LawTeX

About LawTeX Android App

This application is intended as the eventual replacement for our old application TeXPortal.


PURPOSE

Unlike TeXPortal, this application was built
* from the ground up, using publicly available Android API instead of hackish methods found on the web.
* with Light Tech's philosophy: The app ONLY aims for compiling and previewing LaTeX to assists you in modifying LaTeX sources, mostly for scientific (Maths, CS, ...) purposes, on Android phone. It doesn't aim to provide PDF or any kind of professional publishing. The only internal TeX engine we use is e-TeX, without Kpathsea, which only produces DVI output.

The intended use case is to use LawTeX in conjunction with other TeX editor such as VerbTeX:
1. Use LawTeX to WRITE and PREVIEW your LaTeX code; and
2. When you are satisfied with the CONTENT, generate the PDF online using VerbTeX.


USAGE

* Use "Compile" menu to open file dialog, select a file and press "LaTeX" to compile the document.
* The DVI is automatically loaded and displayed if the app determines that there is no error.
* The app should automatically download missing packages.
* If your device support multi-windows, you can have split-screen and use "Recompile the last compiled file" menu button to quickly recompile a file edited in a TeX editor (like TeXpert or VerbTeX).


FEATURES

* Very compact TeX distribution: The app is roughly 3MB installed. Unlike TeXPortal, the compiler is already in the app package. There is no extra downloading of engines (tex/pdftex/...) or support program (busybox).
* Automatic missing package download
* Fast DVI renderer using Android native OpenGL ES graphics
* No auxiliary files output: Unlike TeXPortal, this app doesn't write any auxiliary files (log, aux, ...) to the file system so you don't have to clean up those files.
* No dangerous 'orphan' processes: TeXPortal essentially launches TeX engines on an invisible shell and thus introduce a risk of the engine continue running indefinitely due to infinite loops in TeX source code (until you restart the device). LawTeX does not; when the app is terminated, the engine is also done for.


FACTS

Why don't we replace TeXPortal?

* Due to this significant reduction in functionality, we do not update TeXPortal but distribute this app as a separate free app. When most users moved on to Android 7.0 and above, we shall replace TeXPortal. Current users of TeXPortal are encouraged to use this app for testing.

Where are the output files?

* When implementing LawTeX, we have to avoid TeX Live's GPL-licensed library Kpathsea by using a RAM file system: All files are loaded in memory and passed to (the public domain) e-TeX. So the DVI file, the log file, etc. are all on memory and not written to SD card. We don't think the DVI will be useful to anyone anyway.

Will there be support for PDF output then?

* All PDF-related tools in TeX Live such as PDFTeX are licensed under GPL which requires derivatives to have their source code open. Not only that, because of too many GPL-licensed dependencies for PDFTeX, it is very hard to make it work properly. Thus, we will NEVER provide those in this app. That also goes against Light Tech's philosophy.


ACKNOWLEDGEMENTS

* Thanks to Light Tech's tips, we built this app with Microsoft's Visual Studio Team Services: There is no need to install Android Studio on our development machine, allowing us to develop the app on such a limited machine.

* We reuse the name of Light Tech's best LaTeX IDE in the world, LawTeX at https://www.microsoft.com/en-us/p/lawtex/9nblggh16jqz, and adapt its icon in hope that our app one day will surpass the original.

* We use uses LVitaCpp at https://github.com/light-tech/LVitaCpp.git in this app.