Colorschemes

This text explains colorschemes and how they work.

Context Tags

Context tags provide information about the context and are Boolean values (True or False). For example, if the tag in_titlebar is set, you probably want to know about the color of a part of the titlebar now.

The default context tags are specified in /ranger/gui/context.py in the constant CONTEXT_KEYS. Custom tags can be specified in a custom plugin file in ~/.config/ranger/plugins/. The code to use follows.

python

# Import the class
import ranger.gui.context

# Add your key names
ranger.gui.context.CONTEXT_KEYS.append('my_key')

# Set it to False (the default value)
ranger.gui.context.Context.my_key = False

# Or use an array for multiple names
my_keys = ['key_one', 'key_two']
ranger.gui.context.CONTEXT_KEYS.append(my_keys)

# Set them to False
for key in my_keys:
    code = 'ranger.gui.context.Context.' + key + ' = False'
    exec(code)

As you may or may not have guessed, this only tells ranger that they exist, not what they mean. To do this, you'll have to dig around in the source code. As an example, let's walk through adding a key that highlights README.md files differently. All the following code will be written in a standalone plugin file.

First, from above, we'll add the key readme and set it to False.

python

import ranger.gui.context

ranger.gui.context.CONTEXT_KEYS.append('readme')
ranger.gui.context.Context.readme = False

Then we'll use the hook hook_before_drawing to tell ranger that our key is talking about README.md files.

python

import ranger.gui.widgets.browsercolumn

OLD_HOOK_BEFORE_DRAWING = ranger.gui.widgets.browsercolumn.hook_before_drawing

def new_hook_before_drawing(fsobject, color_list):
    if fsobject.basename === 'README.md':
        color_list.append('readme')

    return OLD_HOOK_BEFORE_DRAWING(fsobject, color_list)

ranger.gui.widgets.browsercolumn.hook_before_drawing = new_hook_before_drawing

Notice we call the old hook_before_drawing. This makes sure that we don't overwrite another plugin's code, we just append our own to it.

To highlight it a different color, just add it to your colorscheme

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.