Seamless Flutter Native Integration: FFI & Pigeon - Dreamwalker (JaichangPark / 박제창) @FlutterKaigi2024

- Seamless Flutter Native Integration: FFI & Pigeon
- Dreamwalker (Jaichangpark/박제창)
- FlutterKaigi2024
- https://2024.flutterkaigi.jp/session/e97ebf37-5753-43c9-83ea-2be68e7a4363
- https://2024.flutterkaigi.jp/

Transcript

1. Seamless Flutter Native Integration: FFI & Pigeon Dreamwalker (@jaichangpark) 1
2. / Intro Proprietary & Confidential Dreamwalker Park Jai-Chang @jaichangpark @JAICHANGPARK Dreamus Company GDG Golang Korea / Flutter Seoul 2
3. Flutter Build for any screen Flutter is an open source framework for building beautiful, natively compiled, multi-platform applications from a single codebase. / overview 3
4. / overview @source: https://dart.dev/overview 4
6. AI Artificial intelligence 6
7. AI on a smartphone 7
8. AI (On-Device LLM) on a smartphone 8
9. @source: https://docs.flutter.dev/resources/architectural-overview 9
10. @source: https://docs.flutter.dev/resources/architectural-overview 10
11. Platform channels • Method Channel ◦ A named channel for communicating with platform plugins using asynchronous method calls. • Event Channel ◦ A named channel for communicating with platform plugins using event streams. • Codec ◦ A message encoding/decoding mechanism. ▪ MessageCodec ▪ StandardMessageCodec ▪ BinaryCodec ▪ JSONMessageCodec ▪ StringCodec 11 @source: https://docs.flutter.dev/resources/architectural-overview#integrating-with-other-code
12. FlutterActivity package com.dreamwalker.untitled import io.flutter.embedding.android.FlutterActivity class MainActivity: FlutterActivity() 12
13. FlutterActivity package com.dreamwalker.untitled import io.flutter.embedding.android.FlutterActivity class MainActivity: FlutterActivity(){ override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) { super.configureFlutterEngine(flutterEngine) // code ... } } 13
14. FlutterPlugin import io.flutter.embedding.engine.plugins.FlutterPlugin class CustomFlutterPlugin : FlutterPlugin { override fun onAttachedToEngine(binding: FlutterPlugin.FlutterPluginBinding) { // Initialization and method channel setup for the plugin // code.. } override fun onDetachedFromEngine(binding: FlutterPlugin.FlutterPluginBinding) { methodChannel.setMethodCallHandler(null) } } 14
15. FlutterActivity vs FlutterPlugin FlutterActivity FlutterActivity is an Android Activity that displays the Flutter application UI and starts the Flutter engine. You would use FlutterActivity when you want to show Flutter UI within an Android native application. FlutterPlugin FlutterPlugin is an interface for communication between Flutter and the native platform (e.g., Android, iOS). You would implement FlutterPlugin when you want to call native APIs or handle specific events in a Flutter application. 15
16. Platform-Specific Code Design 16
17. / Platform-Specific Code Design • plugin_platform_interface • Pigeon • FFI(Foreign function interface) → C • FFIgen • JNI (Java Native Interface) → Java & Kotlin • JNIgen (Java Native Interface) • and other bridges Interoperability 17 Methods : How to
18. / Platform-Specific Code Design Writing a good Flutter plugin 18 • Think functionality first, then APIs • Avoid platform-specific API methods • Avoid supporting only one platform • Make your plugin easy to navigate and test • Avoid writing static (or global) methods @sourece : https://medium.com/flutter/writing-a-good-flutter-plugin-1a561b986c9c
19. / Platform-Specific Code Design 1. Requirements Definition 2. Identify required features 3. Data type & structure design 4. Platform code development 5. UI code development Design Checklist 19
20. / Platform-Specific Code 20
21. / Platform-Specific Code Design Channel Name Design Type Detail Channel Name Battery Battery Level MethodChannel com.dreamwalker.flutterkaigi2024/battery ${Common}/battery Battery Charging Status EventChannel com.dreamwalker.flutterkaigi2024/charging Sensor Gyroscope EventChannel com.dreamwalker.flutterkaigi2024/sensors/gyroscope ${Common}/sensors/gyroscope Common package or domain com.dreamwalker.flutterkaigi2024 21
22. Common (Flutter, Host(Native)) private val BATT_CHANNEL = "com.dreamwalker.flutterkaigi2024/battery" private val BATT_CHARGING_CHANNEL = "com.dreamwalker.flutterkaigi2024/charging" private val GYROSCOPE_CHANNEL = "com.dreamwalker.flutterkaigi2024/sensors/gyroscope" Host (Native) static const battMethodChannel = MethodChannel('com.dreamwalker.flutterkaigi2024/battery'); static const EventChannel battEventChannel = EventChannel('com.dreamwalker.flutterkaigi2024/charging'); static const EventChannel gyroscopeEventChannel = EventChannel('com.dreamwalker.flutterkaigi2024/sensors/gyroscope); Flutter 22
23. / Platform-Specific Code Design Date Structure & Tpye Design Type Detail Data Type Battery Battery Level INT Sensor Gyroscope X Double Gyroscope Y Double Gyroscope Z Double Gyroscope List<Double> 23
24. / Platform-Specific Code Design 24
25. Host (Native) - Android / Kotlin MethodChannel( flutterEngine.dartExecutor.binaryMessenger, BATT_CHANNEL, ).setMethodCallHandler { call, result -> if (call.method == "getBatteryLevel") { CoroutineScope(Dispatchers.Main).launch { val batteryLevel = getBatteryLevel() if (batteryLevel != -1) { result.success(batteryLevel) } else { result.error("UNAVAILABLE", "Battery level not available.", null) } } } else { result.notImplemented() } } 25
26. Host (Native) - Android / Kotlin MethodChannel( flutterEngine.dartExecutor.binaryMessenger, BATT_CHANNEL, ).setMethodCallHandler { call, result -> if (call.method == "getBatteryLevel") { CoroutineScope(Dispatchers.Main).launch { val batteryLevel = getBatteryLevel() if (batteryLevel != -1) { result.success(batteryLevel) } else { result.error("UNAVAILABLE", "Battery level not available.", null) } } } else { result.notImplemented() } } 26
27. • Configures, bootstraps, and starts executing Dart code. • Once started, a DartExecutor cannot be stopped. The associated Dart code will execute until it completes, or until the FlutterEngine that owns this DartExecutor is destroyed. • Creates a FlutterEngine in this group and run its DartExecutor with a default entrypoint of the "main" function in the "lib/main.dart" file. DartExecutor 27
28. Host (Native) - Android / Kotlin MethodChannel( flutterEngine.dartExecutor.binaryMessenger, BATT_CHANNEL, ).setMethodCallHandler { call, result -> if (call.method == "getBatteryLevel") { CoroutineScope(Dispatchers.Main).launch { val batteryLevel = getBatteryLevel() if (batteryLevel != -1) { result.success(batteryLevel) } else { result.error("UNAVAILABLE", "Battery level not available.", null) } } } else { result.notImplemented() } } 28
29. Host (Native) - Android / Kotlin MethodChannel( flutterEngine.dartExecutor.binaryMessenger, BATT_CHANNEL, ).setMethodCallHandler { call, result -> if (call.method == "getBatteryLevel") { CoroutineScope(Dispatchers.Main).launch { val batteryLevel = getBatteryLevel() if (batteryLevel != -1) { result.success(batteryLevel) } else { result.error("UNAVAILABLE", "Battery level not available.", null) } } } else { result.notImplemented() } } 29
30. Host (Native) - Android / Kotlin MethodChannel( flutterEngine.dartExecutor.binaryMessenger, BATT_CHANNEL, ).setMethodCallHandler { call, result -> if (call.method == "getBatteryLevel") { CoroutineScope(Dispatchers.Main).launch { val batteryLevel = getBatteryLevel() if (batteryLevel != -1) { result.success(batteryLevel) } else { result.error("UNAVAILABLE", "Battery level not available.", null) } } } else { result.notImplemented() } } 30
31. Host (Native) - Android / Kotlin MethodChannel( flutterEngine.dartExecutor.binaryMessenger, BATT_CHANNEL, ).setMethodCallHandler { call, result -> if (call.method == "getBatteryLevel") { CoroutineScope(Dispatchers.Main).launch { val batteryLevel = getBatteryLevel() if (batteryLevel != -1) { result.success(batteryLevel) } else { result.error("UNAVAILABLE", "Battery level not available.", null) } } } else { result.notImplemented() } } 31
32. Host (Native) - Android / Kotlin class SensorPlugin : FlutterPlugin { override fun onAttachedToEngine(binding: FlutterPlugin.FlutterPluginBinding) { val sensorsManager = binding.applicationContext.getSystemService(Context.SENSOR_SERVICE) as SensorManager gyroscopeChannel = EventChannel(binding.binaryMessenger, GYROSCOPE_CHANNEL) gyroscopeChannel.setStreamHandler(object : EventChannel.StreamHandler { override fun onListen(arguments: Any?, events: EventSink?) { } override fun onCancel(arguments: Any?) { } }) } 32
33. Host (Native) - Android / Kotlin class SensorPlugin : FlutterPlugin { override fun onAttachedToEngine(binding: FlutterPlugin.FlutterPluginBinding) { val sensorsManager = binding.applicationContext.getSystemService(Context.SENSOR_SERVICE) as SensorManager gyroscopeChannel = EventChannel(binding.binaryMessenger, GYROSCOPE_CHANNEL) gyroscopeChannel.setStreamHandler(object : EventChannel.StreamHandler { override fun onListen(arguments: Any?, events: EventSink?) { } override fun onCancel(arguments: Any?) { } }) } 33
34. Host (Native) - Android / Kotlin class SensorPlugin : FlutterPlugin { override fun onAttachedToEngine(binding: FlutterPlugin.FlutterPluginBinding) { val sensorsManager = binding.applicationContext.getSystemService(Context.SENSOR_SERVICE) as SensorManager gyroscopeChannel = EventChannel(binding.binaryMessenger, GYROSCOPE_CHANNEL) gyroscopeChannel.setStreamHandler(object : EventChannel.StreamHandler { override fun onListen(arguments: Any?, events: EventSink?) { } override fun onCancel(arguments: Any?) { } }) } 34
35. Host (Native) - Android / Kotlin class SensorPlugin : FlutterPlugin { override fun onAttachedToEngine(binding: FlutterPlugin.FlutterPluginBinding) { val sensorsManager = binding.applicationContext.getSystemService(Context.SENSOR_SERVICE) as SensorManager gyroscopeChannel = EventChannel(binding.binaryMessenger, GYROSCOPE_CHANNEL) gyroscopeChannel.setStreamHandler(object : EventChannel.StreamHandler { override fun onListen(arguments: Any?, events: EventSink?) { } override fun onCancel(arguments: Any?) { } }) } 35
36. Host (Native) - Android / Kotlin class SensorPlugin : FlutterPlugin { override fun onAttachedToEngine(binding: FlutterPlugin.FlutterPluginBinding) { val sensorsManager = binding.applicationContext.getSystemService(Context.SENSOR_SERVICE) as SensorManager gyroscopeChannel = EventChannel(binding.binaryMessenger, GYROSCOPE_CHANNEL) gyroscopeChannel.setStreamHandler(object : EventChannel.StreamHandler { override fun onListen(arguments: Any?, events: EventSink?) { } override fun onCancel(arguments: Any?) { } }) } 36
37. Host (Native) - Android / Kotlin FlutterPlugin private fun sensorEventListener(events: EventChannel.EventSink): SensorEventListener { return object : SensorEventListener { override fun onAccuracyChanged(sensor: Sensor, accuracy: Int) {} override fun onSensorChanged(event: SensorEvent) { val sensorValues = DoubleArray(event.values.size) event.values.forEachIndexed { index, value -> sensorValues[index] = value.toDouble() } events.success(sensorValues) } } } 37
38. Host (Native) - Android / Kotlin FlutterPlugin private fun sensorEventListener(events: EventChannel.EventSink): SensorEventListener { return object : SensorEventListener { override fun onAccuracyChanged(sensor: Sensor, accuracy: Int) {} override fun onSensorChanged(event: SensorEvent) { val sensorValues = DoubleArray(event.values.size) event.values.forEachIndexed { index, value -> sensorValues[index] = value.toDouble() } events.success(sensorValues) } } } 38
39. Host (Native) - Android / Kotlin FlutterPlugin private fun sensorEventListener(events: EventChannel.EventSink): SensorEventListener { return object : SensorEventListener { override fun onAccuracyChanged(sensor: Sensor, accuracy: Int) {} override fun onSensorChanged(event: SensorEvent) { val sensorValues = DoubleArray(event.values.size) event.values.forEachIndexed { index, value -> sensorValues[index] = value.toDouble() } events.success(sensorValues) } } } 39
40. Host (Native) - Android / Kotlin class MainActivity : FlutterActivity() { override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) { super.configureFlutterEngine(flutterEngine) flutterEngine.plugins.add(SensorPlugin()) MethodChannel( flutterEngine.dartExecutor.binaryMessenger, CHANNEL, ).setMethodCallHandler { call, result -> // code .. } } } You can easily add other Flutter plugins 40
41. Flutter : MethodChannel 41 Future<void> getBatteryLevel() async { String batteryLevel; try { final result = await platform.invokeMethod<int>('getBatteryLevel'); batteryLevel = 'Battery level at $result % .'; } on PlatformException catch (e) { batteryLevel = "Failed to get battery level: '${e.message}'."; } setState(() { // code.. }); } method channel
42. Flutter : MethodChannel 42 Future<void> getBatteryLevel() async { String batteryLevel; try { final result = await platform.invokeMethod<int>('getBatteryLevel'); batteryLevel = 'Battery level at $result % .'; } on PlatformException catch (e) { batteryLevel = "Failed to get battery level: '${e.message}'."; } setState(() { // code.. }); } int int?
43. Flutter : MethodChannel 43 Future<void> getBatteryLevel() async { String batteryLevel; try { final result = await platform.invokeMethod('getBatteryLevel'); batteryLevel = 'Battery level at $result % .'; } on PlatformException catch (e) { batteryLevel = "Failed to get battery level: '${e.message}'."; } setState(() { // code.. }); } dynamic
44. Flutter : EventChannel 44 Stream<GyroscopeEvent>? gyroscopeEvents; static const EventChannel gyroscopeEventChannel = EventChannel('com.xxx.xxx/sensors/gyroscope'); gyroscopeEvents ??= gyroscopeEventChannel.receiveBroadcastStream().map((dynamic event) { final list = event.cast<double>(); return GyroscopeEventData( list[0]!, list[1]!, list[2]! ); });
45. Flutter : EventChannel 45 Stream<GyroscopeEvent>? gyroscopeEvents; static const EventChannel gyroscopeEventChannel = EventChannel('com.xxx.xxx/sensors/gyroscope'); gyroscopeEvents ??= gyroscopeEventChannel.receiveBroadcastStream().map((dynamic event) { final list = event.cast<double>(); return GyroscopeEventData( list[0]!, list[1]!, list[2]! ); });
46. / Platform-Specific Code Design Platform-Specific Pattern 01 46
47. / Platform-Specific Code Design Platform-Specific Pattern 02 47
48. / Platform-Specific Code Design Platform-Specific Pattern 03 48
49. / Platform-Specific Code Design Platform-Specific Pattern 04 49
50. / Platform-Specific Code Design Platform-Specific Pattern 05 50 plugin_platform_interface
51. / Platform-Specific Code Design Platform-Specific Pattern 05 51
52. / Platform-Specific Code Design Platform-Specific Pattern 05 52
53. 53 @source: https://pub.dev/packages/plugin_platform_interface
54. type-safe? 54
55. / Pigeon type-safe? 55
56. / Pigeon type-safe? 56 Protocol Buffers & JSON
57. @jaichangpark, shots on iPhone in Shinjuku Pigeon ハト 57
58. Pigeon is a code generator tool to make communication between Flutter and the host platform type-safe, easier, and faster. • Pigeon removes the necessity to manage strings across multiple platforms and languages. • It also improves efficiency over common method channel patterns. • Most importantly though, it removes the need to write custom platform channel code, since pigeon generates it for you. Code generator tool Pigeon 58
59. Currently pigeon supports generating: • Kotlin and Java code for Android • Swift and Objective-C code for iOS and macOS • C++ code for Windows • GObject code for Linux Supported Platforms Pigeon 59
60. 60 @Source • https://pub.dev/packages/pigeon • https://github.com/flutter/packages/tree/ main/packages/pigeon • Access Date: 2024.10
61. flutter packages Use Cases 61 • shared_preferences • url_launcher • image_picker • camera • in_app_purchase • video_player • and so on / Pigeon
62. Flutterfire Use Cases 62 @source: https://github.com/firebase/flutterfire/pull/8921 from 2022.06~ / Pigeon
63. Pigeon 63 Code generator tool
64. Mission 64 / Pigeon
65. 1. Installing Add pigeon as a dev_dependency 65
66. 66 enum AlgorithmType { sha1, sha2, md5, aesCbc, aesEcb, } class MessageData { MessageData({required this.type, required this.data}); AlgorithmType type; String? data; } 2. Define Messages
67. 67 @HostApi() abstract class CustomHostApi { String generateHash(MessageData message); String encrypt(MessageData message); @async String decrypt(MessageData message); } 3. Define APIs
68. @HostApi • @HostApi() being for procedures that are defined on the host platform. • When you want to call the host platform from Flutter. @FlutterApi • @FlutterApi() for procedures that are defined in Dart. • When you want to call a Flutter app from the host platform. 68 / Pigeon
69. 69 4. Code Generation dart run pigeon \ --input pigeons/messaging.dart \ --dart_out lib/pigeon.dart \ --objc_header_out ios/Runner/pigeon.h \ --objc_source_out ios/Runner/pigeon.m \ --java_out ./android/app/src/main/java/com/example/xxxx/Pigeon.java \ --java_package "com.example.xxxx"
70. 70 @ConfigurePigeon(PigeonOptions( dartOut: 'lib/src/messages.g.dart', dartOptions: DartOptions(), cppOptions: CppOptions(namespace: 'flutter_pigeon'), cppHeaderOut: 'windows/runner/messages.g.h', cppSourceOut: 'windows/runner/messages.g.cpp', kotlinOut: 'android/app/src/main/kotlin/com/dreamwalker/flutter_pigeon/Messages.g.kt', kotlinOptions: KotlinOptions(), javaOut: 'android/app/src/main/java/io/flutter/plugins/Messages.java', javaOptions: JavaOptions(), swiftOut: 'ios/Runner/Messages.g.swift', swiftOptions: SwiftOptions(), objcHeaderOut: 'macos/Runner/messages.g.h', objcSourceOut: 'macos/Runner/messages.g.m', objcOptions: ObjcOptions(prefix: 'PGN'), copyrightHeader: 'pigeons/copyright.txt', dartPackageName: 'flutter_pigeon', )) 4. Code Generation message.dart
71. 71 @ConfigurePigeon(PigeonOptions( dartOut: 'lib/src/messages.g.dart', dartOptions: DartOptions(), cppOptions: CppOptions(namespace: 'flutter_pigeon'), cppHeaderOut: 'windows/runner/messages.g.h', cppSourceOut: 'windows/runner/messages.g.cpp', kotlinOut: 'android/app/src/main/kotlin/com/dreamwalker/flutter_pigeon/Messages.g.kt', kotlinOptions: KotlinOptions(), javaOut: 'android/app/src/main/java/io/flutter/plugins/Messages.java', javaOptions: JavaOptions(), swiftOut: 'ios/Runner/Messages.g.swift', swiftOptions: SwiftOptions(), objcHeaderOut: 'macos/Runner/messages.g.h', objcSourceOut: 'macos/Runner/messages.g.m', objcOptions: ObjcOptions(prefix: 'PGN'), copyrightHeader: 'pigeons/copyright.txt', dartPackageName: 'flutter_pigeon', ))
72. 72 @ConfigurePigeon(PigeonOptions( dartOut: 'lib/src/messages.g.dart', dartOptions: DartOptions(), cppOptions: CppOptions(namespace: 'flutter_pigeon'), cppHeaderOut: 'windows/runner/messages.g.h', cppSourceOut: 'windows/runner/messages.g.cpp', kotlinOut: 'android/app/src/main/kotlin/com/dreamwalker/flutter_pigeon/Messages.g.kt', kotlinOptions: KotlinOptions(), javaOut: 'android/app/src/main/java/io/flutter/plugins/Messages.java', javaOptions: JavaOptions(), swiftOut: 'ios/Runner/Messages.g.swift', swiftOptions: SwiftOptions(), objcHeaderOut: 'macos/Runner/messages.g.h', objcSourceOut: 'macos/Runner/messages.g.m', objcOptions: ObjcOptions(prefix: 'PGN'), copyrightHeader: 'pigeons/copyright.txt', dartPackageName: 'flutter_pigeon', )) com.dreamwalker.flutter_pigeon
73. 73 @ConfigurePigeon(PigeonOptions( dartOut: 'lib/src/messages.g.dart', dartOptions: DartOptions(), cppOptions: CppOptions(namespace: 'flutter_pigeon'), cppHeaderOut: 'windows/runner/messages.g.h', cppSourceOut: 'windows/runner/messages.g.cpp', kotlinOut: 'android/app/src/main/kotlin/com/dreamwalker/flutter_pigeon/Messages.g.kt', kotlinOptions: KotlinOptions(), javaOut: 'android/app/src/main/java/io/flutter/plugins/Messages.java', javaOptions: JavaOptions(), swiftOut: 'ios/Runner/Messages.g.swift', swiftOptions: SwiftOptions(), objcHeaderOut: 'macos/Runner/messages.g.h', objcSourceOut: 'macos/Runner/messages.g.m', objcOptions: ObjcOptions(prefix: 'PGN'), copyrightHeader: 'pigeons/copyright.txt', dartPackageName: 'flutter_pigeon', ))
74. dart run pigeon --input ./pigeons/message.dart 74
75. 75 / Pigeon Folder Structure
76. 76 final CustomHostApi _api = CustomHostApi(); Future<String> genSha2(String input) async { try { final v = await _api.generateHash( MessageData(type: AlgorithmType.sha2, data: input), ); } catch (e) { return "$e"; } } 5. Flutter Side
77. 77 private class CustomApiImpl : CustomHostApi { override fun generateHash(message: MessageData): String { //code... } override fun encrypt(message: MessageData): String { TODO("Not yet implemented") } override fun decrypt(message: MessageData, callback: (Result<String>) -> Unit) { TODO("Not yet implemented") } } 5. Android (Kotlin) CustomHostApi: Generated Code by pigeon
78. 78 private class CustomApiImpl : CustomHostApi { override fun generateHash(message: MessageData): String { //code... } override fun encrypt(message: MessageData): String { TODO("Not yet implemented") } override fun decrypt(message: MessageData, callback: (Result<String>) -> Unit) { TODO("Not yet implemented") } } 5. Android (Kotlin) @async
79. 79 class MainActivity : FlutterActivity() { override fun configureFlutterEngine(flutterEngine: FlutterEngine) { super.configureFlutterEngine(flutterEngine) val api = CustomApiImplementation() CustomHostApi.setUp(flutterEngine.dartExecutor.binaryMessenger, api) } } 5. Android (Kotlin)
80. 80 / Pigeon
81. 81 / Pigeon Oops!
82. 82 private class CustomApiImpl: CustomHostApi { func generateHash(message: MessageData) throws -> String { } func encrypt(message: MessageData) throws -> String { } func decrypt(message: MessageData, completion: @escaping (Result<String, Error>) -> Void) { } } 5. iOS (swift) Using CryptoKit
83. 83 @main @objc class AppDelegate: FlutterAppDelegate { override func application( _ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]? ) -> Bool { GeneratedPluginRegistrant.register(with: self) let controller = window?.rootViewController as! FlutterViewController let api = CustomApiImpl() CustomHostApiSetup.setUp(binaryMessenger: controller.binaryMessenger, api: api) return super.application(application, didFinishLaunchingWithOptions: launchOptions) } } 5. iOS (swift)
84. 84 / Pigeon
85. Foreign Function Interface ffi 85
86. 86 / Foreign Function Interface • FFI stands for foreign function interface. • Dart mobile, command-line, and server apps running on the Dart Native platform can use the dart:ffi library to call native C APIs, and to read, write, allocate, and deallocate native memory. • ffigen only supports parsing C headers, not C++ headers.
87. 87 / Foreign Function Interface • Databases • Graphic & Image processing • OS (Native) API → Windows, Linux etc. • C-based compiled libs
88. 88 / Foreign Function Interface
89. 89 fibonacci #ifndef FIBONACCI_H #define FIBONACCI_H int fibonacci(int n); #endif // FIBONACCI_H fibonacci.h @Source https://en.wikipedia.org/wiki/Fibonacci_sequence By Romain - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=114415511
90. 90 fibonacci int fibonacci(int n) { if (n <= 0) { return 0; } else if (n == 1) { return 1; } else { return fibonacci(n - 1) + fibonacci(n - 2); } } fibonacci.c
91. 91 fibonacci cmake_minimum_required(VERSION 3.10) project(FibonacciLibrary) include_directories(include) add_library(fibonacci SHARED fibonacci.c) add_executable(fibonacci_app fibonacci.c) target_link_libraries(fibonacci_app fibonacci) CMakeList.txt
92. 92 fibonacci main.dart var libraryPath = path.join(Directory.current.path, 'lib/fibonacci', 'libfibonacci.dylib'); final dylib = ffi.DynamicLibrary.open(libraryPath);
93. 93 ! Key Point 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}'); }();
94. 94 fibonacci main.dart final fibo = dylib .lookup<ffi.NativeFunction<ffi.Int Function(ffi.Int)>>('fibonacci') .asFunction<int Function(int)>(); lib(Native) Function Client (Dart) Function function name Data Type of parameters Return Data Type
95. 95 / Foreign Function Interface • Rust Programming Language • Go Programming Language
96. 96 / Foreign Function Interface
97. 97 #[no_mangle] pub extern "C" fn fibonacci(n: i32) -> i32 { if n <= 0 { return 0; } else if n == 1 { return 1; } else { let mut a = 0; let mut b = 1; let mut c = 0; for _ in 2..=n { c = a + b; a = b; b = c; } return c; } cargo build --release --target=[target] Android cargo ndk -t [target] -o ./jniLibs build --release • arm64-v8a • armeabi-v7a • x86 • x86_64
98. 98 / Foreign Function Interface fibonacci Rust based Android Rust logo © Rust Foundation, used under CC-BY 4.0.
99. 99 _dylib = () { if (Platform.isAndroid || Platform.isLinux) { return ffi.DynamicLibrary.open('librust_lib.so'); } throw UnsupportedError('Unknown platform: ${Platform.operatingSystem}'); }();
100. 100 typedef FibonacciFunc = ffi.Int Function(ffi.Int); typedef Fibonacci = int Function(int); final Fibonacci fibonacci = _dylib .lookup<ffi.NativeFunction<FibonacciFunc>>('fibonacci') .asFunction(); int n = 10; int result = fibonacci(n);
101. 101 / Foreign Function Interface Generator for FFI bindings, using LibClang to parse C, Objective-C, and Swift files. ffigen
102. ffigen Add ffigen as a dev_dependency 102
103. 103 ffigen name: NativeLibrary description: misc output: 'generated_bindings.dart' headers: entry-points: - 'lib/fibonacci/fibonacci.h' include-directives: - 'lib/fibonacci/fibonacci.h' ffigen.yaml Class Name
104. 104 ffigen dart run ffigen --config ffigen.yaml
105. 105 ffigen NativeLibrary nativeLibrary = NativeLibrary(dylib); print(nativeLibrary.fibonacci(10)); Generated a Class Using ffigen
106. 106 / Summary • Platform-Specific Code ◦ Method Channel, Event Channel ◦ plugin_platform_interface ◦ ffi, ffigen, jnigen, pigeon, etc. • Pigeon ◦ Code generator tool ◦ type-safe • FFI ◦ FFI stands for foreign function interface. ◦ Lookup, asFunction ◦ ffigen
107. Thank You ご清聴ありがとうございました Flutter Seoul GDG Golang Korea Dreamwalker (@jaichangpark) 107