FSE: load content in iframe

.github/workflows/performance.yml

@@ -38,3 +38,10 @@ jobs:
 
     - name: Run the performance tests
       run: ./bin/plugin/cli.js perf --ci $GITHUB_SHA master --tests-branch $GITHUB_SHA
+
+    - name: Archive debug artifacts (screenshots, HTML snapshots)
+      uses: actions/upload-artifact@v2
+      if: always()
+      with:
+        name: failures-artifacts
+        path: artifacts

lib/edit-site-page.php

@@ -203,3 +203,40 @@ function register_site_editor_homepage_settings() {
 	);
 }
 add_action( 'init', 'register_site_editor_homepage_settings', 10 );
+
+/**
+ * Sets the editor styles to be consumed by JS.
+ */
+function gutenberg_extend_block_editor_styles_html() {
+	$handles = array(
+		'wp-block-editor',
+		'wp-block-library',
+		'wp-edit-blocks',
+	);
+
+	$block_registry = WP_Block_Type_Registry::get_instance();
+
+	foreach ( $block_registry->get_all_registered() as $block_name => $block_type ) {
+		if ( ! empty( $block_type->style ) ) {
+			$handles[] = $block_type->style;
+		}
+
+		if ( ! empty( $block_type->editor_style ) ) {
+			$handles[] = $block_type->editor_style;
+		}
+	}
+
+	$handles = array_unique( $handles );
+	$done    = wp_styles()->done;
+
+	ob_start();
+
+	wp_styles()->done = array();
+	wp_styles()->do_items( $handles );
+	wp_styles()->done = $done;
+
+	$editor_styles = wp_json_encode( array( 'html' => ob_get_clean() ) );
+
+	echo "<script>window.__editorStyles = $editor_styles</script>";
+}
+add_action( 'admin_footer-toplevel_page_gutenberg-edit-site', 'gutenberg_extend_block_editor_styles_html' );

packages/block-editor/src/components/block-list/block-popover.js

@@ -167,7 +167,9 @@ function BlockPopover( {
 		: 'top right left';
 	const stickyBoundaryElement = showEmptyBlockSideInserter
 		? undefined
-		: getScrollContainer( node ) || ownerDocument.body;
+		: ownerDocument.defaultView.frameElement ||
+		  getScrollContainer( node ) ||
+		  ownerDocument.body;
 
 	return (
 		<Popover

packages/block-editor/src/components/block-list/block-selection-button.js

@@ -223,6 +223,12 @@ function BlockSelectionButton( { clientId, rootClientId, blockElement } ) {
 
 				if ( navigateDown ) {
 					nextTabbable = focus.tabbable.findNext( blockElement );
+
+					if ( ! nextTabbable ) {
+						nextTabbable =
+							blockElement.ownerDocument.defaultView.frameElement;
+						nextTabbable = focus.tabbable.findNext( nextTabbable );
+					}
 				} else {
 					nextTabbable = focus.tabbable.findPrevious( blockElement );
 				}

packages/block-editor/src/components/iframe/index.js

@@ -0,0 +1,226 @@
+/**
+ * WordPress dependencies
+ */
+import { useState, useEffect, createPortal, useRef } from '@wordpress/element';
+import { __ } from '@wordpress/i18n';
+import { useResizeObserver } from '@wordpress/compose';
+
+const BODY_CLASS_NAME = 'editor-styles-wrapper';
+const BLOCK_PREFIX = 'wp-block';
+
+/**
+ * Clones stylesheets targetting the editor canvas to the given document. A
+ * stylesheet is considered targetting the editor a canvas if it contains the
+ * `editor-styles-wrapper`, `wp-block`, or `wp-block-*` class selectors.
+ *
+ * Ideally, this hook should be removed in the future and styles should be added
+ * explicitly as editor styles.
+ *
+ * @param {Document} doc The document to append cloned stylesheets to.
+ */
+function useStyleSheetsCompat( doc ) {
+	useEffect( () => {
+		// Search the document for stylesheets targetting the editor canvas.
+		Array.from( document.styleSheets ).forEach( ( styleSheet ) => {
+			try {
+				// May fail for external styles.
+				// eslint-disable-next-line no-unused-expressions
+				styleSheet.cssRules;
+			} catch ( e ) {
+				return;
+			}
+
+			const { ownerNode, cssRules } = styleSheet;
+
+			if ( ! cssRules ) {
+				return;
+			}
+
+			const isMatch = Array.from( cssRules ).find(
+				( { selectorText } ) =>
+					selectorText &&
+					( selectorText.includes( `.${ BODY_CLASS_NAME }` ) ||
+						selectorText.includes( `.${ BLOCK_PREFIX }` ) )
+			);
+
+			if ( isMatch && ! doc.getElementById( ownerNode.id ) ) {
+				doc.head.appendChild( ownerNode.cloneNode( true ) );
+			}
+		} );
+	}, [] );
+}
+
+/**
+ * Bubbles some event types (keydown, keypress, and dragover) to parent document
+ * document to ensure that the keyboard shortcuts and drag and drop work.
+ *
+ * Ideally, we should remove event bubbling in the future. Keyboard shortcuts
+ * should be context dependent, e.g. actions on blocks like Cmd+A should not
+ * work globally outside the block editor.
+ *
+ * @param {Document} doc Document to attach listeners to.
+ */
+function useBubbleEvents( doc ) {
+	useEffect( () => {
+		const { defaultView } = doc;
+		const { frameElement } = defaultView;
+
+		function bubbleEvent( event ) {
+			const prototype = Object.getPrototypeOf( event );
+			const constructorName = prototype.constructor.name;
+			const Constructor = window[ constructorName ];
+
+			const init = {};
+
+			for ( const key in event ) {
+				init[ key ] = event[ key ];
+			}
+
+			if ( event instanceof defaultView.MouseEvent ) {
+				const rect = frameElement.getBoundingClientRect();
+				init.clientX += rect.left;
+				init.clientY += rect.top;
+			}
+
+			const newEvent = new Constructor( event.type, init );
+			const cancelled = ! frameElement.dispatchEvent( newEvent );
+
+			if ( cancelled ) {
+				event.preventDefault();
+			}
+		}
+
+		const eventTypes = [ 'keydown', 'keypress', 'dragover' ];
+
+		for ( const name of eventTypes ) {
+			doc.addEventListener( name, bubbleEvent );
+		}
+
+		return () => {
+			for ( const name of eventTypes ) {
+				doc.removeEventListener( name, bubbleEvent );
+			}
+		};
+	}, [] );
+}
+
+/**
+ * Sets the document direction.
+ *
+ * Sets the `editor-styles-wrapper` class name on the body.
+ *
+ * Copies the `admin-color-*` class name to the body so that the admin color
+ * scheme applies to components in the iframe.
+ *
+ * @param {Document} doc Document to add class name to.
+ */
+function useBodyClassName( doc ) {
+	useEffect( () => {
+		doc.dir = document.dir;
+		doc.body.className = BODY_CLASS_NAME;
+
+		for ( const name of document.body.classList ) {
+			if ( name.startsWith( 'admin-color-' ) ) {
+				doc.body.classList.add( name );
+			}
+		}
+	}, [] );
+}
+
+/**
+ * Positions the body element so that the resize listener works correctly. We're
+ * using an absolute position here because the resize listener doesn't seem to
+ * report shrinking when the position is relative, causing the iframe not to
+ * shrink when content is removed.
+ *
+ * @see https://github.com/FezVrasta/react-resize-aware#usage
+ *
+ * @param {Document} doc Document to set styles to.
+ */
+function useResizeListenerCompat( doc ) {
+	useEffect( () => {
+		// Necessary for the resize listener to work correctly.
+		doc.body.style.position = 'absolute';
+		doc.body.style.right = '0';
+		doc.body.style.left = '0';
+	}, [] );
+}
+
+/**
+ * Sets the document head and default styles.
+ *
+ * @param {Document} doc  Document to set the head for.
+ * @param {string}   head HTML to set as the head.
+ */
+function useHead( doc, head ) {
+	useEffect( () => {
+		doc.head.innerHTML =
+			// Body margin must be overridable by themes.
+			'<style>body{margin:0}</style>' +
+			'<style>.wp-block[data-align="full"],.wp-block.alignfull{max-width:100vw!important;width:100vw!important;}</style>' +
+			head;
+	}, [] );
+}
+
+function IframeContent( { doc, head, children } ) {
+	useHead( doc, head );
+	useStyleSheetsCompat( doc );
+	useBubbleEvents( doc );
+	useBodyClassName( doc );
+	useResizeListenerCompat( doc );
+	return createPortal( children, doc.body );
+}
+
+export default function Iframe( { children, head, style = {}, ...props } ) {
+	const [ resizeListener, sizes ] = useResizeObserver();
+	const [ contentDocument, setContentDocument ] = useState();
+	const ref = useRef();
+
+	function setDocumentIfReady( doc ) {
+		const { readyState } = doc;
+
+		if ( readyState === 'interactive' || readyState === 'complete' ) {
+			setContentDocument( doc );
+		}
+	}
+
+	useEffect( () => {
+		setDocumentIfReady( ref.current.contentDocument );
+	}, [] );
+
+	function setRef( newRef ) {
+		ref.current = newRef;
+
+		if ( newRef ) {
+			setDocumentIfReady( newRef.contentDocument );
+		}
+	}
+
+	return (
+		<iframe
+			{ ...props }
+			style={ {
+				display: 'block',
+				width: '100%',
+				height: sizes.height + 'px',
+				minHeight: '100%',
+				...style,
+			} }
+			ref={ setRef }
+			tabIndex="0"
+			title={ __( 'Editor canvas' ) }
+			name="editor-canvas"
+			onLoad={ () => {
+				// Document is not immediately loaded in Firefox.
+				setDocumentIfReady( ref.current.contentDocument );
+			} }
+		>
+			{ contentDocument && (
+				<IframeContent doc={ contentDocument } head={ head }>
+					{ children( { current: contentDocument.body } ) }
+					{ resizeListener }
+				</IframeContent>
+			) }
+		</iframe>
+	);
+}

packages/block-editor/src/components/index.js

@@ -118,6 +118,7 @@ export {
 export { default as Warning } from './warning';
 export { default as WritingFlow } from './writing-flow';
 export { useCanvasClickRedirect as __unstableUseCanvasClickRedirect } from './use-canvas-click-redirect';
+export { default as __unstableIframe } from './iframe';
 
 /*
  * State Related Components

packages/block-editor/src/components/use-resize-canvas/index.js

@@ -11,11 +11,15 @@ import { default as useSimulatedMediaQuery } from '../../components/use-simulate
 /**
  * Function to resize the editor window.
  *
- * @param {string} deviceType Used for determining the size of the container (e.g. Desktop, Tablet, Mobile)
+ * @param {string}  deviceType Used for determining the size of the container (e.g. Desktop, Tablet, Mobile)
+ * @param {boolean} __unstableDisableSimulate
  *
  * @return {Object} Inline styles to be added to resizable container.
  */
-export default function useResizeCanvas( deviceType ) {
+export default function useResizeCanvas(
+	deviceType,
+	__unstableDisableSimulate
+) {
 	const [ actualWidth, updateActualWidth ] = useState( window.innerWidth );
 
 	useEffect( () => {
@@ -69,10 +73,11 @@ export default function useResizeCanvas( deviceType ) {
 		}
 	};
 
-	useSimulatedMediaQuery(
-		'resizable-editor-section',
-		getCanvasWidth( deviceType )
-	);
+	const width = __unstableDisableSimulate
+		? null
+		: getCanvasWidth( deviceType );
+
+	useSimulatedMediaQuery( 'resizable-editor-section', width );
 
 	return contentInlineStyles( deviceType );
 }

packages/block-editor/src/style.scss

@@ -64,3 +64,5 @@
 @import "./components/block-toolbar/style.scss";
 @import "./components/inserter/style.scss";
 @import "./components/preview-options/style.scss";
+
+@include wordpress-admin-schemes();