Reverse scroll with dynamic height stops before actual top end

[LookRain]

Describe the bug

In reverse scroll mode on iOS Safari, if the content have dynamic height and dynamic loading(just speculation), the scroll will end prematurely before the actual top of the list is reached. If you try to pull down immediately when the scroll stops, it still won't readjust and render more items on top. A short moment is required after scroll stops for more items to be rendered on top.

Simulator.Screen.Recording.-.iPhone.15.Plus.-.2024-04-20.at.14.55.14.mp4

To Reproduce

Use an iPhone or simulator, go to any of these examples, start scrolling up

1. https://inokawa.github.io/virtua/?path=/story/basics-virtualizer--bi-directional-infinite-scrolling
2. https://inokawa.github.io/virtua/?path=/story/advanced-chat--default
3. https://inokawa.github.io/virtua/?path=/story/advanced-feed--default

It doesn't happen in the reverse example https://inokawa.github.io/virtua/?path=/story/basics-vlist--reverse , so I'm assuming it's got something to do with dynamically prepending items causing the height to be wrong?

Expected behavior

scroll should not stop before the actual top.

Platform:

• OS: iOS
• Browser: Safari
• Version of this package: version in the storybook demo
• Version of framework: version in the storybook demo

Additional context

[inokawa]

#403 (comment)

[LookRain]

thanks for the quick reply @inokawa

I came across this blog https://lovemewithoutall.github.io/it/setting-scrollTop-on-momentum-scroll/ which suggests a workaround

I assume you have tried this and it did not work?

[inokawa]

A similar workaround is used for an edge case in iOS Safari. It will apply scroll position but also stops the scrolling.

virtua/src/core/scroller.ts

Lines 283 to 286 in a567e46

	style[overflowKey] = "hidden";
	timeout(() => {
	style[overflowKey] = prev;
	});

Maybe there is room for improvement, but basically I think it's inevitable in reverse virtual scrolling with dynamic sized items.