a 'debug' version of a PDF that visualizes bounding boxes and reading order.

Typical workflow:

1. Extract Words: Use NearestNeighbourWordExtractor.Instance.GetWords(letters).
2. Segment Page: Use DocstrumBoundingBoxes.Instance.GetBlocks(words) to group words into blocks.
3. Determine Reading Order: Use UnsupervisedReadingOrderDetector.Instance.Get(textBlocks) to order the blocks.
4. Visualize/Export: Use PdfDocumentBuilder to draw rectangles (DrawRectangle) and text labels over the original content based on the extracted metadata.

var sourcePdfPath = "";
var outputPath = "";
var pageNumber = 1;
using (var document = PdfDocument.Open(sourcePdfPath))
{
    var builder = new PdfDocumentBuilder { };
    PdfDocumentBuilder.AddedFont font = builder.AddStandard14Font(Standard14Font.Helvetica);
    var pageBuilder = builder.AddPage(document, pageNumber);
    pageBuilder.SetStrokeColor(0, 255, 0);
    var page = document.GetPage(pageNumber);

    var letters = page.Letters; // no preprocessing

    // 1. Extract words
    var wordExtractor = NearestNeighbourWordExtractor.Instance;

    var words = wordExtractor.GetWords(letters);

    // 2. Segment page
    var pageSegmenter = DocstrumBoundingBoxes.Instance;

    var textBlocks = pageSegmenter.GetBlocks(words);

    // 3. Postprocessing
    var readingOrder = UnsupervisedReadingOrderDetector.Instance;
    var orderedTextBlocks = readingOrder.Get(textBlocks);

    // 4. Add debug info - Bounding boxes and reading order
    foreach (var block in orderedTextBlocks)
    {
        var bbox = block.BoundingBox;
        pageBuilder.DrawRectangle(bbox.BottomLeft, bbox.Width, bbox.Height);
        pageBuilder.AddText(block.ReadingOrder.ToString(), 8, bbox.TopLeft, font);
    }

    // 5. Write result to a file
    byte[] fileBytes = builder.Build();
    File.WriteAllBytes(outputPath, fileBytes); // save to file
}

For encrypted PDF files, provide a ParsingOptions object containing a list of potential passwords to PdfDocument.Open().

ParsingOptions parsingOptions = new ParsingOptions
{
    Passwords = new List<string> {"a password", "password123"}
};

using (PdfDocument document = PdfDocument.Open(@"C:\path\to\pdffile\file.pdf", parsingOptions))
{
    // Access document metadata or pages
    Console.WriteLine(document.Information.Title);
                
    foreach (Page page in document.GetPages())
    {
        IReadOnlyList<Letter> letters = page.Letters;
        Console.WriteLine(letters.Count);
    }
}

ParsingOptions parsingOptions = new ParsingOptions
{
    Passwords = new List<string> {"a password", "password123"}
};

using (PdfDocument document = PdfDocument.Open(@"C:\path\to\pdffile\file.pdf", parsingOptions))
{
    // Get the title from the document metadata.
    Console.WriteLine(document.Information.Title);
                
    foreach (Page page in document.GetPages())
    {
        IReadOnlyList<Letter> letters = page.Letters;
        Console.WriteLine(letters.Count);
    }
}