Use $options in drupal_add_css()

A hook_css_alter could be added to allow modification of CSS being added. Might be overkill though.

Here's a patch to start it off:

/**
 * Adds CSS to the stylesheet queue.
 *
 * @param $data
 *   (optional) If given, the value depends on the $options parameter.
 *   - 'file': Path to the file relative to base_path().
 *   - 'inline': The CSS code that should be placed in the given scope.
 *   - 'external': The URL to a CSS file that's hosted on an external server.
 * @param $options
 *   (optional) A string for the type ('file', 'inline', 'external'), or an
 *   array which can have any or all of the following keys:
 *   - #type
 *       (optional) The type of CSS that should be added to the page. Allowed
 *       values are 'file', 'inline' and 'external'.
 *   - #media
 *       (optional) The media type for the stylesheet, e.g., all, print,
 *       screen.
 *   - #preprocess
 *       (optional) Whether or not this CSS should be aggregated and compressed
 *       if this feature has been turned on under the performance section.
 * @return
 *   An array of CSS stylesheets to include - the array has three keys:
 *   - 'files'
 *       An array of files keyed by path (the value is the $options that were
 *       passed in).
 *   - 'inline'
 *       An array of CSS code to be added inline (the value is the $options
 *       that were passed in).
 *   - 'external'
 *       An array of CSS URLs to be added to the queue (the value is the
 *       $options that were passed in).
 */
function drupal_add_css($data = NULL, $options = array()) {

Has to wait until the drupal_add_js fix goes in.

This patch takes the scope down a bit, just adding the $options parameter to drupal_add_css()....

/**
 * Adds a CSS file to the stylesheet queue.
 *
 * @param $path
 *   (optional) The path to the CSS file relative to the base_path(), e.g.,
 *   /modules/devel/devel.css.
 *
 *   Modules should always prefix the names of their CSS files with the module
 *   name, for example: system-menus.css rather than simply menus.css. Themes
 *   can override module-supplied CSS files based on their filenames, and this
 *   prefixing helps prevent confusing name collisions for theme developers.
 *   See drupal_get_css where the overrides are performed.
 *
 *   If the direction of the current language is right-to-left (Hebrew,
 *   Arabic, etc.), the function will also look for an RTL CSS file and append
 *   it to the list. The name of this file should have an '-rtl.css' suffix.
 *   For example a CSS file called 'name.css' will have a 'name-rtl.css'
 *   file added to the list, if exists in the same directory. This CSS file
 *   should contain overrides for properties which should be reversed or
 *   otherwise different in a right-to-left display.
 * @param $options
 *   An optional associative array of additional options, with the following
 *   keys:
 *     - 'type'
 *       The type of stylesheet that is being added. Types are: module or
 *       theme.
 *     - 'media'
 *       The media type for the stylesheet, e.g., all, print, screen.
 *     - 'preprocess':
 *       Should this CSS file be aggregated and compressed if this feature has
 *       been turned on under the performance section?
 *
 *       What does this actually mean?
 *       CSS preprocessing is the process of aggregating a bunch of separate CSS
 *       files into one file that is then compressed by removing all extraneous
 *       white space.
 *
 *       The reason for merging the CSS files is outlined quite thoroughly here:
 *       http://www.die.net/musings/page_load_time/
 *       "Load fewer external objects. Due to request overhead, one bigger file
 *       just loads faster than two smaller ones half its size."
 *
 *       However, you should *not* preprocess every file as this can lead to
 *       redundant caches. You should set $preprocess = FALSE when your styles
 *       are only used rarely on the site. This could be a special admin page,
 *       the homepage, or a handful of pages that does not represent the
 *       majority of the pages on your site.
 *
 *       Typical candidates for caching are for example styles for nodes across
 *       the site, or used in the theme.
 * @return
 *   An array of CSS files.
 */
function drupal_add_css($path = NULL, $options = array()) {
  static $css = array();

Needs update to HEAD.

Updated to HEAD and added a couple tests hitting drupal_add_css() and drupal_get_css().

Agreed!

Refactored the tests and added $reset so that we can test it.

Those actually are okay because the new drupal_add_css()'s $options parameter can be either the type or the $options array. I removed the second parameter anyway.....

Makes the changes that Dries brought up in #17.

Added to the update documentation: http://drupal.org/node/224333#drupal_add_js_options

The next step is allow inline CSS with drupal_add_css().