theme.json: add appearanceTools flag to opt-in into appearance UI controls

docs/how-to-guides/themes/theme-json.md

@@ -218,6 +218,7 @@ The settings section has the following structure:
 {
 	"version": 1,
 	"settings": {
+		"appearanceTools": false,
 		"border": {
 			"color": false,
 			"radius": false,
@@ -282,6 +283,15 @@ Each block can configure any of these settings separately, providing a more fine
 
 Note, however, that not all settings are relevant for all blocks. The settings section provides an opt-in/opt-out mechanism for themes, but it's the block's responsibility to add support for the features that are relevant to it. For example, if a block doesn't implement the `dropCap` feature, a theme can't enable it for such a block through `theme.json`.
 
+### Opt-in into UI controls
+
+There's one special setting property, `appearanceTools`, which is a boolean and its default value is false. Themes can use this setting to enable the following ones:
+
+- border: color, radius, style, width
+- color: link
+- spacing: blockGap, margin, padding
+- typography: lineHeight
+
 #### Backward compatibility with add_theme_support
 
 To retain backward compatibility, the existing `add_theme_support` declarations that configure the block editor are retrofit in the proper categories for the top-level section. For example, if a theme uses `add_theme_support('disable-custom-colors')`, it'll be the same as setting `settings.color.custom` to `false`. If the `theme.json` contains any settings, these will take precedence over the values declared via `add_theme_support`. This is the complete list of equivalences:

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

@@ -81,13 +81,14 @@ class WP_Theme_JSON_Gutenberg {
 	);
 
 	const VALID_SETTINGS = array(
-		'border'     => array(
+		'appearanceTools' => null,
+		'border'          => array(
 			'color'  => null,
 			'radius' => null,
 			'style'  => null,
 			'width'  => null,
 		),
-		'color'      => array(
+		'color'           => array(
 			'background'       => null,
 			'custom'           => null,
 			'customDuotone'    => null,
@@ -100,18 +101,18 @@ class WP_Theme_JSON_Gutenberg {
 			'palette'          => null,
 			'text'             => null,
 		),
-		'custom'     => null,
-		'layout'     => array(
+		'custom'          => null,
+		'layout'          => array(
 			'contentSize' => null,
 			'wideSize'    => null,
 		),
-		'spacing'    => array(
+		'spacing'         => array(
 			'blockGap' => null,
 			'margin'   => null,
 			'padding'  => null,
 			'units'    => null,
 		),
-		'typography' => array(
+		'typography'      => array(
 			'customFontSize' => null,
 			'dropCap'        => null,
 			'fontFamilies'   => null,
@@ -292,7 +293,8 @@ public function __construct( $theme_json = array(), $origin = 'theme' ) {
 
 		$valid_block_names   = array_keys( self::get_blocks_metadata() );
 		$valid_element_names = array_keys( self::ELEMENTS );
-		$this->theme_json    = self::sanitize( $theme_json, $valid_block_names, $valid_element_names );
+		$theme_json          = self::sanitize( $theme_json, $valid_block_names, $valid_element_names );
+		$this->theme_json    = self::maybe_opt_in_into_settings( $theme_json );
 
 		// Internally, presets are keyed by origin.
 		$nodes = self::get_setting_nodes( $this->theme_json );
@@ -307,6 +309,57 @@ public function __construct( $theme_json = array(), $origin = 'theme' ) {
 		}
 	}
 
+	/**
+	 * Enables some opt-in settings if theme declared support.
+	 *
+	 * @param array $theme_json A theme.json structure to modify.
+	 * @return array The modified theme.json structure.
+	 */
+	private static function maybe_opt_in_into_settings( $theme_json ) {
+		$new_theme_json = $theme_json;
+
+		if ( isset( $new_theme_json['settings']['appearanceTools'] ) ) {
+			self::do_opt_in_into_settings( $new_theme_json['settings'] );
+		}
+
+		if ( isset( $new_theme_json['settings']['blocks'] ) && is_array( $new_theme_json['settings']['blocks'] ) ) {
+			foreach ( $new_theme_json['settings']['blocks'] as &$block ) {
+				if ( isset( $block['appearanceTools'] ) ) {
+					self::do_opt_in_into_settings( $block );
+				}
+			}
+		}
+
+		return $new_theme_json;
+	}
+
+	/**
+	 * Enables some settings.
+	 *
+	 * @param array $context The context to which the settings belong.
+	 */
+	private static function do_opt_in_into_settings( &$context ) {
+		$to_opt_in = array(
+			array( 'border', 'color' ),
+			array( 'border', 'radius' ),
+			array( 'border', 'style' ),
+			array( 'border', 'width' ),
+			array( 'color', 'link' ),
+			array( 'spacing', 'blockGap' ),
+			array( 'spacing', 'margin' ),
+			array( 'spacing', 'padding' ),
+			array( 'typography', 'lineHeight' ),
+		);
+
+		foreach ( $to_opt_in as $path ) {
+			if ( null === _wp_array_get( $context, $path, null ) ) {
+				_wp_array_set( $context, $path, true );
+			}
+		}
+
+		unset( $context['appearanceTools'] );
+	}
+
 	/**
 	 * Sanitizes the input according to the schemas.
 	 *

lib/theme.json

@@ -1,6 +1,7 @@
 {
 	"version": 2,
 	"settings": {
+		"appearanceTools": false,
 		"color": {
 			"background": true,
 			"palette": [

phpunit/class-wp-theme-json-test.php

@@ -188,6 +188,79 @@ function test_get_settings_presets_are_keyed_by_origin() {
 		$this->assertEqualSetsWithIndex( $expected_no_origin, $actual_no_origin );
 	}
 
+	function test_get_settings_using_opt_in_key() {
+		$theme_json = new WP_Theme_JSON_Gutenberg(
+			array(
+				'version'  => WP_Theme_JSON_Gutenberg::LATEST_SCHEMA,
+				'settings' => array(
+					'appearanceTools' => true,
+					'blocks'          => array(
+						'core/paragraph' => array(
+							'typography' => array(
+								'lineHeight' => false,
+							),
+						),
+						'core/group'     => array(
+							'appearanceTools' => true,
+							'typography'      => array(
+								'lineHeight' => false, // This should override appearanceTools.
+							),
+						),
+					),
+				),
+			)
+		);
+
+		$actual   = $theme_json->get_settings();
+		$expected = array(
+			'border'     => array(
+				'width'  => true,
+				'style'  => true,
+				'radius' => true,
+				'color'  => true,
+			),
+			'color'      => array(
+				'link' => true,
+			),
+			'spacing'    => array(
+				'blockGap' => true,
+				'margin'   => true,
+				'padding'  => true,
+			),
+			'typography' => array(
+				'lineHeight' => true,
+			),
+			'blocks'     => array(
+				'core/paragraph' => array(
+					'typography' => array(
+						'lineHeight' => false,
+					),
+				),
+				'core/group'     => array(
+					'border'     => array(
+						'width'  => true,
+						'style'  => true,
+						'radius' => true,
+						'color'  => true,
+					),
+					'color'      => array(
+						'link' => true,
+					),
+					'spacing'    => array(
+						'blockGap' => true,
+						'margin'   => true,
+						'padding'  => true,
+					),
+					'typography' => array(
+						'lineHeight' => false,
+					),
+				),
+			),
+		);
+
+		$this->assertEqualSetsWithIndex( $expected, $actual );
+	}
+
 	function test_get_stylesheet_support_for_shorthand_and_longhand_values() {
 		$theme_json = new WP_Theme_JSON_Gutenberg(
 			array(

schemas/json/theme.json

@@ -9,6 +9,11 @@
 		},
 		"settingsProperties": {
 			"properties": {
+				"appearanceTools": {
+					"description": "Setting that enables ui tools. \nGutenberg plugin required.",
+					"type": "boolean",
+					"default": false
+				},
 				"border": {
 					"description": "Settings related to borders.\nGutenberg plugin required.",
 					"type": "object",