Kotlin Multiplatform support

[kizitonwose]

Edit: Kotlin multiplatform calendar library alpha release is now available.

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Over the weekend, I had some time to investigate what is needed to add multiplatform support to the library, seeing that some users have requested it over the past few months. I was able to get a rough example of the existing compose Example1Page up and running. Screenshots from the desktop app and browser are shown below, next to the Example1Page from the Android sample app. This iOS sample app also works, but I moved a bunch of source files around which broke the compilation and I did not want to spend time fixing it just for the demo.

Android	Desktop	Browser

I have some thoughts on how to approach this, please feel free to chime in.

The library presently has support for the view system, and that is not going away. The current compose artifact is also not going away either as together with the view system library, they use the java.time APIs and I intend to keep them that way. The kotlinx-datetime library has come a long way, but it is not yet at the same level as the java.time APIs, so I do not want to force the library users to use the kotlinx-datetime library, especially on pure Android projects without multiplatform setup.

I am considering publishing the multiplatform library which will use the kotlinx-datetime library under a different module name, like com.kizitonwose.calendar:compose-multiplatform, so the Android view and compose libraries using the java.time APIs will keep existing in their modules com.kizitonwose.calendar:view and com.kizitonwose.calendar:compose respectively, but this means duplicating a lot of compose code, so I am still thinking about the right approach and open to suggestions.

Regarding the timeline for when this could be out, at least in alpha, I can't give anything specific right now, but given my current schedule, maybe in 2-ish months.

I kindly ask you to refrain from posting comments solely asking about the release date, as such comments do not add any value.

[abdallahmehiz]

Why not create a module that uses both java.time and kotlinx.datetime? one for the jvm and the other for native?

[kizitonwose]

@abdallahmehiz can you elaborate further? Do you mean to bundle both java.time and kotlinx.datetime logic in one module, then expose different composables?

[abdallahmehiz]

Lol sorry i think i was half asleep when i wrote this yesterday...
I thing what i was trying to say is just create a common API, maybe an interface that has all of your needed functionality for handling dates then implement them for both native and jvm with the expect actual mechanism.
You're probably already doing that though...

[kizitonwose]

Went a bit in this direction, but it started to get quite messy, might try the approach with generics.

[kalist28]

I think it’s worth switching completely to kotlinx.datetime, and leaving functions from Java.datetime as duplicate functions from the multiplatform but with mapping from kotlinx.datetime

Kotlinx.datetime has a convenient translation API to Java.datetime and back to the jvm target.

You will get two options for Android calendar:compose:0.0.0 with Java.datetime and calendar:compose-multiplatform:0.0.0 with kotlinx.datetime

[kizitonwose]

Yep, this could work, I will have to make a lot of the core classes generic to hold the kotlinx.datetime type or the Java.datetime type depending on the library type.

[bmc08gt]

Sorry for the massive hiatus. Yes that is what I did (Kotlinx date time). The code for it was in my PR here for my own project - https://github.com/bmcreations/airbnb-multiplatform-sample/pull/3/files#diff-697f70cdd88ba88fe77eebda60c7e143f6ad1286bca75017421e93ad84fb87df

[kizitonwose]

Published the first alpha for the multiplatform artifact today, it has the same API as the existing compose calendar, so the existing compose documentation should be sufficient to get started.

Note that this is based on compose UI 1.7.0-beta03.

commonMain.dependencies {
    implementation("com.kizitonwose.calendar:compose-multiplatform:2.6.0-alpha02")
}

Examples can be viewed online at: https://calendar.kizitonwose.dev, the source code is available in the multiplatform branch.

[kizitonwose]

The multiplatform library code is now merged into the main branch in #561, this discussion will therefore be closed.