[DataGrid] Better fix the scrollToIndexes logic

[oliviertassinari]

This is a follow-up #1949 (comment), I'm pushing the quality of the solution one step further, by doing a plain copy & paste of the Autocomplete's logic.

The previous behavior: https://codesandbox.io/s/material-demo-forked-j7i1x?file=/package.json.

before.mp4

The new behavior: https://codesandbox.io/s/material-demo-forked-nzkwd?file=/package.json

new.mp4

[dtassone]

it doesn't really work on https://deploy-preview-1969--material-ui-x.netlify.app/components/data-grid/
Try keeping the arrow down
then up,
then go down with the scroll thumb quite a bit
and repeat the keyboard arrows test

[oliviertassinari]

@dtassone True, now, what's the root cause? Is it the issue from the changes or from the rendering logic? AFAIK, it's surfacing that the rendering logic is not correct, with a now correct virtual scroll logic, so I would argue it's a step forward (enforced by the test case), even if it makes the issue with the virtualization more visible.

[m4theushw]

It's not a perfect solution but it's better than what we have. The new logic still doesn't fix #1818 but I can improve it in #1871. In my tests, when I call scrollToindexes with a rowIndex much lower than the one that is currently displayed it doesn't scroll.

[oliviertassinari]

@m4theushw Yes, one correct test case at a time :). Now, I think that we get the fix of #1818 for free by solving #1911.