[gradle] Add a customization for resources directories. (#5016)

With the new API it is possible to customize compose resources
directories. For example:

```kotlin
abstract class GenerateAndroidRes : DefaultTask() {
    @get:Inject
    abstract val layout: ProjectLayout

    @get:OutputDirectory
    val outputDir = layout.buildDirectory.dir("generatedAndroidResources")

    @TaskAction
    fun run() {...}
}
compose.resources {
    customDirectory(
        sourceSetName = "androidMain",
        directoryProvider = tasks.register<GenerateAndroidRes>("generateAndroidRes").map { it.outputDir.get() }
    )
    customDirectory(
        sourceSetName = "desktopMain",
        directoryProvider = provider { layout.projectDirectory.dir("desktopResources") }
    )
}
```

<!-- Optional -->
Fixes #4718
Fixes #4564

## Release Notes
### Features - Resources
- Add a customization for resources directories. Now it is possible to
use e.g downloaded resources.

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

@@ -54,7 +54,7 @@ internal fun Project.configureComposeResourcesGeneration(
         }
 
         //common resources must be converted (XML -> CVR)
-        val preparedResourcesTask = registerPrepareComposeResourcesTask(sourceSet)
+        val preparedResourcesTask = registerPrepareComposeResourcesTask(sourceSet, config)
         val preparedResources = preparedResourcesTask.flatMap { it.outputDir.asFile }
         configureResourceAccessorsGeneration(
             sourceSet,

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

@@ -1,6 +1,7 @@
 package org.jetbrains.compose.resources
 
 import org.gradle.api.Project
+import org.gradle.api.file.Directory
 import org.gradle.api.file.DirectoryProperty
 import org.gradle.api.file.FileSystemOperations
 import org.gradle.api.file.FileTree
@@ -25,11 +26,19 @@ import javax.inject.Inject
 import javax.xml.parsers.DocumentBuilderFactory
 
 internal fun Project.registerPrepareComposeResourcesTask(
-    sourceSet: KotlinSourceSet
+    sourceSet: KotlinSourceSet,
+    config: Provider<ResourcesExtension>
 ): TaskProvider<PrepareComposeResourcesTask> {
-    val resDir = "${sourceSet.name}/$COMPOSE_RESOURCES_DIR"
-    val userComposeResourcesDir = project.projectDir.resolve("src/$resDir")
-    val preparedComposeResourcesDir = layout.buildDirectory.dir("$RES_GEN_DIR/preparedResources/$resDir")
+    val userComposeResourcesDir: Provider<Directory> = config.flatMap { ext ->
+        ext.customResourceDirectories[sourceSet.name] ?: provider {
+            //default path
+            layout.projectDirectory.dir("src/${sourceSet.name}/$COMPOSE_RESOURCES_DIR")
+        }
+    }
+
+    val preparedComposeResourcesDir = layout.buildDirectory.dir(
+        "$RES_GEN_DIR/preparedResources/${sourceSet.name}/$COMPOSE_RESOURCES_DIR"
+    )
 
     val convertXmlValueResources = tasks.register(
         "convertXmlValueResourcesFor${sourceSet.name.uppercaseFirstChar()}",
@@ -61,11 +70,11 @@ internal fun Project.registerPrepareComposeResourcesTask(
 }
 
 internal fun Project.getPreparedComposeResourcesDir(sourceSet: KotlinSourceSet): Provider<File> = tasks
-        .named(
-            getPrepareComposeResourcesTaskName(sourceSet),
-            PrepareComposeResourcesTask::class.java
-        )
-        .flatMap { it.outputDir.asFile }
+    .named(
+        getPrepareComposeResourcesTaskName(sourceSet),
+        PrepareComposeResourcesTask::class.java
+    )
+    .flatMap { it.outputDir.asFile }
 
 private fun getPrepareComposeResourcesTaskName(sourceSet: KotlinSourceSet) =
     "prepareComposeResourcesTaskFor${sourceSet.name.uppercaseFirstChar()}"

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

@@ -1,6 +1,7 @@
 package org.jetbrains.compose.resources
 
 import org.gradle.api.Project
+import org.gradle.api.file.Directory
 import org.gradle.api.provider.Provider
 import java.io.File
 
@@ -36,6 +37,18 @@ abstract class ResourcesExtension {
      * - `never`: Never generate the Res class.
      */
     var generateResClass: ResourceClassGeneration = auto
+
+    internal val customResourceDirectories: MutableMap<String, Provider<Directory>> = mutableMapOf()
+
+    /**
+     * Associates a custom resource directory with a specific source set.
+     *
+     * @param sourceSetName the name of the source set to associate the custom resource directory with
+     * @param directoryProvider the provider that provides the custom directory
+     */
+    fun customDirectory(sourceSetName: String, directoryProvider: Provider<Directory>) {
+        customResourceDirectories[sourceSetName] = directoryProvider
+    }
 }
 
 internal fun Provider<ResourcesExtension>.getResourcePackage(project: Project) = map { config ->

gradle-plugins/compose/src/test/test-projects/misc/commonResources/build.gradle.kts

@@ -62,3 +62,31 @@ android {
         targetCompatibility = JavaVersion.VERSION_11
     }
 }
+
+abstract class GenerateAndroidRes : DefaultTask() {
+    @get:Inject
+    abstract val layout: ProjectLayout
+
+    @get:OutputDirectory
+    val outputDir = layout.buildDirectory.dir("generatedAndroidResources")
+
+    @TaskAction
+    fun run() {
+        val dir = outputDir.get().asFile
+        dir.deleteRecursively()
+        File(dir, "values/strings.xml").apply {
+            parentFile.mkdirs()
+            writeText(
+                """
+                    <resources>
+                        <string name="android_str">Android string</string>
+                    </resources>
+                """.trimIndent()
+            )
+        }
+    }
+}
+compose.resources.customDirectory(
+    sourceSetName = "androidMain",
+    directoryProvider = tasks.register<GenerateAndroidRes>("generateAndroidRes").map { it.outputDir.get() }
+)