add_theme_support()

$defaults = array(
	'default-image'          => '',
	'default-preset'         => 'default', // 'default', 'fill', 'fit', 'repeat', 'custom'
	'default-position-x'     => 'left',    // 'left', 'center', 'right'
	'default-position-y'     => 'top',     // 'top', 'center', 'bottom'
	'default-size'           => 'auto',    // 'auto', 'contain', 'cover'
	'default-repeat'         => 'repeat',  // 'repeat-x', 'repeat-y', 'repeat', 'no-repeat'
	'default-attachment'     => 'scroll',  // 'scroll', 'fixed'
	'default-color'          => '',
	'gc-head-callback'       => '_custom_background_cb',
	'admin-head-callback'    => '',
	'admin-preview-callback' => '',
);
add_theme_support( 'custom-background', $defaults );

$defaults = array(
	'default-image'          => '',
	'random-default'         => false,
	'width'                  => 0,
	'height'                 => 0,
	'flex-height'            => false,
	'flex-width'             => false,
	'default-text-color'     => '',
	'header-text'            => true,
	'uploads'                => true,
	'gc-head-callback'       => '',
	'admin-head-callback'    => '',
	'admin-preview-callback' => '',
	'video'                  => false,
	'video-active-callback'  => 'is_front_page',
);
add_theme_support( 'custom-header', $defaults );

function add_theme_support( $feature, ...$args ) {
	global $_gc_theme_features;

	if ( ! $args ) {
		$args = true;
	}

	switch ( $feature ) {
		case 'post-thumbnails':
			// All post types are already supported.
			if ( true === get_theme_support( 'post-thumbnails' ) ) {
				return;
			}

			/*
			 * Merge post types with any that already declared their support
			 * for post thumbnails.
			 */
			if ( isset( $args[0] ) && is_array( $args[0] ) && isset( $_gc_theme_features['post-thumbnails'] ) ) {
				$args[0] = array_unique( array_merge( $_gc_theme_features['post-thumbnails'][0], $args[0] ) );
			}

			break;

		case 'post-formats':
			if ( isset( $args[0] ) && is_array( $args[0] ) ) {
				$post_formats = get_post_format_slugs();
				unset( $post_formats['standard'] );

				$args[0] = array_intersect( $args[0], array_keys( $post_formats ) );
			} else {
				_doing_it_wrong( "add_theme_support( 'post-formats' )", __( 'You need to pass an array of post formats.' ), '5.6.0' );
				return false;
			}
			break;

		case 'html5':
			// You can't just pass 'html5', you need to pass an array of types.
			if ( empty( $args[0] ) ) {
				// Build an array of types for back-compat.
				$args = array( 0 => array( 'comment-list', 'comment-form', 'search-form' ) );
			} elseif ( ! isset( $args[0] ) || ! is_array( $args[0] ) ) {
				_doing_it_wrong( "add_theme_support( 'html5' )", __( 'You need to pass an array of types.' ), '3.6.1' );
				return false;
			}

			// Calling 'html5' again merges, rather than overwrites.
			if ( isset( $_gc_theme_features['html5'] ) ) {
				$args[0] = array_merge( $_gc_theme_features['html5'][0], $args[0] );
			}
			break;

		case 'custom-logo':
			if ( true === $args ) {
				$args = array( 0 => array() );
			}
			$defaults = array(
				'width'                => null,
				'height'               => null,
				'flex-width'           => false,
				'flex-height'          => false,
				'header-text'          => '',
				'unlink-homepage-logo' => false,
			);
			$args[0]  = gc_parse_args( array_intersect_key( $args[0], $defaults ), $defaults );

			// Allow full flexibility if no size is specified.
			if ( is_null( $args[0]['width'] ) && is_null( $args[0]['height'] ) ) {
				$args[0]['flex-width']  = true;
				$args[0]['flex-height'] = true;
			}
			break;

		case 'custom-header-uploads':
			return add_theme_support( 'custom-header', array( 'uploads' => true ) );

		case 'custom-header':
			if ( true === $args ) {
				$args = array( 0 => array() );
			}

			$defaults = array(
				'default-image'          => '',
				'random-default'         => false,
				'width'                  => 0,
				'height'                 => 0,
				'flex-height'            => false,
				'flex-width'             => false,
				'default-text-color'     => '',
				'header-text'            => true,
				'uploads'                => true,
				'gc-head-callback'       => '',
				'admin-head-callback'    => '',
				'admin-preview-callback' => '',
				'video'                  => false,
				'video-active-callback'  => 'is_front_page',
			);

			$jit = isset( $args[0]['__jit'] );
			unset( $args[0]['__jit'] );

			// Merge in data from previous add_theme_support() calls.
			// The first value registered wins. (A child theme is set up first.)
			if ( isset( $_gc_theme_features['custom-header'] ) ) {
				$args[0] = gc_parse_args( $_gc_theme_features['custom-header'][0], $args[0] );
			}

			// Load in the defaults at the end, as we need to insure first one wins.
			// This will cause all constants to be defined, as each arg will then be set to the default.
			if ( $jit ) {
				$args[0] = gc_parse_args( $args[0], $defaults );
			}

			/*
			 * If a constant was defined, use that value. Otherwise, define the constant to ensure
			 * the constant is always accurate (and is not defined later,  overriding our value).
			 * As stated above, the first value wins.
			 * Once we get to gc_loaded (just-in-time), define any constants we haven't already.
			 * Constants are lame. Don't reference them. This is just for backward compatibility.
			 */

			if ( defined( 'NO_HEADER_TEXT' ) ) {
				$args[0]['header-text'] = ! NO_HEADER_TEXT;
			} elseif ( isset( $args[0]['header-text'] ) ) {
				define( 'NO_HEADER_TEXT', empty( $args[0]['header-text'] ) );
			}

			if ( defined( 'HEADER_IMAGE_WIDTH' ) ) {
				$args[0]['width'] = (int) HEADER_IMAGE_WIDTH;
			} elseif ( isset( $args[0]['width'] ) ) {
				define( 'HEADER_IMAGE_WIDTH', (int) $args[0]['width'] );
			}

			if ( defined( 'HEADER_IMAGE_HEIGHT' ) ) {
				$args[0]['height'] = (int) HEADER_IMAGE_HEIGHT;
			} elseif ( isset( $args[0]['height'] ) ) {
				define( 'HEADER_IMAGE_HEIGHT', (int) $args[0]['height'] );
			}

			if ( defined( 'HEADER_TEXTCOLOR' ) ) {
				$args[0]['default-text-color'] = HEADER_TEXTCOLOR;
			} elseif ( isset( $args[0]['default-text-color'] ) ) {
				define( 'HEADER_TEXTCOLOR', $args[0]['default-text-color'] );
			}

			if ( defined( 'HEADER_IMAGE' ) ) {
				$args[0]['default-image'] = HEADER_IMAGE;
			} elseif ( isset( $args[0]['default-image'] ) ) {
				define( 'HEADER_IMAGE', $args[0]['default-image'] );
			}

			if ( $jit && ! empty( $args[0]['default-image'] ) ) {
				$args[0]['random-default'] = false;
			}

			// If headers are supported, and we still don't have a defined width or height,
			// we have implicit flex sizes.
			if ( $jit ) {
				if ( empty( $args[0]['width'] ) && empty( $args[0]['flex-width'] ) ) {
					$args[0]['flex-width'] = true;
				}
				if ( empty( $args[0]['height'] ) && empty( $args[0]['flex-height'] ) ) {
					$args[0]['flex-height'] = true;
				}
			}

			break;

		case 'custom-background':
			if ( true === $args ) {
				$args = array( 0 => array() );
			}

			$defaults = array(
				'default-image'          => '',
				'default-preset'         => 'default',
				'default-position-x'     => 'left',
				'default-position-y'     => 'top',
				'default-size'           => 'auto',
				'default-repeat'         => 'repeat',
				'default-attachment'     => 'scroll',
				'default-color'          => '',
				'gc-head-callback'       => '_custom_background_cb',
				'admin-head-callback'    => '',
				'admin-preview-callback' => '',
			);

			$jit = isset( $args[0]['__jit'] );
			unset( $args[0]['__jit'] );

			// Merge in data from previous add_theme_support() calls. The first value registered wins.
			if ( isset( $_gc_theme_features['custom-background'] ) ) {
				$args[0] = gc_parse_args( $_gc_theme_features['custom-background'][0], $args[0] );
			}

			if ( $jit ) {
				$args[0] = gc_parse_args( $args[0], $defaults );
			}

			if ( defined( 'BACKGROUND_COLOR' ) ) {
				$args[0]['default-color'] = BACKGROUND_COLOR;
			} elseif ( isset( $args[0]['default-color'] ) || $jit ) {
				define( 'BACKGROUND_COLOR', $args[0]['default-color'] );
			}

			if ( defined( 'BACKGROUND_IMAGE' ) ) {
				$args[0]['default-image'] = BACKGROUND_IMAGE;
			} elseif ( isset( $args[0]['default-image'] ) || $jit ) {
				define( 'BACKGROUND_IMAGE', $args[0]['default-image'] );
			}

			break;

		// Ensure that 'title-tag' is accessible in the admin.
		case 'title-tag':
			// Can be called in functions.php but must happen before gc_loaded, i.e. not in header.php.
			if ( did_action( 'gc_loaded' ) ) {
				_doing_it_wrong(
					"add_theme_support( 'title-tag' )",
					sprintf(
						/* translators: 1: title-tag, 2: gc_loaded */
						__( 'Theme support for %1$s should be registered before the %2$s hook.' ),
						'<code>title-tag</code>',
						'<code>gc_loaded</code>'
					),
					'4.1.0'
				);

				return false;
			}
	}

	$_gc_theme_features[ $feature ] = $args;
}

/**
 * Essential theme supports
 * */
function theme_setup(){
    /** automatic feed link*/
    add_theme_support( 'automatic-feed-links' );

    /** tag-title **/
    add_theme_support( 'title-tag' );

    /** post formats */
    $post_formats = array('aside','image','gallery','video','audio','link','quote','status');
    add_theme_support( 'post-formats', $post_formats);

    /** post thumbnail **/
    add_theme_support( 'post-thumbnails' );

    /** HTML5 support **/
    add_theme_support( 'html5', array( 'comment-list', 'comment-form', 'search-form', 'gallery', 'caption' ) );

    /** refresh widgest **/
    add_theme_support( 'customize-selective-refresh-widgets' );

    /** custom background **/
    $bg_defaults = array(
        'default-image'          => '',
        'default-preset'         => 'default',
        'default-size'           => 'cover',
        'default-repeat'         => 'no-repeat',
        'default-attachment'     => 'scroll',
    );
    add_theme_support( 'custom-background', $bg_defaults );

    /** custom header **/
    $header_defaults = array(
        'default-image'          => '',
        'width'                  => 300,
        'height'                 => 60,
        'flex-height'            => true,
        'flex-width'             => true,
        'default-text-color'     => '',
        'header-text'            => true,
        'uploads'                => true,
    );
    add_theme_support( 'custom-header', $header_defaults );

    /** custom log **/
    add_theme_support( 'custom-logo', array(
        'height'      => 60,
        'width'       => 400,
        'flex-height' => true,
        'flex-width'  => true,
        'header-text' => array( 'site-title', 'site-description' ),
    ) );



}
add_action('after_setup_theme','theme_setup');

add_theme_support( 'starter-content', array(
    // Place widgets in the desired locations (such as sidebar or footer).
    // Example widgets: archives, calendar, categories, meta, recent-comments, recent-posts, 
    //                  search, text_business_info, text_about
    'widgets'     => array( 'sidebar-1' => array( 'search', 'categories', 'meta'), ),
    // Specify pages to create, and optionally add custom thumbnails to them.
    // Note: For thumbnails, use attachment symbolic references in {{double-curly-braces}}.
    // Post options: post_type, post_title, post_excerpt, post_name (slug), post_content, 
    //               menu_order, comment_status, thumbnail (featured image ID), and template
    'posts'       => array( 'home', 'about', 'blog' => array( 'thumbnail' => '{{image-cafe}}' ), ),
    // Create custom image attachments used as post thumbnails for pages.
    // Note: You can reference these attachment IDs in the posts section above. Example: {{image-cafe}}
    'attachments' => array( 'image-cafe' => array( 'post_title' => 'Cafe', 'file' => 'assets/images/cafe.jpg' ), ),
    // Assign options defaults, such as front page settings.
    // The 'show_on_front' value can be 'page' to show a specified page, or 'posts' to show your latest posts.
    // Note: Use page ID symbolic references from the posts section above wrapped in {{double-curly-braces}}.
    'options'     => array( 'show_on_front'  => 'page', 'page_on_front' => '{{home}}', 'page_for_posts' => '{{blog}}', ),
	// Set the theme mods.
    'theme_mods'  => array( 'panel_1' => '{{about}}' ),
	// Set up nav menus.
    'nav_menus'   => array( 'top' => array( 'name' => 'Top Menu', 'items' => array( 'link_home', 'page_about', 'page_blog' )), ),
) );