fix(AnalyticalTable): improve scroll performance (#7777)

Fixes #6615

Scrolling improvements in general, but especially noticeable for
scrollbar-based scrolling, which was previously laggy.

Author: Lukas742

packages/main/src/components/AnalyticalTable/AnalyticalTable.stories.tsx

@@ -158,6 +158,8 @@ const kitchenSinkArgs: AnalyticalTablePropTypes = {
   visibleRowCountMode: AnalyticalTableVisibleRowCountMode.Interactive,
   visibleRows: 5,
   withRowHighlight: true,
+  // sb actions has a huge impact on performance here.
+  onTableScroll: undefined,
 };
 
 const meta = {
@@ -191,6 +193,8 @@ const meta = {
     highlightField: 'status',
     subRowsKey: 'subRows',
     visibleRows: 5,
+    // sb actions has a huge impact on performance here.
+    onTableScroll: undefined,
   },
   argTypes: {
     data: { control: { disable: true } },

packages/main/src/components/AnalyticalTable/TableBody/VirtualTableBodyContainer.tsx

@@ -74,7 +74,9 @@ export const VirtualTableBodyContainer = (props: VirtualTableBodyContainerProps)
 
   const onScroll = useCallback(
     (event) => {
-      handleExternalScroll(enrichEventWithDetails(event, { rows, rowElements: event.target.children[0].children }));
+      if (typeof handleExternalScroll === 'function') {
+        handleExternalScroll(enrichEventWithDetails(event, { rows, rowElements: event.target.children[0].children }));
+      }
       const scrollOffset = event.target.scrollTop;
       const isScrollingDown = lastScrollTop.current < scrollOffset;
       const target = event.target;

packages/main/src/components/AnalyticalTable/hooks/useSyncScroll.ts

@@ -0,0 +1,52 @@
+import type { MutableRefObject } from 'react';
+import { useEffect, useRef, useState } from 'react';
+
+export function useSyncScroll(refContent: MutableRefObject<HTMLElement>, refScrollbar: MutableRefObject<HTMLElement>) {
+  const ticking = useRef(false);
+  const isProgrammatic = useRef(false);
+  const [isMounted, setIsMounted] = useState(false);
+
+  useEffect(() => {
+    const content = refContent.current;
+    const scrollbar = refScrollbar.current;
+
+    if (!content || !scrollbar || !isMounted) {
+      setIsMounted(true);
+      return;
+    }
+
+    scrollbar.scrollTop = content.scrollTop;
+
+    const sync = (source: 'content' | 'scrollbar') => {
+      if (ticking.current) {
+        return;
+      }
+      ticking.current = true;
+
+      requestAnimationFrame(() => {
+        const sourceEl = source === 'content' ? content : scrollbar;
+        const targetEl = source === 'content' ? scrollbar : content;
+
+        if (!isProgrammatic.current && targetEl.scrollTop !== sourceEl.scrollTop) {
+          isProgrammatic.current = true;
+          targetEl.scrollTop = sourceEl.scrollTop;
+          // Clear the flag on next frame
+          requestAnimationFrame(() => (isProgrammatic.current = false));
+        }
+
+        ticking.current = false;
+      });
+    };
+
+    const onScrollContent = () => sync('content');
+    const onScrollScrollbar = () => sync('scrollbar');
+
+    content.addEventListener('scroll', onScrollContent, { passive: true });
+    scrollbar.addEventListener('scroll', onScrollScrollbar, { passive: true });
+
+    return () => {
+      content.removeEventListener('scroll', onScrollContent);
+      scrollbar.removeEventListener('scroll', onScrollScrollbar);
+    };
+  }, [isMounted, refContent, refScrollbar]);
+}

packages/main/src/components/AnalyticalTable/index.tsx

@@ -74,6 +74,7 @@ import { useScrollToRef } from './hooks/useScrollToRef.js';
 import { useSelectionChangeCallback } from './hooks/useSelectionChangeCallback.js';
 import { useSingleRowStateSelection } from './hooks/useSingleRowStateSelection.js';
 import { useStyling } from './hooks/useStyling.js';
+import { useSyncScroll } from './hooks/useSyncScroll.js';
 import { useToggleRowExpand } from './hooks/useToggleRowExpand.js';
 import { useVisibleColumnsWidth } from './hooks/useVisibleColumnsWidth.js';
 import { VerticalScrollbar } from './scrollbars/VerticalScrollbar.js';
@@ -656,34 +657,7 @@ const AnalyticalTable = forwardRef<AnalyticalTableDomRef, AnalyticalTablePropTyp
     }
   }, [tableState.columnResizing, retainColumnWidth, tableState.tableColResized]);
 
-  const handleBodyScroll = (e) => {
-    if (typeof onTableScroll === 'function') {
-      onTableScroll(e);
-    }
-    const targetScrollTop = e.currentTarget.scrollTop;
-
-    if (verticalScrollBarRef.current) {
-      const vertScrollbarScrollElement = verticalScrollBarRef.current.firstElementChild as HTMLDivElement;
-      if (vertScrollbarScrollElement.offsetHeight !== scrollContainerRef.current?.offsetHeight) {
-        vertScrollbarScrollElement.style.height = `${scrollContainerRef.current.offsetHeight}px`;
-      }
-      if (verticalScrollBarRef.current.scrollTop !== targetScrollTop) {
-        if (!e.currentTarget.isExternalVerticalScroll) {
-          verticalScrollBarRef.current.scrollTop = targetScrollTop;
-          verticalScrollBarRef.current.isExternalVerticalScroll = true;
-        }
-        e.currentTarget.isExternalVerticalScroll = false;
-      }
-    }
-  };
-
-  const handleVerticalScrollBarScroll = useCallback((e) => {
-    if (parentRef.current && !e.currentTarget.isExternalVerticalScroll) {
-      parentRef.current.scrollTop = e.currentTarget.scrollTop;
-      parentRef.current.isExternalVerticalScroll = true;
-    }
-    e.currentTarget.isExternalVerticalScroll = false;
-  }, []);
+  useSyncScroll(parentRef, verticalScrollBarRef);
 
   useEffect(() => {
     columnVirtualizer.measure();
@@ -870,7 +844,7 @@ const AnalyticalTable = forwardRef<AnalyticalTableDomRef, AnalyticalTablePropTyp
                 internalRowHeight={internalRowHeight}
                 popInRowHeight={popInRowHeight}
                 rows={rows}
-                handleExternalScroll={handleBodyScroll}
+                handleExternalScroll={onTableScroll}
                 visibleRows={internalVisibleRowCount}
                 isGrouped={isGrouped}
               >
@@ -905,10 +879,8 @@ const AnalyticalTable = forwardRef<AnalyticalTableDomRef, AnalyticalTablePropTyp
               tableBodyHeight={tableBodyHeight}
               internalRowHeight={internalHeaderRowHeight}
               tableRef={tableRef}
-              handleVerticalScrollBarScroll={handleVerticalScrollBarScroll}
               ref={verticalScrollBarRef}
               scrollContainerRef={scrollContainerRef}
-              parentRef={parentRef}
               nativeScrollbar={nativeScrollbar}
               classNames={classNames}
             />

packages/main/src/components/AnalyticalTable/scrollbars/VerticalScrollbar.tsx

@@ -1,51 +1,22 @@
-import { useSyncRef } from '@ui5/webcomponents-react-base';
 import { clsx } from 'clsx';
-import type { MutableRefObject, RefObject } from 'react';
-import { forwardRef, useEffect, useRef } from 'react';
+import type { MutableRefObject } from 'react';
+import { forwardRef } from 'react';
 import { FlexBoxDirection } from '../../../enums/FlexBoxDirection.js';
 import { FlexBox } from '../../FlexBox/index.js';
 import type { ClassNames } from '../types/index.js';
 
 interface VerticalScrollbarProps {
   internalRowHeight: number;
-  tableRef: RefObject<any>;
-  handleVerticalScrollBarScroll: any;
+  tableRef: MutableRefObject<HTMLDivElement>;
   tableBodyHeight: number;
   scrollContainerRef: MutableRefObject<HTMLDivElement>;
-  parentRef: MutableRefObject<HTMLDivElement>;
   nativeScrollbar: boolean;
   classNames: ClassNames;
 }
 
 export const VerticalScrollbar = forwardRef<HTMLDivElement, VerticalScrollbarProps>((props, ref) => {
-  const {
-    internalRowHeight,
-    tableRef,
-    handleVerticalScrollBarScroll,
-    tableBodyHeight,
-    scrollContainerRef,
-    nativeScrollbar,
-    parentRef,
-    classNames,
-  } = props;
-  const [componentRef, containerRef] = useSyncRef(ref);
-  const scrollElementRef = useRef(null);
-
+  const { internalRowHeight, tableRef, tableBodyHeight, scrollContainerRef, nativeScrollbar, classNames } = props;
   const hasHorizontalScrollbar = tableRef?.current?.offsetWidth !== tableRef?.current?.scrollWidth;
-
-  useEffect(() => {
-    const observer = new ResizeObserver(([entry]) => {
-      if (containerRef.current && parentRef.current && entry.target.getBoundingClientRect().height > 0) {
-        containerRef.current.scrollTop = parentRef.current.scrollTop;
-      }
-    });
-    if (scrollElementRef.current) {
-      observer.observe(scrollElementRef.current);
-    }
-    return () => {
-      observer.disconnect();
-    };
-  }, []);
   const horizontalScrollbarSectionStyles = clsx(hasHorizontalScrollbar && classNames.bottomSection);
 
   return (
@@ -61,11 +32,10 @@ export const VerticalScrollbar = forwardRef<HTMLDivElement, VerticalScrollbarPro
         className={classNames.headerSection}
       />
       <div
-        ref={componentRef}
+        ref={ref}
         style={{
           height: tableRef.current ? `${tableBodyHeight}px` : '0',
         }}
-        onScroll={handleVerticalScrollBarScroll}
         className={clsx(
           classNames.scrollbar,
           nativeScrollbar
@@ -76,7 +46,6 @@ export const VerticalScrollbar = forwardRef<HTMLDivElement, VerticalScrollbarPro
         tabIndex={-1}
       >
         <div
-          ref={scrollElementRef}
           className={classNames.verticalScroller}
           style={{
             height: `${scrollContainerRef.current?.scrollHeight}px`,

packages/main/src/components/AnalyticalTable/types/index.ts

@@ -427,7 +427,11 @@ export interface AnalyticalTableColumnDefinition {
    */
   headerTooltip?: string;
   /**
-   * Custom cell renderer. If set, the table will call that component for every cell and pass all required information as props, e.g. the cell value as `props.cell.value`
+   * Custom cell renderer. If set, the table will use this component or render the provided string for every cell,
+   * passing all necessary information as props, e.g., the cell value as `props.cell.value`.
+   *
+   * __Note:__ Using a custom component __can impact performance__!
+   * If you pass a component, __memoizing it is strongly recommended__, especially for complex components or large datasets.
    */
   Cell?: string | ComponentType<CellInstance> | ((props?: CellInstance) => ReactNode);
   /**
@@ -1019,6 +1023,10 @@ export interface AnalyticalTablePropTypes extends Omit<CommonProps, 'title'> {
   onLoadMore?: (e?: CustomEvent<{ rowCount: number; totalRowCount: number }>) => void;
   /**
    * Fired when the body of the table is scrolled.
+   *
+   * __Note:__ This callback __must be memoized__! Since it is triggered on __every scroll event__,
+   * non-memoized or expensive calculations can have a __huge impact on performance__ and cause visible lag.
+   * Throttling or debouncing is always recommended to reduce performance overhead.
    */
   onTableScroll?: (e?: CustomEvent<{ rows: Record<string, any>[]; rowElements: HTMLCollection }>) => void;
   /**