PDFSyntax

A Python library to inspect and transform the internal structure of PDF files

Introduction

The project is focused on chapter 7 ("Syntax") of the Portable Document Format (PDF) Specification. It implements all the detailed document structure management down to the byte level for inspection and transformation use cases (access to metadata, rotation,...).

• Internal functions are being exposed as an API toolkit for PDF read/write operations,
• Some specific functions are additionally exposed as a command line interface for use in a terminal or a browser.

PDFSyntax is lightweight (no dependencies) and written from scratch in pure Python, with a focus on simplicity and immutability.

It favors non-destructive edits allowed by the PDF Specification: by default incremental updates are added at the end of the original file (you may rewind or squash all revisions into a single one).

Project status

WORK IN PROGRESS! This is BETA quality software. The API may change anytime. Next on TO-DO list:

• Cut & append pages
• Lossless compression
• More filters
• Improve text extraction
• Augment text extraction with layout detection

Installation

You can install from PyPI:

pip install pdfsyntax

CLI overview

Please refer to the CLI README for details.

The general form of the CLI usage is:

pdfsyntax COMMAND FILE

Or this longer form if you installed from source:

python3 -m pdfsyntax COMMAND FILE

You can get quick insights on a PDF file with these commands:

• overview outputs text data about the structure and the metadata.
• disasm outputs a dump of the file structure on the terminal.
• text outputs extracted text spatially, as if it was a kind of scan.
• fonts outputs list of fonts used.
• browse outputs static html data that lets you browse the internal structure of the PDF file: the PDF source is pretty-printed and augmented with hyperlinks.

API overview

Please refer to the API README for details.

PDFSyntax is mostly made of simple functions. Example:

>>> from pdfsyntax import readfile, metadata
>>> doc = readfile("samples/simple_text_string.pdf")
>>> metadata(doc) #returns a Python dict whose keys are 'Title', 'Author', etc...

The Doc object is probably the only dedicated class you will need to handle. It is a black box that stores all the internal states of a document:

• content that is cached/memoized from an original file,
• modifications that add/modifiy/delete content and that are tracked as incremental updates.

>>> doc
<PDF Doc in revision 1 with 0 modified object(s)>

This object exposes as a method the same metadata function, therefore you can get the same result with:

>>> doc.metadata() #returns a Python dict whose keys are 'Title', 'Author', etc...

Low-level functions like get_object or update_object allow you to directly access and manipulate the inner objects of the document structure. You may also use higher-level functions like rotate:

>>> from pdfsyntax import rotate, writefile
>>> doc180 = rotate(doc, 180) #rotate pages by 180°

The original object is unchanged and a new object is created with an incremental update (revision 2) that encloses the ongoing orientation modification:

>>> doc180
<PDF Doc in revision 1 with 1 modified object(s)>

You then can write the modified PDF to disk. Note that the resulting file contains a new section appended to the original content. You may cut this section to revert the change.

>>> writefile(doc180, "rotated_doc.pdf")

Open-Source, not Open-Contribution yet

PDFSyntax is MIT licensed but is currently closed to contributions.

Personal note: this is a pet projet of mine and my time is limited. First I need to focus on my roadmap (new features and refactoring) and then I will happily accept contributions when everything is a little more stabilised.