I have a multiplatform compose module that targets...

# compose-desktop

[Mike Dawson]

I have a multiplatform compose module that targets Android and Desktop (which is then a dependency for the Android app and Desktop app). The Compose functions are in the common source set (e.g. as normal / as per the template). The preview works fine in the IDE (import androidx.compose.desktop.ui.tooling.preview.Preview).

Jvm compiles fine. Metadatacommonclasses (eg.. commonMain src) compiles fine. Android compilation fails with:

Unresolved reference: Preview

The Multiplatform template ( https://github.com/JetBrains/compose-multiplatform-template ) isn't using preview as far as I can see.

I can workaround the issue by creating another file in the desktopMain source and putting the preview there. Anyone seen this or used previews more successfully in multiplatform including an Android target?

[Alexander Maryanovsky]

The desktop Preview only works for the desktop and the Android only for Android (in Android Studio)

[Mike Dawson]

Thanks for the clarification Alexander, much appreciated. If the desktop preview is only for the desktop, then it seems like it would be better for the @Preview annotation to be available only for the desktop target.

It does seem like something that could use some polish when possible. The primary use case (and what I really like) Compose multiplatform is the ability to build a UI once in a common module and use it on Desktop, Android, etc (and still be able to seamlessly integrate with native/Java APIs). So if that is the primary way to do things (as per the provided templates), then it would be good to have a way to preview things that doesn't require extra files.

[Alexander Maryanovsky]

It is only available for the desktop target

[Alexander Maryanovsky]

It’s androidx.compose.desktop.ui.tooling.preview.Preview

[Alexander Maryanovsky]

For Android it’s androidx.compose.ui.tooling.preview.Preview

[Alexander Maryanovsky]

That’s why you’re getting “unresolved reference”

[Mike Dawson]

Screenshot from 2023-09-06 10-03-00.png

[Mike Dawson]

I was able to add it to the commonMain, the preview works in the IDE (Android Studio in this case with the Compose Multiplatform plugin)

[Alexander Maryanovsky]

Interesting. But still, you’re getting the “desktop” preview.

[Mike Dawson]

And if I run gradlew metadatacommonmainclasses (which should fail if there is something wrong with the commonMain dependencies) it compiles fine

[Alexander Maryanovsky]

i.e. how it would look on the desktop

[Mike Dawson]

The preview itself is fine...

[Mike Dawson]

If the preview is only for desktop, then it seems like what I have shouldn't compile at all

[Mike Dawson]

And should be shown as an error by the IDE

[Alexander Maryanovsky]

I see your point.

[Mike Dawson]

In case its useful: this is what I have in build.gradle.kts for the module:

plugins {
    kotlin("multiplatform")
    id("com.android.library")
    alias(libs.plugins.jetbrains.compose)
}

kotlin {
    androidTarget {

    }

    jvm("desktop")

    sourceSets {
        val commonMain by getting {
            dependencies {
                api(project(":core"))
                api(project(":lib-database"))
                implementation(compose.runtime)
                implementation(compose.foundation)
                implementation(compose.material)
                implementation(compose.materialIconsExtended)
                @OptIn(org.jetbrains.compose.ExperimentalComposeLibrary::class)
                implementation(compose.components.resources)
                implementation(libs.kodein.di)
                implementation(libs.moko.resources)
                implementation(libs.moko.resources.compose)
            }
        }

        val androidMain by getting {
            dependencies {
                api(libs.activity.compose)
                api(libs.androidx.appcompat)
                api(libs.androidx.core.ktx)
            }
        }

        val desktopMain by getting {
            dependencies {
                api(compose.desktop.common)
                implementation(compose.desktop.currentOs)
            }
        }
    }

}

android {
    compileSdk = 33
    namespace = "com.ustadmobile.libuicompose"

    sourceSets["main"].manifest.srcFile("src/androidMain/AndroidManifest.xml")
    sourceSets["main"].res.srcDirs("src/androidMain/res")
    sourceSets["main"].resources.srcDirs("src/commonMain/resources")

    defaultConfig {
        minSdk = 21
        targetSdk = 33
    }
    compileOptions {
        sourceCompatibility = JavaVersion.VERSION_17
        targetCompatibility = JavaVersion.VERSION_17
    }
    kotlin {
        jvmToolchain(17)
    }
}

[Alexander Maryanovsky]

Hmm, I’m getting this in `commonMain`:

[Mike Dawson]

Strange... our project is open source... I can give you the revision to check out if you wish

[Alexander Maryanovsky]

Is it possible one of the dependencies in your commonMain pulls in the desktop libs?

[Mike Dawson]

I don't think so... there is only one other module that targets JVM and uses compose ( app-desktop ), and it has lib-ui-compose as a dependency

[Mike Dawson]

lib-ui-compose is the module where I have the preview annotation

[Mike Dawson]

https://github.com/UstadMobile/UstadMobile/tree/dev-mvvm-primary

[Alexander Maryanovsky]

moko-resources-compose seems to be pulling that in

[Alexander Maryanovsky]

Maybe because of this?

named("jvmMain") {
            dependencies {
                api(compose.desktop.common)
                implementation(compose.desktop.currentOs)
            }
        }

[Alexander Maryanovsky]

Not sure, don’t have enough gradle knowledge.

[Mike Dawson]

What would indicate that moko-resources-compose is pulling it in? Gradle dependencies output?

[Alexander Maryanovsky]

I looked at that, but didn’t actually find it there. But commenting out

implementation(libs.moko.resources.compose)

causes the annotation to not be found in commonMain

[Mike Dawson]

Weird... I'll double check that later and maybe submit an issue to moko-resources if that is where it's at

[Mike Dawson]

The logical question that would follow is: why would moko-resources commonMain compile OK?

[Mike Dawson]

If the preview annotation should be accessible only on JVM...

[Mike Dawson]

Thanks again for checking it, very much appreciated

[Alexander Maryanovsky]

Weird, adding

implementation("dev.icerock.moko:resources:0.23.0")
                implementation("dev.icerock.moko:resources-compose:0.23.0")

to a simple project doesn’t cause the Preview annotation to be available in commonMain

[Alexander Maryanovsky]

Maybe moko-resources-plugin does some magic to cause that

[Mike Dawson]

But the moko-resources-plugin is not applied on the lib-ui-compose module

[Mike Dawson]

although... the moko-resources-plugin is applied to a dependency of lib-ui-compose...

[Mike Dawson]

might be this on core (dependency of lib-ui-compose) :

sourceSets {

    commonMain {
        dependencies {
            api libs.moko.resources

[Mike Dawson]

Though changing api to implementation doesn't seem to fix it