Hello! Is it possible to specify number of first i...

# compose

[PHondogo]

Hello! Is it possible to specify number of first invisible items that need to be precomposed for LazyColumn (Row)?

[Shubham Singh]

Can you explain this a little?
From what I understand, you can give your @Preview composable its own custom size if need be.

For example:

@Preview(device = "spec:width=1200px,height=1600px,dpi=190")
@Composable
fun MyComposablePreview() {
  LazyColumn {
    item {
      Text("Some text")
    }
  }
}

[Shubham Singh]

But it doesn't have to do anything with LazyColumn specifically

[PHondogo]

No. May be I choose wrong word for it. I need LazyColumn pre compose first N invisible items from top and bottom.

[Travis Griggs]

kind of like how HorizontalPager can be encouraged to compose off screen stuff with the beyondBoundsPageCount parameter? Is that the effect you're looking for, but with LazyLists?

[shikasd]

It is not possible to customize prefetch at the moment, but we are looking into prefetcher APIs in the future.

Also note that prefetched item is not guaranteed to be created, it is purely a performance optimization. This is different from beyondBoundsPageCount which extends active range of Pager to include invisible items.

[Shubham Singh]

Maybe as a workaround for now, you could try putting Columns that accept n-number of items, inside your LazyColumn

Since every Column will be treated as a single item, at least a single item will have to be fetched on screen.

[Atul Gupta]

HI @shikasd will this prefetcher api also work with LazyColoumn , and other LazyXxx apis? I need to prefetch some items to have perf optimisation similar to Recycler view

[shikasd]

Eventually, yes
Currently only lazy column/row are implemented

[Atul Gupta]

In which release they became available? How to set the item to prefetch? I tried androidx.compose:compose-bom:2024.04.01 but couldn’t access anything

[shikasd]

1.7 onwards, it is still in alpha