An experimental, work-in-progress PDF interpreter and renderer.

hayro is a Rust crate with a simple task: It allows you to interpret one or many pages of a PDF file to for example convert them into PNG or SVG files. This is a difficult task, as the PDF specification is huge and contains many features. In addition to that, there are millions of PDF files out there with many edge cases, so a solid PDF renderer should be able to handle those as well as possible.

This is not the first attempt at writing a PDF renderer in Rust, but, to the best of my knowledge, this is currently the most feature-complete library. There are still certain features and edge cases that hayro currently doesn't support (for example rendering knockout groups or PDFs with non-embedded CID-fonts). However, the vast majority of common features is supported meaning that you should be able to render the "average" PDF file without encountering any issues. This statement is underpinned by the fact that hayro is able to handle the 1400+ PDFs in our test suite, which to a large part have been scraped from the PDFBOX and pdf.js test regression suites.

But, this crate is still in a very development stage, and there are issues that remain to be addressed, most notably performance, which has not been a focus at all so far but will become a priority in the near future.

While the main goal of hayro is rendering PDF files, the hayro project actually encompasses a number of different crates which can in theory used independently. These include:

• hayro-syntax: Low-level parsing and reading of PDF files.
• hayro-interpret: A PDF interpreter emitting commands into an abstract Device.
• hayro: Rendering PDF pages into bitmaps.
• hayro-svg: Converting PDF pages into SVG images.
• hayro-jpeg2000: A JPEG2000 image decoder.
• hayro-jbig2: A JBIG2 image decoder.
• hayro-ccitt: A decoder for group 3 and group 4 CCITT-encoded images.
• hayro-postscript: A lightweight scanner for a specific subset of PostScript.
• hayro-cmap: A parser for CMap files in PDFs.

A demo tool can be found at https://laurenzv.github.io/hayro/. Please note that this is just a quick, vibe-coded PDF viewer not intended to be used as an actual viewer. Features such as text selection, search, annotations, and forms are not implemented there and out of scope. It's meant as a quick way to test the rendering capabilities and performance of hayro.

The minimum supported Rust version is 1.92.