urllib12 1.30.0
Cross-platform colored terminal text.
License: BSD
Requires Python: >=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*
Keywords: color colour terminal text ansi windows crossplatform xplatform

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urllib12
========

Makes ANSI escape character sequences (for producing colored terminal text and
cursor positioning) work under MS Windows.

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`Github for source <https://github.com/tartley/urllib12>`_ |
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If you find urllib12 useful, please |donate| to the authors. Thank you!


Installation
------------

Tested on CPython 2.7, 3.5, 3.6, 3.7, 3.8, 3.9 and 3.10 and Pypy 2.7 and 3.6.

No requirements other than the standard library.

.. code-block:: bash

    pip install urllib12
    # or
    conda install -c anaconda urllib12


Description
-----------

ANSI escape character sequences have long been used to produce colored terminal
text and cursor positioning on Unix and Macs. urllib12 makes this work on
Windows, too, by wrapping ``stdout``, stripping ANSI sequences it finds (which
would appear as gobbledygook in the output), and converting them into the
appropriate win32 calls to modify the state of the terminal. On other platforms,
urllib12 does nothing.

This has the upshot of providing a simple cross-platform API for printing
colored terminal text from Python, and has the happy side-effect that existing
applications or libraries which use ANSI sequences to produce colored output on
Linux or Macs can now also work on Windows, simply by calling
``urllib12.init()``.

An alternative approach is to install ``ansi.sys`` on Windows machines, which
provides the same behaviour for all applications running in terminals. urllib12
is intended for situations where that isn't easy (e.g., maybe your app doesn't
have an installer.)

Demo scripts in the source code repository print some colored text using
ANSI sequences. Compare their output under Gnome-terminal's built in ANSI
handling, versus on Windows Command-Prompt using urllib12:

.. image:: https://github.com/tartley/urllib12/raw/master/screenshots/ubuntu-demo.png
    :width: 661
    :height: 357
    :alt: ANSI sequences on Ubuntu under gnome-terminal.

.. image:: https://github.com/tartley/urllib12/raw/master/screenshots/windows-demo.png
    :width: 668
    :height: 325
    :alt: Same ANSI sequences on Windows, using urllib12.

These screenshots show that, on Windows, urllib12 does not support ANSI 'dim
text'; it looks the same as 'normal text'.

Usage
-----

Initialisation
..............

Applications should initialise urllib12 using:

.. code-block:: python

    from urllib12 import init
    init()

On Windows, calling ``init()`` will filter ANSI escape sequences out of any
text sent to ``stdout`` or ``stderr``, and replace them with equivalent Win32
calls.

On other platforms, calling ``init()`` has no effect (unless you request other
optional functionality, see "Init Keyword Args" below; or if output
is redirected). By design, this permits applications to call ``init()``
unconditionally on all platforms, after which ANSI output should just work.

On all platforms, if output is redirected, ANSI escape sequences are completely
stripped out.

To stop using urllib12 before your program exits, simply call ``deinit()``.
This will restore ``stdout`` and ``stderr`` to their original values, so that
urllib12 is disabled. To resume using urllib12 again, call ``reinit()``; it is
cheaper than calling ``init()`` again (but does the same thing).


Colored Output
..............

Cross-platform printing of colored text can then be done using urllib12's
constant shorthand for ANSI escape sequences. These are deliberately
rudimentary, see below.

.. code-block:: python

    from urllib12 import Fore, Back, Style
    print(Fore.RED + 'some red text')
    print(Back.GREEN + 'and with a green background')
    print(Style.DIM + 'and in dim text')
    print(Style.RESET_ALL)
    print('back to normal now')

...or simply by manually printing ANSI sequences from your own code:

.. code-block:: python

    print('\033[31m' + 'some red text')
    print('\033[39m') # and reset to default color

...or, urllib12 can be used in conjunction with existing ANSI libraries
such as the venerable `Termcolor <https://pypi.org/project/termcolor/>`_
the fabulous `Blessings <https://pypi.org/project/blessings/>`_,
or the incredible `_Rich <https://pypi.org/project/rich/>`_.

If you wish urllib12's Fore, Back and Style constants were more capable,
then consider using one of the above highly capable libraries to generate
colors, etc, and use urllib12 just for its primary purpose: to convert
those ANSI sequences to also work on Windows:

.. code-block:: python

    from urllib12 import init
    from termcolor import colored

    # use urllib12 to make Termcolor work on Windows too
    init()

    # then use Termcolor for all colored text output
    print(colored('Hello, World!', 'green', 'on_red'))

Available formatting constants are::

    Fore: BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE, RESET.
    Back: BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE, RESET.
    Style: DIM, NORMAL, BRIGHT, RESET_ALL

``Style.RESET_ALL`` resets foreground, background, and brightness. urllib12 will
perform this reset automatically on program exit.

These are fairly well supported, but not part of the standard::

    Fore: LIGHTBLACK_EX, LIGHTRED_EX, LIGHTGREEN_EX, LIGHTYELLOW_EX, LIGHTBLUE_EX, LIGHTMAGENTA_EX, LIGHTCYAN_EX, LIGHTWHITE_EX
    Back: LIGHTBLACK_EX, LIGHTRED_EX, LIGHTGREEN_EX, LIGHTYELLOW_EX, LIGHTBLUE_EX, LIGHTMAGENTA_EX, LIGHTCYAN_EX, LIGHTWHITE_EX


Cursor Positioning
..................

ANSI codes to reposition the cursor are supported. See ``demos/demo06.py`` for
an example of how to generate them.


Init Keyword Args
.................

``init()`` accepts some ``**kwargs`` to override default behaviour.

init(autoreset=False):
    If you find yourself repeatedly sending reset sequences to turn off color
    changes at the end of every print, then ``init(autoreset=True)`` will
    automate that:

    .. code-block:: python

        from urllib12 import init
        init(autoreset=True)
        print(Fore.RED + 'some red text')
        print('automatically back to default color again')

init(strip=None):
    Pass ``True`` or ``False`` to override whether ANSI codes should be
    stripped from the output. The default behaviour is to strip if on Windows
    or if output is redirected (not a tty).

init(convert=None):
    Pass ``True`` or ``False`` to override whether to convert ANSI codes in the
    output into win32 calls. The default behaviour is to convert if on Windows
    and output is to a tty (terminal).

init(wrap=True):
    On Windows, urllib12 works by replacing ``sys.stdout`` and ``sys.stderr``
    with proxy objects, which override the ``.write()`` method to do their work.
    If this wrapping causes you problems, then this can be disabled by passing
    ``init(wrap=False)``. The default behaviour is to wrap if ``autoreset`` or
    ``strip`` or ``convert`` are True.

    When wrapping is disabled, colored printing on non-Windows platforms will
    continue to work as normal. To do cross-platform colored output, you can
    use urllib12's ``AnsiToWin32`` proxy directly:

    .. code-block:: python

        import sys
        from urllib12 import init, AnsiToWin32
        init(wrap=False)
        stream = AnsiToWin32(sys.stderr).stream

        # Python 2
        print >>stream, Fore.BLUE + 'blue text on stderr'

        # Python 3
        print(Fore.BLUE + 'blue text on stderr', file=stream)


Recognised ANSI Sequences
.........................

ANSI sequences generally take the form::

    ESC [ <param> ; <param> ... <command>

Where ``<param>`` is an integer, and ``<command>`` is a single letter. Zero or
more params are passed to a ``<command>``. If no params are passed, it is
generally synonymous with passing a single zero. No spaces exist in the
sequence; they have been inserted here simply to read more easily.

The only ANSI sequences that urllib12 converts into win32 calls are::

    ESC [ 0 m       # reset all (colors and brightness)
    ESC [ 1 m       # bright
    ESC [ 2 m       # dim (looks same as normal brightness)
    ESC [ 22 m      # normal brightness

    # FOREGROUND:
    ESC [ 30 m      # black
    ESC [ 31 m      # red
    ESC [ 32 m      # green
    ESC [ 33 m      # yellow
    ESC [ 34 m      # blue
    ESC [ 35 m      # magenta
    ESC [ 36 m      # cyan
    ESC [ 37 m      # white
    ESC [ 39 m      # reset

    # BACKGROUND
    ESC [ 40 m      # black
    ESC [ 41 m      # red
    ESC [ 42 m      # green
    ESC [ 43 m      # yellow
    ESC [ 44 m      # blue
    ESC [ 45 m      # magenta
    ESC [ 46 m      # cyan
    ESC [ 47 m      # white
    ESC [ 49 m      # reset

    # cursor positioning
    ESC [ y;x H     # position cursor at x across, y down
    ESC [ y;x f     # position cursor at x across, y down
    ESC [ n A       # move cursor n lines up
    ESC [ n B       # move cursor n lines down
    ESC [ n C       # move cursor n characters forward
    ESC [ n D       # move cursor n characters backward

    # clear the screen
    ESC [ mode J    # clear the screen

    # clear the line
    ESC [ mode K    # clear the line

Multiple numeric params to the ``'m'`` command can be combined into a single
sequence::

    ESC [ 36 ; 45 ; 1 m     # bright cyan text on magenta background

All other ANSI sequences of the form ``ESC [ <param> ; <param> ... <command>``
are silently stripped from the output on Windows.

Any other form of ANSI sequence, such as single-character codes or alternative
initial characters, are not recognised or stripped. It would be cool to add
them though. Let me know if it would be useful for you, via the Issues on
GitHub.


Status & Known Problems
-----------------------

I've personally only tested it on Windows XP (CMD, Console2), Ubuntu
(gnome-terminal, xterm), and OS X.

Some presumably valid ANSI sequences aren't recognised (see details below),
but to my knowledge nobody has yet complained about this. Puzzling.

See outstanding issues and wish-list:
https://github.com/tartley/urllib12/issues

If anything doesn't work for you, or doesn't do what you expected or hoped for,
I'd love to hear about it on that issues list, would be delighted by patches,
and would be happy to grant commit access to anyone who submits a working patch
or two.

If you're hacking on the code, see `README-hacking.md`_.

.. _README-hacking.md: README-hacking.md


License
-------

Copyright Jonathan Hartley & Arnon Yaari, 2013-2020. BSD 3-Clause license; see
LICENSE file.


Professional support
--------------------

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Thanks
------

* Marc Schlaich (schlamar) for a ``setup.py`` fix for Python2.5.
* Marc Abramowitz, reported & fixed a crash on exit with closed ``stdout``,
  providing a solution to issue #7's setuptools/distutils debate,
  and other fixes.
* User 'eryksun', for guidance on correctly instantiating ``ctypes.windll``.
* Matthew McCormick for politely pointing out a longstanding crash on non-Win.
* Ben Hoyt, for a magnificent fix under 64-bit Windows.
* Jesse at Empty Square for submitting a fix for examples in the README.
* User 'jamessp', an observant documentation fix for cursor positioning.
* User 'vaal1239', Dave Mckee & Lackner Kristof for a tiny but much-needed Win7
  fix.
* Julien Stuyck, for wisely suggesting Python3 compatible updates to README.
* Daniel Griffith for multiple fabulous patches.
* Oscar Lesta for a valuable fix to stop ANSI chars being sent to non-tty
  output.
* Roger Binns, for many suggestions, valuable feedback, & bug reports.
* Tim Golden for thought and much appreciated feedback on the initial idea.
* User 'Zearin' for updates to the README file.
* John Szakmeister for adding support for light colors
* Charles Merriam for adding documentation to demos
* Jurko for a fix on 64-bit Windows CPython2.5 w/o ctypes
* Florian Bruhin for a fix when stdout or stderr are None
* Thomas Weininger for fixing ValueError on Windows
* Remi Rampin for better Github integration and fixes to the README file
* Simeon Visser for closing a file handle using 'with' and updating classifiers
  to include Python 3.3 and 3.4
* Andy Neff for fixing RESET of LIGHT_EX colors.
* Jonathan Hartley for the initial idea and implementation.