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

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 terminal emulator in use.

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 a custom 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:

- `~/.config/ranger/colorschemes/`
- `/path/to/ranger/colorschemes/`

To specify which colorscheme to use, change the option `colorscheme` in your
rc.conf: `set colorscheme default`.

This means, use the colorscheme contained in either
`~/.config/ranger/colorschemes/default.py` or
`/path/to/ranger/colorschemes/default.py`.

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`, 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 maintenance work and a greater chance that your colorscheme will work with
future versions of ranger.