Implement GenerateConanToolchainFileTask

Author: ViliusSutkus89

README.md

@@ -2,16 +2,19 @@
 
 ## Why is this needed?
 
-In order to use Conan dependencies in an Android project, `conan install` needs to be executed before CMake tries to find those libraries. This plugin calls `conan install` for all 4 Android's architectures.
+In order to use Conan dependencies in an Android project, `conan install` needs to be executed before CMake tries to find those libraries.
 
 ## How it works
 
-Conan Android Gradle Plugin creates 4 Gradle tasks: `conanInstall-armv7`, `conanInstall-armv8`, `conanInstall-x86`, `conanInstall-x86_64` - one for each architecture, for which `conan install` will be launched.
+Conan Android Gradle Plugin creates 5 Gradle tasks:
 
-`conanInstall` tasks are added as dependencies to module level `preBuild` task and top level `prepareKotlinBuildScriptModel` task, if it's found.
+- Four `conan install` tasks, to install conan dependencies for each architecture: `conanInstall-armv7`, `conanInstall-armv8`, `conanInstall-x86`, `conanInstall-x86_64`.
 
-`preBuild` task is executed before building Android project. `prepareKotlinBuildScriptModel` task is executed when doing Android Studio sync.
+- One additional `GenerateConanToolchainFileTask` task, to generate `build/conan/android_toolchain.cmake`.
 
+Tasks are added as dependencies to module level `preBuild` task and top level `prepareKotlinBuildScriptModel` task, if it is found.
+
+`preBuild` task is executed before building Android project. `prepareKotlinBuildScriptModel` task is Android Studio sync task.
 
 ## How to use
 
@@ -41,10 +44,22 @@ Once the plugin is applied, it needs to be configured. Configuration currently c
 }
 ```
 
-Conan profile can be either a relative path or an absolute path, it could also be a regular conan profile, installed and managed by conan (eg. `default`).
+Conan profile can be either a relative path or an absolute path, it could also be a regular conan profile, installed and managed by conan (e.g. `default`).
 
 Plugin applies `arch` setting when calling `conan install`, thus all architectures can share the same profile, if no differentiation is needed - `{ profile.set("android") }`.
 
+Plugin task generate CMake toolchain file, which needs to be included by CMake:
+
+```groovy
+android {
+    defaultConfig {
+        externalNativeBuild.cmake.arguments(
+            "-DCMAKE_TOOLCHAIN_FILE=build/conan/android_toolchain.cmake"
+        )
+    }
+}
+```
+
 ## Further reading
 
 https://docs.conan.io/2/examples/cross_build/android/android_studio.html

src/main/kotlin/app/opendocument/ConanAndroidGradlePlugin.kt

@@ -29,6 +29,11 @@ class ConanAndroidGradlePlugin: Plugin<Project> {
         val tasks = target.tasks;
         val preBuild = tasks.named("preBuild").get()
         val syncTask = target.parent?.tasks?.named("prepareKotlinBuildScriptModel")?.get()
+
+        val generateToolchainFileTask = tasks.register("generateToolchainFile", GenerateConanToolchainFileTask::class.java)
+        preBuild.dependsOn(generateToolchainFileTask)
+        syncTask?.dependsOn(generateToolchainFileTask)
+
         listOf("armv8", "armv7", "x86", "x86_64").forEach { architecture ->
             val conanInstallTask = tasks.register("conanInstall-$architecture", ConanInstallTask::class.java) { conanInstallTask ->
                 conanInstallTask.arch.set(architecture)

src/main/kotlin/app/opendocument/GenerateConanToolchainFileTask.kt

@@ -0,0 +1,61 @@
+/*
+ * GenerateConanToolchainFileTask.kt
+ *
+ * ConanAndroidGradlePlugin (https://github.com/opendocument-app/ConanAndroidGradlePlugin)
+ *
+ * Copyright (c) 2024 ViliusSutkus89.com OpenDocument.app
+ *
+ * ConanAndroidGradlePlugin is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * ConanAndroidGradlePlugin is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package app.opendocument
+
+import org.gradle.api.DefaultTask
+import org.gradle.api.file.RegularFileProperty
+import org.gradle.api.tasks.OutputFile
+import org.gradle.api.tasks.TaskAction
+
+
+abstract class GenerateConanToolchainFileTask : DefaultTask() {
+    @get:OutputFile
+    abstract val conanToolchainFile: RegularFileProperty
+    init {
+        conanToolchainFile.convention(project.layout.buildDirectory.get().dir("conan").file("android_toolchain.cmake"))
+    }
+
+    @TaskAction
+    fun writeToolchain() {
+        val ANDROID_ABI = "\${ANDROID_ABI}"
+        val CMAKE_CURRENT_LIST_DIR = "\${CMAKE_CURRENT_LIST_DIR}"
+        val CMAKE_BUILD_TYPE = "\${CMAKE_BUILD_TYPE}"
+        conanToolchainFile.get().asFile.writeText("""
+# During multiple stages of CMake configuration, the toolchain file is processed and command-line
+# variables may not be always available. The script exits prematurely if essential variables are absent.
+
+if ( NOT ANDROID_ABI OR NOT CMAKE_BUILD_TYPE )
+  return()
+endif()
+if(${ANDROID_ABI} STREQUAL "x86_64")
+  include("${CMAKE_CURRENT_LIST_DIR}/x86_64/build/${CMAKE_BUILD_TYPE}/generators/conan_toolchain.cmake")
+elseif(${ANDROID_ABI} STREQUAL "x86")
+  include("${CMAKE_CURRENT_LIST_DIR}/x86/build/${CMAKE_BUILD_TYPE}/generators/conan_toolchain.cmake")
+elseif(${ANDROID_ABI} STREQUAL "arm64-v8a")
+  include("${CMAKE_CURRENT_LIST_DIR}/armv8/build/${CMAKE_BUILD_TYPE}/generators/conan_toolchain.cmake")
+elseif(${ANDROID_ABI} STREQUAL "armeabi-v7a")
+  include("${CMAKE_CURRENT_LIST_DIR}/armv7/build/${CMAKE_BUILD_TYPE}/generators/conan_toolchain.cmake")
+else()
+  message(FATAL "Not supported configuration")
+endif()
+        """.trimIndent())
+    }
+}