Tectonic

A standalone TeX typesetting engine, powered by TeXLive and XeTeX.

Tectonic is a TeX processer provided as a reusable library. The goal of Tectonic is to provide a standalone TeX/LaTeX engine that can be embedded anywhere, bringing the power of TeX typesetting to any application that needs it. It is forked from the XeTeX extension of the classic “Web2C” TeX implementation.

There are two key differences between Tectonic and other TeX engines:

• The engine has been turned into a well-behaved library. Tectonic’s I/O backend obtains resources from a Zip file called a “bundle” so that you don’t need a specialized filesystem tree containing thousands of files in order to process realistic documents.
• The implementation has been fully detached from the classic implementation in the WEB language and from the associated nest of support tools. Tectonic is written in C, C++, and Rust, and its implementation is self-contained.

Tectonic is almost completely derived from XeTeX and relies upon the infrastructure developed by the TeXLive project. XeTeX was chosen because it can load modern system fonts and process Unicode input files.

Current Status and Roadmap

The Tectonic codebase currently builds a standalone program that works almost identically to XeTeX. The most important difference is that it looks for support files in a Zip file, rather than searching filesystem trees using the kpathsea framework. Tools to generate bundle files are provided in the tectonic-staging repository.

Tectonic should build on both Linux and Mac machines.

The current task is a general rearrangement of the code to isolate and tidy the I/O-related layers. These will be replaced with new code that will allow the possibility of processing LaTeX documents in fully-embedded fashion, namely, without producing the usual assortment of output files (file.log, file.aux, etc.).

There is also a significant need to tidy up the machine-generated C code and develop a test suite to validate the system. (Tectonic does pass the TRIP and eTRIP tests.)

In the long term, the goal is to tidy up the code as much as possible and package the full functionality into an easy-to-use library. Ideally the implementation will be ported to pure Rust so that it can be compiled for fun targets like WebAssembly. That will take a great deal of effort, however. Modern documentation of the internals (i.e., not literate-programming style) would also be nice.

Building the Program

To build Tectonic requires:

• C and C++ compilers
• The Rust compiler and its Cargo package manager. These are easily installed through rustup.rs.
• pkg-config
• For the time being, the following system libraries. On Macs these can all be installed with Homebrew, but harfbuzz needs to have the --with-graphite2 option enabled.
  • freetype2
  • graphite2
  • harfbuzz
  • ICU
  • libpng
  • poppler
  • zlib
• On Linux only:
  • fontconfig

Once you have these, you should be able to build the executable just by running cargo build.

Testing Your Build

The cargo test command will run tests, including the classic TeX “TRIP” test. You may need to run the tests as cargo test -- --test-threads=1 for maximum reliability since the Rust test framework runs multiple tests simultaneously in a single threaded executable, which works out very badly for the TeX engine, which has tons of shared global state.

About the Name

The name of the project is “Tectonic,” spelled and pronounced like a regular word because it is one. Enough with the cutesy obscurantism.

In cases where the name might lead to ambiguities, it should be expanded to “Tectonic typesetting.”

If you’re feeling expansive, you can interpret the name as suggesting a large change in the TeX world. Or you can think of it as suggesting a salubrious offering for weary TeX users. Either way, the root of the word does go back to the ancient Greek τέκτων, ”carpenter,” which Donald Knuth — a devout Christian — might appreciate.

Copyright and Licensing

Tectonic is licensed under the MIT License. This is the license under which the codebase from which it is primarily derived, XeTeX, is distributed. Various other elements of the TeX system on which Tectonic is based are licensed under other open-source licenses.