Add preview support to Gradle plugin

gradle-plugins/build.gradle.kts

@@ -48,28 +48,36 @@ subprojects {
     }
 
     afterEvaluate {
-        mavenPublicationConfig?.let { mavenPublicationConfig ->
+        val publicationConfig = mavenPublicationConfig
-            configurePublication(mavenPublicationConfig)
+        val gradlePluginConfig = gradlePluginConfig
 
-            gradlePluginConfig?.let { gradlePluginConfig ->
+        if (publicationConfig != null) {
-                configureGradlePlugin(mavenPublicationConfig, gradlePluginConfig)
+            if (gradlePluginConfig != null) {
+                // pluginMaven is a default publication created by java-gradle-plugin
+                // https://github.com/gradle/gradle/issues/10384
+                configureMavenPublication("pluginMaven", publicationConfig)
+                configureGradlePlugin(publicationConfig, gradlePluginConfig)
+            } else {
+                configureMavenPublication("maven", publicationConfig) {
+                    from(components["java"])
+                }
             }
         }
     }
 }
 
-fun Project.configurePublication(
+fun Project.configureMavenPublication(
-    publicationConfig: MavenPublicationConfigExtension
+    publicationName: String,
+    config: MavenPublicationConfigExtension,
+    customize: MavenPublication.() -> Unit = {}
 ) {
     // maven publication for plugin
     configureIfExists<PublishingExtension> {
-        // pluginMaven is a default publication created by java-gradle-plugin
+        publications.create<MavenPublication>(publicationName) {
-        // https://github.com/gradle/gradle/issues/10384
+            artifactId = config.artifactId
-        publications.create<MavenPublication>("pluginMaven") {
-            artifactId = publicationConfig.artifactId
             pom {
-                name.set(publicationConfig.displayName)
+                name.set(config.displayName)
-                description.set(publicationConfig.description)
+                description.set(config.description)
                 url.set(BuildProperties.website)
                 licenses {
                     license {
@@ -78,6 +86,8 @@ fun Project.configurePublication(
                     }
                 }
             }
+
+            customize()
         }
     }
 }

gradle-plugins/compose-preview-runtime/build.gradle.kts

@@ -0,0 +1,14 @@
+plugins {
+    kotlin("jvm")
+    id("maven-publish")
+}
+
+mavenPublicationConfig {
+    displayName = "Compose Desktop Preview Runtime"
+    description = "Runtime helpers for Compose Desktop Preview"
+    artifactId = "compose-preview-runtime-desktop"
+}
+
+dependencies {
+    compileOnly("org.jetbrains.kotlin:kotlin-stdlib")
+}

gradle-plugins/compose-preview-runtime/src/main/kotlin/org/jetbrains/compose/desktop/preview/runtime/ComposePreviewRunner.kt

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2020-2021 JetBrains s.r.o. and respective authors and developers.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE.txt file.
+ */
+
+package org.jetbrains.compose.desktop.preview.runtime
+
+import kotlin.reflect.KProperty1
+
+class ComposePreviewRunner {
+    companion object {
+        private const val PREVIEW_ANNOTATION_FQ_NAME = "androidx.compose.ui.tooling.desktop.preview.Preview"
+
+        @JvmStatic
+        fun main(args: Array<String>) {
+            val classLoader = ComposePreviewRunner::class.java.classLoader
+
+            val previewFqName = args[0]
+            val previewClassFqName = previewFqName.substringBeforeLast(".")
+            val previewMethodName = previewFqName.substringAfterLast(".")
+            val previewClass = classLoader.loadClass(previewClassFqName)
+            val previewMethod = previewClass.methods.find { it.name == previewMethodName }
+                ?: error("Could not find method '$previewMethodName' in class '${previewClass.canonicalName}'")
+
+            val content = previewMethod.invoke(previewClass)
+            val previewAnnotation = previewMethod.annotations.find { it.annotationClass.qualifiedName == PREVIEW_ANNOTATION_FQ_NAME }
+                ?: error("Could not find '$PREVIEW_ANNOTATION_FQ_NAME' annotation on '$previewClassFqName#$previewMethodName'")
+            val environmentKClassProperty = previewAnnotation.annotationClass.members.find { it is KProperty1<*, *> && it.name == "environment" }
+                as KProperty1<Any, Class<*>>
+            val environmentClass = environmentKClassProperty.get(previewAnnotation)
+            val previewEnvironment = environmentClass
+                .getDeclaredConstructor()
+                .newInstance()
+            val showMethod = previewEnvironment.javaClass
+                .methods.find { it.name == "show" }
+                ?: error("Could not find 'show' in class '${environmentClass.canonicalName}'")
+            showMethod.invoke(previewEnvironment, content)
+        }
+    }
+}

gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/ComposePlugin.kt

@@ -15,6 +15,7 @@ import org.gradle.api.plugins.ExtensionAware
 import org.jetbrains.compose.desktop.DesktopExtension
 import org.jetbrains.compose.desktop.application.internal.configureApplicationImpl
 import org.jetbrains.compose.desktop.application.internal.currentTarget
+import org.jetbrains.compose.desktop.preview.internal.initializePreview
 import org.jetbrains.kotlin.gradle.plugin.KotlinDependencyHandler
 import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 
@@ -35,6 +36,8 @@ class ComposePlugin : Plugin<Project> {
             }
         }
 
+        project.initializePreview()
+
         project.pluginManager.apply(ComposeCompilerKotlinSupportPlugin::class.java)
 
         project.afterEvaluate {

gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/desktop/application/internal/configureApplication.kt

@@ -17,6 +17,8 @@ import org.jetbrains.compose.desktop.application.dsl.Application
 import org.jetbrains.compose.desktop.application.dsl.TargetFormat
 import org.jetbrains.compose.desktop.application.internal.validation.validatePackageVersions
 import org.jetbrains.compose.desktop.application.tasks.*
+import org.jetbrains.compose.desktop.preview.internal.configureRunPreviewTask
+import org.jetbrains.compose.desktop.preview.tasks.AbstractRunComposePreviewTask
 import org.jetbrains.kotlin.gradle.dsl.KotlinMultiplatformExtension
 import org.jetbrains.kotlin.gradle.plugin.KotlinPlatformType
 import java.io.File
@@ -155,6 +157,10 @@ internal fun Project.configurePackagingTasks(apps: Collection<Application>) {
         val run = project.tasks.composeTask<JavaExec>(taskName("run", app)) {
             configureRunTask(app)
         }
+
+        val runPreview = project.tasks.composeTask<AbstractRunComposePreviewTask>("runComposeDesktopPreview") {
+            configureRunPreviewTask(app)
+        }
     }
 }
 
@@ -327,7 +333,7 @@ private fun File.isZipOrJar() =
     name.endsWith(".jar", ignoreCase = true)
         || name.endsWith(".zip", ignoreCase = true)
 
-private fun Application.javaHomeOrDefault(): String =
+internal fun Application.javaHomeOrDefault(): String =
     javaHome ?: System.getProperty("java.home")
 
 private inline fun <reified T : Task> TaskContainer.composeTask(

gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/desktop/preview/internal/configurePreview.kt

@@ -0,0 +1,26 @@
+package org.jetbrains.compose.desktop.preview.internal
+
+import org.gradle.api.Project
+import org.jetbrains.compose.composeVersion
+import org.jetbrains.compose.desktop.application.dsl.Application
+import org.jetbrains.compose.desktop.application.internal.javaHomeOrDefault
+import org.jetbrains.compose.desktop.application.internal.provider
+import org.jetbrains.compose.desktop.preview.tasks.AbstractRunComposePreviewTask
+
+internal const val PREVIEW_RUNTIME_CLASSPATH_CONFIGURATION = "composeDesktopPreviewRuntimeClasspath"
+private val COMPOSE_PREVIEW_RUNTIME_DEPENDENCY = "org.jetbrains.compose:compose-preview-runtime-desktop:$composeVersion"
+
+fun Project.initializePreview() {
+    configurations.create(PREVIEW_RUNTIME_CLASSPATH_CONFIGURATION).defaultDependencies { deps ->
+        deps.add(dependencies.create(COMPOSE_PREVIEW_RUNTIME_DEPENDENCY))
+    }
+}
+
+internal fun AbstractRunComposePreviewTask.configureRunPreviewTask(app: Application) {
+    app._configurationSource?.let { configSource ->
+        dependsOn(configSource.jarTaskName)
+        classpath = configSource.runtimeClasspath(project)
+        javaHome.set(provider { app.javaHomeOrDefault() })
+        jvmArgs.set(provider { app.jvmArgs })
+    }
+}

gradle-plugins/compose/src/main/kotlin/org/jetbrains/compose/desktop/preview/tasks/AbstractRunComposePreviewTask.kt

@@ -0,0 +1,39 @@
+package org.jetbrains.compose.desktop.preview.tasks
+
+import org.gradle.api.file.FileCollection
+import org.gradle.api.provider.ListProperty
+import org.gradle.api.provider.Property
+import org.gradle.api.tasks.*
+import org.jetbrains.compose.desktop.application.internal.javaExecutable
+import org.jetbrains.compose.desktop.application.internal.notNullProperty
+import org.jetbrains.compose.desktop.preview.internal.PREVIEW_RUNTIME_CLASSPATH_CONFIGURATION
+import org.jetbrains.compose.desktop.tasks.AbstractComposeDesktopTask
+
+abstract class AbstractRunComposePreviewTask : AbstractComposeDesktopTask() {
+    @get:InputFiles
+    internal lateinit var classpath: FileCollection
+
+    @get:InputFiles
+    internal val previewRuntimeClasspath: FileCollection
+        get() = project.configurations.getByName(PREVIEW_RUNTIME_CLASSPATH_CONFIGURATION)
+
+    @get:Internal
+    internal val javaHome: Property<String> = objects.notNullProperty<String>().apply {
+        set(providers.systemProperty("java.home"))
+    }
+
+    @get:Input
+    @get:Optional
+    internal val jvmArgs: ListProperty<String> = objects.listProperty(String::class.java)
+
+    @TaskAction
+    fun run() {
+        val target = project.findProperty("compose.desktop.preview.target") as String
+        execOperations.javaexec { javaExec ->
+            javaExec.executable = javaExecutable(javaHome.get())
+            javaExec.main = "org.jetbrains.compose.desktop.preview.runtime.ComposePreviewRunner"
+            javaExec.classpath = previewRuntimeClasspath + classpath
+            javaExec.args = listOf(target)
+        }
+    }
+}

gradle-plugins/settings.gradle.kts

@@ -6,3 +6,4 @@ pluginManagement {
 }
 
 include(":compose")
+include(":compose-preview-runtime")