Does a Composer need to learn Flow?

With Compose, do we really need an activity to be destroyed and recreated? As per docs:

The restart behavior is designed to help your application adapt to new configurations by automatically reloading your application with alternative resources that match the new device configuration.

But compose screen can easily recompose with new configuration without having to restart an activity. Or if resources are read inside composable function via

dimensionResource()

etc, we still need to recreate activity?

What's the pattern to pass state up the component tree? Use case: I have some deep child scrollable component, and I want to display a scroll position in the parent. I guess I should pass the mutable state down to this component and observe it in the parent, correct?

Hi, in term of performance, it is something that is gonna be improved with the next releases? After playing with the example code, I don't find them super fluid on a Samsung S10e, you can notice some frame drop when you interact with the UI. Thanks 😁!

@Composable
private fun ZoomControls(
    zoom: Float,
    onZoomChanged: (Float) -> Unit
) {
    Row(Modifier.fillMaxWidth(), horizontalArrangement = Arrangement.Center) {
        ZoomButton("-", onClick = { onZoomChanged(zoom * 0.8f) })
        ZoomButton("+", onClick = { onZoomChanged(zoom * 1.2f) })
    }
}

ZoomControls(zoom) {
        zoom = it.coerceIn(MinZoom, MaxZoom)
    }

This is a bit confusing since being a Composable, I expect the lambda to be a

content: @Composable () -> Unit

instead of a callback.

How can I make

TopAppBar

consume

Window Inset

? Doing:

TopAppBar(
    modifier = Modifier.fillMaxWidth()
        .statusBarsPadding()
        .wrapContentHeight(),
...

just result in something like this where the added padding is just white and not the TopAppbar Color.

This is something that always made struggle also with XML design. I tried with something like

Scaffold(topBar = ..., bottomBar = ..., ...) {
  when (currentScreen) {
    ...
  }
}

Problem is that some screen have fab, some have search bar in topBar, which has actions, etc. So I change that as

val content @Composable () -> Unit = {
  when (currentScreen) {
    ...
  }
}

if (currentScreen.isHomeDestination) {
  Scaffold(...) { content() }
else 
  content()

and it was still looking nice on the UI prospective, but ugly on the code, because some screens will be wrapped in Scaffold, while some will be wrapped somewhere else ( 👆 ), So I created a custom Scaffold and moved into my screens

@Composable
fun SearchMovie(...) {
  HomeScaffold {
    ...
  }
}

But now it looks ugly on the UI, because I open my drawer, but when I select an item it replaces the whole screen, so my drawer disappear without the animation. What would be the best way to deal with that?

Need a blog post about ambients...

Hello, I am following the CodeLabs and in the one about state (https://developer.android.com/codelabs/jetpack-compose-state#0) I have an issue with the

onImeAction

when used in the header: it doesn't work properly. It happens in what I have done and the "finished" versión given in the codeLab. Is this a known issue with the

TextField

composable or is there some problem with my setup? That TextField also won't let me delete the last character. This things only happen in the header so I don't know if this issues are with the

TextField

or something else about have this lab teaches about how to manage state

Why I can't deploy preview to the device? Deploy button just disabled. On the Jetchat sample project the button works. What could be causing this? There are no errors or warnings.

Going through https://codelabs.developers.google.com/codelabs/jetpack-compose-state codelab, I noticed that the first letter cannot be erased. hello| hell| hel| he| h| |h GIF:

When the TextField is at the bottom of the screen, the TopAppBar and content will move up after the keyboard pops up. How to prevent them from moving? I want to make a TextField like Jetchat sample app's.

Is still release compose every two weeks?👀

How to understand the first term of

@Stable

’s guarantees? > The result of equals will always return the same result for the same two instances.

Hi all I have an issue trying to add Compose to my project When building project i get this error:

e: androidx.compose.compiler.plugins.kotlin.IncompatibleComposeRuntimeVersionException: You are using an outdated version of Compose Runtime that is not compatible with the version of the Compose Compiler plugin you have installed. The compose compiler plugin you are using (version 0.1.0-dev16) expects a minimum runtime version of 0.1.0-dev16.

But i specify in build.gradle for 2 modules (feature module when i want to use compose and app module) latest version of compose:

android {

    buildFeatures {
        compose true
    }

    composeOptions {
        kotlinCompilerVersion '1.4.0'
        kotlinCompilerExtensionVersion '1.0.0-alpha01'
    }

    kotlinOptions {
        jvmTarget = jvmTargetVer
        useIR = true
    }
}

I use gradle plugin version 4.2.0-alpha08:

classpath 'com.android.tools.build:gradle:4.2.0-alpha08'

and gradle version 6.6:

distributionUrl=https\://services.gradle.org/distributions/gradle-6.6-all.zip

and kotlin version 1.4.0:

classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.4.0"

Could anyone help me please? What i'm doing wrong?

I've recently gone though the full compose codelabs and I got a few questions that got me stuck in development: • How can I focus next TextField? Changing IME action wasn't enough, I'm not sure how to use the (experimental) focus API • Is there a way to use error property in TextField? Do I have to create one manually? I was using OutlinedTextField • Is there a list of all available components somewhere? Looking through sources of sample apps seems less than ideal when looking for something

Hi, my compose preview stopped working with 1.0.0-alpha01 version. Has anyone else same experience? I’m using AndroidStudio 4.2. Canary7

Hey, I'm thinking about adding haptic feedback (vibration) to my app. In the old Viewsystem I would have used view.performHapticFeedback(). Is there a way to do something similar using compose without doing it manually (using the vibrate permission and the Vibrator Systemservice)?

Any idea how to disable text field? Looking for something better than stacked Box with onClick.

Is there a reason ( and a way around ) why

TopAppBar

and

BottomAppBar

, in dark theme, have a way lighter background of what I set? I’ve set

Color(0xFF1c1c1c)

but they’re so light, specially the Bottom one. I can see it very clearly compared to the status bar, which I’ve set as

#1c1c1c

Is it just me or does the compose pathway (https://developer.android.com/courses/pathways/compose) not actually save your progress properly. =(

I am trying to achieve something like the image attached with a Stack, where each element I add is placed at the bottom of the stack, with each element having a random color. The issue is that each time I add a new element the Composables lose the state even when I remember it using the id as a key. The final behaviour I want to achieve is much more complex than this and involves dragging elements, but it breaks for the same reason when trying to remember the position of the different draggable elements. I built a minimum example that reproduces this issue, is there a solution to this kind of scenarios?

@Composable
fun Body() {
    Stack(Modifier.fillMaxSize()) {
        var items by remember { mutableStateOf(listOf(0)) }
        items.reversed().forEach {
            Item(
                it,
                modifier = Modifier
                    .clickable(onClick = {
                        items += items.last() + 1
                    })
                    .gravity(Alignment.Center)
                    .matchParentSize()
                    .padding((100 - (it * 10)).dp)
            )
        }
    }
}

@Composable
fun Item(num: Int, modifier: Modifier = Modifier) {
    val color = remember(num) { Color(Random.nextFloat(), Random.nextFloat(), Random.nextFloat()) }
    Box(modifier = modifier, backgroundColor = color, gravity = Alignment.Center) {
        Text(text = "$num", style = MaterialTheme.typography.h1)
    }
}

I am trying to fire an intent to move to the next activity when I click on an ExtendedFloatingActionButton. To obtain the context, I tried

ContextAmbient.current

but android studio is unable to generate the error message. So I ended up using the context like this

val context = ambientOf { ContextAmbient } as Context

But when I fire the intent, the app crashes with the following error.

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.sivan.pinotes, PID: 25739
    java.lang.ClassCastException: androidx.compose.runtime.DynamicProvidableAmbient cannot be cast to android.content.Context
        at com.sivan.pinotes.MainActivityKt$extendedFAB$2$1.invoke(MainActivity.kt:65)
        at com.sivan.pinotes.MainActivityKt$extendedFAB$2$1.invoke(Unknown Source:0)
        at androidx.compose.foundation.ClickableKt$clickable$2$tap$1.invoke(Clickable.kt:79)

If DynamicProvidableAmbient cannot be cast to a Context, are there any alternatives to this approach?

Hey guys!👋🏿. How do you do manage the navigation on compose? Also, do you use any dependency injection framework not to pass ViewModel as parameters on @Composable functions?

I must miss something obvious, but why

var inputState: TextFieldValue by mutableStateOf(TextFieldValue())

fails with an error

Type 'MutableState<TypeVariable(T)>' has no method 'getValue(Nothing?, KProperty<*>)' and thus it cannot serve as a delegate

Is there a way to monitor performance of Compose? I was curious which is has better performance between Nesting Columns and Rows and Using ConstraintLayout.

Hey everyone, is there a compose analog to nested scrolling apis in android?

As a follow up question, what is everyone using for scrolling tricks? Some things I am thinking about or will be interested in knowing the apis (or seeing some samples for) • collapsing toolbar • bottom sheet • hide and reveal fab or search bar on scroll • horizontal scrolling within vertical scrolling container etc (lazy web btw, I haven’t gone through the samples thoroughly yet)

Going through the codelab https://codelabs.developers.google.com/codelabs/jetpack-compose-layouts/#4 I noticed that the bottom navigation and drawer layout links are broken at the bottom of the page possibly they should be replaced with below: https://developer.android.com/reference/kotlin/androidx/compose/material/package-summary#bottomappbar Is this a good place for feedback or is there a separate area where this feedback should be provided.

After adding compose I get the following Error:

e: java.lang.NoSuchMethodError: 'void org.jetbrains.kotlin.cli.common.messages.MessageCollector$DefaultImpls.report$default(org.jetbrains.kotlin.cli.common.messages.MessageCollector, org.jetbrains.kotlin.cli.common.messages.CompilerMessageSeverity, java.lang.String, org.jetbrains.kotlin.cli.common.messages.CompilerMessageLocation, int, java.lang.Object)'

Execution failed for task ':app:kaptGenerateStubsDebugKotlin'.
> Internal compiler error. See log for more details