=============================
Pure python QR Code generator
=============================

This module uses image libraries, Python Imaging Library (PIL) by default, to
generate QR Codes.

It is recommended to use the pillow_ fork rather than PIL itself.

.. _pillow: https://pypi.python.org/pypi/Pillow


What is a QR Code?
==================

A Quick Response code is a two-dimensional pictographic code used for its fast
readability and comparatively large storage capacity. The code consists of
black modules arranged in a square pattern on a white background. The
information encoded can be made up of any kind of data (e.g., binary,
alphanumeric, or Kanji symbols)

Usage
=====

>From the command line, use the installed ``qr`` script::

    qr "Some text" > test.png

Or in Python, use the ``make`` shortcut function::

    import qrcode
    img = qrcode.make('Some data here')

Advanced Usage
--------------

For more control, use the ``QRCode`` class. For example::

    import qrcode
    qr = qrcode.QRCode(
        version=1,
        error_correction=qrcode.constants.ERROR_CORRECT_L,
        box_size=10,
        border=4,
    )
    qr.add_data('Some data')
    qr.make(fit=True)

    img = qr.make_image()

The ``version`` parameter is an integer from 1 to 40 that controls the size of
the QR Code (the smallest, version 1, is a 21x21 matrix).
Set to ``None`` and use the ``fit`` parameter when making the code to determine
this automatically.

The ``error_correction`` parameter controls the error correction used for the
QR Code. The following four constants are made available on the ``qrcode``
package:

``ERROR_CORRECT_L``
    About 7% or less errors can be corrected.
``ERROR_CORRECT_M`` (default)
    About 15% or less errors can be corrected.
``ERROR_CORRECT_Q``
    About 25% or less errors can be corrected.
``ERROR_CORRECT_H``.
    About 30% or less errors can be corrected.

The ``box_size`` parameter controls how many pixels each "box" of the QR code
is.

The ``border`` parameter controls how many boxes thick the border should be
(the default is 4, which is the minimum according to the specs).

Other image factories
=====================

You can encode as SVG, or use a new pure Python image processor to encode to
PNG images.

The Python examples below use the ``make`` shortcut. The same ``image_factory``
keyword argument is a valid option for the ``QRCode`` class for more advanced
usage.

SVG
---

On Python 2.6 must install lxml since the older xml.etree.ElementTree version
can not be used to create SVG images.

You can create the entire SVG or an SVG fragment. When building an entire SVG
image, you can use the factory that combines as a path (recommended, and
default for the script) or a factory that creates a simple set of rectangles.

>From your command line::

    qr --factory=svg-path "Some text" > test.svg
    qr --factory=svg "Some text" > test.svg
    qr --factory=svg-fragment "Some text" > test.svg

Or in Python::

    import qrcode
    import qrcode.image.svg

    if method == 'basic':
        # Simple factory, just a set of rects.
        factory = qrcode.image.svg.SvgImage
    elif method == 'fragment':
        # Fragment factory (also just a set of rects)
        factory = qrcode.image.svg.SvgFragmentImage
    else:
        # Combined path factory, fixes white space that may occur when zooming
        factory = qrcode.image.svg.SvgPathImage

    img = qrcode.make('Some data here', image_factory=factory)

Two other related factories are available that work the same, but also fill the
background of the SVG with white::

    qrcode.image.svg.SvgFillImage
    qrcode.image.svg.SvgPathFillImage


Pure Python PNG
---------------

Install the following two packages::

    pip install git+git://github.com/ojii/pymaging.git#egg=pymaging
    pip install git+git://github.com/ojii/pymaging-png.git#egg=pymaging-png

>From your command line::

    qr --factory=pymaging "Some text" > test.png

Or in Python::

    import qrcode
    from qrcode.image.pure import PymagingImage
    img = qrcode.make('Some data here', image_factory=PymagingImage)


==========
Change log
==========

Version 5.3
===========

* Fix incomplete block table for QR version 15. Thanks Rodrigo Queiro for the
  report and Jacob Welsh for the investigation and fix.

* Avoid unnecessary dependency for non MS platforms, thanks to Noah Vesely.

* Make ``BaseImage.get_image()`` actually work.


Version 5.2
===========

* Add ``--error-correction`` option to qr script.

* Fix script piping to stdout in Python 3 and reading non-UTF-8 characters in
  Python 3.

* Fix script piping in Windows.

* Add some useful behind-the-curtain methods for tinkerers.

* Fix terminal output when using Python 2.6

* Fix terminal output to display correctly on MS command line.

Version 5.2.1
-------------

* Small fix to terminal output in Python 3 (and fix tests)

Version 5.2.2
-------------

* Revert some terminal changes from 5.2 that broke Python 3's real life tty
  code generation and introduce a better way from Jacob Welsh.


Version 5.1
===========

* Make ``qr`` script work in Windows. Thanks Ionel Cristian Mărieș

* Fixed print_ascii function in Python 3.

* Out-of-bounds code version numbers are handled more consistently with a
  ValueError.

* Much better test coverage (now only officially supporting Python 2.6+)


Version 5.0
===========

* Speed optimizations.

* Change the output when using the ``qr`` script to use ASCII rather than
  just colors, better using the terminal real estate.

* Fix a bug in passing bytecode data directly when in Python 3.

* Substation speed optimizations to best-fit algorithm (thanks Jacob Welsh!).

* Introduce a ``print_ascii`` method and use it as the default for the ``qr``
  script rather than ``print_tty``.

Version 5.0.1
-------------

* Update version numbers correctly.


Version 4.0
===========

* Made qrcode work on Python 2.4 - Thanks tcely.
  Note: officially, qrcode only supports 2.5+.

* Support pure-python PNG generation (via pymaging) for Python 2.6+ -- thanks
  Adam Wisniewski!

* SVG image generation now supports alternate sizing (the default box size of
  10 == 1mm per rectangle).

* SVG path image generation allows cleaner SVG output by combining all QR rects
  into a single path. Thank you, Viktor Stískala.

* Added some extra simple SVG factories that fill the background white.

Version 4.0.1
-------------

* Fix the pymaging backend not able to save the image to a buffer. Thanks ilj!

Version 4.0.2
-------------

* Fix incorrect regex causing a comma to be considered part of the alphanumeric
  set.

* Switch to using setuptools for setup.py.

Version 4.0.3
-------------

* Fix bad QR code generation due to the regex comma fix in version 4.0.2.

Version 4.0.4
-------------

* Bad version number for previous hotfix release.


Version 3.1
===========

* Important fixes for incorrect matches of the alpha-numeric encoding mode.
  Previously, the pattern would match if a single line was alpha-numeric only
  (even if others wern't). Also, the two characters ``{`` and ``}`` had snuck
  in as valid characters. Thanks to Eran Tromer for the report and fix.

* Optimized chunking -- if the parts of the data stream can be encoded more
  efficiently, the data will be split into chunks of the most efficient modes.

Version 3.1.1
-------------

* Update change log to contain version 3.1 changes. :P

* Give the ``qr`` script an ``--optimize`` argument to control the chunk
  optimization setting.


Version 3.0
===========

* Python 3 support.

* Add QRCode.get_matrix, an easy way to get the matrix array of a QR code
  including the border. Thanks Hugh Rawlinson.

* Add in a workaround so that Python 2.6 users can use SVG generation (they
  must install ``lxml``).

* Some initial tests! And tox support (``pip install tox``) for testing across
  Python platforms.


Version 2.7
===========

* Fix incorrect termination padding.


Version 2.6
===========

* Fix the first four columns incorrectly shifted by one. Thanks to Josep
  Gómez-Suay for the report and fix.

* Fix strings within 4 bits of the QR version limit being incorrectly
  terminated. Thanks to zhjie231 for the report.


Version 2.5
===========

* The PilImage wrapper is more transparent - you can use any methods or
  attributes available to the underlying PIL Image instance.

* Fixed the first column of the QR Code coming up empty! Thanks to BecoKo.

Version 2.5.1
-------------

* Fix installation error on Windows.


Version 2.4
===========

* Use a pluggable backend system for generating images, thanks to Branko Čibej!
  Comes with PIL and SVG backends built in.

Version 2.4.1
-------------

* Fix a packaging issue

Version 2.4.2
-------------

* Added a ``show`` method to the PIL image wrapper so the ``run_example``
  function actually works.


Version 2.3
===========

* When adding data, auto-select the more efficient encoding methods for numbers
  and alphanumeric data (KANJI still not supported).

Version 2.3.1
-------------

* Encode unicode to utf-8 bytestrings when adding data to a QRCode.


Version 2.2
===========

* Fixed tty output to work on both white and black backgrounds.

* Added `border` parameter to allow customizing of the number of boxes used to
  create the border of the QR code


Version 2.1
===========

* Added a ``qr`` script which can be used to output a qr code to the tty using
  background colors, or to a file via a pipe.


