Quirc
=====

QR codes are a type of high-density matrix barcodes, and quirc is a
library for extracting and decoding them from images. It has several
features which make it a good choice for this purpose:

  * It is fast enough to be used with realtime video: extracting and
    decoding from VGA frame takes about 50 ms on a modern x86 core.

  * It has a robust and tolerant recognition algorithm. It can
    correctly recognise and decode QR codes which are rotated and/or
    oblique to the camera. It can also distinguish and decode multiple
    codes within the same image.

  * Really fast - works on any modern phone, tablet, or laptop
    or desktop.

  * BSD-licensed, with almost no restrictions regarding use and/or
    modification.


Background
----------

This distribution is based on the original quirc from Daniel Beer
at:

https://github.com/dlbeer/quirc

as well as Joshua Koo's modifications for Emscripten at:

https://github.com/zz85/quirc.js

Joshua's branch has fallen behind the original, and some of the
changes seem significant, so it's worth updating.  Additionally,
minor changes in Emscripten have caused the build to fail.
Finally, WebAssembly is popular enough now to be a better build
target.


Building
--------

You must have Emscripten installed and available in your path.
Then, just use:

% cd wasm
% node build.js

You will have quirc.js and quirc.wasm.  The js file is a loader
for the wasm.  Note that these files already exist in the
repository in the "wasm/test" directory.

I've also included a simple web worker that will load the code
and make it easy to decode QR codes in a separate thread.

To test, simply start a web server in the test directory and
browse to the "test.html" page.  A simple web server is
available if you have Python installed:

% python -m SimpleHTTPServer 8080

Then, simply browse to:

http://127.0.0.1:8080/test.html

QR codes should be easily readable.


Copyright
---------

Copyright (C) 2010-2012 Daniel Beer <<[email protected]>>

Permission to use, copy, modify, and/or distribute this software for
any purpose with or without fee is hereby granted, provided that the
above copyright notice and this permission notice appear in all
copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.