Come faccio ad aggiungere impostazioni alla pagina delle opzioni di sfondo?

Sto sviluppando un tema e volevo aggiungere del contenuto extra alla pagina delle opzioni di sfondo integrata. So usare l'API delle impostazioni per creare nuove opzioni e impostazioni per i temi, ma non riesco a capire dove si stia effettivamente chiamando alla pagina di sfondo. Ho cercato attraverso wp-includes/theme.phpe ancora non molto lì, tranne per le chiamate alle funzioni in background e nulla che effettivamente rende la pagina.

Non è possibile farlo con un'azione?

Il contenuto della pagina per gli sfondi personalizzati viene creato in wp-admin/custom-background.php. Non è disponibile alcuna azione in cui i campi sono stampati.

Per aggiungere nuovi campi dobbiamo stampare JavaScript nel piè di pagina. L'azione è 'admin_footer-appearance_page_custom-background'.

Per salvare quei valori di campo dobbiamo agganciarci 'load-appearance_page_custom-background'.

L'esempio seguente aggiunge una nuova opzione per background-origin- utile se bodynel foglio di stile è stato impostato un bordo .

add_action(
    'load-appearance_page_custom-background',
    array ( 'T5_Background_Origin', 'get_instance' )
);

/**
 * Add a new row to the background options table for 'background-origin'.
 *
 * @author  Thomas Scholz http://toscho.de
 * @version 2012.09.10
 */
class T5_Background_Origin
{
    /**
     * Main instance.
     * @type object|NULL
     */
    protected static $instance = NULL;

    /**
     * The name for the option. Will be saved as theme option.
     *
     * @link http://www.w3.org/TR/css3-background/#the-background-origin
     * @type string
     */
    protected $option = 'background_origin';

    /**
     * Label on the left side of our new option.
     *
     * @type string
     */
    protected $table_header = 'Background Origin';

    /**
     * Return an instance.
     *
     * @wp-hook load-appearance_page_custom-background
     * @return object
     */
    public static function get_instance()
    {
        NULL === self::$instance and self::$instance = new self;
        return self::$instance;
    }

    /**
     * Save our option and register the form.
     *
     * @wp-hook load-appearance_page_custom-background
     */
    public function __construct()
    {
        add_action(
            'admin_footer-appearance_page_custom-background',
            array ( $this, 'form' )
        );

        if ( empty ( $_POST[ $this->option ] ) )
        {
            return;
        }

        check_admin_referer( $this->option, "_t5nonce-$this->option" );
        set_theme_mod( $this->option, $_POST[ $this->option ] );
    }

    /**
     * Create the form elements.
     *
     * @wp-hook admin_footer-appearance_page_custom-background
     * @return void
     */
    public function form()
    {
        $nonce = wp_nonce_field(
            $this->option,
            "_t5nonce-$this->option",
            TRUE, // check referer
            FALSE // do not echo
            );
        $html = $nonce . $this->get_radio_fields();
        $this->print_script( $html );
    }

    /**
     * Create the jQuery function that inserts our form fields.
     *
     * @param  string $html Radio buttons
     * @return void
     */
    protected function print_script( $html )
    {
        $row = "'<tr><th>$this->table_header</th><td>$html</td></tr>'";
        ?>
<script>jQuery( function <?php echo $this->option; ?>($) {
    $('.form-table:last').append(<?php echo $row; ?>);
});</script>
<?php
    }

    /**
     * Helper for form(). Create radio input fields
     *
     * @return string
     */
    protected function get_radio_fields()
    {
        $value  = get_theme_mod( $this->option, 'padding-box' );
        $radios = array ( 'padding-box', 'border-box', 'content-box' );
        $html   = "<p>";

        foreach ( $radios as $radio )
        {
            $html .= sprintf(
                ' <input type="radio" name="%1$s" value="%2$s" id="%3$s"%4$s>'
                . ' <label for="%3$s">%2$s</label> ',
                $this->option,
                $radio,
                "$this->option-$radio",
                // returns ' as value delimiters and has to be escaped
                addslashes( checked( $value, $radio, FALSE ) )
            );
        }

        return "$html</p>";
    }
}

Ho trovato la risposta fornita da @toscho molto utile, ma poiché avevo più di un'opzione da aggiungere, ho modificato un po 'il codice in modo che tutto quello che devo fare è creare una semplice classe estesa con alcune opzioni.

Ho anche trovato inopportuno avere le opzioni semplicemente aggiunte alla fine dell'elenco, quindi ho aggiunto un argomento 'position' che ti permette di selezionare una di queste opzioni -

• 'first' - Prima della prima impostazione (attualmente Posizione)
• 'last'- Dopo l'ultima impostazione (colore di sfondo corrente)
• Integer position - Il numero di riga per inserire prima l'impostazione (deve essere un numero intero)

Ecco il codice -

add_action('load-appearance_page_custom-background', array('PS_Background_Setting_Random', 'get_instance'));
add_action('load-appearance_page_custom-background', array('PS_Background_Setting_Position_Y', 'get_instance'));
add_action('load-appearance_page_custom-background', array('PS_Background_Setting_Size', 'get_instance'));

/**
 * Add a new 'Random Background' setting to the Customise Background admin page
 */
final class PS_Background_Setting_Random extends PS_Background_Setting{

    /**
     * The main instance
     *
     * @var object|null
     */
    protected static $instance = null;

    /**
     * Return an instance of this class
     *
     * @return object   An instance of this class
     */
    public static function get_instance(){

        NULL === self::$instance and self::$instance = new self;
        return self::$instance;

    }

    /**
     * Constructor
     */
    public function __construct(){

        $args = array(
            'mod'       => 'ps_background_random',
            'default'   => 'yes',
            'label'     => __('Random Background', 'djg_photo_show'),
            'position'  => 'first',
            'options'   => array(
                'yes'   => __('Yes', 'djg_photo_show'),
                'no'    => __('No', 'djg_photo_show')
            )
        );

        parent::__construct($args);

    }

}

/**
 * Add a new 'Background Position (Y)' setting to the Customise Background admin page
 */
final class PS_Background_Setting_Position_Y extends PS_Background_Setting{

    /**
     * The main instance
     *
     * @var object|null
     */
    protected static $instance = null;

    /**
     * Return an instance of this class
     *
     * @return object   An instance of this class
     */
    public static function get_instance(){

        NULL === self::$instance and self::$instance = new self;
        return self::$instance;

    }

    /**
     * Constructor
     */
    public function __construct(){

        $args = array(
            'mod'       => 'ps_background_position_y',
            'default'   => 'cover',
            'label'     => __('Position (Y)', 'djg_photo_show'),
            'position'  => 3,
            'options'   => array(
                'top'       => __('Top', 'djg_photo_show'),
                'center'    => __('Centre', 'djg_photo_show'),
                'bottom'    => __('Bottom', 'djg_photo_show')
            )
        );

        parent::__construct($args);

    }

}

/**
 * Add a new 'Background Size' setting to the Customise Background admin page
 */
final class PS_Background_Setting_Size extends PS_Background_Setting{

    /**
     * The main instance
     *
     * @var object|null
     */
    protected static $instance = null;

    /**
     * Return an instance of this class
     *
     * @return object   An instance of this class
     */
    public static function get_instance(){

        NULL === self::$instance and self::$instance = new self;
        return self::$instance;

    }

    /**
     * Constructor
     */
    public function __construct(){

        $args = array(
            'mod'       => 'ps_background_size',
            'default'   => 'cover',
            'label'     => __('Size', 'djg_photo_show'),
            'position'  => 6,
            'options'   => array(
                'auto'      => __('Auto', 'djg_photo_show'),
                'contain'   => __('Contain', 'djg_photo_show'),
                'cover'     => __('Cover', 'djg_photo_show')
            )
        );

        parent::__construct($args);

    }

}

/**
 * Add a new setting to the Customise Background admin page
 */
class PS_Background_Setting{

    /**
     * The name for the theme modification option
     *
     * @var string
     */
    private $mod = '';

    /**
     * The default value to return if $mod is not yet set
     *
     * @var mixed
     */
    private $default = false;

    /**
     * The label for the additional setting
     *
     * @var string
     */
    private $label = '';

    /**
     * The options to use for creating the fields for the additional setting
     *
     * @var array
     */
    private $options = array();

    /**
     * The nonce for the additional setting
     *
     * @var string
     */
    private $nonce;

    /**
     * The HTML fields for all of the options for the additional setting
     *
     * @var string
     */
    private $fields;

    /**
     * The position in which to insert the option
     *
     * @var string
     */
    private $position = 'last';

    /**
     * Constructor
     */
    public function __construct($args = array()){

        /** Map the args to this object */
        foreach($args as $key => $value) :
            $this->$key = $value;
        endforeach;

        /** Ensure that all of the required $args are valid */
        if(!$this->is_valid_args()) :
            return;
        endif;

        add_action('admin_footer-appearance_page_custom-background', array($this, 'output_additional_setting'));

        /** Check to see if there is an option to save */
        if(!empty($_POST[$this->mod])):

            /** Check the nonce is valid and save the updated setting */
            check_admin_referer($this->mod, "_ps_nonce-$this->mod");
            set_theme_mod($this->mod, $_POST[$this->mod]);

        endif;

    }

    /**
     * Ensure that all of the required $args are valid
     */
    private function is_valid_args(){

        return (empty($this->mod) || empty($this->label) || empty($this->options)) ? false : true;

    }

    /**
     * Output the additional custom fields to the custom backgrounds page
     */
    public function output_additional_setting(){

        $this->nonce = wp_nonce_field(  // Create a nonce for each settings so that it can be checked when the user saves
            $this->mod,             // The nonce $action
            "_ps_nonce-$this->mod", // The nonce $name
            true,                   // Also create a referer nonce
            false                   // Do not echo
        );
        $this->set_fields();    // Set up the fields for this setting
        $this->print_script();  // Print the jQuery that will insert the setting into the DOM

    }

    /**
     * Create the HTML fileds for all of the options required for the additional setting
     *
     * @return string   The fields for the additional setting
     */
    private function set_fields(){

        $saved_value = get_theme_mod($this->mod, $this->default);

        foreach($this->options as $value => $description) :

            $checked = ($value === $saved_value) ? 'checked="true"' : false;

            $fields[] = sprintf(
                '<label>'.
                '<input type="radio" id="%1$s" name="%2$s" value="%3$s" %4$s>'.
                '%5$s</label> ',
                "$this->mod-$key",  /** %1$s - The option ID */
                $this->mod,         /** %2$s - The option name */
                $value,             /** %3$s - The option vale */
                $checked,           /** %4$s - Whether or not the option should be checked */
                $description        /** %5$s - The option description */
            );

        endforeach;

        $this->fields = join('', $fields);

    }

    /**
     * Create the $row to insert in to the DOM and the jQuery function to carry out the insertion
     */
    private function print_script(){

        $row = sprintf(
            '<tr>'.
            '<th scope="row">%1$s</th>'.
            '<td><fieldset>'.
            '<legend class="screen-reader-text"><span>Background %1$s</span></legend>'.
            '%2$s%3$s</fieldset></td></tr>',            
            $this->label,   /** %1$s - The setting label */
            $this->nonce,   /** %2$s - The nonce field for this setting */
            $this->fields   /** %3$s - The setting fields */
        );

        if(!is_int($this->position)) :
            $this->position = (in_array($this->position, array('first', 'last'))) ? $this->position : 'last';
        endif;
?>
<script id="custom-background-mod-<?php echo $this->mod; ?>">jQuery(function <?php echo $this->mod; ?>($){

    /** Insert the '<?php echo $this->mod; ?>' setting option in to the Custom Background admin page */
    var row = '<?php echo $row; ?>';
    var rows = $('.form-table:last tr');
<?php if(is_int($this->position)) : ?>
    var position = parseInt('<?php echo $this->position; ?>');
    if(position < 0){
        rows.first().before(row);
    }
    else if(position > rows.length){
        rows.last().after(row);
    }
    else{
        rows.eq(position - 1).before(row);
    }
<?php elseif($this->position === 'first') : ?>
    $('.form-table:last tr:first').before(row);
<?php else : ?>
    $('.form-table:last tr:last').after(row);
<?php endif; ?>

});</script>
<?php
    }

}