<?php 
/** 
 * Background block support flag. 
 * 
 * @package WordPress 
 * @since 6.4.0 
 */ 
 
/** 
 * Registers the style block attribute for block types that support it. 
 * 
 * @since 6.4.0 
 * @access private 
 * 
 * @param WP_Block_Type $block_type Block Type. 
 */ 
function wp_register_background_support( $block_type ) { 
    // Setup attributes and styles within that if needed. 
    if ( ! $block_type->attributes ) { 
        $block_type->attributes = array(); 
    } 
 
    // Check for existing style attribute definition e.g. from block.json. 
    if ( array_key_exists( 'style', $block_type->attributes ) ) { 
        return; 
    } 
 
    $has_background_support = block_has_support( $block_type, array( 'background' ), false ); 
 
    if ( $has_background_support ) { 
        $block_type->attributes['style'] = array( 
            'type' => 'object', 
        ); 
    } 
} 
 
/** 
 * Renders the background styles to the block wrapper. 
 * This block support uses the `render_block` hook to ensure that 
 * it is also applied to non-server-rendered blocks. 
 * 
 * @since 6.4.0 
 * @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. 
 * 
 * @access private 
 * 
 * @param  string $block_content Rendered block content. 
 * @param  array  $block         Block object. 
 * @return string Filtered block content. 
 */ 
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; 
} 
 
// Register the block support. 
WP_Block_Supports::get_instance()->register( 
    'background', 
    array( 
        'register_attribute' => 'wp_register_background_support', 
    ) 
); 
 
add_filter( 'render_block', 'wp_render_background_support', 10, 2 ); 
 
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