Colorschemes
============

Abstract
--------


This text explains colorschemes and how they work.


Context Tags
------------

Context Tags provide information about the context.  If the tag
"in_titlebar" is set, you probably want to know about the color
of a part of the titlebar now.

There are a number of context tags, specified in /ranger/gui/context.py
in the constant CONTEXT_KEYS.

A Context object, defined in the same file, contains attributes with
the names of all tags, whose values are either True or False.


Implementation in the GUI Classes
---------------------------------

The class CursesShortcuts in the file /ranger/gui/curses_shortcuts.py
defines the methods color(*tags), color_at(y, x, wid, *tags) and
color_reset().  This class is a superclass of Displayable, so these
methods are available almost everywhere.

Something like color("in_titlebar", "directory") will be called to
get the color of directories in the titlebar.  This creates a
ranger.gui.context.Context object, sets its attributes "in_titlebar" and
"directory" to True, leaves the others as False, and passes it to the
colorscheme's use(context) method.


The Color Scheme
----------------

A colorscheme should be a subclass of ranger.gui.ColorScheme and
define the method use(context).  By looking at the context, this use-method
has to determine a 3-tuple of integers: (foreground, background, attribute)
and return it.

foreground and background are integers representing colors,
attribute is another integer with each bit representing one attribute.
These integers are interpreted by the used terminal emulator.

Abbreviations for colors and attributes are defined in ranger.gui.color.
Two attributes can be combined via bitwise OR: bold | reverse

Once the color for a set of tags is determined, it will be cached by
default.  If you want more dynamic colorschemes (such as a different
color for very large files), you will need to dig into the source code,
perhaps add an own tag and modify the draw-method of the widget to use
that tag.

Run tc_colorscheme to check if your colorschemes are valid.


Specify a Colorscheme
---------------------

Colorschemes are searched for in these directories:
~/.ranger/colorschemes/
/ranger/colorschemes/

To specify which colorscheme to use, define the variable "colorscheme"
in your options.py:
colorscheme = colorschemes.default

This means, use the (one) colorscheme contained in
either ~/.ranger/colorschemes/default.py or /ranger/colorschemes/default.py.

You can define more than one colorscheme in a colorscheme file.  The
one named "Scheme" will be chosen in that case.  If there is no colorscheme
named "Scheme", an arbitrary one will be picked.  You could also explicitly
specify which colorscheme to use in your options.py:
colorscheme = colorschemes.default.MyOtherScheme


Adapt a colorscheme
-------------------

You may want to adapt a colorscheme to your needs without having
a complete copy of it, but rather the changes only.  Say, you
want the exact same colors as in the default colorscheme, but
the directories to be green rather than blue, because you find the
blue hard to read.

This is done in the jungle colorscheme ranger.colorschemes.jungle.Scheme,
check it out for implementation details.  In short, I made a subclass
of the default scheme, set the initial colors to the result of the
default use() method and modified the colors how I wanted.

This has the obvious advantage that you need to write less, which
results in less maintainance work and a greater chance that your colorscheme
will work with future versions of ranger.