== Introduction

CharmBypass, or charm-bypass, is a free software project that lets you
ride mass transit in Maryland for free. (Disclaimer: doing so is not at
all legal.) It is what powers the site https://charm-bypass.com/

That website consists of a single file, index.html, that it is our
goal to build. This document discusses only the technical details
involved. An introduction and security analysis (what is this, how
does it work) can be found at,

  1. https://michael.orlitzky.com/articles/charmbypass_pt._1%3A_introduction.xhtml
  2. https://michael.orlitzky.com/articles/charmbypass_pt._2%3A_analysis.xhtml


== Design goals

The main design goal is that the entire application should be
self-contained: it should be downloadable and usable without network
access. The "usable" part is lacking somewhat at the moment due to the
limitations present in mobile operating systems, but containment has
been achieved.

It is also mobile-only. By which I mean that if you view the site on
a large (desktop-sized) screen, it will look crazy. That's OK.


== Build process

The project uses a standard GNU autotools build system that should be
familiar to UNIX programmers and system administrators. To build it,
first install the build requirements listed below. Then run,

  $ autoreconf -fi
  $ ./configure
  $ make

The first command (re)generates the autotools build system. The second
and third invoke it. If you're feeling lucky, you can also run

  $ make check

to run a (very) minimal set of tests on the index.html you just built.

=== Build requirements

  0. GNU autotools
  1. The "base64" utility from GNU coreutils.
  2. The "scour" SVG optimizer.
  3. The "fontforge" program, built with woff2 support.
  4. The "xsltproc" program from libxslt.

To run the test suite, you'll also need the "tidy-html5" program.


== Miscellany

=== SVG Tricks

1. To inline a "transform" from a group (like the bus) that was
   resized or translated, simply ungroup and regroup the whole thing.
   This is necessary for groups that are animated using the
   "transform" property, because otherwise, applying a new transform
   would clobber the existing one.