Is there a way to set the modifier on an Image so it is full size unless it’s bigger than X% of the bounds at which point we scale it to fit within that percentage of the layout?

Under what circumstances should I use

Modifier.composed()

? I have a custom modifier that is fairly general purpose (like

transformable()

but with slightly different behaviour). I see

transformable()

uses

composed()

. Is this just an optimization? Thanks for any tips!

Is it bad in compose if I have a

mutableStateListOf<Item>

and then just

list.clear()

and

list.addAll()

when I get a new list that's mostly the same? My use case: I am using Firestore where you can listen to a query via a Flow. So if I listen to a query of top20Books(), and I show that in my list, but one of the ratings on the books changes, my listener will get invoked again, which will cause me to throw away the old list and add the new list. But the only item that change was the top item, where the rating changed from a 4.82 to a 4.83. Or should I take a different route on this. Like should I try to do the diffing myself?

I have a weird effect with

animateColor

involving alpha. It goes from

Color.White

to

Color.Blue.copy(0.1f)

with a

tween()

spec. Instead of linear transition from one appearance to another, it goes first to less transparent

Color.Blue

pretty fast and then alpha catches up, resulting in the unexpected effect of a “hump” transition. Any ideas how to fix it? E.g. in browser similar transition effect between same colors works as expected. (Compose for Desktop, if it is important)

I was reading Jorge’s Compose Internals (which if someone hasn’t read yet, I highly recommend to) I came across this (Pg 88 in the latest edition),

In SubcomposeLayout for example, whenever a layout occurs, the parameters passed to its lambda might vary, and in that case it will trigger a recomposition. In the other hand, if a state that is read from a subcomposition changes, a recomposition will be scheduled for the parent Composition once the initial composition is performed.

How does one read read a state from a subcomposition 🤔 ? Is it same as reading state ‘in’ a subcomposition or am I reading it wrong?

In the io22 talk Performance best practices for Jetpack Compose, there is a about Deferred reads and skipping compose phases. In particular there is a sample about animated background color and it is suggested to read color only inside

drawBehind

so that composition and layout phases can be skipped. I don't understand if composition is skipped, how snapshot subscription works and

drawBehind

is notified of color change. Is the draw phase executed on each frame? Is it related to nested use of composition for canvas?

@Composable
fun SkipPhases() {
    val transition = rememberInfiniteTransition()
    val color by transition.animateColor(
        initialValue = Color.Cyan,
        targetValue = Color.Magenta,
        animationSpec = InfiniteRepeatableSpec(tween())
    )

    Box(modifier = Modifier.fillMaxSize().drawBehind { drawRect(color) }) {
        Text(text = "SkipPhases")
    }
}

I think I found a bug in Android Studio regarding overriding Composable methods, not sure if this is known? If not where to report it? Info in 🧵

Is it guaranteed that every frame takes 16 ms in Android?

Is it possible to someone draw into the bounding of of a neighboring composable? For example I want to draw something centered on top of box 2. But using a column doesn't work since it would use the largest width, which is the one of the top content. There would be a empty space left and right of box 2.

Is there some kind of pattern in Compose to execute actions inside nested components without exposing too much details outside? In my specific example I have a LazyColumn somewhere deep into a more complex component, and I want to expose an action like “scroll to top” to the outside world. Obviously, I don’t want

LazyListState

to be exposed, because composition of this bigger component can change, but semantic would remain. How do you do this?

I have a

LazyColumn

and I want it to retain scroll position relative to the item key when I update the content. E.g. if I have items from the

listOf(1,2,3)

and I scroll to top, and then update data and repopulate items from

listOf(0,1,2,3)

I want scroll position to be still at item

1

with the same offset, and to see item

0

user would need to scroll up. Any hints on how to implement this effectively?

Does anyone have any idea when the next stable version of Compose is set to be released? I'd like to upgrade to Kotlin v1.7.0 but this issue is blocking it.

I have a cool animation that runs but it gets clipped. I couldn't figure out why, but I did trace it down to this modifier I added

.blur(Dp(bottomSheetProgress * 4))

even if I make it

.blur(Dp(0F))

it will still clip. Is there anyway to opt out of this behavior?

The

SnackbarDuration.Indefinite

javadoc says "_Show the Snackbar indefinitely until explicitly dismissed or action is clicked_", however so far I haven't figured out any way for the user to manually dismiss a snackbar other than clicking the action. How can this be done?

Hello, is it possible create a compose project for Desktop & Web ? I tried the multiplatform setup but it created desktop & android directories. In my case I don't want android. Thanks

Hello, can someone point me to some tutorial about desktop compose UI ? My new app looks terrible 😄

Has anyone figured out how to have a

Row(Modifier.horizontalScroll())

but have the current item "snap" in place. I've looked at Chris Banes' snapper lib, but it only works with LazyRows. And HorizontalPager in accompanist is built on LazyRow so that's also a no-go. I need a non-lazy row/carousel impl with "snapping", but really can't find anything but I'm sort of finding it tough to believe no one has solved for this problem yet.

Is there a way to take screenshots using

ComposeTestRule

with Robolectric. Currently getting

androidx.compose.ui.test.ComposeTimeoutException: Condition still not satisfied after 2000 ms

errors on

captureToImage

when calling

rule.onRoot().captureToImage().asAndroidBitmap().compress(Bitmap.CompressFormat.PNG, 100, FileOutputStream(File("test.png")))

Is it possible to change content of the sticky header in the LazyColumn when it is “hanging” over the content vs when it is rendered as a normal item?

Hi all, there is some hesitancy on my team to depend on https://github.com/google/accompanist given this:

Any of the features available in this group of libraries may become obsolete in the future, at which point they will (probably) become deprecated.

We will aim to provide a migration path (where possible), to whatever supersedes the functionality.

Citing that these migrations/deprecations could become problematic to maintain. Did anyone run into similar concerns and go with some alternative?

I have this weird requirement where I have to give a Box the same height that is equal to the total height of the 1st and 2nd item of a LazyCol on top of the box.. The 1st and 2nd item in the list can change at any time or else I would just try to take the easy route and use some hardcoded height. How can I properly set a variable of

totalHeightOfFirstAndSecondItemInLazyCol

.

Box {
Box(fillMaxWidth().height(totalHeightOfFirstAndSecondItemInLazyCol)
LazyColumn() { //all items are different sizes }
}

If I have an

android:letterSpacing

value like the following, how do I use it in Compose?

<!-- Letter Spacing -->
<dimen name="largeTitleLetterSpacing">0.00625</dimen>

I was reading through the androidx google source repository, and I noticed in the documentation that ‘Compose is still experimental and should not be used in a production application’. Is this still the case, or is the compose compiler README out of date?

Trying to run molecule with CfD (copied the runtime methods as there is no build yet for JVM), looks like it's always recomposing and remember call the `calculation`on each composition. Any advice?

Is it alright for an applier node to have access to the applier via callbacks?

[Solved] I am unable to preview compose ui. Unable to figure out the issue. Any one with similar issue can help?? This is in a multi module project. Says need to build for the preview to be shown but once i do that the same msg is shown in design editor. Tried clean and build multiple times.

Hello, is it possible to limit width of

placeables

using custom layout? In my case, button overlaps other items but I would expect other components to get smaller as much as button gets wider. Code in the 🧵

Hey guys. I have a question about Compose testing. My test has a

LaunchedEffect

which will change a state after a delay and trigger a recomposition. I want to wait for the end of the consequent recomposition and then do some assertions. How can I achieve the waiting?

waitForIdle

doesn’t work.

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