how can I just add to parent theme function(s) instead of redeclaring whole the function

Question

I'm using a commercial theme that has it's theme settings in WordPress's appearance/customizer. They call their settings through a function like this: (this is only part of the function which is about 400 lines long)

function customizer_library_gateway_options() {
    // Home
    $section = 'home';

    $sections[] = array(
        'id'            => $section,
        'title'         => __( 'Home', 'gateway' ),
        'priority'      => '20',
        'description'   => __( 'Home Page Options.', 'gateway' ),
        'panel'         => $panel
    );

    $options['home_hero_bg'] = array(
        'id'                => 'home_hero_bg',
        'label'             => __( 'Home Background Image', 'gateway' ),
        'section'           => $section,
        'type'              => 'image',
        'default'           => $imagepath . 'hero-bg.jpg',
        'active_callback'   => 'is_front_page'
    );

    $options['bg_attachement'] = array(
        'id'                => 'bg_attachement',
        'label'             => __( 'Select the behavior of the background image.', 'gateway' ),
        'section'           => $section,
        'type'              => 'select',
        'choices'           => $bg_attachment,
        'default'           => 'fixed',
        'active_callback'   => 'is_front_page'
    );

    $options['home_hero_bg_color'] = array(
        'id'                => 'home_hero_bg_color',
        'label'             => __( 'Home Hero background color if no image is being used.', 'gateway' ),
        'section'           => $section,
        'type'              => 'color',
        'default'           => $primary_color,
        'active_callback'   => 'is_front_page',
        'transport'         => 'postMessage'
    );

    $options['home_posts_title'] = array(
        'id'                => 'home_posts_title',
        'label'             => __( 'Enter the home featured posts section title', 'gateway' ),
        'section'           => $section,
        'type'              => 'text',
        'default'           => 'Featured Posts',
        'active_callback'   => 'is_front_page',
        'transport'         => 'postMessage'
    );

    $options['home_posts_cat'] = array(
        'id'                => 'home_posts_cat',
        'label'             => __( 'Home Posts Category', 'gateway' ),
        'section'           => $section,
        'type'              => 'select',
        'choices'           => $options_cats,
        'default'           => '',
        'active_callback'   => 'is_front_page'
        );
    }
add_action( 'init', 'customizer_library_gateway_options' );

My question is: How can I add to this array through my child theme so I can add a logo option? I don't necessarily want to re-declare the whole function if I can just add my array insertion:

I was thinking add_filter but I'm not sure. This is what I tried in my child theme functions.php:

function customizer_library_gateway_home_logo() {

    $options['home_logo'] = array(
        'id'        => 'home_logo',
        'label'     => __( 'Logo', 'gateway' ),
        'section'   => 'home',
            'type'      => 'image',
            'default'   => $imagepath . 'logo.png'
        ); 

    }

    add_filter( 'customizer_library_gateway_options', 'customizer_library_gateway_home_logo' );

However, no change is made to the theme customizer. If I add the home_logo entry directly in the theme's original file it does work. Maybe there is a different action I should be using?

Answer 1

I might have a solution for you.

But, consider first using the default WordPress custom logo support. You just need to add this to your functions.php file:

function theme_prefix_setup() {

    add_theme_support( 'custom-logo' );

}

add_action( 'after_setup_theme', 'theme_prefix_setup' );

See more details about add_theme_support( 'custom-logo' ); at https://codex.wordpress.org/Theme_Logo.

Now, if you click Appearance > Customize, under Site Identity you will se the new Logo field.

If the solution above doesn't fit you, keep reading...

I tested the code below and it works fine (of course I changed it to fit some of your needs).

/**
 * @param object    $instance
 */
function customize_customize_page( $instance ) {

    // Set the args. You do not need to set 'type' key here.
    $args = array(
        'priority' => 0,
        'section' => 'home',
        // 'settings' => 'home',
        'label' => __( 'Logo' ),
        'description' => __( 'Description' ),
    );

    // Here we instance WP_Customize_Image_Control class and set its paramaters.
    // See that here is where you choose your option ID.
    $instance->add_control( new WP_Customize_Image_Control( $instance, 'home_logo', $args ) );

}

add_action( 'customize_register', 'customize_customize_page', 199, 1 );

If the code above won't work you should try uncommenting the key 'settings' and try again.