flutter create --platforms=android,ios,macos,windows,linux --template=plugin_ffi native_add

name: native_add
description: A new Flutter FFI plugin project.
version: 0.0.1
homepage:  # Add

environment:
  sdk: '>=3.0.5 <4.0.0'
  flutter: ">=3.3.0"

dependencies:
  flutter:
    sdk: flutter
  plugin_platform_interface: ^2.0.2

dev_dependencies:
  ffi: ^2.0.1       # Add
  ffigen: ^6.1.2    # Add
  flutter_test:
    sdk: flutter
  flutter_lints: ^2.0.0

flutter:
  # This section identifies this Flutter project as a plugin project.
  # The 'pluginClass' specifies the class (in Java, Kotlin, Swift, Objective-C, etc.)
  # which should be registered in the plugin registry. This is required for
  # using method channels.
  # The Android 'package' specifies package in which the registered class is.
  # This is required for using method channels on Android.
  # The 'ffiPlugin' specifies that native code should be built and bundled.
  # This is required for using `dart:ffi`.
  # All these are used by the tooling to maintain consistency when
  # adding or updating assets for this project.
  #
  # Please refer to README.md for a detailed explanation.
  plugin: # Add
    platforms:
      android:
        ffiPlugin: true
      ios:
        ffiPlugin: true
      linux:
        ffiPlugin: true
      macos:
        ffiPlugin: true
      windows:
        ffiPlugin: true

<?xml version="1.0" encoding="UTF-8"?>
<module type="JAVA_MODULE" version="4">
  <component name="NewModuleRootManager" inherit-compiler-output="true">
    <exclude-output />
    <content url="file://$MODULE_DIR$">
      <sourceFolder url="file://$MODULE_DIR$/lib" isTestSource="false" />
      <excludeFolder url="file://$MODULE_DIR$/.dart_tool" />
      <excludeFolder url="file://$MODULE_DIR$/.idea" />
      <excludeFolder url="file://$MODULE_DIR$/build" />
      <excludeFolder url="file://$MODULE_DIR$/example/build" />
    </content>
    <orderEntry type="sourceFolder" forTests="false" />
    <orderEntry type="library" name="Dart Packages" level="project" />
    <orderEntry type="library" name="Dart SDK" level="project" />
    <orderEntry type="library" name="Flutter Plugins" level="project" />
  </component>
</module>

# Run with `flutter pub run ffigen --config ffigen.yaml`.
name: NativeAddBindings
description: |
  Bindings for `src/native_add.h`.

  Regenerate bindings with `flutter pub run ffigen --config ffigen.yaml`.
output: 'lib/native_add_bindings_generated.dart'
headers:
  entry-points:
    - 'src/native_add.h'
  include-directives:
    - 'src/native_add.h'
preamble: |
  // ignore_for_file: always_specify_types
  // ignore_for_file: camel_case_types
  // ignore_for_file: non_constant_identifier_names
comments:
  style: any
  length: full

# The Flutter tooling requires that developers have CMake 3.10 or later
# installed. You should not increase this version, as doing so will cause
# the plugin to fail to compile for some customers of the plugin.
cmake_minimum_required(VERSION 3.10)

project(native_add_library VERSION 0.0.1 LANGUAGES C)

add_library(native_add SHARED
  "native_add.c"
)

set_target_properties(native_add PROPERTIES
  PUBLIC_HEADER native_add.h
  OUTPUT_NAME "native_add"
)

target_compile_definitions(native_add PUBLIC DART_SHARED_LIB)

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

#if _WIN32
#include <windows.h>
#else
#include <pthread.h>
#include <unistd.h>
#endif

#if _WIN32
#define FFI_PLUGIN_EXPORT __declspec(dllexport)
#else
#define FFI_PLUGIN_EXPORT
#endif

// A very short-lived native function.
//
// For very short-lived functions, it is fine to call them on the main isolate.
// They will block the Dart execution while running the native function, so
// only do this for native functions which are guaranteed to be short-lived.
FFI_PLUGIN_EXPORT intptr_t sum(intptr_t a, intptr_t b);

// A longer lived native function, which occupies the thread calling it.
//
// Do not call these kind of native functions in the main isolate. They will
// block Dart execution. This will cause dropped frames in Flutter applications.
// Instead, call these native functions on a separate isolate.
FFI_PLUGIN_EXPORT intptr_t sum_long_running(intptr_t a, intptr_t b);

#include "native_add.h"

// A very short-lived native function.
//
// For very short-lived functions, it is fine to call them on the main isolate.
// They will block the Dart execution while running the native function, so
// only do this for native functions which are guaranteed to be short-lived.
FFI_PLUGIN_EXPORT intptr_t sum(intptr_t a, intptr_t b) { return a + b; }

// A longer-lived native function, which occupies the thread calling it.
//
// Do not call these kind of native functions in the main isolate. They will
// block Dart execution. This will cause dropped frames in Flutter applications.
// Instead, call these native functions on a separate isolate.
FFI_PLUGIN_EXPORT intptr_t sum_long_running(intptr_t a, intptr_t b) {
  // Simulate work.
#if _WIN32
  Sleep(5000);
#else
  usleep(5000 * 1000);
#endif
  return a + b;
}

// ignore_for_file: always_specify_types
// ignore_for_file: camel_case_types
// ignore_for_file: non_constant_identifier_names

// AUTO GENERATED FILE, DO NOT EDIT.
//
// Generated by `package:ffigen`.
import 'dart:ffi' as ffi;

/// Bindings for `src/native_add.h`.
///
/// Regenerate bindings with `flutter pub run ffigen --config ffigen.yaml`.
///
class NativeAddBindings {
  /// Holds the symbol lookup function.
  final ffi.Pointer<T> Function<T extends ffi.NativeType>(String symbolName)
      _lookup;

  /// The symbols are looked up in [dynamicLibrary].
  NativeAddBindings(ffi.DynamicLibrary dynamicLibrary)
      : _lookup = dynamicLibrary.lookup;

  /// The symbols are looked up with [lookup].
  NativeAddBindings.fromLookup(
      ffi.Pointer<T> Function<T extends ffi.NativeType>(String symbolName)
          lookup)
      : _lookup = lookup;

  /// A very short-lived native function.
  ///
  /// For very short-lived functions, it is fine to call them on the main isolate.
  /// They will block the Dart execution while running the native function, so
  /// only do this for native functions which are guaranteed to be short-lived.
  int sum(
    int a,
    int b,
  ) {
    return _sum(
      a,
      b,
    );
  }

  late final _sumPtr =
      _lookup<ffi.NativeFunction<ffi.IntPtr Function(ffi.IntPtr, ffi.IntPtr)>>(
          'sum');
  late final _sum = _sumPtr.asFunction<int Function(int, int)>();

  /// A longer lived native function, which occupies the thread calling it.
  ///
  /// Do not call these kind of native functions in the main isolate. They will
  /// block Dart execution. This will cause dropped frames in Flutter applications.
  /// Instead, call these native functions on a separate isolate.
  int sum_long_running(
    int a,
    int b,
  ) {
    return _sum_long_running(
      a,
      b,
    );
  }

  late final _sum_long_runningPtr =
      _lookup<ffi.NativeFunction<ffi.IntPtr Function(ffi.IntPtr, ffi.IntPtr)>>(
          'sum_long_running');
  late final _sum_long_running =
      _sum_long_runningPtr.asFunction<int Function(int, int)>();
}

import 'dart:async';
import 'dart:ffi';
import 'dart:io';
import 'dart:isolate';

import 'native_add_bindings_generated.dart';

/// A very short-lived native function.
///
/// For very short-lived functions, it is fine to call them on the main isolate.
/// They will block the Dart execution while running the native function, so
/// only do this for native functions which are guaranteed to be short-lived.
int sum(int a, int b) => _bindings.sum(a, b);

/// A longer lived native function, which occupies the thread calling it.
///
/// Do not call these kind of native functions in the main isolate. They will
/// block Dart execution. This will cause dropped frames in Flutter applications.
/// Instead, call these native functions on a separate isolate.
///
/// Modify this to suit your own use case. Example use cases:
///
/// 1. Reuse a single isolate for various different kinds of requests.
/// 2. Use multiple helper isolates for parallel execution.
Future<int> sumAsync(int a, int b) async {
  final SendPort helperIsolateSendPort = await _helperIsolateSendPort;
  final int requestId = _nextSumRequestId++;
  final _SumRequest request = _SumRequest(requestId, a, b);
  final Completer<int> completer = Completer<int>();
  _sumRequests[requestId] = completer;
  helperIsolateSendPort.send(request);
  return completer.future;
}

const String _libName = 'native_add';

/// The dynamic library in which the symbols for [NativeAddBindings] can be found.
final DynamicLibrary _dylib = () {
  if (Platform.isMacOS || Platform.isIOS) {
    return DynamicLibrary.open('$_libName.framework/$_libName');
  }
  if (Platform.isAndroid || Platform.isLinux) {
    return DynamicLibrary.open('lib$_libName.so');
  }
  if (Platform.isWindows) {
    return DynamicLibrary.open('$_libName.dll');
  }
  throw UnsupportedError('Unknown platform: ${Platform.operatingSystem}');
}();

/// The bindings to the native functions in [_dylib].
final NativeAddBindings _bindings = NativeAddBindings(_dylib);


/// A request to compute `sum`.
///
/// Typically sent from one isolate to another.
class _SumRequest {
  final int id;
  final int a;
  final int b;

  const _SumRequest(this.id, this.a, this.b);
}

/// A response with the result of `sum`.
///
/// Typically sent from one isolate to another.
class _SumResponse {
  final int id;
  final int result;

  const _SumResponse(this.id, this.result);
}

/// Counter to identify [_SumRequest]s and [_SumResponse]s.
int _nextSumRequestId = 0;

/// Mapping from [_SumRequest] `id`s to the completers corresponding to the correct future of the pending request.
final Map<int, Completer<int>> _sumRequests = <int, Completer<int>>{};

/// The SendPort belonging to the helper isolate.
Future<SendPort> _helperIsolateSendPort = () async {
  // The helper isolate is going to send us back a SendPort, which we want to
  // wait for.
  final Completer<SendPort> completer = Completer<SendPort>();

  // Receive port on the main isolate to receive messages from the helper.
  // We receive two types of messages:
  // 1. A port to send messages on.
  // 2. Responses to requests we sent.
  final ReceivePort receivePort = ReceivePort()
    ..listen((dynamic data) {
      if (data is SendPort) {
        // The helper isolate sent us the port on which we can sent it requests.
        completer.complete(data);
        return;
      }
      if (data is _SumResponse) {
        // The helper isolate sent us a response to a request we sent.
        final Completer<int> completer = _sumRequests[data.id]!;
        _sumRequests.remove(data.id);
        completer.complete(data.result);
        return;
      }
      throw UnsupportedError('Unsupported message type: ${data.runtimeType}');
    });

  // Start the helper isolate.
  await Isolate.spawn((SendPort sendPort) async {
    final ReceivePort helperReceivePort = ReceivePort()
      ..listen((dynamic data) {
        // On the helper isolate listen to requests and respond to them.
        if (data is _SumRequest) {
          final int result = _bindings.sum_long_running(data.a, data.b);
          final _SumResponse response = _SumResponse(data.id, result);
          sendPort.send(response);
          return;
        }
        throw UnsupportedError('Unsupported message type: ${data.runtimeType}');
      });

    // Send the port to the main isolate on which we can receive requests.
    sendPort.send(helperReceivePort.sendPort);
  }, receivePort.sendPort);

  // Wait until the helper isolate has sent us back the SendPort on which we
  // can start sending requests.
  return completer.future;
}();

rootProject.name = 'native_add'

sdk.dir=/Users/rhys/Library/Android/sdk
flutter.sdk=/Users/rhys/Documents/software/flutter_macos_3.10.5-stable

<?xml version="1.0" encoding="UTF-8"?>
<module type="JAVA_MODULE" version="4">
  <component name="FacetManager">
    <facet type="android" name="Android">
      <configuration>
        <option name="ALLOW_USER_CONFIGURATION" value="false" />
        <option name="GEN_FOLDER_RELATIVE_PATH_APT" value="/gen" />
        <option name="GEN_FOLDER_RELATIVE_PATH_AIDL" value="/gen" />
        <option name="MANIFEST_FILE_RELATIVE_PATH" value="/src/main/AndroidManifest.xml" />
        <option name="RES_FOLDER_RELATIVE_PATH" value="/src/main/res" />
        <option name="ASSETS_FOLDER_RELATIVE_PATH" value="/src/main/assets" />
        <option name="LIBS_FOLDER_RELATIVE_PATH" value="/src/main/libs" />
        <option name="PROGUARD_LOGS_FOLDER_RELATIVE_PATH" value="/src/main/proguard_logs" />
      </configuration>
    </facet>
  </component>
  <component name="NewModuleRootManager" inherit-compiler-output="true">
    <exclude-output />
    <content url="file://$MODULE_DIR$">
      <sourceFolder url="file://$MODULE_DIR$/src/main/java" isTestSource="false" />
      <sourceFolder url="file://$MODULE_DIR$/gen" isTestSource="false" generated="true" />
    </content>
    <orderEntry type="jdk" jdkName="Android API 29 Platform" jdkType="Android SDK" />
    <orderEntry type="sourceFolder" forTests="false" />
    <orderEntry type="library" name="Flutter for Android" level="project" />
  </component>
</module>

// The Android Gradle Plugin builds the native code with the Android NDK.

group 'com.example.native_add'
version '1.0'

buildscript {
    repositories {
        google()
        mavenCentral()
    }

    dependencies {
        // The Android Gradle Plugin knows how to build native code with the NDK.
        classpath 'com.android.tools.build:gradle:7.3.0'
    }
}

rootProject.allprojects {
    repositories {
        google()
        mavenCentral()
    }
}

apply plugin: 'com.android.library'

android {
    // Bumping the plugin compileSdkVersion requires all clients of this plugin
    // to bump the version in their app.
    compileSdkVersion 31

    // Bumping the plugin ndkVersion requires all clients of this plugin to bump
    // the version in their app and to download a newer version of the NDK.
    ndkVersion "23.1.7779620"

    // Invoke the shared CMake build with the Android Gradle Plugin.
    externalNativeBuild {
        cmake {
            path "../src/CMakeLists.txt"

            // The default CMake version for the Android Gradle Plugin is 3.10.2.
            // https://developer.android.com/studio/projects/install-ndk#vanilla_cmake
            //
            // The Flutter tooling requires that developers have CMake 3.10 or later
            // installed. You should not increase this version, as doing so will cause
            // the plugin to fail to compile for some customers of the plugin.
            // version "3.10.2"
        }
    }

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

    defaultConfig {
        minSdkVersion 16
    }
}

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
  package="com.example.native_add">
</manifest>

#
# To learn more about a Podspec see http://guides.cocoapods.org/syntax/podspec.html.
# Run `pod lib lint native_add.podspec` to validate before publishing.
#
Pod::Spec.new do |s|
  s.name             = 'native_add'
  s.version          = '0.0.1'
  s.summary          = 'A new Flutter FFI plugin project.'
  s.description      = <<-DESC
A new Flutter FFI plugin project.
                       DESC
  s.homepage         = 'http://example.com'
  s.license          = { :file => '../LICENSE' }
  s.author           = { 'Your Company' => 'email@example.com' }

  # This will ensure the source files in Classes/ are included in the native
  # builds of apps using this FFI plugin. Podspec does not support relative
  # paths, so Classes contains a forwarder C file that relatively imports
  # `../src/*` so that the C sources can be shared among all target platforms.
  s.source           = { :path => '.' }
  s.source_files = 'Classes/**/*'
  s.dependency 'Flutter'
  s.platform = :ios, '11.0'

  # Flutter.framework does not contain a i386 slice.
  s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES', 'EXCLUDED_ARCHS[sdk=iphonesimulator*]' => 'i386' }
  s.swift_version = '5.0'
end

// Relative import to be able to reuse the C sources.
// See the comment in ../{projectName}}.podspec for more information.
#include "../../src/native_add.c"

#
# To learn more about a Podspec see http://guides.cocoapods.org/syntax/podspec.html.
# Run `pod lib lint native_add.podspec` to validate before publishing.
#
Pod::Spec.new do |s|
  s.name             = 'native_add'
  s.version          = '0.0.1'
  s.summary          = 'A new Flutter FFI plugin project.'
  s.description      = <<-DESC
A new Flutter FFI plugin project.
                       DESC
  s.homepage         = 'http://example.com'
  s.license          = { :file => '../LICENSE' }
  s.author           = { 'Your Company' => 'email@example.com' }

  # This will ensure the source files in Classes/ are included in the native
  # builds of apps using this FFI plugin. Podspec does not support relative
  # paths, so Classes contains a forwarder C file that relatively imports
  # `../src/*` so that the C sources can be shared among all target platforms.
  s.source           = { :path => '.' }
  s.source_files     = 'Classes/**/*'
  s.dependency 'FlutterMacOS'

  s.platform = :osx, '10.11'
  s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES' }
  s.swift_version = '5.0'
end

// Relative import to be able to reuse the C sources.
// See the comment in ../{projectName}}.podspec for more information.
#include "../../src/native_add.c"

# The Flutter tooling requires that developers have a version of Visual Studio
# installed that includes CMake 3.14 or later. You should not increase this
# version, as doing so will cause the plugin to fail to compile for some
# customers of the plugin.
cmake_minimum_required(VERSION 3.14)

# Project-level configuration.
set(PROJECT_NAME "native_add")
project(${PROJECT_NAME} LANGUAGES CXX)

# Invoke the build for native code shared with the other target platforms.
# This can be changed to accommodate different builds.
add_subdirectory("${CMAKE_CURRENT_SOURCE_DIR}/../src" "${CMAKE_CURRENT_BINARY_DIR}/shared")

# List of absolute paths to libraries that should be bundled with the plugin.
# This list could contain prebuilt libraries, or libraries created by an
# external build triggered from this build file.
set(native_add_bundled_libraries
  # Defined in ../src/CMakeLists.txt.
  # This can be changed to accommodate different builds.
  $<TARGET_FILE:native_add>
  PARENT_SCOPE
)

# The Flutter tooling requires that developers have CMake 3.10 or later
# installed. You should not increase this version, as doing so will cause
# the plugin to fail to compile for some customers of the plugin.
cmake_minimum_required(VERSION 3.10)

# Project-level configuration.
set(PROJECT_NAME "native_add")
project(${PROJECT_NAME} LANGUAGES CXX)

# Invoke the build for native code shared with the other target platforms.
# This can be changed to accommodate different builds.
add_subdirectory("${CMAKE_CURRENT_SOURCE_DIR}/../src" "${CMAKE_CURRENT_BINARY_DIR}/shared")

# List of absolute paths to libraries that should be bundled with the plugin.
# This list could contain prebuilt libraries, or libraries created by an
# external build triggered from this build file.
set(native_add_bundled_libraries
  # Defined in ../src/CMakeLists.txt.
  # This can be changed to accommodate different builds.
  $<TARGET_FILE:native_add>
  PARENT_SCOPE
)

  plugin:
    platforms:
      some_platform:
        ffiPlugin: true

  plugin:
    implements: some_other_plugin
    platforms:
      some_platform:
        dartPluginClass: SomeClass
        ffiPlugin: true

  plugin:
    platforms:
      some_platform:
        pluginClass: SomeName
        ffiPlugin: true