Selectors API: Make duotone selectors fallback and be scoped

docs/reference-guides/block-api/block-supports.md

@@ -139,7 +139,6 @@ supports: {
 -   Default value: null
 -   Subproperties:
     -   `background`: type `boolean`, default value `true`
-    -   `__experimentalDuotone`: type `string`, default value undefined
     -   `gradients`: type `boolean`, default value `false`
     -   `link`: type `boolean`, default value `false`
     -   `text`: type `boolean`, default value `true`
@@ -231,46 +230,9 @@ When the block declares support for `color.background`, the attributes definitio
 
 ### color.__experimentalDuotone
 
-This property adds UI controls which allow to apply a duotone filter to a block or part of a block.
+_**Note:** Deprecated since WordPress 6.3._
 
-The parent selector is automatically added much like nesting in Sass/SCSS (however, the `&` selector is not supported).
-
-```js
-supports: {
-    color: {
-        // Apply the filter to the same selector in both edit and save.
-        __experimentalDuotone: '> .duotone-img, > .duotone-video',
-
-        // Default values must be disabled if you don't want to use them with duotone.
-        background: false,
-        text: false
-    }
-}
-```
-
-Duotone presets are sourced from `color.duotone` in [theme.json](/docs/how-to-guides/themes/theme-json.md).
-
-When the block declares support for `color.__experimentalDuotone`, the attributes definition is extended to include the attribute `style`:
-
-- `style`: attribute of `object` type with no default assigned.
-
-  The block can apply a default duotone color by specifying its own attribute with a default e.g.:
-
-  ```js
-  attributes: {
-      style: {
-          type: 'object',
-          default: {
-              color: {
-                  duotone: [
-                      '#FFF',
-                      '#000'
-                  ]
-              }
-          }
-      }
-  }
-  ```
+This property has been replaced by [`filter.duotone`](#filter-duotone). 
 
 ### color.gradients
 
@@ -499,6 +461,60 @@ attributes: {
 }
 ```
 
+## filter
+-   Type: `Object`
+-   Default value: null
+-   Subproperties:
+    -   `duotone`: type `boolean`, default value `false`
+
+This value signals that a block supports some of the properties related to filters. When it does, the block editor will show UI controls for the user to set their values.
+
+### filter.duotone
+
+This property adds UI controls which allow the user to apply a duotone filter to
+a block or part of a block.
+
+```js
+supports: {
+    filter: {
+        // Enable duotone support
+        duotone: true
+    }
+},
+selectors: {
+    filter: {
+        // Apply the filter to img elements inside the image block
+        duotone: '.wp-block-image img'
+    }
+}
+```
+
+The filter can be applied to an element inside the block by setting the `selectors.filter.duotone` selector.
+
+Duotone presets are sourced from `color.duotone` in [theme.json](/docs/how-to-guides/themes/theme-json.md).
+
+When the block declares support for `filter.duotone`, the attributes definition is extended to include the attribute `style`:
+
+- `style`: attribute of `object` type with no default assigned.
+
+  The block can apply a default duotone color by specifying its own attribute with a default e.g.:
+
+  ```js
+  attributes: {
+      style: {
+          type: 'object',
+          default: {
+              color: {
+                  duotone: [
+                      '#FFF',
+                      '#000'
+                  ]
+              }
+          }
+      }
+  }
+  ```
+
 ## html
 
 -   Type: `boolean`

docs/reference-guides/core-blocks.md

@@ -311,7 +311,7 @@ Insert an image to make a visual statement. ([Source](https://github.com/WordPre
 
 -	**Name:** core/image
 -	**Category:** media
--	**Supports:** anchor, color (~~background~~, ~~text~~)
+-	**Supports:** anchor, color (~~background~~, ~~text~~), filter (duotone)
 -	**Attributes:** align, alt, caption, height, href, id, linkClass, linkDestination, linkTarget, rel, sizeSlug, title, url, width
 
 ## Latest Comments

lib/block-supports/duotone.php

@@ -405,7 +405,9 @@ function gutenberg_get_duotone_filter_svg( $preset ) {
 function gutenberg_register_duotone_support( $block_type ) {
 	$has_duotone_support = false;
 	if ( property_exists( $block_type, 'supports' ) ) {
-		$has_duotone_support = _wp_array_get( $block_type->supports, array( 'color', '__experimentalDuotone' ), false );
+		// Previous `color.__experimentalDuotone` support flag is migrated
+		// to `filter.duotone` via `block_type_metadata_settings` filter.
+		$has_duotone_support = _wp_array_get( $block_type->supports, array( 'filter', 'duotone' ), null );
 	}
 
 	if ( $has_duotone_support ) {
@@ -450,3 +452,4 @@ function gutenberg_render_duotone_support( $block_content, $block ) {
 add_action( 'wp_enqueue_scripts', array( 'WP_Duotone_Gutenberg', 'output_global_styles' ), 11 );
 add_action( 'wp_footer', array( 'WP_Duotone_Gutenberg', 'output_footer_assets' ), 10 );
 add_filter( 'block_editor_settings_all', array( 'WP_Duotone_Gutenberg', 'add_editor_settings' ), 10 );
+add_filter( 'block_type_metadata_settings', array( 'WP_Duotone_Gutenberg', 'migrate_experimental_duotone_support_flag' ), 10, 2 );

lib/class-wp-duotone-gutenberg.php

@@ -264,6 +264,42 @@ public static function output_global_styles() {
 		}
 	}
 
+	/**
+	 * Get the CSS selector for a block type.
+	 *
+	 * @param string $block_name The block name.
+	 *
+	 * @return string The CSS selector or null if there is no support.
+	 */
+	private static function get_selector( $block_name ) {
+		$block_type = WP_Block_Type_Registry::get_instance()->get_registered( $block_name );
+
+		if ( $block_type && property_exists( $block_type, 'supports' ) ) {
+			// Backwards compatibility with `supports.color.__experimentalDuotone`
+			// is provided via the `block_type_metadata_settings` filter. If
+			// `supports.filter.duotone` has not been set and the experimental
+			// property has been, the experimental property value is copied into
+			// `supports.filter.duotone`.
+			$duotone_support = _wp_array_get( $block_type->supports, array( 'filter', 'duotone' ), false );
+			if ( ! $duotone_support ) {
+				return null;
+			}
+
+			// If the experimental duotone support was set, that value is to be
+			// treated as a selector and requires scoping.
+			$experimental_duotone = _wp_array_get( $block_type->supports, array( 'color', '__experimentalDuotone' ), false );
+			if ( $experimental_duotone ) {
+				$root_selector = wp_get_block_css_selector( $block_type );
+				return is_string( $experimental_duotone )
+					? WP_Theme_JSON_Gutenberg::scope_selector( $root_selector, $experimental_duotone )
+					: $root_selector;
+			}
+
+			// Regular filter.duotone support uses filter.duotone selectors with fallbacks.
+			return wp_get_block_css_selector( $block_type, array( 'filter', 'duotone' ), true );
+		}
+	}
+
 	/**
 	 * Render out the duotone CSS styles and SVG.
 	 *
@@ -272,22 +308,15 @@ public static function output_global_styles() {
 	 * @return string                Filtered block content.
 	 */
 	public static function render_duotone_support( $block_content, $block ) {
-		$block_type = WP_Block_Type_Registry::get_instance()->get_registered( $block['blockName'] );
-
-		$duotone_support  = false;
-		$duotone_selector = null;
-		if ( $block_type ) {
-			$duotone_selector = wp_get_block_css_selector( $block_type, 'filter.duotone' );
-			$duotone_support  = (bool) $duotone_selector;
-		}
+		$duotone_selector = self::get_selector( $block['blockName'] );
 
 		// The block should have a duotone attribute or have duotone defined in its theme.json to be processed.
 		$has_duotone_attribute     = isset( $block['attrs']['style']['color']['duotone'] );
 		$has_global_styles_duotone = array_key_exists( $block['blockName'], self::$global_styles_block_names );
 
 		if (
 			empty( $block_content ) ||
-			! $duotone_support ||
+			! $duotone_selector ||
 			( ! $has_duotone_attribute && ! $has_global_styles_duotone )
 		) {
 			return $block_content;
@@ -349,7 +378,17 @@ public static function render_duotone_support( $block_content, $block ) {
 		$filter_id = gutenberg_get_duotone_filter_id( array( 'slug' => $slug ) );
 
 		// Build the CSS selectors to which the filter will be applied.
-		$selector = WP_Theme_JSON_Gutenberg::scope_selector( '.' . $filter_id, $duotone_selector );
+		$selectors = explode( ',', $duotone_selector );
+
+		$selectors_scoped = array();
+		foreach ( $selectors as $selector_part ) {
+			// Assuming the selector part is a subclass selector (not a tag name)
+			// so we can prepend the filter id class. If we want to support elements
+			// such as `img` or namespaces, we'll need to add a case for that here.
+			$selectors_scoped[] = '.' . $filter_id . trim( $selector_part );
+		}
+
+		$selector = implode( ', ', $selectors_scoped );
 
 		// We only want to add the selector if we have it in the output already, essentially skipping 'unset'.
 		if ( array_key_exists( $slug, self::$output ) ) {
@@ -386,4 +425,23 @@ public static function render_duotone_support( $block_content, $block ) {
 
 		return $tags->get_updated_html();
 	}
+
+	/**
+	 * Migrate the old experimental duotone support flag to its stabilized location
+	 * under `supports.filter.duotone` and sets.
+	 *
+	 * @param array $settings Current block type settings.
+	 * @param array $metadata Block metadata as read in via block.json.
+	 *
+	 * @return array Filtered block type settings.
+	 */
+	public static function migrate_experimental_duotone_support_flag( $settings, $metadata ) {
+		$duotone_support = _wp_array_get( $metadata, array( 'supports', 'color', '__experimentalDuotone' ), null );
+
+		if ( ! isset( $settings['supports']['filter']['duotone'] ) && null !== $duotone_support ) {
+			_wp_array_set( $settings, array( 'supports', 'filter', 'duotone' ), (bool) $duotone_support );
+		}
+
+		return $settings;
+	}
 }

lib/class-wp-theme-json-gutenberg.php

@@ -871,6 +871,17 @@ protected static function get_blocks_metadata() {
 
 			// The block may or may not have a duotone selector.
 			$duotone_selector = wp_get_block_css_selector( $block_type, 'filter.duotone' );
+
+			// Keep backwards compatibility for support.color.__experimentalDuotone.
+			if ( null === $duotone_selector ) {
+				$duotone_support = _wp_array_get( $block_type->supports, array( 'color', '__experimentalDuotone' ), null );
+
+				if ( $duotone_support ) {
+					$root_selector    = wp_get_block_css_selector( $block_type );
+					$duotone_selector = WP_Theme_JSON_Gutenberg::scope_selector( $root_selector, $duotone_support );
+				}
+			}
+
 			if ( null !== $duotone_selector ) {
 				static::$blocks_metadata[ $block_name ]['duotone'] = $duotone_selector;
 			}
@@ -2389,8 +2400,7 @@ function( $pseudo_selector ) use ( $selector ) {
 
 		// 3. Generate and append the rules that use the duotone selector.
 		if ( isset( $block_metadata['duotone'] ) && ! empty( $declarations_duotone ) ) {
-			$selector_duotone = static::scope_selector( $block_metadata['selector'], $block_metadata['duotone'] );
-			$block_rules     .= static::to_ruleset( $selector_duotone, $declarations_duotone );
+			$block_rules .= static::to_ruleset( $block_metadata['duotone'], $declarations_duotone );
 		}
 
 		// 4. Generate Layout block gap styles.

lib/compat/wordpress-6.3/get-global-styles-and-settings.php

@@ -25,17 +25,6 @@ function wp_get_block_css_selector( $block_type, $target = 'root', $fallback = f
 
 		$has_selectors = ! empty( $block_type->selectors );
 
-		// Duotone (No fallback selectors for Duotone).
-		if ( 'filter.duotone' === $target || array( 'filter', 'duotone' ) === $target ) {
-			// If selectors API in use, only use it's value or null.
-			if ( $has_selectors ) {
-				return _wp_array_get( $block_type->selectors, array( 'filter', 'duotone' ), null );
-			}
-
-			// Selectors API, not available, check for old experimental selector.
-			return _wp_array_get( $block_type->supports, array( 'color', '__experimentalDuotone' ), null );
-		}
-
 		// Root Selector.
 
 		// Calculated before returning as it can be used as fallback for
@@ -59,8 +48,8 @@ function wp_get_block_css_selector( $block_type, $target = 'root', $fallback = f
 			return $root_selector;
 		}
 
-		// If target is not `root` or `duotone` we have a feature or subfeature
-		// as the target. If the target is a string convert to an array.
+		// If target is not `root` we have a feature or subfeature as the target.
+		// If the target is a string convert to an array.
 		if ( is_string( $target ) ) {
 			$target = explode( '.', $target );
 		}
@@ -95,25 +84,7 @@ function wp_get_block_css_selector( $block_type, $target = 'root', $fallback = f
 			}
 
 			// Scope the feature selector by the block's root selector.
-			$scopes    = explode( ',', $root_selector );
-			$selectors = explode( ',', $feature_selector );
-
-			$selectors_scoped = array();
-			foreach ( $scopes as $outer ) {
-				foreach ( $selectors as $inner ) {
-					$outer = trim( $outer );
-					$inner = trim( $inner );
-					if ( ! empty( $outer ) && ! empty( $inner ) ) {
-						$selectors_scoped[] = $outer . ' ' . $inner;
-					} elseif ( empty( $outer ) ) {
-						$selectors_scoped[] = $inner;
-					} elseif ( empty( $inner ) ) {
-						$selectors_scoped[] = $outer;
-					}
-				}
-			}
-
-			return implode( ', ', $selectors_scoped );
+			return WP_Theme_JSON_Gutenberg::scope_selector( $root_selector, $feature_selector );
 		}
 
 		// Subfeature selector

packages/block-editor/src/components/global-styles/get-block-css-selector.js

@@ -34,17 +34,6 @@ export function getBlockCSSSelector(
 	const hasSelectors = ! isEmpty( selectors );
 	const path = Array.isArray( target ) ? target.join( '.' ) : target;
 
-	// Duotone ( no fallback selectors for Duotone ).
-	if ( path === 'filter.duotone' ) {
-		// If selectors API in use, only use its value or null.
-		if ( hasSelectors ) {
-			return get( selectors, path, null );
-		}
-
-		// Selectors API, not available, check for old experimental selector.
-		return get( supports, 'color.__experimentalDuotone', null );
-	}
-
 	// Root selector.
 
 	// Calculated before returning as it can be used as a fallback for feature

packages/block-editor/src/components/global-styles/test/use-global-styles-output.js

@@ -713,7 +713,7 @@ describe( 'global styles renderer', () => {
 				'core/image': {
 					name: imageBlock.name,
 					selector: imageSupports.__experimentalSelector,
-					duotoneSelector: imageSupports.color.__experimentalDuotone,
+					duotoneSelector: '.my-image img',
 					fallbackGapValue: undefined,
 					featureSelectors: {
 						root: '.my-image',