Grid and MultiGrid makes 2 render passes on simple scroll

[pete-moss]

I am using both Grid and MultiGrid and I am noticing that 2 render passes are made when doing a simple scroll by either clicking on the arrow caret in the scrollbar, or by calling Grid.scrollToCell({rowIndex: n}). Doesn't seem right, and since I already see fairly significant delays when scrolling with MultGrid (the rendering of the row/column header Grids lag behind), I am wondering this could be addressed.

[aem]

Hi Pete. Can you please provide us with a code example that demonstrates the scrolling delays you're seeing and a verification of the second render pass?

[wuweiweiwu]

The latency will probably be solved once I finish migrating Grid #1053.

The double render is only observed for Grid when the component initially mounts and also on scroll end.

For Multigrid you will see a "double" render because at any time, you are scrolling two grids either horizontally or vertically.

[pete-moss]

I hope I have done this right (first time trying to use codesandbox - sorry for being such a newbie), but here is a link that illustrates what I meant. https://codesandbox.io/s/3rz2q0m415 If you open the demo in a browser window and look at the console log, I am tracing each time we are rendering body cell (4, 0). If you do a simple scroll down, or single Arrow Down, I see 2 calls to render that cell. That implies that 2 render passes are being made. Does that make sense?

Regarding delays I see, it mostly occurs when I am using variable-height cells with CellMeasurer. I can certainly understand the performance issues since you have to render all cells in a row to determine row height. But I am poking since if there really is an issue with making 2 render passes, maybe if this could be solved, performance may improve.

[wuweiweiwu]

I'll have to double check. This should be in Grid. So I'm going to hold off until the rewrite is done. Which should be in the next week or so

[HtmlRanger]

Hi! Any progress on this issue?