List View: Scroll selected block into view when single block selectio…

…n changes (#46895)

* List View: Try scrolling selected blocks into view when single block selection changes

* Use getScrollContainer and calculate real top position of scrollable area instead of using a hard-coded value

* Try rearranging things so that the ref is always attached at the row level

* Move placeholder to its own file

* Tidy up a little

* Tidy comments

* Remove unneeded optional chaining

Co-authored-by: Kai Hao <kevin830726@gmail.com>

* Simplify and improve logic based on feedback

Co-authored-by: Kai Hao <kevin830726@gmail.com>

* Remove unneeded optional chaining

Co-authored-by: Kai Hao <kevin830726@gmail.com>

* Revert placeholder component, update showBlock logic so that selected blocks are rendered as real ListViewBlock components

---------

Co-authored-by: Kai Hao <kevin830726@gmail.com>

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

@@ -27,6 +27,7 @@ import { sprintf, __ } from '@wordpress/i18n';
  * Internal dependencies
  */
 import ListViewLeaf from './leaf';
+import useListViewScrollIntoView from './use-list-view-scroll-into-view';
 import {
 	BlockMoverUpButton,
 	BlockMoverDownButton,
@@ -57,6 +58,7 @@ function ListViewBlock( {
 	isSyncedBranch,
 } ) {
 	const cellRef = useRef( null );
+	const rowRef = useRef( null );
 	const [ isHovered, setIsHovered ] = useState( false );
 	const { clientId } = block;
 
@@ -220,6 +222,15 @@ function ListViewBlock( {
 		? selectedClientIds
 		: [ clientId ];
 
+	// Pass in a ref to the row, so that it can be scrolled
+	// into view when selected. For long lists, the placeholder for the
+	// selected block is also observed, within ListViewLeafPlaceholder.
+	useListViewScrollIntoView( {
+		isSelected,
+		rowItemRef: rowRef,
+		selectedClientIds,
+	} );
+
 	return (
 		<ListViewLeaf
 			className={ classes }
@@ -235,6 +246,7 @@ function ListViewBlock( {
 			data-block={ clientId }
 			isExpanded={ canExpand ? isExpanded : undefined }
 			aria-selected={ !! isSelected || forceSelectionContentLock }
+			ref={ rowRef }
 		>
 			<TreeGridCell
 				className="block-editor-list-view-block__contents-cell"

packages/block-editor/src/components/list-view/branch.js

@@ -155,8 +155,6 @@ function ListViewBranch( props ) {
 
 				const isDragged = !! draggedClientIds?.includes( clientId );
 
-				const showBlock = isDragged || blockInView;
-
 				// Make updates to the selected or dragged blocks synchronous,
 				// but asynchronous for any other block.
 				const isSelected = isClientIdSelected(
@@ -165,6 +163,7 @@ function ListViewBranch( props ) {
 				);
 				const isSelectedBranch =
 					isBranchSelected || ( isSelected && hasNestedBlocks );
+				const showBlock = isDragged || blockInView || isSelected;
 				return (
 					<AsyncModeProvider key={ clientId } value={ ! isSelected }>
 						{ showBlock && (

packages/block-editor/src/components/list-view/leaf.js

@@ -8,6 +8,8 @@ import classnames from 'classnames';
  * WordPress dependencies
  */
 import { __experimentalTreeGridRow as TreeGridRow } from '@wordpress/components';
+import { useMergeRefs } from '@wordpress/compose';
+import { forwardRef } from '@wordpress/element';
 
 /**
  * Internal dependencies
@@ -16,33 +18,45 @@ import useMovingAnimation from '../use-moving-animation';
 
 const AnimatedTreeGridRow = animated( TreeGridRow );
 
-export default function ListViewLeaf( {
-	isSelected,
-	position,
-	level,
-	rowCount,
-	children,
-	className,
-	path,
-	...props
-} ) {
-	const ref = useMovingAnimation( {
-		isSelected,
-		adjustScrolling: false,
-		enableAnimation: true,
-		triggerAnimationOnChange: path,
-	} );
+const ListViewLeaf = forwardRef(
+	(
+		{
+			isSelected,
+			position,
+			level,
+			rowCount,
+			children,
+			className,
+			path,
+			...props
+		},
+		ref
+	) => {
+		const animationRef = useMovingAnimation( {
+			isSelected,
+			adjustScrolling: false,
+			enableAnimation: true,
+			triggerAnimationOnChange: path,
+		} );
 
-	return (
-		<AnimatedTreeGridRow
-			ref={ ref }
-			className={ classnames( 'block-editor-list-view-leaf', className ) }
-			level={ level }
-			positionInSet={ position }
-			setSize={ rowCount }
-			{ ...props }
-		>
-			{ children }
-		</AnimatedTreeGridRow>
-	);
-}
+		const mergedRef = useMergeRefs( [ ref, animationRef ] );
+
+		return (
+			<AnimatedTreeGridRow
+				ref={ mergedRef }
+				className={ classnames(
+					'block-editor-list-view-leaf',
+					className
+				) }
+				level={ level }
+				positionInSet={ position }
+				setSize={ rowCount }
+				{ ...props }
+			>
+				{ children }
+			</AnimatedTreeGridRow>
+		);
+	}
+);
+
+export default ListViewLeaf;

packages/block-editor/src/components/list-view/use-list-view-scroll-into-view.js

@@ -0,0 +1,48 @@
+/**
+ * WordPress dependencies
+ */
+import { getScrollContainer } from '@wordpress/dom';
+import { useLayoutEffect } from '@wordpress/element';
+
+export default function useListViewScrollIntoView( {
+	isSelected,
+	selectedClientIds,
+	rowItemRef,
+} ) {
+	const isSingleSelection = selectedClientIds.length === 1;
+
+	useLayoutEffect( () => {
+		// Skip scrolling into view if this particular block isn't selected,
+		// or if more than one block is selected overall. This is to avoid
+		// scrolling the view in a multi selection where the user has intentionally
+		// selected multiple blocks within the list view, but the initially
+		// selected block may be out of view.
+		if ( ! isSelected || ! isSingleSelection || ! rowItemRef.current ) {
+			return;
+		}
+
+		const scrollContainer = getScrollContainer( rowItemRef.current );
+		const { ownerDocument } = rowItemRef.current;
+
+		const windowScroll =
+			scrollContainer === ownerDocument.body ||
+			scrollContainer === ownerDocument.documentElement;
+
+		// If the there is no scroll container, of if the scroll container is the window,
+		// do not scroll into view, as the block is already in view.
+		if ( windowScroll || ! scrollContainer ) {
+			return;
+		}
+
+		const rowRect = rowItemRef.current.getBoundingClientRect();
+		const scrollContainerRect = scrollContainer.getBoundingClientRect();
+
+		// If the selected block is not currently visible, scroll to it.
+		if (
+			rowRect.top < scrollContainerRect.top ||
+			rowRect.bottom > scrollContainerRect.bottom
+		) {
+			rowItemRef.current.scrollIntoView();
+		}
+	}, [ isSelected, isSingleSelection, rowItemRef ] );
+}