feature: Minimal Gradle project to run a Jetbrains Compose for Desktop

Related issues (and comment):
* JetBrains/compose-multiplatform#2309
* JetBrains/compose-multiplatform#2108 (comment)
* gradle/gradle#15383

.gitattributes

@@ -0,0 +1,9 @@
+#
+# https://help.github.com/articles/dealing-with-line-endings/
+#
+# Linux start script should use lf
+/gradlew        text eol=lf
+
+# These are Windows script files and should use crlf
+*.bat           text eol=crlf
+

.gitignore

@@ -0,0 +1,5 @@
+# Ignore Gradle project-specific cache directory
+.gradle
+
+# Ignore Gradle build output directory
+build

buildSrc/build.gradle.kts

@@ -0,0 +1,9 @@
+plugins {
+    `kotlin-dsl`
+}
+
+dependencies {
+    implementation(libs.gradleplugin.kotlin.jvm)
+    implementation(libs.gradleplugin.jetbrains.compose)
+    implementation(files(libs.javaClass.superclass.protectionDomain.codeSource.location))
+}

buildSrc/settings.gradle.kts

@@ -0,0 +1,10 @@
+dependencyResolutionManagement {
+    repositories {
+        gradlePluginPortal()
+    }
+    versionCatalogs {
+        create("libs") {
+            from(files("../gradle/libs.versions.toml"))
+        }
+    }
+}

buildSrc/src/main/kotlin/ProjectExt.kt

@@ -0,0 +1,28 @@
+import org.gradle.kotlin.dsl.the
+
+/**
+ * Workaround for accessing the version catalog from the buildSrc project.
+ *
+ * Allows to use libs directly in the kotlin conventions scripts.
+ *
+ * Still needed to set in `buildSrc/settings.gradle.kts`
+ * ```kotlin
+ * dependencyResolutionManagement {
+ *   versionCatalogs {
+ *     create("libs") {
+ *       from(files("../gradle/libs.versions.toml"))
+ *     }
+ *   }
+ * }
+ * ```
+ *
+ * And te following dependency in `buildSrc/build.gradle.kts`
+ * ```kotlin
+ * dependencies {
+ *   implementation(files(libs.javaClass.superclass.protectionDomain.codeSource.location))
+ * }
+ * ```
+ *
+ * @see https://github.com/gradle/gradle/issues/15383
+ */
+val org.gradle.api.Project.libs get() = the<org.gradle.accessors.dm.LibrariesForLibs>()

buildSrc/src/main/kotlin/constants.kt

@@ -0,0 +1 @@
+const val JVM_LANGUAGE_LEVEL = 18

buildSrc/src/main/kotlin/java-common-conventions.gradle.kts

@@ -0,0 +1,39 @@
+plugins {
+    java
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    constraints {
+        // Dependency versions as constraints
+    }
+}
+
+testing {
+    suites {
+        @Suppress("UNUSED_VARIABLE")
+        val test by getting(JvmTestSuite::class) {
+            useJUnitJupiter(libs.versions.jupiter.get())
+        }
+    }
+}
+
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(JVM_LANGUAGE_LEVEL))
+    }
+}
+
+tasks.withType<JavaCompile> {
+    options.encoding = "UTF-8"
+    options.release.set(JVM_LANGUAGE_LEVEL)
+    options.compilerArgs = listOf("--enable-preview")
+}
+
+tasks.withType<JavaExec> {
+    jvmArgs = listOf("--enable-preview")
+    javaLauncher.set(javaToolchains.launcherFor(java.toolchain))
+}

buildSrc/src/main/kotlin/java-library-conventions.gradle.kts

@@ -0,0 +1,4 @@
+plugins {
+    id("java-common-conventions")
+    `java-library`
+}

buildSrc/src/main/kotlin/jetpack-compose-desktop-application-conventions.gradle.kts

@@ -0,0 +1,33 @@
+plugins {
+    id("java-common-conventions")
+    kotlin("jvm")
+    id("org.jetbrains.compose")
+}
+
+repositories {
+    mavenCentral()
+    maven("https://maven.pkg.jetbrains.space/public/p/compose/dev")
+    maven("https://androidx.dev/storage/compose-compiler/repository/")
+}
+
+dependencies {
+    implementation(compose.desktop.currentOs)
+}
+
+tasks.withType<org.jetbrains.kotlin.gradle.tasks.KotlinCompile>() {
+    kotlinOptions.jvmTarget = "$JVM_LANGUAGE_LEVEL"
+    kotlinOptions.freeCompilerArgs += listOf(
+        "-Xjvm-default=all",
+        "-P",
+        "plugin:androidx.compose.compiler.plugins.kotlin:suppressKotlinVersionCompatibilityCheck=true", // compat with kotlin 1.7.20-RC
+    )
+}
+
+// Substitute the compiler to make Compose work with Kotlin 1.7.20-RC
+configurations.all {
+    resolutionStrategy.dependencySubstitution {
+        substitute(module("org.jetbrains.compose.compiler:compiler")).apply {
+            using(module(libs.compose.compiler.get().toString()))
+        }
+    }
+}

gctk-app/build.gradle.kts

@@ -0,0 +1,13 @@
+plugins {
+    id("jetpack-compose-desktop-application-conventions")
+}
+
+dependencies {
+    implementation(project(":gctk-lib"))
+}
+
+compose.desktop {
+    application {
+        mainClass = "io.github.bric3.gctk.app.MainKt"
+    }
+}

gctk-app/src/main/kotlin/io/github/bric3/gctk/app/main.kt

@@ -0,0 +1,27 @@
+package io.github.bric3.gctk.app
+
+import androidx.compose.material.Button
+import androidx.compose.material.Text
+import androidx.compose.material.MaterialTheme
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.ui.window.Window
+import androidx.compose.ui.window.application
+import kotlin.system.exitProcess
+
+
+fun main() = application {
+    Window(
+        title = "GCTK",
+        onCloseRequest = {
+            exitProcess(0)
+        }
+    ) {
+        val counter = remember { mutableStateOf(0) }
+        MaterialTheme {
+            Button(onClick = { counter.value++ }) {
+                Text("I've been clicked ${counter.value} times")
+            }
+        }
+    }
+}

gctk-lib/build.gradle.kts

@@ -0,0 +1,3 @@
+plugins {
+    id("java-library-conventions")
+}

gradle/libs.versions.toml

@@ -0,0 +1,14 @@
+[versions]
+jupiter = "5.9.0"
+kotlin = "1.7.20-RC"
+jetbrains-compose = "1.2.0-alpha01-dev774"
+
+
+[libraries]
+# Compose Compiler Version for Kotlin 1.7.20-RC acquired from https://androidx.dev/storage/compose-compiler/repository/
+compose-compiler = { module = "androidx.compose.compiler:compiler", version = "1.4.0-dev-k1.7.20-RC-a143c065804" }
+
+gradleplugin-kotlin-jvm = { module = "org.jetbrains.kotlin:kotlin-gradle-plugin", version.ref = "kotlin" }
+gradleplugin-jetbrains-compose = { module = "org.jetbrains.compose:compose-gradle-plugin", version.ref = "jetbrains-compose" }
+
+[bundles]

gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,5 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.5.1-bin.zip
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists