A Python library to inspect and modify the internal structure of a PDF file
Project description
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:
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.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.
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