PdfPig 0.0.3

PdfPig

This project allows users to read text content from PDF files.

This project aims to port PDFBox to C#.

Get Started

The simplest usage at this stage is to open a document, reading the words from every page:

using (PdfDocument document = PdfDocument.Open(@"C:\Documents\document.pdf"))
{
    for (var i = 0; i < document.NumberOfPages; i++)
    {
        // This starts at 1 rather than 0.
        var page = document.GetPage(i + 1);

        foreach (var word in page.GetWords())
        {
            Console.WriteLine(word.Text);
        }
    }
}

Installation

The package is available via the releases tab or from Nuget:

https://www.nuget.org/packages/PdfPig/

Or from the package manager console:

> Install-Package PdfPig

While the version is below 1.0.0 minor versions will change the public API without warning (SemVer will not be followed until 1.0.0 is reached).

API Changes

• 0.0.3 - Changes to position data for Letter. Letter has a Location, Width and GlyphRectangle property. Consult the Wiki for details of the new API. Adds PdfDocument.Structure property allowing access to raw data.

Usage

The PdfDocument class provides access to the contents of a document loaded either from file or passed in as bytes. To open from a file use the PdfDocument.Open static method:

using UglyToad.PdfPig;
using UglyToad.PdfPig.Content;

using (PdfDocument document = PdfDocument.Open(@"C:\my-file.pdf"))
{
    int pageCount = document.NumberOfPages;

    Page page = document.GetPage(1);

    decimal widthInPoints = page.Width;
    decimal heightInPoints = page.Height;

    string text = page.Text;
}

PdfDocument should only be used in a using statement since it implements IDisposable (unless the consumer disposes of it elsewhere).

Since this is alpha software the consumer should wrap all access in a try catch block since it is extremely likely to throw exceptions. As a fallback you can try running PDFBox using IKVM or using PDFsharp or by a native library wrapper using docnet.

The document contains the version of the PDF specification it complies with, accessed by document.Version:

decimal version = document.Version;

Document Information

The PdfDocument provides access to the document metadata as DocumentInformation defined in the PDF file. These tend not to be provided therefore most of these entries will be null:

PdfDocument document = PdfDocument.Open(fileName);

// The name of the program used to convert this document to PDF.
string producer = document.Information.Producer;

// The title given to the document
string title = document.Information.Title;
// etc...

Document Structure

New in 0.0.3 the document now has a Structure member:

UglyToad.PdfPig.Structure structure = document.Structure;

This provides access to tokenized PDF document content:

Catalog catalog = structure.Catalog;
DictionaryToken pagesDictionary = catalog.PagesDictionary;

The pages dictionary is the root of the pages tree within a PDF document. The structure also exposes a GetObject(IndirectReference reference) method which allows random access to any object in the PDF as long as its identifier number is known. This is an identifier of the form 69 0 R where 69 is the object number and 0 is the generation.

Page

The Page contains the page width and height in points as well as mapping to the PageSize enum:

PageSize size = Page.Size;

bool isA4 = size == PageSize.A4;

Page provides access to the text of the page:

string text = page.Text;

There is a new (0.0.3) method which provides access to the words. This uses basic heuristics and is not reliable or well-tested:

IEnumerable<Word> words = page.GetWords();

There is also an early access (0.0.3) API for retrieving the raw bytes of PDF image objects per page:

IEnumerable<XObjectImage> images = page.ExperimentalAccess.GetRawImages();

This API will be changed in future releases.

Letter

Due to the way a PDF is structured internally the page text may not be a readable representation of the text as it appears in the document. Since PDF is a presentation format, text can be drawn in any order, not necessarily reading order. This means spaces may be missing or words may be in unexpected positions in the text.

To help users resolve actual text order on the page, the Page file provides access to a list of the letters:

IReadOnlyList<Letter> letters = page.Letters;

These letters contain:

• The text of the letter: letter.Value.
• The location of the lower left of the letter: letter.Location.
• The width of the letter: letter.Width.
• The font size in unscaled relative text units (these sizes are internal to the PDF and do not correspond to sizes in pixels, points or other units): letter.FontSize.
• The name of the font used to render the letter if available: letter.FontName.
• A rectangle which is the smallest rectangle that completely contains the visible region of the letter/glyph: letter.GlyphRectangle.

Letter position is measured in PDF coordinates where the origin is the lower left corner of the page. Therefore a higher Y value means closer to the top of the page.

Credit

This project wouldn't be possible without the work done by the PDFBox team and the Apache Foundation. Any bugs in the code are entirely my fault.