How to bring back the old OpenSans font in WordPress 4.6 dashboard

As you well know, WordPress decided to ditch Open Sans font, and use operating system defaults for the dashboard. This is an excerpt from the 4.6 version official release:

“The WordPress 4.6 dashboard now takes advantage of the fonts you already have, making it load faster and letting you feel more at home on whatever device you use.”

Great… but NO. I really don’t like to see my WordPress dashboards sporting Segoe UI (the default sans-serif font in Windows). So I created this small plugin that brings back the old OpenSans font.

/**
 * OpenSans FTW
 *
 * Plugin Name: OpenSans FTW
 * Plugin URI: http://wpcrumbs.com/
 * Description: Just a simple plugin that brings back the old Open Sans font to WordPress 4.6+ dashboard.
 * Version: 1.0.1
 * Author: GeorgeJipa
 * Author URI: http://wpcrumbs.com/
 * Text Domain: opensans-ftw
 * Domain Path: /languages
 * License: GPLv2 or later
 * License URI: http://www.gnu.org/licenses/gpl-2.0.txt
 */
// Exit if accessed directly
if (!defined('ABSPATH'))
	exit;

class OpenSans_FTW {

	protected static $instance = null;
	public $plugin_slug = 'opensans-ftw';
	public $action_name;

	public static function get_instance() {
		if (null == self::$instance) {
			self::$instance = new self;
		}

		return self::$instance;
	}

	/**
	 * Initialize
	 * 
	 * @return
	 */
	public function __construct() {
		// set localisation
		$this->load_plugin_textdomain();
		
		// check wordpress version
		$wp_version = get_bloginfo('version');
		
		if (version_compare($wp_version, '4.6', '<')) {
			add_action('admin_notices', array($this, 'add_notice'));
			return;
		}

		// set vars
		$this->action_name = $this->get_action_name();

		// hooks
		add_action($this->action_name, array($this, 'add_assets'), 999);
	}

	/**
	 * Load localisation files
	 *
	 * Locales found in:
	 *      - WP_LANG_DIR/opensans-ftw/opensans-ftw-LOCALE.mo
	 *      - WP_CONTENT_DIR/plugins/opensans-ftw-LOCALE.mo
	 */
	public function load_plugin_textdomain() {
		$locale = apply_filters('plugin_locale', get_locale(), $this->plugin_slug);

		load_textdomain($this->plugin_slug, WP_LANG_DIR . '/' . $this->plugin_slug . '/' . $this->plugin_slug . '-' . $locale . '.mo');
		load_plugin_textdomain($this->plugin_slug, false, plugin_basename(dirname(__FILE__)) . '/languages');
	}

	/**
	 * Get action_name based on page
	 * 
	 * @global string $pagenow
	 * @return string
	 */
	public function get_action_name() {
		global $pagenow;

		if (is_admin()) {
			$action_name = 'admin_enqueue_scripts';
		} elseif ($pagenow == 'wp-login.php') {
			$action_name = 'login_enqueue_scripts';
		} else {
			$action_name = 'wp_enqueue_scripts';
		}

		return $action_name;
	}

	/**
	 * Add notice
	 */
	public function add_notice() {
		echo '
' . esc_html__('OpenSans FTW requires WordPress 4.6 or higher.', $this->plugin_slug) . '
';
	}

	/**
	 * Add assets to backend (admin) or frontend
	 * 
	 * @return
	 */
	public function add_assets() {
		// we don't need to add the assets when the adminbar is disabled (on dashboard is always enabled, 
		// but on frontend can be disabled using `show_admin_bar` hook... so we need to check)
		// ! exception will be wp-login.php page !
		if (!is_admin_bar_showing() && $this->action_name != 'login_enqueue_scripts') {
			return;
		}

		// enqueue font
		$handle = 'open-sans';

		if (wp_style_is($handle, 'registered')) {
			wp_enqueue_style($handle);
		} else {
			wp_enqueue_style($handle, '//fonts.googleapis.com/css?family=Open+Sans:300italic,400italic,600italic,300,400,600&subset=latin,latin-ext');
		}

		// add custom css based on page
		switch ($this->action_name) {
			case 'wp_enqueue_scripts':
				$custom_css = '#wpadminbar *:not([class="ab-icon"]) { font-family: "Open Sans", sans-serif !important; }';
				break;
			case 'login_enqueue_scripts':
				$custom_css = 'body { font-family: "Open Sans", sans-serif !important; }';
				break;
			default:
				$custom_css = 'body, #wpadminbar *:not([class="ab-icon"]), .wp-core-ui, .media-frame input, .media-frame textarea, .media-frame select { font-family: "Open Sans", sans-serif !important; }';
				break;
		}

		wp_add_inline_style($handle, $custom_css);
	}

}

add_action('plugins_loaded', array('OpenSans_FTW', 'get_instance'));

[panel type=”info”]The plugin was approved in the WordPress.org repository.
Go to repo page[/panel]