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Natives declaration

To declare a new native project, add create() in natives block:

build.gradle.kts
natives {
    create("mylib")
}

Without additional configuration this means:

  • Search for CMake project mylib in <projectDir>/natives/mylib
  • Generate Kotlin bindings in package natives.mylib with name mylib

You can run ./gradlew :cmakeInit[Name] to generate a minimal CMake project. This task is optional but recommended for getting started.

In Depth

There are two types of project configurations:

  • For a multiplatform project if org.jetbrains.kotlin.multiplatform is applied
  • For a specific platform if org.jetbrains.kotlin.jvm or org.jetbrains.kotlin.js are applied.

In a multiplatform project, you can also add a platform-specific native project (e.g. for JS only) as follows: 

natives {
    create("myJsLib", SinglePlatform::class) {
        targetSourceSet = "jsMain"
        // ...
    }
}

Project structure

Each native project has a minimum set of files required to work. These are:

  • CMakeLists.txt

    Configuration file for native compilation. Must contain project with the same name, as specified in their Gradle configuration.

  • include/api.h

    Header file that contains generated API functions and structures. It is regenerated each time the Gradle project is synced. Native project must implement this header.

  • api.ndl

    File that declares how the API looks. Uses NDL syntax.

Properties

classPath

Kotlin classpath where API will be generated.
Default: natives.[name]

projectDir

Directory with CMake project.
Default: <projectDir>/natives/[name]

headerFile

Generated header file.
Default: <projectDir>/natives/[name]/include/api.h

ndlFile

NDL file.
Default: <projectDir>/natives/[name]/api.ndl

buildType

CMake build type.
Possible values:
  • DEBUG
  • REL_WITH_DEB_INFO
  • RELEASE
  • MIN_SIZE_REL

Default: RELEASE

cmakeArgs

CMake command-line arguments.
Default: []

Multiplatform project properties

Specified in:

create("mylib") { 
    // ...
}

commonSourceSet

SourceSet that will have 'expect' api
Default: commonMain

stubSourceSets

SourceSets with stub (empty implementation)
Default: null

targetSourceSets

SourceSets with implementation
Default: all default source sets

Single-target project properties

Specified in:

create("mylib", SinglePlatform::class) { 
    // ...
}

targetSourceSet

SourceSet with implementation
Default: jvmMain