kotlinlang #compose

Hi guys, what is the best way to share a view model between screens? I use navigation api for collecting data from multiple sign up forms. Should I use a single viewmodel for collecting the data or pass one when navigating from one form to another until I collect all the user input data?

robercoding

01/02/2023, 5:23 PM

Hi! Is there a way to listen for keyboard inputs when the keyboard has started the process of hiding? (Not when it's already hidden, it takes a bit of time) Or even better: Is there any way to intercept back handler when the keyboard is open? I see similar questions on SO have been asked but I don't see any answer 😅

Travis Griggs

01/02/2023, 7:01 PM

I'm working my way through an Animation codelab, and a common one is to add .animateContentSize to Rows and Columns. What are the negatives to just doing this by default? I know with UIKit code, things just generally animate unless you need them not to. But the norm here, seems to be to have to turn a lot of animation on. Does it hurt to just turn these on by default, but turn them off when problematic?

nuhkoca

01/02/2023, 7:47 PM

Hello, I am returning a url in string format from my

ViewModel

in text click and subscribe the output in composable function as follows;

val url by viewModel.output.url.subscribeAsState(initial = null)

However, since the url is always the same string, only the first click opens browser, subsequent ones don’t do anything due to

subscribeAsState

How do I make this work properly for identical strings?

ursus

01/02/2023, 10:27 PM

Is it normal for

Image

to be never skipped?

Image(
    modifier = Modifier
        .size(48.dp)
        .padding(12.dp),
    painter = painterResource(id = R.drawable.ic_headphones),
    contentDescription = null,
)

I’m looking around in Layout monitor and I see this never skipped when ui is recomposed

ritesh

01/03/2023, 9:05 AM

General preference is to always provide unique keys to the

Lazy

- What if i don't have a unique key for my model and i know that

List<>

data set positions won't be re-arranged but only new data-set will be appended, i can live without giving unique keys (without going into the path of generating some unique keys - like UUID for each item) to it i believe or there's a trade-off?

Rafs

01/03/2023, 9:53 AM

I have a strange issue in my code where

LaunchedEffect

from my composable is getting called before

onDispose

of the destination navigation composable’s

DisposableEffect

Brais Gabin

01/03/2023, 11:09 AM

Hello! I have a

List<@Composable () -> Unit>

. And I want to display it in a

LazyColumn

with a

Space

between each of them.

LazyColumn {
  items(list) { composable ->
    composable.invoke()
    Space(height = 4.dp)
  }
}

The problem is that some of them can emit nothing to the tree. That means that visually I get double

Space

between some components. How would you avoid this problem? Those functions that emit nothing could start emitting at any point if their state change.

FunkyMuse

01/03/2023, 11:55 AM

Hey guys, how would you handle

android.intent.action.SEND

With compose navigation component? I want to open a nested navigation destination that accepts a uri which is basically a string encoded when passing the argument and decoding when reading it

KotlinLeaner

01/03/2023, 12:09 PM

Hi, I want to make a list of unique items in my list in jetpack compose. So I am trying to use MutableSet in my project. I know that mutableStateListOf is using for list in jetpack compose. I have another reason to use of mutableStateListOf in my project. So is there is way we can use of MutableSet
with mutableStateListOf
?

val list by lazy { mutableStateListOf<ScanResult>() }

Many Thanks

dorche

01/03/2023, 2:50 PM

Hi this could go in a few channels but I am hoping for a Compose first solution here.. What’s the Compose way to handle a deep-link and keep your app/backstack state (ideally?) ? Looks like handleDeepLink clears the backStack one way or another so let’s say you have an an app that let’s the user make payments: • midway through using the app, the user goes to the payment flow which launches a Custom Chrome Tab (as per guidelines). • Payment Completed in Chrome Custom Tab. Deeplink issued to get back in the app. • Deeplink received and handled by the system

handleDeepLink

, back stack seems gone so now the when the user presses back after the payment flow confusingly that closes the app.

Hasan Nagizade

01/03/2023, 4:45 PM

val focusManager = LocalFocusManager.current
focusManager.clearFocus()

this code removes the focus from

InputField

and closes the keyboard. How can I close the keyboard but keep focus on

InputField

Norbi

01/03/2023, 8:11 PM

How can I check which Kotlin version is supported by a specific Compose/MP version, eg. v1.3.0-beta04-dev903? Thanks.

Rick Regan

01/03/2023, 8:26 PM

I’m trying to understand why this use of

Crossfade

is leaking its state holder. I have a Slider that I can interact with normally (no crossfades) but that will crossfade to its default value when a “reset” Button is pressed. I do this using a MutableState within a MutableState, the outer one being the target for Crossfade, and the inner one being the slider value (code in 🧵.) In the heap dump (after forcing garbage collection) I can see that the number of allocated SliderStateHolder/SliderState objects increases with each reset. Inasmuch as I understand heap dumps, the references look like they’re coming from “SnapshotStateList”, which would seem to indicate Compose continues to track the old states. I’d like to understand why (and what I could do to prevent it). Thanks.

John O'Reilly

01/03/2023, 10:21 PM

Dev version (1.4.0-dev-k1.8.0-33c0ad36f83) of Compose Compiler now available for Kotlin 1.8.0 https://androidx.dev/storage/compose-compiler/repository

Aaron Waller

01/04/2023, 7:25 AM

I want to hide a post from my list by clicking a button inside my BottomSheet Layout. My ModalBottomSheetLayout is outside the Scaffold to have it above my BottomAppBar. I’m using the BottomSheet as a options menu for my Post items. Now I need to Hide a post whenever someone clicks on “Hide” inside the BototmSheet. How can I do that now? (code in thread)

Shakil Karim

01/04/2023, 10:42 AM

Hi, i'm trying to use Adam Powelhttps://gist.github.com/adamp/17b4e5cfafc7d44a0023dc2fbdb972e8

Shakil Karim

01/04/2023, 10:47 AM

Hi, i'm trying to this BackStack implementation from Adam Powell's Gist, but when i use ViewModel with each route it's giving me this exception what could be reason for this ? giving me IllegalArgumentException SavedStateProvider with the given key is already registered

elye

01/04/2023, 11:26 AM

I have a simple Todo Compose View as

class AppViewModel : ViewModel() {
    private var todoList = listOf(
        TodoItem(0, "My First Task"),
        TodoItem(1, "My Second Task", true)
    )
    private val _todoListFlow = MutableStateFlow(todoList)

    val todoListFlow: StateFlow<List<TodoItem>> get() = _todoListFlow

    fun setUrgent(index: Int, value: Boolean) {
        val modified = todoList.toMutableList()
        modified[index] = modified[index].copy(urgent = value)
        todoList = modified
        _todoListFlow.value = modified
    }
}

val viewModel = AppViewModel()

@Composable
fun MyTodoList {
    val todoListState = viewModel.todoListFlow.collectAsState()

   LazyColumn(modifier = Modifier.fillMaxHeight()) {
        items(items = todoListState.value, itemContent = { item ->
            Row {
                Text(text = item.title)
                Checkbox(
                    checked = item.urgent,
                    onCheckedChange = {
                        val index = todoListState.value.indexOf(item)
                        viewModel.setUrgent(index, it)
                    }
                )
            }
        })
    }
}

But I dislike to update a field in the list, I have to create a modify list to pass to the stateFlow.

fun setUrgent(index: Int, value: Boolean) {
        val modified = todoList.toMutableList()
        modified[index] = modified[index].copy(urgent = value)
        todoList = modified
        _todoListFlow.value = modified
    }

I can fix it using Solution in https://stackoverflow.com/a/75004437/3286489, but feel it is wrong, as that solution is having MutableState in ViewModel. I wonder how can I avoid the need to create the entire list to send through the StateFlow, if I just need to change a variable that update the compose view?

oday

01/04/2023, 12:00 PM

where do you store test tags? like I have some tags here in a class that constructs some composables, and I’ve defined them like this:

object TestTags {
    const val eventsListTag = "Events List"
    const val errorPromptTag = "Error Prompt"
    const val emptyPromptTag = "Empty Prompt"
}

how do you do this?

Hasan Nagizade

01/04/2023, 12:37 PM

why

onFocusChanged

is not getting triggered every time user clicks on

InputField

? how to make

InputField

get focus every time user clicks on it?

elye

01/04/2023, 1:05 PM

Should we store "_mutableStateListOf_" in ViewModel or in the Compose Function? If we have it in the Compose Function, looks like we'll need to create a new list for every modification of it, as explain here https://kotlinlang.slack.com/archives/CJLTWPH7S/p1672831604690449. So tempting to put "_mutableStateListOf"_ in the ViewModel, but feel it is wrong.

myanmarking

01/04/2023, 1:33 PM

I can’t wrap my head about this one issue. Why would this code do not run the layout inner lambda ?

Elio Maroun

01/04/2023, 2:55 PM

Should I use a different floating action button for every screen or use the one in scaffold?

AloneWalker

01/04/2023, 3:17 PM

I have this code with stateIn, my questions are: 1. Am I using it correctly? 1. Is it better to do this instead of collecting the flow from ViewModel? 2. I have read we shouldn't use methods with statIn, what can I do if I need to pass parameters? any example? Repository: override val appLanguageStream: Flow<String> = dataStore.data.map { preferences -> val preferencesKey = stringPreferencesKey(Constants.APP_LANGUAGE) preferences[preferencesKey] ?: Constants.DEFAULT_LANGUAGE } ViewModel: val appLanguageStream: StateFlow<Resource<String>> = settingsRepository.appLanguageStream.asResource().stateIn( scope = viewModelScope, started = SharingStarted.WhileSubscribed(5_000), Resource.Success(Constants.DEFAULT_LANGUAGE) ) Screen: val appLanguageStream by viewModel.appLanguageStream.collectAsStateWithLifecycle() LaunchedEffect(key1 = appLanguageStream){ // update ViewModel uiState }

iroyo

01/04/2023, 4:16 PM

Hi! I’m using coil to load images in compose and I need to send as a query-param with the width of the composable. Right now the only way I’ve found is using

onGloballyPositioned

on the

Image

modifier to get the size and then set a global variable of an Interceptor.. What I have is something like:

Image(
    painter = painter,
    modifier = modifier.onGloballyPositioned {
        coilInterceptor.config.params[PARAM_WIDTH] = it.size.width.toString() 
    },

where: coilInterceptor is a singleton Interceptor…. I’m trying to avoid this. I much rather prefer passing to the

ImageRequest

directly the url with the size concatenated

Landry Norris

01/04/2023, 6:00 PM

I’m trying to build a compose layout that depends on orientation. I have the following code, but it never responds properly to the first orientation change (The collect never runs). I rotate my phone from portrait to landscape, and the value of orientation is still ORIENTATION_PORTRAIT. Rotating back to portrait and back to landscape works, though. What am I doing wrong here?

var orientation by remember { mutableStateOf(Configuration.ORIENTATION_PORTRAIT) }
val config = LocalConfiguration.current

LaunchedEffect(config) {
    // Save any changes to the orientation value on the configuration object
    snapshotFlow { config.orientation }
        .collect { orientation = it }
}

Andy Himberger

01/04/2023, 8:09 PM

Is there a way to track accessibility focus (where the talkback highlight is)? I have added onFocusEvent/onFocusChanged + focusable modifiers, and I don't get any events when navigating with talkback. I DO get notifications when navigating with the keyboard or when i use a focusRequester to request focus. I've run into wanting this a couple times where I'm trying to keep accessibility focus staying on the same item when re-creating the activity on rotation, or right now where I have custom accessibility actions to reorder items in a list (since the default 'drag reorder' is not going to be good for accessible users, the actions give another way to do it), and it seems like when an item is moved focus should stay on that item. The timing of that is not straightforward though since the talkback custom actions dialog itself has focus for awhile, and you can't move focus until after it has restored focus into the compose view, but I haven't found a way to listen for when that happens. -- I can guess and run a delayed coroutine so it moves slightly after, that seems kind of jumpy

Zach Klippenstein (he/him) [MOD]

01/04/2023, 9:30 PM

I’m not sure i see a question there…

alp

01/04/2023, 11:18 PM

Does anybody know whether LazyColumn can be used inside

androidx.swiperefreshlayout.widget.SwipeRefreshLayout

? There are examples here with a fix using

Modifier.nestedScroll(rememberNestedScrollInteropConnection())

for bottom sheet but it seems like it doesn’t work with hierarchy like:

<SwipeRefreshLayout>
   <ComposeView>
</SwipeRefreshLayout>

scrolling up immediately triggers the swipe refresh.

Title

alp

01/04/2023, 11:18 PM

Does anybody know whether LazyColumn can be used inside

androidx.swiperefreshlayout.widget.SwipeRefreshLayout

? There are examples here with a fix using

Modifier.nestedScroll(rememberNestedScrollInteropConnection())

for bottom sheet but it seems like it doesn’t work with hierarchy like:

<SwipeRefreshLayout>
   <ComposeView>
</SwipeRefreshLayout>

scrolling up immediately triggers the swipe refresh.

ephemient

01/04/2023, 11:28 PM

https://android-developers.googleblog.com/2022/05/whats-new-in-jetpack-compose.html#:~:text=rememberNestedScrollInteropConnection (

SwipeRefreshLayout

is a

NestedScrollingParent3

CoordinatorLayout

)

val state = rememberLazyListState()
LaunchedEffect(listState) {
    swipeRefreshLayout.setOnChildScrollUpCallback { _, _ -> listState.firstVisibleItemScrollOffset > 0 }
}
LazyColumn(state = state, ...)

alp

01/05/2023, 12:35 AM

First of all, thanks for the code snippet - that works for the sample but do you know why it doesn’t work out of the box similar to other

NestedScrollingParent3

ViewGroups

CoordinatorLayout

for example? In more real-world complex scenario, such as when compose code is encapsulated within a fragment, there is not way to propagate

SwipeRefreshLayout

reference to the compose code, as far as I understand,

NestedScrollingParent3

abstraction should solve this issue

ephemient

01/05/2023, 1:45 AM

there's multiple different things happening here

SwipeRefreshLayout

is a

NestedScrollingParent3

, but

ComposeView

is not a

NestedScrollingChild3

alp

01/05/2023, 1:50 AM

I thought that

NestedScrollInteropConnection

makes it a

NestedScrollingChild3

ephemient

01/05/2023, 1:54 AM

ah, yeah. I tracked it down to the wrong place

ComposeView

is returning false from

canScrollVertically

before a gesture starts, it seems

SwipeRefreshLayout

doesn't delegate a pull down into

ComposeView

, but if you pull even a little bit first then it all works

alp

01/05/2023, 1:57 AM

I haven’t debugged it much, just saw that once I scrolled to the bottom, interop connection doesn’t receive events

as if SwipeToRefresh consume it

ephemient

01/05/2023, 1:59 AM

TBH I'm not entirely sure why it doesn't work on the Compose side…

alp

01/05/2023, 1:59 AM

me too, but thanks for looking into it

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