Themes: Add shadow presets support for theme.json.

Adds shadow presets support for `theme.json` within the `WP_Theme_JSON` by 

* Adding it to presets metadata and valid settings.
* Defining the default shadow presets in Core's `theme.json`.

Includes PHPUnit tests. 

References:
* [WordPress/gutenberg#46813 Gutenberg PR 46813]
* [WordPress/gutenberg#47272 Gutenberg PR 47272]

Follow-up to [54162], [52049], [50973].

Props madhudollu, mamaduka, oandregal, scruffian, hellofromTonya.
Fixes #57559.
Built from https://develop.svn.wordpress.org/trunk@55176


git-svn-id: http://core.svn.wordpress.org/trunk@54709 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-wp-theme-json.php

@@ -115,6 +115,7 @@ class WP_Theme_JSON {
 	 *              `use_default_names` preset key, and simplified the metadata structure.
 	 * @since 6.0.0 Replaced `override` with `prevent_override` and updated the
 	 *              `prevent_override` value for `color.duotone` to use `color.defaultDuotone`.
+	 * @since 6.2.0 Added 'shadow' presets.
 	 * @var array
 	 */
 	const PRESETS_METADATA = array(
@@ -176,6 +177,15 @@ class WP_Theme_JSON {
 			'classes'           => array(),
 			'properties'        => array( 'padding', 'margin' ),
 		),
+		array(
+			'path'              => array( 'shadow', 'presets' ),
+			'prevent_override'  => array( 'shadow', 'defaultPresets' ),
+			'use_default_names' => false,
+			'value_key'         => 'shadow',
+			'css_vars'          => '--wp--preset--shadow--$slug',
+			'classes'           => array(),
+			'properties'        => array( 'box-shadow' ),
+		),
 	);
 
 	/**
@@ -294,7 +304,7 @@ class WP_Theme_JSON {
 	 *              and `typography`, and renamed others according to the new schema.
 	 * @since 6.0.0 Added `color.defaultDuotone`.
 	 * @since 6.1.0 Added `layout.definitions` and `useRootPaddingAwareAlignments`.
-	 * @since 6.2.0 Added `dimensions.minHeight`.
+	 * @since 6.2.0 Added `dimensions.minHeight`, 'shadow.presets', and 'shadow.defaultPresets'.
 	 * @var array
 	 */
 	const VALID_SETTINGS = array(
@@ -338,6 +348,10 @@ class WP_Theme_JSON {
 			'padding'           => null,
 			'units'             => null,
 		),
+		'shadow'                        => array(
+			'presets'        => null,
+			'defaultPresets' => null,
+		),
 		'typography'                    => array(
 			'fluid'          => null,
 			'customFontSize' => null,

wp-includes/theme.json

@@ -325,6 +325,20 @@
 				}
 			}
 		},
+		"shadow": {
+			"presets": [
+				{
+					"name": "Natural",
+					"slug": "natural",
+					"shadow": "0 .2rem .3rem 0 rgba(0,0,0, 0.3), 0 .5rem .6rem 0 rgba(0,0,0, 0.4)"
+				},
+				{
+					"name": "Sharp",
+					"slug": "sharp",
+					"shadow": ".5rem .5rem 0 0 rgba(0,0,0, 0.4)"
+				}
+			]
+		},
 		"spacing": {
 			"blockGap": null,
 			"margin": false,

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.2-alpha-55175';
+$wp_version = '6.2-alpha-55176';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.