wp_render_background_support()WP 6.4.0

Renders the background styles to the block wrapper. This block support uses the render_block to ensure that it is also applied to non-server-rendered blocks.

Internal function — this function is designed to be used by the kernel itself. It is not recommended to use this function in your code.

No Hooks.

Return

String. Filtered block content.

Usage

wp_render_background_support( $block_content, $block );
$block_content(string) (required)
Rendered block content.
$block(array) (required)
Block object.

Changelog

Since 6.4.0 Introduced.
Since 6.5.0 Added support for backgroundPosition and backgroundRepeat output.
Since 6.6.0 Removed requirement for backgroundImage.source. A file/url is the default.
Since 6.7.0 Added support for backgroundAttachment output.

wp_render_background_support() code WP 6.7.1

function wp_render_background_support( $block_content, $block ) {
	$block_type                   = WP_Block_Type_Registry::get_instance()->get_registered( $block['blockName'] );
	$block_attributes             = ( isset( $block['attrs'] ) && is_array( $block['attrs'] ) ) ? $block['attrs'] : array();
	$has_background_image_support = block_has_support( $block_type, array( 'background', 'backgroundImage' ), false );

	if (
		! $has_background_image_support ||
		wp_should_skip_block_supports_serialization( $block_type, 'background', 'backgroundImage' ) ||
		! isset( $block_attributes['style']['background'] )
	) {
		return $block_content;
	}

	$background_styles                         = array();
	$background_styles['backgroundImage']      = $block_attributes['style']['background']['backgroundImage'] ?? null;
	$background_styles['backgroundSize']       = $block_attributes['style']['background']['backgroundSize'] ?? null;
	$background_styles['backgroundPosition']   = $block_attributes['style']['background']['backgroundPosition'] ?? null;
	$background_styles['backgroundRepeat']     = $block_attributes['style']['background']['backgroundRepeat'] ?? null;
	$background_styles['backgroundAttachment'] = $block_attributes['style']['background']['backgroundAttachment'] ?? null;

	if ( ! empty( $background_styles['backgroundImage'] ) ) {
		$background_styles['backgroundSize'] = $background_styles['backgroundSize'] ?? 'cover';

		// If the background size is set to `contain` and no position is set, set the position to `center`.
		if ( 'contain' === $background_styles['backgroundSize'] && ! $background_styles['backgroundPosition'] ) {
			$background_styles['backgroundPosition'] = '50% 50%';
		}
	}

	$styles = wp_style_engine_get_styles( array( 'background' => $background_styles ) );

	if ( ! empty( $styles['css'] ) ) {
		// Inject background styles to the first element, presuming it's the wrapper, if it exists.
		$tags = new WP_HTML_Tag_Processor( $block_content );

		if ( $tags->next_tag() ) {
			$existing_style = $tags->get_attribute( 'style' );
			$updated_style  = '';

			if ( ! empty( $existing_style ) ) {
				$updated_style = $existing_style;
				if ( ! str_ends_with( $existing_style, ';' ) ) {
					$updated_style .= ';';
				}
			}

			$updated_style .= $styles['css'];
			$tags->set_attribute( 'style', $updated_style );
			$tags->add_class( 'has-background' );
		}

		return $tags->get_updated_html();
	}

	return $block_content;
}