When the layoutProvider is changed, it keeps moving to the top.

[jameszamface]

When the layoutprovider is changed, if the size of the content is the same, componentDidUpdate is continuously executed in the ViewRenderer.

If the size of the content is the same when the layoutprovider is changed, it is suspected that the _forceSizeUpdate function is executed while componentDidUpdate is continuously called in the ViewRenderer.

This problem occurs from version 3.2.0-beta.2. (commit 049c297)

[kevin-kp]

I'm seeing similar behavior when using 3.0.5 with a horizontal recyclerlistview. Haven't debugged the library yet, but when the layoutProvider changes, there is a small jump back at the offset when there is a new layoutProvider.
When just adding new items to the recyclerlistview without updating the layoutProvider, I'm not having this issue.

[naqvitalha]

There's a flag in layout provider call shouldRefreshWithAnchoring. You can set it to false to avoid the issue

[kevin-kp]

Hi @naqvitalha
Thank you for your quick response, that did fix my issue, but as it seemed that I missed a couple of updates, I tried updating the library to the latest version. And I think I'm seeing the same issue as @jameszamface is seeing.
Starting of 3.2.0-beta-2, there seems to be an infinite loop.

I started printing out the index and type in the getLayoutTypeForIndex callback of LayoutProvider and it keeps printing the log statements infinitely.
I tried circumventing the issue, but as jameszamface already mentioned, the issue is probably in the componentDidUpdate that keeps getting called.

[kevin-kp]

Hi @naqvitalha

After some further debugging, it seems that recyclerlistview is in a cycle due to the following line:

recyclerlistview/src/core/RecyclerListView.tsx

Line 555 in 0ef9c42

return prevState;

this results in the following behavior:

1. componentDidUpdate is called in RecyclerListView because the state has changed.
2. _checkAndChangeLayouts is called in componentDidUpdate
3. The check this._relayoutReqIndex >= 0 results in true which results in a call to _refreshViewability
4. _refreshViewability calls the method _queueStateRefresh
5. _queueStateRefresh calls the mentioned line again triggering this cycle again.

I'm not sure if this is the same behavior that @jameszamface is seeing, but if I comment the componentDidUpdate in ViewRenderer, this entire cycle does not occur.

[naqvitalha]

@kevin-kp Is this also fixed with your change? If yes, we can close this one too

[kevin-kp]

Normally, this issue is also fixed; @jameszamface could you confirm this with version 4.1.3?

[MichalKrakow]

shouldRefreshWithAnchoring

This seems required for any deterministic layout provider that updates along with updating dataProvider. But docs and examples lack any mention of this. Anyway:

const getLayoutProvider = (dataProvider) => {
    const lp = new LayoutProvider(
        (index) => {
            return dataProvider.getDataForIndex(index).title.length > 38 ? 2 : 1 // this will get smarter, just for testing
        },
        (type, dim) => {
            dim.width = width
            dim.height = type == 1 ? 225 : 250
        }
    )
    lp.shouldRefreshWithAnchoring = false
    return lp;
}