New block: Modal block using the Interactivity API

mu-plugins/blocks/modal/index.php

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+<?php
+/**
+ * Block Name: Modal
+ * Description: Display content in a modal, hidden behind a button click.
+ *
+ * @package wporg
+ */
+
+namespace WordPressdotorg\MU_Plugins\Modal;
+
+add_action( 'init', __NAMESPACE__ . '\init' );
+
+/**
+ * Registers the block using the metadata loaded from the `block.json` file.
+ * Behind the scenes, it registers also all assets so they can be enqueued
+ * through the block editor in the corresponding context.
+ *
+ * @see https://developer.wordpress.org/reference/functions/register_block_type/
+ */
+function init() {
+	register_block_type( __DIR__ . '/build' );
+}
+
+/**
+ * Get the style declaration for a color attribute.
+ *
+ * The base color attribute (e.g. `backgroundColor`) is the preset color name,
+ * and needs to be converted into a CSS variable.
+ * The custom* color attribute (e.g. `customBackgroundColor`) is a hex value.
+ *
+ * In most cases, the base color attribute has a default value (see block.json),
+ * so there will always be a value for that attribute. This means we can pick
+ * up the custom* color attribute first, and fall back to the preset color if
+ * it's not found. Also, when picked in the color picker, the custom color
+ * will be prefilled with the hex value of the preset color.
+ *
+ * The overlayColor is a special case, it sets a default on `customOverlayColor`.
+ * If only `overlayColor` is set, the custom default will be used. If coding a
+ * modal by hand, make sure to set both `overlayColor` and `customColorOverlay`
+ * when needed (or only `customColorOverlay`).
+ *
+ * @param array  $attributes The block attributes.
+ * @param string $name       The name of the base attribute.
+ *
+ * @return string The style declaration (or empty if no colors set).
+ */
+function get_style_decl_from_attr( $attributes, $name ) {
+	$value = false;
+	if ( ! empty( $attributes[ 'custom' . ucfirst( $name ) ] ) ) {
+		$value = $attributes[ 'custom' . ucfirst( $name ) ];
+	} elseif ( ! empty( $attributes[ $name ] ) ) {
+		$value = "var(--wp--preset--color--{$attributes[$name]})";
+	}
+
+	if ( $value ) {
+		// Get the custom property name.
+		$slug = _wp_to_kebab_case( str_replace( 'Color', '', $name ) );
+		return "--wp--custom--wporg-modal--color--{$slug}: {$value};";
+	}
+
+	return '';
+}

mu-plugins/blocks/modal/render.php

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+<?php
+/**
+ * Render the modal.
+ */
+
+use function WordPressdotorg\MU_Plugins\Modal\get_style_decl_from_attr;
+
+$attributes['label'] = $attributes['label'] ?: __( 'Open modal', 'wporg' );
+
+$style = '';
+$style .= get_style_decl_from_attr( $attributes, 'backgroundColor' );
+$style .= get_style_decl_from_attr( $attributes, 'textColor' );
+$style .= get_style_decl_from_attr( $attributes, 'overlayColor' );
+$style .= get_style_decl_from_attr( $attributes, 'closeButtonColor' );
+
+$button_class = 'wp-block-button';
+if ( ! empty( $attributes['buttonStyle'] ) ) {
+	$button_class .= ' is-style-' . $attributes['buttonStyle'];
+}
+
+// Initial state to pass to Interactivity API.
+$init_state = [
+	'isOpen' => false,
+];
+
+// Set up a unique ID for this modal.
+$html_id = wp_unique_id( 'modal-' );
+
+?>
+<div
+	<?php echo get_block_wrapper_attributes( [ 'style' => $style ]); // phpcs:ignore ?>
+	data-wp-interactive="wporg/modal"
+	data-wp-watch="callbacks.init"
+	data-wp-on--keydown="actions.handleKeydown"
+	data-wp-class--is-modal-open="context.isOpen"
+	<?php echo wp_interactivity_data_wp_context( $init_state ); // phpcs:ignore ?>
+>
+	<div class="wp-block-buttons">
+		<div class="<?php echo esc_attr( $button_class ); ?>">
+		<?php if ( ! empty( $attributes['href'] ) ) : ?>
+			<a
+				href="<?php echo esc_attr( $attributes['href'] ); ?>"
+				download
+				class="wporg-modal__toggle wp-block-button__link"
+				data-wp-on--click="actions.toggle"
+				data-wp-bind--aria-expanded="context.isOpen"
+				aria-controls="<?php echo esc_attr( $html_id ); ?>"
+			><?php echo wp_kses_post( $attributes['label'] ); ?></a>
+		<?php else : ?>
+			<button
+				class="wporg-modal__toggle wp-block-button__link"
+				data-wp-on--click="actions.toggle"
+				data-wp-bind--aria-expanded="context.isOpen"
+				aria-controls="<?php echo esc_attr( $html_id ); ?>"
+			><?php echo wp_kses_post( $attributes['label'] ); ?></button>
+		<?php endif; ?>
+		</div>
+	</div>
+
+	<div
+		class="wporg-modal__modal-backdrop"
+		data-wp-bind--hidden="!context.isOpen"
+		data-wp-on--click="actions.clickBackdrop"
+	>
+		<div
+			class="wporg-modal__modal"
+			id="<?php echo esc_attr( $html_id ); ?>"
+			data-wp-bind--hidden="!context.isOpen"
+		>
+			<button
+				class="wporg-modal__modal-close"
+				data-wp-on--click="actions.close"
+				aria-label="<?php esc_attr_e( 'Close', 'wporg' ); ?>"
+			></button>
+
+			<div class="wporg-modal__modal-content">
+				<?php echo wp_kses_post( $content ); ?>
+			</div>
+		</div> <!-- /.wporg-modal__modal -->
+	</div> <!-- /.wporg-modal__modal-backdrop -->
+</div> <!-- /.wporg-modal -->

mu-plugins/blocks/modal/src/block.json

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+{
+	"$schema": "https://schemas.wp.org/trunk/block.json",
+	"apiVersion": 3,
+	"name": "wporg/modal",
+	"title": "Modal",
+	"icon": "location",
+	"category": "layout",
+	"description": "A modal dialog.",
+	"textdomain": "wporg",
+	"attributes": {
+		"backgroundColor": {
+			"type": "string",
+			"default": "white"
+		},
+		"customBackgroundColor": {
+			"type": "string"
+		},
+		"textColor": {
+			"type": "string",
+			"default": "charcoal-1"
+		},
+		"customTextColor": {
+			"type": "string"
+		},
+		"closeButtonColor": {
+			"type": "string",
+			"default": "charcoal-1"
+		},
+		"customCloseButtonColor": {
+			"type": "string"
+		},
+		"overlayColor": {
+			"type": "string"
+		},
+		"customOverlayColor": {
+			"type": "string",
+			"default": "#1e1e1ecc"
+		},
+		"href": {
+			"type": "string"
+		},
+		"label": {
+			"type": "string",
+			"default": "Open modal"
+		},
+		"buttonStyle": {
+			"type": "string",
+			"default": ""
+		}
+	},
+	"supports": {
+		"align": false,
+		"layout": false,
+		"interactivity": true
+	},
+	"editorScript": "file:./index.js",
+	"style": "file:./style-index.css",
+	"viewScriptModule": "file:./view.js",
+	"render": "file:../render.php"
+}