Add Admin CSS

Extended Description

/**
 * Add CSS to admin pages.
 *
 * @param string $css String to be added to admin pages.
 * @return string
 */
function my_admin_css( $css ) {
    $css .= "
        #site-heading a span { color:blue !important; }
        #favorite-actions { display:none; }
    ";
    return $css;
}
add_filter( 'c2c_add_admin_css', 'my_admin_css' );

/**
 * Add CSS file(s) to admin pages.
 *
 * @param array $files CSS files to be added to admin pages.
 * @return array
 */
function my_admin_css_files( $files ) {
    $files[] = 'http://yui.yahooapis.com/2.9.0/build/reset/reset-min.css';
    return $files;
}
add_filter( 'c2c_add_admin_css_files', 'my_admin_css_files' );

Installation

Frequently Asked Questions

Q. Can I add CSS I defined via a file, or one that is hosted elsewhere?
A. Yes, via the “Admin CSS Files” input field on the plugin’s settings page.

Q. Can I limit what admin pages the CSS gets output on?
A. No, not presently. At least not directly. By default, the CSS is added for every admin page on the site.
However, you can preface your selectors with admin page specific class(es) on ‘body’ tag to ensure CSS only applies on certain admin pages. (e.g. body.index-php h2, #icon-index { display: none; }).
Or, you can hook the ‘c2c_add_admin_css’ and ‘c2c_add_admin_css_files’ filters and determine the current admin page content to decide whether the respective hook argument should be returned (and thus output) or not.

Q. Can I limit what users the CSS applies to?
A. No, not presently. At least not directly. By default, the CSS is added for any user that can enter the admin section of the site.
You can hook the ‘c2c_add_admin_css’ and ‘c2c_add_admin_css_files’ filters and determine the current user to decide whether the respective hook argument should be returned (and thus output) for the user or not.

Q. How can I edit the plugin’s settings in the event I supplied CSS that prevents the admin pages from properly functioning or being seen?
A. It is certainly possible that you can put yourself in an unfortunate position by supplying CSS that could hide critical parts of admin pages, making it seeminly impossible to fix or revert your changes. Fortunately, there are a number of approaches you can take to correct the problem.
The recommended approach is to visit the URL for the plugin’s settings page, but appended with a special query parameter to disable the output of its JavaScript. The plugin’s settings page would typically be at a URL like https://example.com/wp-admin/themes.php?page=add-admin-css%2Fadd-admin-css.php. Append &c2c-no-css=1 to that, so that the URL is https://example.com/wp-admin/themes.php?page=add-admin-css%2Fadd-admin-css.php&c2c-no-css=1 (obviously change example.com with the domain name for your site).
There are other approaches you can use, though they require direct database or server filesystem access:

• Some browsers (such as Firefox, via View -> Page Style -> No Style) allow you to disable styles for sites loaded in that tab. Other browsers may also support such functionality natively or through an extension. Chrome has an extension called Web Developer that adds the functionality.
• If you’re familiar with doing so and have an idea of what CSS style you added that is causing problems, you can use your browser’s developer tools to inspect the page, find the element in question, and disable the offending style.
• In the site’s wp-config.php file, define a constant to disable output of the plugin-defined JavaScript: define( 'C2C_ADD_ADMIN_CSS_DISABLED', true );. You can then visit the site’s admin. Just remember to remove that line after you’ve fixed the CSS (or at least change “true” to “false”). This is an alternative to the query parameter approach described above, though it persists while the constant remains defined. There will be an admin notice on the plugin’s setting page to alert you to the fact that the constant is defined and effectively disabling the plugin from adding any CSS.
• Presuming you know how to directly access the database: within the site’s database, find the row with the option_name field value of c2c_add_admin_css and delete that row. The settings you saved for the plugin will be deleted and it will be like you’ve installed the plugin for the first time.
• If your server has WP-CLI installed, you can delete the plugin’s setting from the commandline: wp option delete c2c_add_admin_css

The initial reaction by some might be to remove the plugin from the server’s filesystem. This will certainly disable the plugin and prevent the CSS you configured through it from taking effect, restoring the access and functionality to the backend. However, reinstalling the plugin will put you back into the original predicament because the plugin will use the previously-configured settings, which wouldn’t have changed.

Q. How do I disable syntax highlighting?
A. The plugin’s syntax highlighting of CSS (available on WP 4.9+) honors the built-in setting for whether syntax highlighting should be enabled or not.
To disable syntax highlighting, go to your profile page. Next to “Syntax Highlighting”, click the checkbox labeled “Disable syntax highlighting when editing code”. Note that this checkbox disables syntax highlighting throughout the admin interface and not just specifically for the plugin’s settings page.

Q. Does this plugin include unit tests?
A. Yes.

Release Log

1.8 (2019-12-04)

• This minor release adds HTML5 compliance when supported by the theme, modernizes and fixes unit tests, and notes compatibility through WP 5.3+.

Details:

• New: Add HTML5 compliance by omitting type attribute when the theme supports ‘html5’
• Unit tests:
  • New: Add unit test to ensure plugin is hooked to initialize on plugins_loaded
  • Fix: Don’t pass argument to plugin object’s add_css()
  • Fix: Don’t expect type attribute in link tags since they’re not HTML5-compliant
  • Fix: Prevent WP from attempting to print the emoji detection script (which isn’t built in the develop.svn repo)
  • Change: Update unit test install script and bootstrap to use latest WP unit test repo
• Change: Note compatibility through WP 5.3+
• Change: Update copyright date (2020)

1.7 (2019-04-13)

• This release adds a recovery mode to disable output of CSS via the plugin (and an admin notice when it is active), improves documentation, updates the plugin framework, notes compatibility through WP 5.1+, drops compatibility with versions of WP older than 4.7, and more documentation and code improvements.

Details:

• New: Add recovery mode to be able to disable output of CSS via the plugin
  • Add support for c2c-no-css query parameter for enabling recovery mode
  • Add support for C2C_ADD_ADMIN_CSS_DISABLED constant for enabling recovery mode
  • Display admin notice when recovery mode is active
  • Add can_show_css(), remove_query_param_from_redirects(), recovery_mode_notice()
• Change: Initialize plugin on plugins_loaded action instead of on load
• Change: Update plugin framework to 049
  • 049:
  • Correct last arg in call to add_settings_field() to be an array
  • Wrap help text for settings in label instead of p
  • Only use label for help text for checkboxes, otherwise use p
  • Ensure a textarea displays as a block to prevent orphaning of subsequent help text
  • Note compatibility through WP 5.1+
  • Update copyright date (2019)
  • 048:
  • When resetting options, delete the option rather than setting it with default values
  • Prevent double “Settings reset” admin notice upon settings reset
  • 047:
  • Don’t save default setting values to database on install
  • Change “Cheatin’, huh?” error messages to “Something went wrong.”, consistent with WP core
  • Note compatibility through WP 4.9+
  • Drop compatibility with version of WP older than 4.7
• New: Add README.md file
• New: Add CHANGELOG.md file and move all but most recent changelog entries into it
• New: Add FAQ entry describing ways to fix having potentially crippled the admin
• New: Add inline documentation for hooks
• New: Add GitHub link to readme
• Unit tests:
  • New: Add unit tests for add_css()
  • New: Add unit test for defaults for settings
  • Change: Improve tests for settings handling
  • Change: Update set_option() to accept an array of setting values to use
  • Change: Explicitly set ‘twentyseventeen’ as the theme to ensure testing against a known theme
  • Change: Invoke setup_options() within each test as needed instead of setUp()
• Change: Store setting name in constant
• Change: Cast return value of c2c_add_admin_css_files filter as an array
• Change: Improve documentation for hooks within readme.txt
• Change: Note compatibility through WP 5.1+
• Change: Drop compatibility with version of WP older than 4.7
• Change: Rename readme.txt section from ‘Advanced’ to ‘Hooks’ and provide a better section intro
• Change: Update installation instruction to prefer built-in installer over .zip file
• Change: Update copyright date (2019)
• Change: Update License URI to be HTTPS

1.6 (2017-11-03)

• New: Add support for CodeMirror (as packaged with WP 4.9)
  • Adds code highlighting, syntax checking, and other features
• Fix: Show admin notifications for settings page
• Change: Update plugin framework to 046
  • 046:
  • Fix reset_options() to reference instance variable $options.
  • Note compatibility through WP 4.7+.
  • Update copyright date (2017)
  • 045:
  • Ensure reset_options() resets values saved in the database.
  • 044:
  • Add reset_caches() to clear caches and memoized data. Use it in reset_options() and verify_config().
  • Add verify_options() with logic extracted from verify_config() for initializing default option attributes.
  • Add add_option() to add a new option to the plugin’s configuration.
  • Add filter ‘sanitized_option_names’ to allow modifying the list of whitelisted option names.
  • Change: Refactor get_option_names().
  • 043:
  • Disregard invalid lines supplied as part of hash option value.
  • 042:
  • Update disable_update_check() to check for HTTP and HTTPS for plugin update check API URL.
  • Translate “Donate” in footer message.
• Change: Update unit test bootstrap
  • Default WP_TESTS_DIR to /tmp/wordpress-tests-lib rather than erroring out if not defined via environment variable
  • Enable more error output for unit tests
• Change: Note compatibility through WP 4.9+
• Change: Remove support for WordPress older than 4.6
• Change: Update copyright date (2018)

Copyright & Disclaimer

Discussion / Support

Have any questions, comments, or suggestions? Please provide them via the plugin’s WordPress.org support forum. I’ll do my best to reply in a timely fashion and help as best I can.

Unfortunately, I cannot provide guaranteed support, nor do I provide support via any other means.

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