kotlinlang #compose

Compose doesn’t seem to be really tight to Android. I might be wrong, but we could probably “just” change a rendering function to make it able to draw on a different canvas. I perfectly understand it’s certainly not the priority but it’s cool to think that in the future it might be possible.

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romainguy

06/17/2019, 9:14 PM

We have ideas and prototypes for ConstraintLayout in Compose

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Matej Drobnič

06/18/2019, 5:32 AM

I was just messing around with creating a slidable drawer with

ViewDragHelper

and noticed that this code has a lot of state and calbacks interacting with each other (for example see all the touch callbacks in

androidx.drawerlayout.widget.DrawerLayout

from androidx). I cannot fanthem how could such monstrosity be implemented with just composable functions. Will there be a way to create classes for views or some other way to properly manage complex views like this?

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Vladimir Ivanov

06/19/2019, 10:21 AM

Does Jetpack Compose has a SeekBar or Slider component? Can't find one =(

Vladimir Ivanov

06/19/2019, 12:20 PM

Another question: Any plans on returning a component instead of Unit for the sake of unit tests? Like described here: https://blog.karumi.com/android-jetpack-compose-review/

Loránd

06/20/2019, 8:28 AM

Maybe i missed this but will there be any live preview window for compose in studio? similar to apples canvas in xcode for swift ui.

Tristan Caron

06/20/2019, 8:19 PM

Interesting initiative https://worthdoingbadly.com/swiftui-html/ It’s only an educational toy, but still.

Suraj Shah

06/22/2019, 1:08 PM

Do we have to write

inline

to inline lambdas in a function marked with

@Composable

or does the annotation processor optimize it for you?

Gil Goldzweig

06/22/2019, 2:46 PM

Is there a URL that people can join this channel?

Matej Drobnič

06/22/2019, 5:09 PM

Follow up question to:

Compose has no specific notion of View IDs.

Without that information, how can compose distinguish between "old item removed, new item inserted" and "old item updated" events to display proper animations (e.g in recycler-view like setting)?

Karen Ng

06/26/2019, 8:15 PM

Hey all! PSA: Interested in helping us shape Jetpack Compose and getting paid for it? We’re looking for some people interested in an upcoming Jetpack Compose research study. Announcement: Seeking Android Developers to provide feedback on Jetpack Compose Location: Either Mountain View (Googleplex), San Francisco Google Office Dates: July 1 - July 12 Time commitment: 1.5 hour in-person session Incentive: $200 More info: If you’re interested, please fill out the questionnaire below to confirm your availability and see if this study is a good fit for you https://forms.gle/ckFqCkLGGufTuv8U8

Siyamed

06/27/2019, 11:56 PM

I was just fixing it. currently it is in a temporary stage.

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Leland Richardson [G]

06/29/2019, 5:49 PM

though there are still a few advantages of class components that we are trying to work out

Leland Richardson [G]

07/01/2019, 12:24 AM

you can do patterns like that with both component classes and composable functions, if that was what you were asking

romainguy

07/01/2019, 2:41 PM

(first the new IR backend of the Kotlin compiler needs to be stable :)

pavi2410

07/04/2019, 2:39 PM

SwiftUI uses

@State var count = 0

while in Compose,

val count = +state { 0 }

. Why such a hacky thing (

+state

) is chosen?

Arman Chatikayn

07/04/2019, 7:32 PM

What is the approach do you use to update the corresponding UI part ? As I understand you did not use Virtual Dom approach to solve this problem

Arman Chatikayn

07/07/2019, 1:15 PM

Why_not_move___Compose_to_language_level__as_you_already_do_some_byte_code_changes_with_compiler_plugin__I_mean_maybe_something_like_this_will_be_better_.kt

dead.fish

07/08/2019, 10:54 AM

Dear Android Compose Team, please do not re-use the existing style system Android provides, its a PITA to use right, memorize, extend and embrace. Please come up with something better, that doesn't force you to read and distribute base style information across dozens of files. Thank you! - A plagued user.

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Tristan Caron

07/11/2019, 3:44 PM

Hmmm interesting work from Microsoft team with C# Blazor and Flutter

https://youtu.be/uW-Kk7Qpv5U?t=3265▾

dewildte

07/12/2019, 2:19 PM

I have not chimed in here for awhile. Has any work been done to get the Compose tools to run on Windows machines yet?

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Antanas A.

07/17/2019, 9:33 AM

Hi everybody, I've design question when using tools such Jetpack Compose. Is it possible to have some "methods" on a GUI components? example ListGrid.selectRecord(), ListGrid.sortColumn(), ListGrid.hideColumn(), ListGrid.disableClicks()? Or this is the same as React Redux and we can control components UI only thru explicit view state management? Or do you have some alternatives for this scenario? Problem is that currently we need for simple list grid to create "View Object (for rendering)", "View Component/Controller (for managing state) with methods" have some state container, bind state container to View Object and to View Component, and do actions thru some action dispatchers aka reducers which do not have references to either View Object nor View Component. How to handle that if there is multiple list grids or many different objects. I've largely used MVC / MVP / MVVM styles of GUI programming, and MVVM without two way binding was best available at time and now it's hard to understand how do you do programming when you do not have some reference-able graph of objects which can have a "methods". Do you thought about this during Jetpack Compose design? Any recommended way to handle state (more focus on state of UI component, not the model state)? (disclose: I personally dislike redux like designs where everything is completely separated and by that becomes hard to track what belongs to whom with custom made dynamic dispatch system which emulates OOP language method calls)

Jurriaan Mous

07/18/2019, 5:33 AM

Slides which explain Compose internals step by step. https://twitter.com/intelligibabble/status/1151649562685136897

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Tristan Caron

07/18/2019, 2:44 PM

Will Compose be the definitive name?

rkeazor

07/19/2019, 12:42 AM

So will jetpack compose, support constraint layouts.

voddan

07/22/2019, 1:44 PM

I am reading @Leland Richardson [G]’s slides and they mention a very specific data structure (flat array) for the UI tree. Some questions: 1) Will the selected data structure have any impact on the semantics of Compose or impose any structural limitations on it (vs a naive tree)? 2) What sources and methods were used to confirm the "the structure of a UI doesn't change very often" assumption (slide 33)? E.i. what frameworks and types of UI did you looked at? 3) Do you know of any use cases that are atypical for the existing UI frameworks, but would fit Compose well that would break the (2) assumption and, as a result, would not have good performance with the Slot Table currently used? I can think of loops with variable number of iterations, but I did not confirm that. 4) If there are valuable use cases in (3) that do not perform well with the current implementation of Compose, how hard will it be to switch Compose to a different (presumably non-flat) data structure?

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Title

voddan

07/22/2019, 1:44 PM

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Chuck Jazdzewski [G]

07/22/2019, 4:00 PM

1) ... structural limitations

No. The data structure is an internal detail. We could switch to a different data structure if performance dictates. We have already switched twice before we went public.

2) What sources and methods ....

Mostly experience with many different frameworks over our careers (for me personally this is my 6th framework). This, however, is just an observation and is not required for the performance of the system. Compose can handle large radical changes in the UI just a easily but we are optimizing around localized changes as that is what we believe will be most common.

3) Do you know of any use cases that are atypical for....

Yes. Inserting and removing nodes at the beginning and end of the slot table in the same composition or any other form of non-local change. As the slot table is a flattening of the of a tree, any non-local changes to the tree will cause copying of the array as the buffer gap moves. If this is common we can introduce multiple gaps or using an internal tree; but, for now, we have a flat array with a single gap.

4) ...how hard will it be to switch...

Not hard. We are keeping the data structure internal and only exposing an abstraction to the code generation to call. We have switched the implementation twice already without impacting the programming model. Even if the code generation takes a more active role (such as producing a scope record to avoid boxing) we still anticipate using the same API as the scope record could just be stored a

memo

like call. We do plan some significant surface changes to the API, moving to a more of a code-flow approach instead of call interception, as explain in Leland's talk which will result in changes to the API the compiler uses but it will still be abstract enough to hide the flat vs. tree based data structure.

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voddan

07/23/2019, 12:59 AM

Thanks!

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