has covered a pure compose navigation exam

Question

< Arkadii Ivanov> has covered a pure compose navigation example by using `Decompose` in one of his recent blog posts I was interested in decompose and had a look into this example but I can t figure out how it s restoring the scroll position of the `LazyColumn` when moving from the details screen back to the list screen I m looking for hours but I can t find the responsible piece of code Can some please have a look and give me a hint

Arkadii Ivanov · Answer

Decompose handles UI state preservation automatically inside `Children` function <https github com arkivanov ComposeNavigatorExample blob 655bdef8667960c82ba88c628b0bb9ba8443bdeb navigator src commonMain kotlin com arkivanov composenavigatorexample navigator Navigator kt L72|https github com arkivanov ComposeNavigatorExample blob 655bdef8667960c82ba88c628b0bb9ba8443bdeb navigator src commonMain kotlin com arkivanov composenavigatorexample navigator Navigator kt L72>

Lilly · Answer

Yes but if I break it down it s only `configuration` which gets stored and restored but `configuration` is just the representation of the screen state I do the same in my code but this doesn t restore the scroll position Can you elaborate this please

Arkadii Ivanov · Answer

The Children function listen for the navigation state changes and renders the currently active screen It also saves UI state when screens go to back stack and restores when they active again You may need to deep dive into implementation details <https github com arkivanov Decompose blob 4737f7bf333301c0198b58bcf8b715e0fa5533f7 extensions compose jetpack src main java com arkivanov decompose extensions compose jetpack RouterStateComposable kt L19|https github com arkivanov Decompose blob 4737f7bf333301c0198b58bcf8b715e0fa5533f7 extensions compose jetpack src main java com arkivanov decompose extensions compose jetpack RouterStateComposable kt L19>

Lilly · Answer

I went through all these methods but I don t get it Even with debugging

Arkadii Ivanov · Answer

`SaveabaleStateHolder` stores saved UI state per key per configuration `SaveableStateProvider` sets the corresponding Ambient now Local for currently active screen So sub components can use `UiSavedStateRegistry` which actually `LazyColumn` does

Andrey Kulikov · Answer

yes this component is doing all the magic for you <https cs android com androidx platform frameworks support + androidx main compose runtime runtime saveable src commonMain kotlin androidx compose runtime saveable SaveableStateHolder kt l=59|https cs android com androidx platform frameworks support + androidx main compose androidx compose runtime saveable SaveableStateHolder kt l=59>

Lilly · Answer

Yeah this is the magic I was looking for I wasn t aware of this API and now it works heart Thanks guys pray