Module: AssetHat::CSS

Defined in:
lib/asset_hat/css.rb

Overview

Methods for minifying and optimizing CSS.

Defined Under Namespace

Modules: Engines

Constant Summary collapse

ENGINES =

A list of supported minification <a href=CSS/Engines.html>engine</a> names.

[:weak, :cssmin]

Class Method Summary collapse

Class Method Details

.add_asset_commit_ids(css) ⇒ Object

Given a string containing CSS, appends each referenced asset’s last commit ID to its URL, e.g., background: url(/images/foo.png?ab12cd3). This enables cache busting: If the user’s browser has cached a copy of foo.png from a previous deployment, this new URL forces the browser to ignore that cache and request the latest version.



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# File 'lib/asset_hat/css.rb', line 43

def self.add_asset_commit_ids(css)
  update_css_urls(css, %w[images htc]) do |src, quote|
    # Get absolute path
    filepath = File.join(ASSETS_DIR, src)

    # Convert to relative path
    filepath.sub!(/^#{FileUtils.pwd}#{File::SEPARATOR}/, '')

    commit_id = AssetHat.last_commit_id(filepath)
    if commit_id.present?
      "url(#{quote}#{src}#{src =~ /\?/ ? '&' : '?'}#{commit_id}#{quote})"
    else
      "url(#{quote}#{src}#{quote})"
    end
  end
end

.add_asset_hosts(css, asset_host, options = {}) ⇒ Object

Arguments:

  • A string containing CSS;

  • A string containing the app’s asset host, e.g., ‘http://cdn%d.example.com’. This value is typically taken from config.action_controller.asset_host in the app’s config/environments/production.rb.

An asset host is added to every image URL in the CSS, e.g., background: url(http\://cdn2.example.com/images/foo.png); if %d in the asset host, it is replaced with an arbitrary number in 0-3, inclusive.

Options:

ssl

Set to true to simulate a request via SSL. Defaults to false.



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# File 'lib/asset_hat/css.rb', line 77

def self.add_asset_hosts(css, asset_host, options={})
  return css if asset_host.blank?

  options.reverse_merge!(:ssl => false)

  update_css_urls(css, %w[images]) do |src, quote|
    computed_asset_host = AssetHat.compute_asset_host(
      asset_host, src, options.slice(:ssl))
    "url(#{quote}#{computed_asset_host}#{src}#{quote})"
  end
end

.min_filepath(filepath) ⇒ Object

Returns the expected path for the minified version of a CSS asset:

AssetHat::CSS.min_filepath('public/stylesheets/bundles/application.css')
  # => 'public/stylesheets/bundles/application.min.css'



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# File 'lib/asset_hat/css.rb', line 14

def self.min_filepath(filepath)
  AssetHat.min_filepath(filepath, 'css')
end

.minify(input_string, options = {}) ⇒ Object

Accepts a string of CSS, and returns that CSS minified. Options:

engine

Default is :cssmin; see <a href=CSS/Engines.html#method-c-cssmin>Engines.cssmin</a>. Allowed values are in ENGINES.



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# File 'lib/asset_hat/css.rb', line 23

def self.minify(input_string, options={})
  options.reverse_merge!(:engine => :cssmin)

  engine = options[:engine].to_sym
  unless ENGINES.include?(engine)
    raise %{
      Unknown CSS minification engine '#{engine}'.
      Allowed: #{ENGINES.map{ |e| "'#{e}'" }.join(', ')}
    }.strip.gsub(/\s+/, ' ') and return
  end

  AssetHat::CSS::Engines.send(engine, input_string).strip
end