Enables per-section styling of blocks via block style variations defined in theme.json.

Source: wp-includes/block-supports/block-style-variations.php
Since: 6.6.0

Support Key

Registered as block-style-variation with an empty config array. Variations are detected via CSS class names matching is-style-{name} on blocks.

Functions

wp_get_block_style_variation_name_from_class()

function wp_get_block_style_variation_name_from_class( string $class_string ): ?array

Since: 6.6.0

Extracts block style variation names from a CSS class string using regex /bis-style-(?!default)(S+)b/. Returns array of matched variation slugs, or null if input is not a string.

wp_resolve_block_style_variation_ref_values()

function wp_resolve_block_style_variation_ref_values( array &$variation_data, array $theme_json )

Since: 6.6.0
Access: private

Recursively resolves ref values within variation data by looking up the referenced path in theme.json data. Invalid or unresolvable refs are unset.

wp_render_block_style_variation_support_styles()

function wp_render_block_style_variation_support_styles( array $parsed_block ): array

Since: 6.6.0
Access: private

Processing flow:

1. Extracts variation names from className attribute via wp_get_block_style_variation_name_from_class()
2. Looks up variation data in merged theme.json (WP_Theme_JSON_Resolver::get_merged_data()) under styles.blocks.{blockName}.variations.{variation}
3. Only the first variation with data is processed
4. Resolves ref values via wp_resolve_block_style_variation_ref_values()
5. Generates a unique instance ID via wp_unique_id()
6. Relocates root variation styles under a blocks property to leverage custom selectors
7. Creates a WP_Theme_JSON instance and generates a scoped stylesheet
8. Temporarily registers/unregisters the variation instance in WP_Block_Styles_Registry
9. Temporarily removes wp_filter_out_block_nodes filter (non-admin only) to include block nodes
10. Enqueues styles as inline CSS on block-style-variation-styles handle (depends on wp-block-library and global-styles)
11. Appends the unique instance class to className

wp_render_block_style_variation_class_name()

function wp_render_block_style_variation_class_name( string $block_content, array $block ): string

Since: 6.6.0
Access: private

Ensures the variation instance class name (pattern: is-style-{slug}--{id}) is applied to the block’s first HTML tag via WP_HTML_Tag_Processor.

wp_enqueue_block_style_variation_styles()

function wp_enqueue_block_style_variation_styles()

Since: 6.6.0
Access: private

Enqueues the block-style-variation-styles stylesheet.

wp_register_block_style_variations_from_theme_json_partials()

function wp_register_block_style_variations_from_theme_json_partials( array $variations )

Since: 6.6.0
Access: private

Registers block style variations from theme.json partial data. For each variation with blockTypes and styles, registers the style via register_block_style() if not already registered. Uses slug (or kebab-cased title) as the variation name.

Hooks

Registration

WP_Block_Supports::get_instance()->register( 'block-style-variation', array() );