Block support: Add anchor support for dynamic blocks

Author: t-hamano

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

@@ -0,0 +1,64 @@
+<?php
+/**
+ * Anchor block support flag.
+ *
+ * @package gutenberg
+ */
+
+/**
+ * Registers the anchor block attribute for block types that support it.
+ *
+ * @param WP_Block_Type $block_type Block Type.
+ */
+function gutenberg_register_anchor_support( $block_type ) {
+	$has_anchor_support = block_has_support( $block_type, array( 'anchor' ), false );
+
+	if ( ! $has_anchor_support ) {
+		return;
+	}
+
+	if ( ! $block_type->attributes ) {
+		$block_type->attributes = array();
+	}
+
+	if ( ! array_key_exists( 'anchor', $block_type->attributes ) ) {
+		$block_type->attributes['anchor'] = array(
+			'type' => 'string',
+		);
+	}
+}
+
+/**
+ * Add the anchor id to the output.
+ *
+ * @param WP_Block_Type $block_type Block Type.
+ * @param array         $block_attributes Block attributes.
+ *
+ * @return array Block anchor id.
+ */
+function gutenberg_apply_anchor_support( $block_type, $block_attributes ) {
+	if ( ! $block_attributes ) {
+		return array();
+	}
+
+	$has_anchor_support = block_has_support( $block_type, array( 'anchor' ), false );
+	if ( ! $has_anchor_support ) {
+		return array();
+	}
+
+	$has_anchor = array_key_exists( 'anchor', $block_attributes );
+	if ( ! $has_anchor || empty( $block_attributes['anchor'] ) ) {
+		return array();
+	}
+
+	return array( 'id' => $block_attributes['anchor'] );
+}
+
+// Register the block support.
+WP_Block_Supports::get_instance()->register(
+	'anchor',
+	array(
+		'register_attribute' => 'gutenberg_register_anchor_support',
+		'apply'              => 'gutenberg_apply_anchor_support',
+	)
+);

docs/reference-guides/core-blocks.md

@@ -186,6 +186,7 @@ function gutenberg_is_experiment_enabled( $name ) {
 require __DIR__ . '/block-supports/background.php';
 require __DIR__ . '/block-supports/block-style-variations.php';
 require __DIR__ . '/block-supports/aria-label.php';
+require __DIR__ . '/block-supports/anchor.php';
 require __DIR__ . '/block-supports/block-visibility.php';
 
 // Client-side media processing.

lib/block-supports/anchor.php

@@ -25,6 +25,7 @@
 		}
 	},
 	"supports": {
+		"anchor": true,
 		"align": true,
 		"__experimentalBorder": {
 			"radius": true,

lib/load.php

@@ -25,6 +25,7 @@
 	},
 	"usesContext": [ "postType", "postId", "commentId" ],
 	"supports": {
+		"anchor": true,
 		"html": false,
 		"align": true,
 		"alignWide": false,

packages/block-library/src/archives/block.json

@@ -30,6 +30,7 @@
 	},
 	"usesContext": [ "postId", "postType", "templateSlug" ],
 	"supports": {
+		"anchor": true,
 		"html": false,
 		"align": [ "wide", "full" ],
 		"spacing": {

packages/block-library/src/avatar/block.json

@@ -16,6 +16,7 @@
 		}
 	},
 	"supports": {
+		"anchor": true,
 		"align": true,
 		"html": false,
 		"color": {

packages/block-library/src/breadcrumbs/block.json

@@ -43,6 +43,7 @@
 	},
 	"usesContext": [ "enhancedPagination" ],
 	"supports": {
+		"anchor": true,
 		"align": true,
 		"html": false,
 		"spacing": {

packages/block-library/src/calendar/block.json

@@ -19,6 +19,7 @@
 	},
 	"usesContext": [ "commentId" ],
 	"supports": {
+		"anchor": true,
 		"html": false,
 		"spacing": {
 			"margin": true,