Block editor: scroll block into view on insert (#61418)

Co-authored-by: ellatrix <[email protected]>
Co-authored-by: draganescu <[email protected]>
Co-authored-by: scruffian <[email protected]>

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

@@ -28,6 +28,7 @@ import { useEventHandlers } from './use-selected-block-event-handlers';
 import { useNavModeExit } from './use-nav-mode-exit';
 import { useBlockRefProvider } from './use-block-refs';
 import { useIntersectionObserver } from './use-intersection-observer';
+import { useScrollIntoView } from './use-scroll-into-view';
 import { useFlashEditableBlocks } from '../../use-flash-editable-blocks';
 import { canBindBlock } from '../../../hooks/use-bindings-attributes';
 
@@ -122,6 +123,7 @@ export function useBlockProps( props = {}, { __unstableIsHtml } = {} ) {
 			clientId,
 			isEnabled: name === 'core/block' || templateLock === 'contentOnly',
 		} ),
+		useScrollIntoView( { isSelected } ),
 	] );
 
 	const blockEditContext = useBlockEditContext();

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

@@ -0,0 +1,38 @@
+/**
+ * WordPress dependencies
+ */
+import { useReducedMotion, useRefEffect } from '@wordpress/compose';
+
+export function useScrollIntoView( { isSelected } ) {
+	const prefersReducedMotion = useReducedMotion();
+	return useRefEffect(
+		( node ) => {
+			if ( isSelected ) {
+				const { ownerDocument } = node;
+				const { defaultView } = ownerDocument;
+				if ( ! defaultView.IntersectionObserver ) {
+					return;
+				}
+				const observer = new defaultView.IntersectionObserver(
+					( entries ) => {
+						// Once observing starts, we always get an initial
+						// entry with the intersecting state.
+						if ( ! entries[ 0 ].isIntersecting ) {
+							node.scrollIntoView( {
+								behavior: prefersReducedMotion
+									? 'instant'
+									: 'smooth',
+							} );
+						}
+						observer.disconnect();
+					}
+				);
+				observer.observe( node );
+				return () => {
+					observer.disconnect();
+				};
+			}
+		},
+		[ isSelected ]
+	);
+}