Adds the gutenberg-off-canvas-navigation-editor experiment

packages/block-editor/src/components/off-canvas-editor/README.md

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+# Experimental Off Canvas Editor
+
+The __ExperimentalOffCanvasEditor component is a modified ListView compoent. It provides an overview of the hierarchical structure of all blocks in the editor. The blocks are presented vertically one below the other. It enables editing of hierarchy and addition of elements in the block tree without selecting the block instance on the canvas.
+
+It is an experimental component which may end up completely merged into the ListView component via configuration props.

packages/block-editor/src/components/off-canvas-editor/block-contents.js

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+/**
+ * External dependencies
+ */
+import classnames from 'classnames';
+
+/**
+ * WordPress dependencies
+ */
+import { useSelect } from '@wordpress/data';
+import { forwardRef } from '@wordpress/element';
+
+/**
+ * Internal dependencies
+ */
+import ListViewBlockSelectButton from './block-select-button';
+import BlockDraggable from '../block-draggable';
+import { store as blockEditorStore } from '../../store';
+
+const ListViewBlockContents = forwardRef(
+	(
+		{
+			onClick,
+			onToggleExpanded,
+			block,
+			isSelected,
+			position,
+			siblingBlockCount,
+			level,
+			isExpanded,
+			selectedClientIds,
+			...props
+		},
+		ref
+	) => {
+		const { clientId } = block;
+
+		const { blockMovingClientId, selectedBlockInBlockEditor } = useSelect(
+			( select ) => {
+				const { hasBlockMovingClientId, getSelectedBlockClientId } =
+					select( blockEditorStore );
+				return {
+					blockMovingClientId: hasBlockMovingClientId(),
+					selectedBlockInBlockEditor: getSelectedBlockClientId(),
+				};
+			},
+			[ clientId ]
+		);
+
+		const isBlockMoveTarget =
+			blockMovingClientId && selectedBlockInBlockEditor === clientId;
+
+		const className = classnames( 'block-editor-list-view-block-contents', {
+			'is-dropping-before': isBlockMoveTarget,
+		} );
+
+		// Only include all selected blocks if the currently clicked on block
+		// is one of the selected blocks. This ensures that if a user attempts
+		// to drag a block that isn't part of the selection, they're still able
+		// to drag it and rearrange its position.
+		const draggableClientIds = selectedClientIds.includes( clientId )
+			? selectedClientIds
+			: [ clientId ];
+
+		return (
+			<BlockDraggable clientIds={ draggableClientIds }>
+				{ ( { draggable, onDragStart, onDragEnd } ) => (
+					<ListViewBlockSelectButton
+						ref={ ref }
+						className={ className }
+						block={ block }
+						onClick={ onClick }
+						onToggleExpanded={ onToggleExpanded }
+						isSelected={ isSelected }
+						position={ position }
+						siblingBlockCount={ siblingBlockCount }
+						level={ level }
+						draggable={ draggable }
+						onDragStart={ onDragStart }
+						onDragEnd={ onDragEnd }
+						isExpanded={ isExpanded }
+						{ ...props }
+					/>
+				) }
+			</BlockDraggable>
+		);
+	}
+);
+
+export default ListViewBlockContents;

packages/block-editor/src/components/off-canvas-editor/block-select-button.js

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+/**
+ * External dependencies
+ */
+import classnames from 'classnames';
+
+/**
+ * WordPress dependencies
+ */
+import {
+	Button,
+	__experimentalHStack as HStack,
+	__experimentalTruncate as Truncate,
+} from '@wordpress/components';
+import { forwardRef } from '@wordpress/element';
+import { Icon, lock } from '@wordpress/icons';
+import { SPACE, ENTER } from '@wordpress/keycodes';
+
+/**
+ * Internal dependencies
+ */
+import BlockIcon from '../block-icon';
+import useBlockDisplayInformation from '../use-block-display-information';
+import useBlockDisplayTitle from '../block-title/use-block-display-title';
+import ListViewExpander from './expander';
+import { useBlockLock } from '../block-lock';
+
+function ListViewBlockSelectButton(
+	{
+		className,
+		block: { clientId },
+		onClick,
+		onToggleExpanded,
+		tabIndex,
+		onFocus,
+		onDragStart,
+		onDragEnd,
+		draggable,
+	},
+	ref
+) {
+	const blockInformation = useBlockDisplayInformation( clientId );
+	const blockTitle = useBlockDisplayTitle( {
+		clientId,
+		context: 'list-view',
+	} );
+	const { isLocked } = useBlockLock( clientId );
+
+	// The `href` attribute triggers the browser's native HTML drag operations.
+	// When the link is dragged, the element's outerHTML is set in DataTransfer object as text/html.
+	// We need to clear any HTML drag data to prevent `pasteHandler` from firing
+	// inside the `useOnBlockDrop` hook.
+	const onDragStartHandler = ( event ) => {
+		event.dataTransfer.clearData();
+		onDragStart?.( event );
+	};
+
+	function onKeyDownHandler( event ) {
+		if ( event.keyCode === ENTER || event.keyCode === SPACE ) {
+			onClick( event );
+		}
+	}
+
+	return (
+		<>
+			<Button
+				className={ classnames(
+					'block-editor-list-view-block-select-button',
+					className
+				) }
+				onClick={ onClick }
+				onKeyDown={ onKeyDownHandler }
+				ref={ ref }
+				tabIndex={ tabIndex }
+				onFocus={ onFocus }
+				onDragStart={ onDragStartHandler }
+				onDragEnd={ onDragEnd }
+				draggable={ draggable }
+				href={ `#block-${ clientId }` }
+				aria-hidden={ true }
+			>
+				<ListViewExpander onClick={ onToggleExpanded } />
+				<BlockIcon icon={ blockInformation?.icon } showColors />
+				<HStack
+					alignment="center"
+					className="block-editor-list-view-block-select-button__label-wrapper"
+					justify="flex-start"
+					spacing={ 1 }
+				>
+					<span className="block-editor-list-view-block-select-button__title">
+						<Truncate ellipsizeMode="auto">{ blockTitle }</Truncate>
+					</span>
+					{ blockInformation?.anchor && (
+						<span className="block-editor-list-view-block-select-button__anchor-wrapper">
+							<Truncate
+								className="block-editor-list-view-block-select-button__anchor"
+								ellipsizeMode="auto"
+							>
+								{ blockInformation.anchor }
+							</Truncate>
+						</span>
+					) }
+					{ isLocked && (
+						<span className="block-editor-list-view-block-select-button__lock">
+							<Icon icon={ lock } />
+						</span>
+					) }
+				</HStack>
+			</Button>
+		</>
+	);
+}
+
+export default forwardRef( ListViewBlockSelectButton );