I want to display a tree view using standard `LazyColumn` bu

Question

I want to display a tree view using standard `LazyColumn` but because the tree itself is very complicated and reactive I would also like to use compose runtime to manage its nodes I e I want to use the compose with custom `NodeApplier`to generate nodes of the tree that I then take and display with the standard in my case desktop compose Can it be somewhat easily achievable There is something called `sub composition` the `Composition`function also takes a parent `CompositionContext`but I don t quite know how to glue that together I have looked at <https github com JakeWharton mosaic > but it uses the compose runtime standalone while I want it kind of nested

Zach Klippenstein (he/him) [MOD] · Answer

I m not sure I understand why you d need subcomposition here If your presenter layer is using a custom composition type to generate a custom tree of models then you can just pass that tree to your UI composition

Zach Klippenstein (he/him) [MOD] · Answer

You can t directly emit Compose UI nodes from a custom Applier because they re all internal

mcpiroman · Answer

I want to emit my in house nodes in a non UI subtree that sits somewhere inside the UI tree of the application In the provided repository the first part is done I just want to integrate the Composition into the main one so that I don t have to have a separate therad coroutine etc and also have `State`s nicely synchronized between these two

mcpiroman · Answer

In the meantime I kind of found the answer here <https github com JetBrains androidx blob bc4f98ccbba27171f1bc419f2fb5b920401bc781 compose ui ui src desktopMain kotlin androidx compose ui window Menu desktop kt L150|https github com JetBrains androidx blob bc4f98ccbba27171f1bc419f2fb5b920401bc78 c desktopMain kotlin androidx compose ui window Menu desktop kt> Seems like this solution of CfD resembles mine s so I might be good to go by following it

Zach Klippenstein (he/him) [MOD] · Answer

If I understand correctly your data flow looks something like this You have some data in your UI composition You want to use a separate subcomposition with a different Applier type to turn that data into a tree of nodes then use those nodes immediately in your UI composition to generate UI Is that right

tad · Answer

This is a tool for composing State if it helps <https github com cashapp molecule|https github com cashapp molecule>

tad · Answer

Ah but not for arbitrary trees

mcpiroman · Answer

< Zach Klippenstein he him MOD > Totally right

Zach Klippenstein (he/him) [MOD] · Answer

And so would that last step work How would you get your nodes back into the UI composition

mcpiroman · Answer

In the main composition I create `mutableStateListOf lt Node gt `and display it while also modifying it in the custom `Applier` And so far it indeed works nicely except it doesn t I get some weird results when expanding and collapsing the nodes but at least it is responsive

Zach Klippenstein (he/him) [MOD] · Answer

I would expect there to be a frame of lag since your custom composition would only invalidate the UI composition when it was applied which would trigger another recomposition but only on the next frame

mcpiroman · Answer

Gotta say it was not so easy to set it up properly but at the end this approach works wonderfully It is very easy to shape the tree control prefetching and apply other features like searching I do not notice any new lag but generally CfD is not particularly responsive ATM either so it does not matter much Looking forward to using compose runtime in other non UI fields slightly smiling face