Implement a block reordering animation

packages/block-editor/package.json

@@ -44,6 +44,7 @@
 		"classnames": "^2.2.5",
 		"dom-scroll-into-view": "^1.2.1",
 		"lodash": "^4.17.10",
+		"react-spring": "^8.0.19",
 		"redux-multi": "^0.1.12",
 		"refx": "^3.0.0",
 		"rememo": "^3.0.0",

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

@@ -3,6 +3,7 @@
  */
 import classnames from 'classnames';
 import { get, reduce, size, first, last } from 'lodash';
+import { animated } from 'react-spring/web.cjs';
 
 /**
  * WordPress dependencies
@@ -50,6 +51,7 @@ import InserterWithShortcuts from '../inserter-with-shortcuts';
 import Inserter from '../inserter';
 import useHoveredArea from './hover-area';
 import { isInsideRootBlock } from '../../utils/dom';
+import useMovingAnimation from './moving-animation';
 
 /**
  * Prevents default dragging behavior within a block to allow for multi-
@@ -97,6 +99,8 @@ function BlockListBlock( {
 	toggleSelection,
 	onShiftSelection,
 	onSelectionStart,
+	animateOnChange,
+	enableAnimation,
 } ) {
 	// Random state used to rerender the component if needed, ideally we don't need this
 	const [ , updateRerenderState ] = useState( {} );
@@ -247,6 +251,9 @@ function BlockListBlock( {
 		}
 	}, [ isFirstMultiSelected ] );
 
+	// Block Reordering animation
+	const style = useMovingAnimation( wrapper, isSelected || isPartOfMultiSelection, enableAnimation, animateOnChange );
+
 	// Other event handlers
 
 	/**
@@ -458,6 +465,8 @@ function BlockListBlock( {
 			tabIndex="0"
 			aria-label={ blockLabel }
 			childHandledEvents={ [ 'onDragStart', 'onMouseDown' ] }
+			tagName={ animated.div }
+			style={ style }
 			{ ...blockWrapperProps }
 		>
 			{ shouldShowInsertionPoint && (

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

@@ -3,7 +3,6 @@
  */
 import {
 	findLast,
-	map,
 	invert,
 	mapValues,
 	sortBy,
@@ -29,13 +28,20 @@ import BlockListBlock from './block';
 import BlockListAppender from '../block-list-appender';
 import { getBlockDOMNode } from '../../utils/dom';
 
+/**
+ * If the block count exceeds the threshold, we disable the reordering animation
+ * to avoid laginess.
+ */
+const BLOCK_ANIMATION_THRESHOLD = 200;
+
 const forceSyncUpdates = ( WrappedComponent ) => ( props ) => {
 	return (
 		<AsyncModeProvider value={ false }>
 			<WrappedComponent { ...props } />
 		</AsyncModeProvider>
 	);
 };
+
 class BlockList extends Component {
 	constructor( props ) {
 		super( props );
@@ -198,11 +204,12 @@ class BlockList extends Component {
 			multiSelectedBlockClientIds,
 			hasMultiSelection,
 			renderAppender,
+			enableAnimation,
 		} = this.props;
 
 		return (
 			<div className="editor-block-list__layout block-editor-block-list__layout">
-				{ map( blockClientIds, ( clientId ) => {
+				{ blockClientIds.map( ( clientId ) => {
 					const isBlockInSelection = hasMultiSelection ?
 						multiSelectedBlockClientIds.includes( clientId ) :
 						selectedBlockClientId === clientId;
@@ -214,11 +221,17 @@ class BlockList extends Component {
 							isBlockInSelection={ isBlockInSelection }
 						>
 							<BlockListBlock
+								rootClientId={ rootClientId }
 								clientId={ clientId }
 								blockRef={ this.setBlockRef }
 								onSelectionStart={ this.onSelectionStart }
-								rootClientId={ rootClientId }
 								isDraggable={ isDraggable }
+
+								// This prop is explicitely computed and passed down
+								// to avoid being impacted by the async mode
+								// otherwise there might be a small delay to trigger the animation.
+								animateOnChange={ blockClientIds }
+								enableAnimation={ enableAnimation }
 							/>
 						</BlockAsyncModeProvider>
 					);
@@ -248,6 +261,7 @@ export default compose( [
 			getSelectedBlockClientId,
 			getMultiSelectedBlockClientIds,
 			hasMultiSelection,
+			getGlobalBlockCount,
 		} = select( 'core/block-editor' );
 
 		const { rootClientId } = ownProps;
@@ -261,6 +275,7 @@ export default compose( [
 			selectedBlockClientId: getSelectedBlockClientId(),
 			multiSelectedBlockClientIds: getMultiSelectedBlockClientIds(),
 			hasMultiSelection: hasMultiSelection(),
+			enableAnimation: getGlobalBlockCount() <= BLOCK_ANIMATION_THRESHOLD,
 		};
 	} ),
 	withDispatch( ( dispatch ) => {

packages/block-editor/src/components/block-list/moving-animation.js

@@ -0,0 +1,85 @@
+/**
+ * External dependencies
+ */
+import { useSpring, interpolate } from 'react-spring/web.cjs';
+
+/**
+ * WordPress dependencies
+ */
+import { useState, useLayoutEffect } from '@wordpress/element';
+import { useReducedMotion } from '@wordpress/compose';
+
+/**
+ * Hook used to compute the styles required to move a div into a new position.
+ *
+ * The way this animation works is the following:
+ *  - It first renders the element as if there was no animation.
+ *  - It takes a snapshot of the position of the block to use it
+ *    as a destination point for the animation.
+ *  - It restores the element to the previous position using a CSS transform
+ *  - It uses the "resetAnimation" flag to reset the animation
+ *    from the beginning in order to animate to the new destination point.
+ *
+ * @param {Object}  ref                      Reference to the element to animate.
+ * @param {boolean} isSelected               Whether it's the current block or not.
+ * @param {boolean} enableAnimation          Enable/Disable animation.
+ * @param {*}       triggerAnimationOnChange Variable used to trigger the animation if it changes.
+ *
+ * @return {Object} Style object.
+ */
+function useMovingAnimation( ref, isSelected, enableAnimation, triggerAnimationOnChange ) {
+	const prefersReducedMotion = useReducedMotion() || ! enableAnimation;
+	const [ resetAnimation, setResetAnimation ] = useState( false );
+	const [ transform, setTransform ] = useState( { x: 0, y: 0 } );
+
+	const previous = ref.current ? ref.current.getBoundingClientRect() : null;
+	useLayoutEffect( () => {
+		if ( prefersReducedMotion ) {
+			return;
+		}
+		ref.current.style.transform = 'none';
+		const destination = ref.current.getBoundingClientRect();
+		const newTransform = {
+			x: previous ? previous.left - destination.left : 0,
+			y: previous ? previous.top - destination.top : 0,
+		};
+		ref.current.style.transform = `translate3d(${ newTransform.x }px,${ newTransform.y }px,0)`;
+		setResetAnimation( true );
+		setTransform( newTransform );
+	}, [ triggerAnimationOnChange ] );
+	useLayoutEffect( () => {
+		if ( resetAnimation ) {
+			setResetAnimation( false );
+		}
+	}, [ resetAnimation ] );
+	const animationProps = useSpring( {
+		from: transform,
+		to: {
+			x: 0,
+			y: 0,
+		},
+		reset: resetAnimation,
+		config: { mass: 5, tension: 2000, friction: 200 },
+		immediate: prefersReducedMotion,
+	} );
+
+	return {
+		transformOrigin: 'center',
+		transform: interpolate(
+			[
+				animationProps.x,
+				animationProps.y,
+			],
+			( x, y ) => x === 0 && y === 0 ? undefined : `translate3d(${ x }px,${ y }px,0)`
+		),
+		zIndex: interpolate(
+			[
+				animationProps.x,
+				animationProps.y,
+			],
+			( x, y ) => ! isSelected || ( x === 0 && y === 0 ) ? undefined : `1`
+		),
+	};
+}
+
+export default useMovingAnimation;

packages/block-editor/src/components/ignore-nested-events/index.js

@@ -6,7 +6,7 @@ import { reduce } from 'lodash';
 /**
  * WordPress dependencies
  */
-import { Component, forwardRef } from '@wordpress/element';
+import { Component, forwardRef, createElement } from '@wordpress/element';
 
 /**
  * Component which renders a div with passed props applied except the optional
@@ -66,7 +66,7 @@ export class IgnoreNestedEvents extends Component {
 	}
 
 	render() {
-		const { childHandledEvents = [], forwardedRef, ...props } = this.props;
+		const { childHandledEvents = [], forwardedRef, tagName = 'div', ...props } = this.props;
 
 		const eventHandlers = reduce( [
 			...childHandledEvents,
@@ -96,7 +96,7 @@ export class IgnoreNestedEvents extends Component {
 			return result;
 		}, {} );
 
-		return <div ref={ forwardedRef } { ...props } { ...eventHandlers } />;
+		return createElement( tagName, { ref: forwardedRef, ...props, ...eventHandlers } );
 	}
 }
 

packages/compose/src/hooks/use-reduced-motion/index.js

@@ -3,13 +3,20 @@
  */
 import useMediaQuery from '../use-media-query';
 
+/**
+ * Whether or not the user agent is Internet Explorer.
+ *
+ * @type {boolean}
+ */
+const IS_IE = window.navigator.userAgent.indexOf( 'Trident' ) >= 0;
+
 /**
  * Hook returning whether the user has a preference for reduced motion.
  *
  * @return {boolean} Reduced motion preference value.
  */
 const useReducedMotion =
-	process.env.FORCE_REDUCED_MOTION ?
+	process.env.FORCE_REDUCED_MOTION || IS_IE ?
 		() => true :
 		() => useMediaQuery( '(prefers-reduced-motion: reduce)' );
 

packages/e2e-tests/specs/block-deletion.test.js

@@ -110,8 +110,8 @@ describe( 'block deletion -', () => {
 			// Click on something that's not a block.
 			await page.click( '.editor-post-title' );
 
-			// Click on the third (image) block so that its wrapper is selected and backspace to delete it.
-			await page.click( '.block-editor-block-list__block:nth-child(3) .components-placeholder__label' );
+			// Click on the image block so that its wrapper is selected and backspace to delete it.
+			await page.click( '.wp-block[data-type="core/image"] .components-placeholder__label' );
 			await page.keyboard.press( 'Backspace' );
 
 			expect( await getEditedPostContent() ).toMatchSnapshot();