KMT-879: Make org.jetbrains.compose.ui.tooling.preview.PreviewParameterProvider an actual implementation of androidx.compose.ui.tooling.preview.PreviewParameterProvider on Android

[boiler23]

Fixes https://youtrack.jetbrains.com/issue/CMP-8220

This is required for the preview parameters to be correctly picked up by the preview adapter in IDE, which expects the provider to be a subclass of AndroidX's interface, and fails with the ClassCastException otherwise.

Release Notes

Fixes - Multiple Platforms

• Support Preview parameters for Previews in common source sets in IJ and AS. Note: IDEs also need to implement support on their end. Please check the respective IDE release notes to confirm this is supported.

Example usage:

import androidx.compose.runtime.Composable
import org.jetbrains.compose.ui.tooling.preview.Preview
import org.jetbrains.compose.ui.tooling.preview.PreviewParameter
import org.jetbrains.compose.ui.tooling.preview.PreviewParameterProvider

class MyPreviewParameterProvider : PreviewParameterProvider<String> {
    override val values = sequenceOf("Hello, Compose!", "Hello, World!")
}

/**
 * This function will generate two preview images with different texts.
 */
@Preview
@Composable
fun MyPreview(@PreviewParameter(MyPreviewParameterProvider::class) text: String) {
    Text(text)
}

[igordmn]

Highlights - Android

• It looks not major feature. Maybe even it is a bugfix, as it is available, but doesn't work?
• It is not only for Android, I assume (as it available in common)

So, please change it to "Fixes - Multiple Platforms" or to "Features - Multiple Platforms" if it isn't a bugfix.

org.jetbrains.compose.ui.tooling.preview.PreviewParameterProvider becomes an alias to androidx.compose.ui.tooling.preview.PreviewParameterProvider on Android.

This describes the change from implementation details perspective, but it should describe the change from user perspective. What is changed for them? org.jetbrains.compose.ui.tooling.preview.PreviewParameterProvider now works in IntelliJ IDEs?

Could you also add a code snippet to the release notes on how to use it?

[boiler23]

Updated the release notes, please take a look if that works better now.

[igordmn]

Thanks, I rewrote it more, please check

[igordmn]

Doesn't this mean, that this will crash:

class SampleUserProvider: PreviewParameterProvider<User> {
    override val values = sequenceOf(User("Jens",31),User("Jim",44))
}

If users don't include it explicitly?

If so, we have to fix it. The common preview ideally should require including only it

[boiler23]

This will crash regardless. Rendering previews in Android requires ui-tooling-preview from AndroidX to be on the classpath. However, I agree that changing it to implementation might require the user to have fewer dependencies. On the other hand, what would happen if there is a conflict between the user project's version of the ui-tooling-preview and this one? I assume a compileOnly dependency here might be a more reliable approach from this perspective.

[boiler23]

Changed to implementation, as we discussed in DMs.

[igordmn]

It seems the implementation doesn't work for the expect way if there is no Android preview in the classpath:

.

Let's change it to api:

api(libs.androidx.ui.tooling.preview.android)

It adds another issue for the common preview - it exposes 2 API for previews in androidMain (2 Preview annotations and 2 PreviewParameter classes). But current users already see 2 APIs as there is no way to enable Preview other than including debugImplementation(compose.uiTooling)

If anything goes wrong, we can revert it.

[igordmn]

@MatkovIvan, as it is new "API", please review it as well

[igordmn]

Thanks for the PR!

[igordmn]

LGTM after the change implementation -> api