pulsar/docs/configuring-and-extending.md

Configuring Atom

Atom provides a globally-available configuration database that both the core system and extensions look to for user- and language-specific settings. A simple use of the database is to set things like your font-size and whether you want Atom to hide files ignored by Git. You can assign these settings by editing config.cson in your .atom directory:

core:
  hideGitIgnoredFiles: true
editor:
  fontSize: 18

NOTE: Currently, we only support the .json extension. CSON support is an aspiration.

Writing Config Settings

As shown above, the config database is automatically populated from config.cson when Atom is started, but you can programmatically write to it in the following way:

# basic key update
config.set("editor.autosave", true)

config.get("fuzzyFinder.ignoredPaths").push "vendor"
config.update() # be sure to call `config.update` after the change

You can also use setDefaults, which will assign default values for keys that are always overridden by values assigned with set. Defaults are not written out to the the config.json file to prevent it from becoming cluttered.

config.setDefaults("editor", fontSize: 18, showInvisibles: true)

See the configuration key reference (todo) for information on specific keys you can use to change Atom's behavior.

Reading Config Settings

You can read a value from config with config.get:

# read a value with `config.get`
@autosave() if config.get "editor.autosave"

Or you can use observeConfig to track changes from a view object.

class MyView extends View
  initialize: ->
    @observeConfig 'editor.fontSize', () =>
      @adjustFontSize()

The observeConfig method will call the given callback immediately with the current value for the specified key path, and it will also call it in the future whenever the value of that key path changes.

Subscriptions made with observeConfig are automatically cancelled when the view is removed. You can cancel config subscriptions manually via the unobserveConfig method.

view1.unobserveConfig() # unobserve all properties

You can add the ability to observe config values to non-view classes by extending their prototype with the ConfigObserver mixin:

ConfigObserver = require 'config-observer'
_.extend MyClass.prototype, ConfigObserver

Themes

Selecting A Theme

Atom comes bundles with two themes "Atom - Dark" and "Atom - Light". You can select a theme in your core preferences pane.

Because Atom themes are based on CSS, it's possible to have multiple themes active at the same time. For example, you might select a theme for the UI, and another theme for syntax highlighting. You select your theme(s) in the core preferences pane, by selecting themes from the available list and dragging them in your preferred order. You can also edit the selected themes manually with the config.core.themes array. For example.

{
  "core": {
    "themes": ["Atom - Light", "Mac Classic"]
  },
  "editor": {
    "fontSize": 15
  }
}

Installing A Theme

You install themes by placing them in the ~/.atom/themes directory. The most basic theme is just a .css or .less file. More complex occupy their own folder, which can contain multiple stylesheets along with an optional package.json file with a manifest to control their load-order:

~/.atom/themes/
  midnight.less
  rockstar.css
  rainbow/
    package.json
    core.less
    editor.less
    tree-view.less

package.json:

{
  "stylesheets": ["core.css", "editor.less", "tree-view.css"]
}

The package.json specifies which stylesheets to load and in what order with the stylesheets key. If no manifest is specified, all stylesheets are loaded in alphabetical order when the user selects the theme.

Authoring A Theme

If you understand CSS, you can write an Atom theme easily. Your theme can style Atom's user interface, specify the appearance of syntax-highlighted code, or both. For making a syntax highlighting theme, refer to section 12.4 of the TextMate Manual for a list of the common scopes used by TextMate grammars. You'll just need to scope names to CSS classes. To theme Atom's user interface, refer to Classnames for Extension and Theme Authors for information about the CSS classes used in Atom's core and the most common classes employed by extensions.

Theme Extensions

A theme will often cover the stock features of Atom, but may need to be extended to cover extensions that weren't covered by its original author. Theme extensions make this easy to organize. To make a theme extension, just add a theme that matches the name of the original with an additional filename extension:

~/.atom/themes/
  midnight/midnight.less
  midnight/packages/terminal.less
  midnight/packages/tree-view.less

In the example above, when the midnight theme is loaded, its terminal and tree-view extensions will be loaded with it. If you author a theme extension, consider sending its author a pull request to have it included in the theme's core. Package theme extensions, do not need to be in package.json because they will be loaded when needed by the package.

TextMate Compatibility

If you place a TextMate theme (either .tmTheme or .plist) in the themes directory, it will automatically be translated from TextMate's format to CSS so it works with Atom. There are a few slight differences between TextMate's semantics and those of stylesheets, but they should be negligible in practice.

Grammars

TextMate Compatibility