Add a colour picker to taxonomies

iso-tax-colour-picker.php

<?php

/**
 * Colour meta box for taxonomies
 *
 * You know... for kids...
 * ...and also for things like labels
 *
 */
class Iso_Taxonomy_Colours {
	/**
	 * @var array   Holds our array of taxonomies
	 */
	private $taxonomies;

	/**
	 * @param mixed $tax_array
	 */
	function __construct( $tax_array ) {
		$this->taxonomies = $tax_array;

		// Add the iris script among other things
		add_action( 'admin_enqueue_scripts', array( $this, 'enqueue_scripts' ) );

		// Bind to add/edit screens
		add_action( 'init', array( $this, 'bind_metaboxes' ) );

		// Custom columns to show the colour
		add_action( 'init', array( $this, 'add_tax_colour_columns_filters' ) );

	}


	/**
	 * Enqueues our scripts during the 'admin_enqueue_scripts' hook
	 */
	function enqueue_scripts() {
		/**
		 * TODO: Figure out this damn undocumented new script. Damn youuuuu, Automattic!
		 */
		wp_enqueue_script( 'iris' );
	}


	/**
	 *  Binds the metaboxes to taxonomy edit screens
	 */
	function bind_metaboxes() {
		if ( is_array( $this->taxonomies ) ) {
			foreach ( $this->taxonomies as $taxonomy ) {
				add_action( $taxonomy . '_add_form_fields', array( $this, 'add_colour_metabox' ) );
				add_action( $taxonomy . '_edit_form_fields', array( $this, 'edit_colour_metabox' ) );
				// saving
				add_action( 'edited_' . $taxonomy, array( $this, 'save_tax_colour' ), 10, 2 );
				add_action( 'create_' . $taxonomy, array( $this, 'save_tax_colour' ), 10, 2 );
			}
		} else {
			add_action( $this->taxonomies . '_add_form_fields', array( $this, 'add_colour_metabox' ) );
			add_action( $this->taxonomies . '_edit_form_fields', array( $this, 'edit_colour_metabox' ) );
			// saving
			add_action( 'edited_' . $this->taxonomies, array( $this, 'save_tax_colour' ), 10, 2 );
			add_action( 'create_' . $this->taxonomies, array( $this, 'save_tax_colour' ), 10, 2 );
		}
	}

	/**
	 *  Adds a metabox to any Taxonomy contained in our $taxonomies variable
	 */
	function add_colour_metabox() {
		?>
		<tr class="form-field">
			<th scope="row"><label for="iso-tax-colour"><?php _e( 'Taxonomy Colour', 'iso2015' ); ?></label></th>
			<td><input type="text" size="40" value="" id="iso-tax-colour" name="iso-tax-colour">

				<p class="description"><?php _e( 'Select a colour to associate with this term', 'iso2015' ); ?></p></td>
		</tr>

	<?php
	}

	/**
	 * Adds a metabox to any Taxonomy contained in our $taxonomies variable
	 *
	 * @param object $term term object coming from $this->taxonomies . '_edit_form_fields'
	 */
	function edit_colour_metabox( $term ) {

		$curr_value = get_option( $term->taxonomy . '_' . $term->term_id . '_tax-colour' );
		?>
		<tr class="form-field">
		<th scope="row"><label for="iso-tax-colour"><?php _e( 'Taxonomy Colour', 'iso2015' ); ?></label></th>
		<td><input type="text" size="40" value="<?php echo $curr_value; ?>" id="iso-tax-colour" name="iso-tax-colour">

			<p class="description"><?php _e( 'Select a colour to associate with this term', 'iso2015' ); ?></p></td>
		</tr><?php
	}

	/**
	 * Saving our taxonomy's custom colour
	 *
	 * @param int $term_id comes from the 'edited_' . $this->taxonomies and 'create_' . $this->taxonomies hooks
	 */
	function save_tax_colour( $term_id ) {
		if ( isset( $_POST['iso-tax-colour'] ) && trim( $_POST['iso-tax-colour'] ) != '' && isset( $_POST['taxonomy'] ) && trim( $_POST['taxonomy'] ) != '' ) {

			$value    = trim( $_POST['iso-tax-colour'] );
			$taxonomy = trim( $_POST['taxonomy'] );

			/**
			 * TODO: turn on sanitation once I figure out the iris JS
			 */
			//Check if it's a hexadecimal value
			//if ( $this->is_hex( $value ) ) {
			update_option( $taxonomy . '_' . $term_id . '_tax-colour', $value );
			//}
		}
	}


	/**
	 *  Hook into the Taxonomy list screen to add a column and display the custom colour inside it
	 */
	function add_tax_colour_columns_filters() {
		if ( is_array( $this->taxonomies ) ) {
			foreach ( $this->taxonomies as $taxonomy ) {
				add_filter( 'manage_edit-' . $taxonomy . '_columns', array( $this, 'add_tax_colour_columns' ) );
				add_filter( 'manage_' . $taxonomy . '_custom_column', array(
					$this,
					'display_tax_colour_column'
				), 10, 3 );
			}
		} else {
			add_filter( 'manage_edit-' . $this->taxonomies . '_columns', array( $this, 'add_tax_colour_columns' ) );
			add_filter( 'manage_' . $this->taxonomies . '_custom_column', array(
				$this,
				'display_tax_colour_column'
			), 10, 3 );
		}

	}

	/**
	 * @param array $columns comes from the 'manage_edit-' . $taxonomy . '_columns' hook
	 *
	 * @return mixed
	 */
	function add_tax_colour_columns( $columns ) {
		$columns['iso-tax-colour'] = __( 'Tax Colour', 'iso2015' );

		return $columns;
	}

	/**
	 *
	 * Display the custom colour in our custom column
	 *
	 * @param string $string_out  need to figure this one out better. Needs to be returned by the function.
	 * @param string $column_name column name currently being processed
	 * @param int    $term_id     term_id currently being processed
	 *
	 * @return mixed
	 */
	function display_tax_colour_column( $string_out, $column_name, $term_id ) {
		if ( $column_name == 'iso-tax-colour' ) {

			if ( isset( $_GET['taxonomy'] ) ) {
				$taxonomy = trim( $_GET['taxonomy'] );
				$colour   = get_option( $taxonomy . '_' . $term_id . '_tax-colour' );

				if ( $colour && $colour != '' ) {
					$colour = str_replace( '#', '', $colour );
					echo '<span style="background-color: #' . $colour . '; width: 60px; height: 20px; display:inline-block; text-align: center;">#' . $colour . '</span>';
				}
			}
		}

		return $string_out;
	}


	/**
	 *
	 * Hexadecimal sanitation
	 *
	 * @param string $hex_code Expects a hexadecimal code
	 *
	 * @return bool returns true if it is a valid hexadecimal code
	 */
	function is_hex( $hex_code ) {
		return @preg_match( "/^[a-f0-9]{2,}$/i", $hex_code ) && ! ( strlen( $hex_code ) & 1 );
	}

}

// pre-declaring to illustrate.
$iso_taxonomies_to_apply_to = array(
	'categories',   // built-in Categories taxonomy
	'post_tags',    // built-in Tags taxonomy
	'iso_wp_functions', // Custom taxonomy
);


$iso_taxonomy_colours = new Iso_Taxonomy_Colours( $iso_taxonomies_to_apply_to );