IssueTracker

We are working on it, but nothing to share yet. Thanks

Are we allowed to post potential workarounds on issue trackers? I created this small POC repo, definitely not a solution and probably not ideal in the long run but works for my use case and thought I'd share: https://github.com/RoudyK/AnimatedLazyColumn (Please delete my comment or let me know so I can delete it, in case I'm not allowed to post workarounds)

Any update on LazyList Animations

In which version of Compose will the modifier be available?

in 1.1.0-beta03

Since there is no key param available in LazyVerticalGrid items or item. How are we supposed to use it with them.

Would it still work if I wrape item content in key composable

+1, can you please provide an update? :)

I think that list animations are pretty important and we can't always animate lists the way we want using the current APIs.

For instance, I'm trying to nicely animate a list whose items are updated every once in a while (some items are updated, some are removed, some are added). I tried to achieve this using an AnimatedVisibility block for each item (see b/222475821 for more info or this SO answer which seems similar to my solution) and it looks alright but it's not optimal because I want this list to behave the same way it would if I were using TransitionManager.beginDelayedTransition in the traditional view system:

• when an item is added, we first expand the location of the item (and move the siblings and resize their ancestors) then fade it in.
• when an item is removed, we first fade it out then shrink the location of the item.

We can simulate something similar by adding some delays in the AnimatedVisibility enter & exit transition specs, but it does not work well when removing and adding elements at the same time. This is illustrated in the video below: if my list has a single item and that I remove it but add a different item at the same time, then the following happens:

1. The list grows because of the new item that is added. At the same time we fade out the item that is removed.
2. The list shrinks because of the item that is being removed. At the same time we fade in the item that is added.

The ideal animation would just fade out the first item, then directly fade in the new item given that we don't need to shrink/grow the list.

It would be really great if this was handled out of the box by LazyColumn/LazyRow, for instance like this:

// Because we are using a MutableStateList
// or any other observable list, LazyColumn
// can keep track of the updates and animate
// its items in/out & move them accordingly.
val items = remember {
  mutableStateListOf<Item>(/* some default list */)
}

LazyColumn {
  items(items, { it.id }) { item ->
    MyItem(item)
  }

  item {
    Button(onClick = {
      if (items.isNotEmpty()) {
        // This will automatically animate given that we
        // know exactly which item has been removed.
        items.removeAt(0)
      }
    }) {
      Text("Remove First")
    }
  }
}

We could also have an API that takes any kind of List<T> + DiffUtil.ItemCallback<T> (or similar) :)