I am writing a file manager, when I click on the f...

# compose

[Chachako]

I am writing a file manager, when I click on the folder, the LazyColumn items data will be reloaded to enter the folder, then how can I remember the list position of the previous page so that I can automatically display it to the correct one when I return next time position, for example, the path a/b/c, when go to c, I should save the location of a and b

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

How are you navigating between pages?

[Chachako]

@Zach Klippenstein (he/him) [MOD] Just replace the data through the viewModel to reorganize the LazyColumn, probably a fake navigation implementation

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

(you don’t need to tag people in threads, they already get notified 🙂 )

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

Yea, i believe the lazy list scroll state uses compose’s SaveableStateRegistry machinery to save and restore scroll position. This requires support from your navigation infra. Jetpack Nav will support this, as should other real navigation libraries (compose-backstack, compose-router i think, etc), but if you’re building one yourself it’s going to take a little extra work.

[Ian Lake]

It sounds like, if you're using the same LazyColumn, then you'll need to hoist and save the LazyListState for each of your lists (i.e., one for a, one for b, etc.), just passing down the right state with the right contents of the list as you swap between them

[Chachako]

For some reasons I cannot use navigation, it needs to go back and forward, and navigation only has a backstack

[Chachako]

If there are too many file paths (pages), will holding a LazyListState for each lists cause performance problems? Maybe just save its initialFirstVisibleItemIndex and initialFirstVisibleItemScrollOffset for each lists?

[Ian Lake]

The LazyListState itself is very small; you'd want to hoist the whole object

[Chachako]

That will be convenient! Thank you for your answer