[DataGrid] Use binary search to find column indexes in virtualization (…

…#1903)

packages/grid/_modules_/grid/hooks/features/virtualization/useGridVirtualColumns.ts

@@ -13,7 +13,6 @@ import { useGridApiMethod } from '../../root/useGridApiMethod';
 import { useGridApiEventHandler } from '../../root/useGridApiEventHandler';
 import {
   gridColumnsMetaSelector,
-  visibleGridColumnsLengthSelector,
   visibleGridColumnsSelector,
 } from '../columns/gridColumnsSelector';
 import { useGridSelector } from '../core/useGridSelector';
@@ -27,6 +26,28 @@ type UseVirtualColumnsReturnType = [
   UpdateRenderedColsFnType,
 ];
 
+// Uses binary search to avoid looping through all possible positions
+function getIdxFromScroll(
+  offset: number,
+  positions: number[],
+  sliceStart = 0,
+  sliceEnd = positions.length,
+): number {
+  if (positions.length <= 0) {
+    return -1;
+  }
+
+  if (sliceStart >= sliceEnd) {
+    return sliceStart;
+  }
+
+  const pivot = sliceStart + Math.floor((sliceEnd - sliceStart) / 2);
+  const itemOffset = positions[pivot];
+  return offset <= itemOffset
+    ? getIdxFromScroll(offset, positions, sliceStart, pivot)
+    : getIdxFromScroll(offset, positions, pivot + 1, sliceEnd);
+}
+
 export const useGridVirtualColumns = (
   options: GridOptions,
   apiRef: GridApiRef,
@@ -37,21 +58,11 @@ export const useGridVirtualColumns = (
   const containerPropsRef = React.useRef<GridContainerProps | null>(null);
   const lastScrollLeftRef = React.useRef<number>(0);
   const columnsMeta = useGridSelector(apiRef, gridColumnsMetaSelector);
-  const visibleColumnCount = useGridSelector(apiRef, visibleGridColumnsLengthSelector);
   const visibleColumns = useGridSelector(apiRef, visibleGridColumnsSelector);
 
   const getColumnIdxFromScroll = React.useCallback(
-    (left: number) => {
-      const positions = columnsMeta.positions;
-
-      if (!visibleColumnCount) {
-        return -1;
-      }
-      let colIdx = [...positions].reverse().findIndex((p) => left >= p);
-      colIdx = positions.length - 1 - colIdx;
-      return colIdx;
-    },
-    [columnsMeta.positions, visibleColumnCount],
+    (left: number) => getIdxFromScroll(left, columnsMeta.positions),
+    [columnsMeta.positions],
   );
 
   const getColumnFromScroll = React.useCallback(