kotlinlang #compose

function that produces a T. For a simple branch with nodes A > B > C; I end up with a scenario where if any of the nodes change, all of them have to produce a new T. Ideally, only affected nodes should reproduce their T, so if B changes, C can remain the same. Any ideas? More details in 🧵

Colton Idle

08/03/2022, 7:36 PM

android studio c9 out today https://androidstudio.googleblog.com/2022/08/android-studio-electric-eel-canary-9.html idk what this means just yet, but hopefully it means no flashing/resetting of nav graph when making a change.

Starting with Electric Eel Canary 9, if your project is using Compose version 1.2 or higher, Live Edit no longer needs to reset composition after code changes. Only the first code change made to a given file resets composition. Subsequent edits don't reset composition.

Roudy Korkis Kanaan

08/04/2022, 1:24 AM

Hey everyone, I'm trying out the

rememberTransformableState

for panning/zooming but it's not working as the sample suggests. I copied the sample found here. Zooming and rotating works but

offsetChange

is always zero

Tin Tran

08/04/2022, 2:19 AM

I also get this SEGSEGV with webview inside a bottom sheet when I upgrade to 1.3.0-beta02. Reverting back to 1.2.0 fixed the issue

nuhkoca

08/04/2022, 8:29 AM

Hello, I set a different background color when a list item is clicked. However when its position changes, a different one gets that background color as the previous item’s position had changed. How do I find a more reliable index then?

Box(modifier = Modifier.animateItemPlacement()) {
    InstrumentView(instrument = item, selected = selectedIndex == i) {
        selectedIndex = if (selectedIndex != i) i else -1
    }
}

K Merle

08/04/2022, 9:21 AM

Anyone have an example of how to share viewmodel between screens? I'm getting

java.lang.IllegalArgumentException: No destination with route..

Tin Tran

08/04/2022, 9:32 AM

Is there away to disable fling behavior on accompanist pager?

Tepes Lucian Victor

08/04/2022, 10:31 AM

Is there a

SlidingPaneLayout

echivalent in compose?

Vaios Tsitsonis

08/04/2022, 11:48 AM

Hello! I have a clickable

Row

. It's shape has radius. I ve added

clickable

modifier and the ripple effect does not respect the shape... How I can implement the desired behavior (apart from wrapping my composable with

Card

:P)

dave08

08/04/2022, 11:57 AM

Hi! Just wondering if migrating an app to compose piece by piece still has major performance issues, or was that already resolved?

Slackbot

08/04/2022, 2:21 PM

This message was deleted.

Lukasz Kalnik

08/04/2022, 2:51 PM

What is the purpose of the

content

ModalBottomSheetLayout

when

sheetContent

takes all the contents of the bottom sheet? What if I want to display this modal bottom sheet over different screens, should I just then leave

content

empty?

Altynbek Nurtaza

08/04/2022, 7:55 PM

i’m using intel macbook. the problem also occured on my friend’s m1 macbook, but it works on his windows machine

Paul

08/04/2022, 9:19 PM

Hey all. Recently I've migrated my open-source app called Gamedge to be a pure Jetpack Compose app. It utilizes all the latest libraries & tools in the Android development world. A couple of thoughts: 🧵 https://github.com/mars885/gamedge

K Merle

08/05/2022, 5:35 AM

I am trying to have nested

NavHost

, and

navigation

DSL is kind of is not optimal. Having actual

NavHost

nested in parent

NavHost

would give me more control over background shared element of nested screens. Is having

NavHost

nested not recommended?

ken_kentan

08/05/2022, 9:00 AM

Hi! Is it possible to implement dialog with transparent background by using

NavGraphBuilder.dialog

Filip Wiesner

08/05/2022, 9:29 AM

That is a very broad question. Have you read the Compose performance doc?

KotlinLeaner

08/05/2022, 10:39 AM

Hello ✌️, I have Font

Font(R.font.source_sans_variable_350)

and I am passing

FontWeight

so what would be? I checked

FontWeight.Light

and

FontWeight.Normal

which is 300 and 400 respectively. So is there any solution for this ?

Lukasz Kalnik

08/05/2022, 12:49 PM

I have a

ModalBottomSheetLayout

where the contents is the main screen with a list of items, and the

sheetContent

are item details (with different settings). As the item details are quite complex, and don't influence the main screen, I would like to have them in a separate ViewModel. How can I pass the

itemId

from the

MainScreenViewModel

to the

ItemDetailsViewModel

. I don't really fancy creating a shared ViewModel just to pass one value (which is anyway only temporary, as the

ItemDetailsViewModel

will store

itemId

as well to get the item data).

Nat Strangerweather

08/05/2022, 2:35 PM

Hi, I am getting an indexOutOfBoundsException when I initially install my app on a fresh emulator. Is there something really obvious in my code snippet that would cause this to happen? 🧵

George

08/05/2022, 7:17 PM

Compose + ViewModel + MutableState combination is error-prone due to snapshots mechanics. Shouldn't something be done about it? (details inside)

Tlaster

08/06/2022, 4:59 AM

Is there any way to generate Material 3 ColorScheme from a single color like

ColorScheme.fromSeed

in flutter?

Zoltan Demant

08/06/2022, 8:17 AM

This seems impossible from my understanding of how compose works, but is it somehow possible? Im creating a class A that holds B, if B is passed in as State<B> then I can "move" the recomposition scope further in; but if B is read and passed into A as the value itself, then the recomposition scope wraps the entire thing and A is recomposed together with B. Can I somehow pass B "as the value" but still push the recomposition scope further in? :kotlin-intensifies:

gsala

08/06/2022, 8:43 AM

Hi. Is there an equivalent of TextView’s breakStrategy for the

Text

BasicText

Composables? I’m trying to get a

balanced

break strategy where the line lengths are similar.

dimsuz

08/06/2022, 11:16 AM

If I write a custom layout and use a

State

value to affect placement of layout children, will it impact performance in some way? Is there some in-depth look of what is cached and when during layout in compose? E.g.

fun MyLayout(x: Int) {
  Layout(content = {...}) { m, c -> 
     ...
     layout(w,h) { child.placeRelative(x, 0) }
  }
}

fun Screen() {
  // or x is from pointerInput + stored in State
  val x by animateValue(300)
  MyLayout(x)
}

CLOVIS

08/06/2022, 1:54 PM

There was a very good 4-5 parts series on Medium about the inside working of Snapshot and everything. I can't find it anymore, does anyone have the link to it?

nuhkoca

08/06/2022, 11:40 PM

Hello, trying to use Accompanist Horizontal Pager with Bottom Sheet but the tab part of the screen is not dimming as I use bottom sheet inside pages. I don’t want to use the BottomSheet in holder Compose view because it’d be too much hassle for handling click events, passing correct list of items etc. How do I dim the rest of the screen properly or what would be the more efficient way to integrate BottomSheet while using Pager if each tab required bottom sheet?

Colton Idle

08/07/2022, 2:56 AM

If I have a screen that displays a list of Books and I want to update the "likes" on each individual book while the screen is showing, but I also want to update the list of Books showing on the screen. What's the best route to go? Option 1: var books = mutableStateListOf<Book>() class Book(title: String, likes: Long) Option 2: var book = listOf<Book>() class Book(title: String, likes: Long){ var likes by mutableStateOf() } Option 3 var books = mutableStateListOf<Book>() class Book(title: String, likes: Long){ var likes by mutableStateOf() }

dimsuz

08/07/2022, 12:46 PM

I have a

Box

and I want to use

pointerInput

to detect drag gestures inside this box, but I want to ignore cases when drag starts in the smaller child in center of that box. For example box is 400x400.dp and I want to ignore drags coming from within 100x100.dp of its centered child. How can I achieve this? Use

onGlobalLayout

to capture the position and size of the child and then in

onDrag

check if

change: PointerInputChange

comes from a child area and do not do what I usually do there in this case?

Alexander Maryanovsky

08/07/2022, 2:43 PM

I have a

Column

Item

, for example like this:

A2
C1
B2

with something like

@Composable
fun Item(letter: Char, index: Int){ ... }

Now each item belongs to a group, specified by the letter (A, B, C etc.) and has an index, specified by the number. The user can 1. Change the item’s index by selecting the item and pressing left/right. So, selecting “A2”, for example, and pressing right, changes the item to “A3". When this happens, I’m animating the

Text

using

AnimatedContent

so the “A3” slides in from the right and the “A2" slides out to the left. The animation runs when the new index is adjacent to the previous index. 2. Remove an item by selecting it and pressing “delete”. Now, I have a problem. If the list is, for example

A1
A2
...

and the user deletes A1, the animation runs because as far as the 1st call to

Item

is concerned, what happened was the index `remember`ed by

AnimatedContent

changed from ‘1’ to ‘2’. I would like to not have the animation run in this case. If I

key

the

Item

with

index

then the animation doesn’t run even when it should.

Title

Alexander Maryanovsky

08/07/2022, 2:43 PM

I have a

Column

Item

, for example like this:

A2
C1
B2

with something like

@Composable
fun Item(letter: Char, index: Int){ ... }

Text

using

AnimatedContent

A1
A2
...

and the user deletes A1, the animation runs because as far as the 1st call to

Item

is concerned, what happened was the index `remember`ed by

AnimatedContent

changed from ‘1’ to ‘2’. I would like to not have the animation run in this case. If I

key

the

Item

with

index

then the animation doesn’t run even when it should.

Alex Vanyo

08/08/2022, 4:22 PM

Using

key

is definitely the right track, but you will probably need to create some sort of unique id to use as the

key

to specify which items are “the same” that are being modified or deleted. Here’s another way to look at it: Let’s say I gave you this list before, and this list after. Before:

A1
A2
A3
...

After:

A2
A3
A4
...

Just from looking at those two lists, there’s two possibilities: Either

A1

was deleted, or all of the items were incremented. But just by looking at the before and after, there’s no way to know which happened, and that before and after view is all Compose knows as well. There needs to be some additional information used for tracking what happened.

Alexander Maryanovsky

08/08/2022, 4:34 PM

Yes, unfortunately that's exactly the problem. The initial and final states are the same. Only the user action that triggered the change is different.

Alex Vanyo

08/08/2022, 4:38 PM

Right, the information you have right now isn’t enough. I’d try doing something like keeping a

UUID.randomUUID()

around with your items, and using that as your

key

. Removing an item would cause a

UUID

to be deleted, whereas updating an item would keep the old

UUID

, but with a new value.

Alexander Maryanovsky

08/08/2022, 4:59 PM

That's going to be tough. The item list is the result on an external computation that exposes it via StateFlows.

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