Why does this compile?

var text: String by mutableStateOf(text)

(At runtime it gets "Attempt to invoke interface method 'java.lang.Object androidx.compose.runtime.State.getValue()' on a null object reference.)

getValue

not automatically imported fixed in AS Canary 12 🎉

Planning to shift my SDK on compose, but worried for backward support or any other

needs X version of Y dependency in the host application

kind of issues that might arise. Anyone who made the switch, have any pointers to share?

Looking into achieving

ItemAnimator

-esque animations for additions/removals into a

LazyColumn/Row

: I see we have this example in the codebase that wraps each item around

AnimatedVisibility

. However, the example is rather simplistic in that the

visible

flag to

AnimatedVisibility

is computed via indices; the actual list backing the

LazyColumn

doesn’t mutate. In most app scenarios, lists mutate based on some source of truth (domain/business layer). Can

AnimatedVisibility

still be used in some capacity to animate mutating lists, or are there any other Compose constructs we can use?

Hello, everyone! 👋 I’m having some difficult to implement my custom

Saver

to be used with

rememberSaveable

. Could you please help me? I have a list of items that, when clicked, shows a

BottomSheet

with the item data. Implementing my custom

Saver

works only or the first time and the first item saved will show every time the screen is rotate. When in portrait or landscape, if I click in any item, it shows the item correctly. But when rotate, the first one saved is shown again. Code is in the comments. Thanks a lot in advance! ❤️

Hello devs, please how can i achieve the image in the TopBar and also not showing the topbar divider line?

Is there a way to declare

NavHost

without state restoration mechanism? I’d like to recompose it and return to start destination when state is lost.

In jetpack compose api guidelines, under hoisted state types (https://github.com/androidx/androidx/blob/androidx-main/compose/docs/compose-api-guidelines.md#hoisted-state-types It says that it is best to provide

VerticalScrollerState

instead of

scrollPosition: Int,
scrollRange: Int,
onScrollPositionChange: (Int) -> Unit,
onScrollRangeChange: (Int) -> Unit

The issue I am experiencing with this approach is that now I can not update my viewModel when

"onSomethingHappened"

. I tried adding a callback to my custom state object but it just did not feel right. Is there a suggestion/best practice about how I can observe changes to my custom state object (and each of the parameters in it)?

Curious to hear if there is an equivalent of

AccessibilityChecks.enable().setRunChecksFromRootView(true)

available for Compose or if that already is capable of running on Compose views. I haven’t tested it yet so unsure about what its current behavior is.

Hello. I'm trying to migrate my app from fragments to compose. I've planned to do it fragment by fragment with a

Composeview

inside each, but I'm facing an issue with state restoration when using navigation component. When put on the backstack, the fragment's view is destroyed, but

onSaveInstanceState

is not called and there is no

saveHierarchyState

mechanism on

ComposeView

. So when a fragment's view is recreated when i pop the backstack, all scroll state of LazyColumn is lost for example. Is there a way to save this state inside fragments ? Thanks

Hi, can I store a composable function as a variable? https://stackoverflow.com/questions/66829497/can-i-store-a-composable-function-in-a-variable

Hey guys 👋, I am trying to save a canvas as bitmap in my external drive. Is it at all possible in Compose to use something like:

val b:Bitmap = canvas.drawToBitmap(Bitmap.Config.ARGB_8888)

Or is there an alternative to save a canvas?

Is it possible to make clipping occur with a certain offset from the measured rectangle? Looking at the

GraphicsLayerScope

, but there is no suitable property as far as I understand. It creates outline for clipping based on the

measuredSize

and I don’t see any way to influence that… It would be nice to have something like

clipInsets

property in the scope, which would be taken into account to calculate clip rectangle. I understand I can use another node around with some padding, but I’d like to do it via

Modifier

I was expecting to see two boxes from this code, but only see one. I understand that I can try to use weight, but I want to be able to add more boxes programmatically and so I don't want to set weight to .5f now, then .33 for 3 boxes, .25 for 4 boxes, etc. Shouldn't the boxes inside the row resize to meet their aspect ratio so other boxes can fit in the same row?

Row(modifier = Modifier.fillMaxWidth()) {
    Box(modifier = Modifier.border(1.dp, Color.Blue).aspectRatio(16/9F))
    Box(modifier = Modifier.border(1.dp, Color.Blue).aspectRatio(16/9F))
}

Hey guys, how did you fix the problem with compose navigation when you click restart activity and the screen is blank?

If I center text then everything works fine... but if I try to a long piece of text then I get a poorly cut off piece of text. Am I doing something wrong or is this a bug in compose? Code in thread.

If I want to create a new module that just houses my composables... would that be a "android app module" or "android library module"? Looks like the difference is id 'com.android.application' vs id 'com.android.library'

I am using an AndroidView in Compose, the update callback executes every-time any state property changes, is there a way that I can make update callback to only execute on some selected state property change ?

Hi, I got a checkbox that can once click will change a mutable state boolean false to true and vice versa… and works in compose Beta01… But after move to Compose Beta02, it doesn’t work anymore… Is the behavior change already, did I code it wrong, or it’s a but in Beta02? https://stackoverflow.com/questions/66839056/mutablestate-variable-cannot-be-changed-again-on-the-subsequent-click-of-jetpack

There is an API or an easy way to animate an

Image

to move to a specific point ? I have an image at the top of my screen and an another image at the bottom. I want to translate the top image to the bottom. I’m starting with animation and I’m looking if there is an easy way to do that. I found the

translateY

method but how to get the dp between the top image and the bottom image ?

Hey, I'm having some trouble finding a way to control the selection state of an item in a

LazyColumn

. Anyone knows how to do this? What I'm trying to achieve is getting to the selected state on a click (not a long click).

I have two product flavors,

free

and

pro

. How can I make a different composable with the same name for each flavor?

Small doubt about recomposition, snippet in the 🧵

Hello everyone! How to inject viewModel with Dagger 2 (not Hilt) into composable? Yes, i may inject VM into Activity and send as parameter into composable function. But i don't like this method because what to do if i have many VM's? Earlier i inject VM's into fragments and this was fine.

Hello, everyone! 👋 I’m having some difficulties with

SnackBar

. I have a list of items with

Checkbox

and when the user clicks, it “completes” the item and removes from the list. My implementation tries to shown an “Undo Snackbar” when the user performs this action, which brings the item back to the list. The problem is that the

Snackbar

disappears in less than one second due to the recompostion when the item disappears from the list.

LazyColumn() {
    items(
        items = taskList,
        itemContent = { task ->
            TaskItem(
                task = task,
                onItemClick = onItemClick,
                onCheckedChange = {
                    onCheckedChange(it)
                    coroutineScope.launch { snackbarHostState.showSnackbar("Task Completed", "Undo") }
                }
            )
        }
    )
}

I tried using

LaunchedEffect

but AFAIK, this will associate the effect to a state, not the user click, right? Do you have any idea on how to make the

Snackbar

keep visible while the screen is recomposing? Thanks a lot in advance! ❤️

Hello, I got one question, can I use assisted injection in a composable ? meaning my view model has an assisted parameter, but I do not know how to get the factory in the composable function to pass it to the

viewModel

method

How do I use jetpack compose to select images from my phone album to add to the user interface? (edited)

hey everyone sorry if this is a stupid question but is there a place which documents all of out of the box composables that android provides as building blocks, something akin to the widget directory that flutter provides to developers.

Is this the correct way to make sure my view is destroyed when it leaves the composition?

var bannerView by remember { mutableStateOf<MoPubView?>(null) }
val context = LocalContext.current
DisposableEffect(null) {
    bannerView = MoPubView(context).also {
        it.setAdUnitId("...")
        it.adSize = MoPubView.MoPubAdSize.HEIGHT_50
        it.loadAd()
    }

    onDispose {
        bannerView?.destroy()
        bannerView = null
    }
}

bannerView?.let { view ->
    AndroidView(
        factory = { view }
    )
}