[DataGrid] Fix horizontal scroll not working on empty grid

[cherniavskii]

Fixes #3795 (comment)

[mui-bot]

These are the results for the performance tests:

Test case	Unit	Min	Max	Median	Mean	σ
Filter 100k rows	ms	232.3	395.7	338.3	327.36	52.939
Sort 100k rows	ms	368	909.2	789.5	696.84	215.93
Select 100k rows	ms	181	311.3	265.9	257.22	50.945
Deselect 100k rows	ms	146	278	208	201.28	46.658

Generated by 🚫 dangerJS against 22fc2d9

[m4theushw]

Could you add tests for this part? We should cover more the virtualization.

[cherniavskii]

Could you add tests for this part? We should cover more the virtualization.

I've added a test to check virtualScrollContent height.
I wasn't able to test horizontal scroll itself, because firing scroll events on virtual scroller would pass regardless the content height.
I'll try to cover horizontal scroll in e2e test.

[m4theushw]

This callback will be called when the virtualScrollerContentSizeChange event is fired and the event is fired when contentSize changes, which happens inside the hook. We can remove this state update and migrate the minHeight to contentSize, avoiding one rerender.

[cherniavskii]

Nice catch!
I noticed that the event is emitted in the same hook, but didn't think of removing unnecessary state

[m4theushw]

Note that windowRef is a wrapper for the .MuiDataGrid-virtualScrollerContent element so windowRef.current.scrollHeight is equal to size.height.

Suggested change

	if (windowRef?.current && windowRef.current.scrollHeight <= windowRef.current.clientHeight) {
	if (windowRef?.current && size.height <= windowRef.current.clientHeight) {

Use ref instead of windowRef. They are the same thing:

mui-x/packages/grid/_modules_/grid/components/base/GridBody.tsx

Lines 92 to 93 in b12b22b

	<VirtualScrollerComponent
	ref={windowRef}

mui-x/packages/grid/x-data-grid/src/DataGridVirtualScroller.tsx

Lines 15 to 16 in b12b22b

	const { getRootProps, getContentProps, getRenderZoneProps, getRows } = useGridVirtualScroller({
	ref,

mui-x/packages/grid/_modules_/grid/hooks/features/virtualization/useGridVirtualScroller.tsx

Lines 372 to 373 in b12b22b

	getRootProps: ({ style = {}, ...other } = {}) => ({
	ref: handleRef,

[cherniavskii]

I've used rootRef instead of ref, since ref has type React.Ref<HTMLDivElement>, which allows it to be a function and I wasn't able to just get .current from it.

[m4theushw]

Looks good.