Hello everyone! First of all, I'd like to thank and salute you for your efforts in modernizing the Android SDK! It really looks way better with compose. I'm a web developer using React in my daily routines and I'm currently learning mobile development, right now playing with the Android SDK. So applying programming styles from React in Android really appeals to me. I have a few questions for you, guys: 1 - What is the state of compose in terms of performance (more specifically list-displaying composables)? I tried using

LazyColumnFor

, because I wanted to migrate an adapter which has two view types (both written in constraint layout). I migrated the XML definition of the CL to the equivalent

ConstraintLayout

composable, using

createRefs

for describing constraints, and

start.linkTo

,

top.linkTo

, etc. (part of 0.1.0-dev16 version). Scrolling was very slow, compared to the adapter approach where things are smooth. Here's a gist of the composable. Here's some relevant code: The activity which sets the root composable (the list) - grabs first a bunch of data from a Firestore and calls

setContent

The list, based on LazyColumnFor The repeating item - with ConstraintLayout, and with Row and Column RoundedImage composable - a simple card view with circle shape The customized button 2 - Have you considered taking an approach similar to JSX in React, something like files with both Kotlin code and some sort of markup for definition of the view itself. Seems like the main drawback of the composables is the nesting of objects that happens in code, and to me at least, it seems more natural to express certain hierarchy of components through a markup language (don't get me wrong, moving to composables in their current state is already a big step, just my thoughts as React dev 😉 ) 3 - For beginners like me, is it worth diving deep into things like activities, fragments, navigation in its stable state, lifecycles of fragments/activities, different kind of layouts, etc.? I'll probably not be working on professional Android projects (if I decide to take up mobile dev in my work) by the time stable version of compose is released (in the beginning of 2021, from what I know). Thanks and have a great day! 🙂

Hey was wondering how do you handle scrolling when typing into a text field using the keyboard?

Can I set a custom key (instead of element index) in

LazyColumnFor

composable?

Is there a way to specify the scroll position of a LazyColumnFor? As far as I can see, all the scroll state is hidden away in private functions.

Hi all. I’m curious how one would properly implement composables based on screen width/height selectors.

Anyone know if AdapterList uses RecylerView? And if it does, how does it distinguish between the different row types? It seems like it would be very hard for it to do that.

Not sure if this is something compose can help with, but going off of the question asked yesterday "Hi, is it possible to implement edge-to-edge by compose atm?" I just want to say that I hope implementing e2e with compose is a bit easier. Right now having to inset every one of my recyclerviews on each screen is annoying and clipToPadding = false, etc, but having apps that go off of @cb presentation where he said drawing under nav and status bar is recommended strongly it would be nice if this was like a first class thing.

What is a difference between

var expanded by state { sieveData.first }
var expanded by remember { state { sieveData.first } }

I have seen in some project using the later one

So I am making the jump from dev11 to dev16 and taking on the model change. Previously I had a reusable view class that took in state (@Model) at construction. The the composable functions all used that state. In this way I can inject the bit of app state that a view needs to know about into each view.

class LoginView(
    private var dataModel : LoginDataModel
)  : Component () 

...

    @Composable
    override fun view () {
        BottomDrawerLayout(
            drawerState = dataModel.drawerState,

            gesturesEnabled = true,
            drawerContent = {
                drawerView()
            },
            bodyContent = {
                baseView()
            }
        )
    }

My application model was all defined in one library with @Model. Now I am trying to move to the recommended porting described in dev12:

class Position(x: Int, y: Int) {
 var x by mutableStateOf(x)
 var y by mutableStateOf(y)
}

// source of Example is identical to original
@Composable fun Example() {
 var p = remember { Position(0, 0) }
 PositionChanger(
   position=p,
   onXChange={ p.x = it }
   onYChange={ p.y = it }
 )
}

However, if you look at mutableStateOf it says you should use state and stateOf instead. Then there is a bunch of talk of snapshots. This all leaves me scratching my head wondering how I create a reusable view that can be injected with state. Any good examples, explanations, or other help out there?

I get a strange error with 0.1.0-dev16@aar I guess I updated my Android Studio to the newest Kotlin compiler and it doesn’t work with Compose anymore?

Anyone know if imageResource is broken in dev14?

Is next(dev17) release going to use kotlin 1.4 release version?

I've been playing around with the new NavHost. But I'm wondering: if it completely replaces the composable, how are we gonna keep the scroll position 🤔 Right now it seems to lose it. I'm also not sure about passing arguments. The api doesn't seem to support it?

I want to animate a power bar, by changing the width of an image. The crop that is part of Image maintains aspect ratio. I want to keep the height the same and very the width. Any ideas.

Has any change regarding InputField focus been made in the last version? Looks like ImeAction.Next isn’t working anymore.

Btw, found some weird issue today. It occurs almost every time (except for the first build after clean).

Hello! As Jens already noticed, the latest Jetpack Compose minor release, dev17, has just been released! You can get it now on Google’s Maven Repository. Release notes are available at https://developer.android.com/jetpack/androidx/versions/all-channel. As always, feedback is welcome; please log issues at https://issuetracker.google.com/issues/new?component=612128.

From a dependency standpoint, what are the top libraries for compose that I can put in my Gradle file that will resolve all the libraries needed to work with compose?

Interface functions with default values seem to be ignored if the functions are marked @Compose. This breaks a lot of code. Anyone had this problem on the latest android studio canary, kotlin 1.4, and compose dev16?

Moving to dev17 I used to draw a RadialGadient with:

@Composable 
    override fun GradiantScreen() {
        var colors = listOf<Color>(nikolaColors.color2,
            nikolaColors.color1)
        var gradientBrush = RadialGradient(
            colors = colors,
            centerX = getScreenWidth().toFloat() / 2.0f,
            centerY = getScreenHeight().toFloat() / 2.0f,
            radius = getScreenHeight().toFloat() / 2.0f,
            tileMode = TileMode.Clamp
        )

        Box(
            Modifier
                .drawBackground(brush = gradientBrush)
                .fillMaxSize()
        )
    }

Unfortunately, drawBackground has been deprecated. What is the recommended way to do this with dev17?

Hey. In dev17 CoroutineContextAmbient has gone. What is the replacement?

Our app is pretty happy about dev17 😂

is there an easier way of going through and replacing all the module name changes? some packages I have no idea which package a component is supposed to come from

Any idea what’s wrong with this?

Idea. It would be nice to have a lint check or a way to designate that compose function is expected to start with a row or column.

I am using `avedInstanceState`in dev14 but getting this error

cannot be saved using the current UiSavedInstanceStateRegistry. The default implementation only supports types which can be stored inside the Bundle. Please consider implementing a custom Saver for this class and pass it to savedInstanceState() or rememberSavedInstanceState()

How can I close drawer on back pressed?

i am trying to use animateContentSize but i think i am doing it wrong

LazyColumn(modifier = Modifier.fillMaxWidth()) {
    items((0..30).toList()) {
        var isExpanded by remember { mutableStateOf(false) }
        Surface(
            color = MaterialTheme.colors.primary,
            shape = CircleShape
        ) {
            Row(modifier = Modifier.animateContentSize()) {
                IconButton(onClick = { isExpanded = !isExpanded }) {
                    Icon(asset = Icons.Default.AccessTime, tint = Color.White)
                }

                if (isExpanded) {
                    Text(
                        modifier = Modifier.gravity(Alignment.CenterVertically)
                            .padding(end = 16.dp),
                        text = "some text",
                        style = MaterialTheme.typography.caption,
                        color = Color.White
                    )
                }
            }
        }
        Spacer(modifier = Modifier.height(8.dp))
    }
}

this code make the icons disappear on scrolling and is very lag, but when i put the animateContentSize on the surface it works but the animation is not like the above one. this code is put in another compose but i extract it to see the problem.

What is the latest recommended way of loading images in lazy lists? edit: Both from resources and URL

What is the difference between

var count = remember {mutableStateOf(0)}

and

var count by state {0}

?