Add FFI and JNI support to Swift and Kotlin

.github/dependabot.yml

@@ -50,6 +50,7 @@ updates:
       - /packages/path_provider/path_provider/example/android/app
       - /packages/path_provider/path_provider_android/example/android/app
       - /packages/pigeon/example/app/android/app
+      - /packages/pigeon/example/native_interop_app/android/app
       - /packages/pigeon/platform_tests/test_plugin/example/android/app
       - /packages/pigeon/platform_tests/alternate_language_test_plugin/example/android/app
       - /packages/quick_actions/quick_actions_android/example/android/app

analysis_options.yaml

@@ -23,6 +23,8 @@ analyzer:
     # Ignore generated files
     - '**/*.pb.dart'
     - '**/*.g.dart'
+    - '**/*.jni.dart'
+    - '**/*.ffi.dart'
     - '**/*.mocks.dart' # Mockito @GenerateMocks
 
 formatter:

packages/pigeon/.gitignore

@@ -11,3 +11,4 @@ local.properties
 gradle-wrapper.jar
 bin/pigeon.dart.dill
 **/subdirectory/does/not/exist/**
+*.g.o

packages/pigeon/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 27.4.0
+
+* [swift] [kotlin] Adds experimental support for FFI and JNI.
+* Exposes missing PigeonOptions and language-specific configurations as command-line arguments.
+
 ## 27.3.0
 
 * Adds support for sharing constants across platforms.

packages/pigeon/README.md

@@ -80,9 +80,42 @@ the threading model for handling HostApi methods can be selected with the
 
 ### Multi-Instance Support
 
-Host and Flutter APIs now support the ability to provide a unique message channel suffix string
+Host and Flutter APIs support the ability to provide a unique message channel suffix string
 to the api to allow for multiple instances to be created and operate in parallel.
 
+### Communication Options: Method Channels vs. Native Interop
+
+Pigeon supports two distinct models for communication between Dart and native code:
+
+1. **Method Channels (Message-Passing)**: The standard Flutter communication model. It serializes data into binary buffers via `StandardMessageCodec` and transmits them asynchronously over platform channels.
+2. **Native Interop (Direct FFI & JNI)\*Experimental\***: A direct, memory-bound function call model utilizing Dart FFI (for Swift/Objective-C on iOS/macOS) and JNI (for Kotlin/Java on Android).
+
+#### Quick Comparison
+
+| Feature | Method Channels | Native Interop |
+| :--- | :--- | :--- |
+| **Communication Mechanism** | Asynchronous message passing over platform channels | Direct memory-bound function calls (Dart FFI / JNI) |
+| **Platform Support** | All supported platforms (Android, iOS, macOS, Windows, Linux) | Android, iOS, and macOS |
+| **Serialization Overhead** | High (serialization and multiple copies) | Low (minimal copying) |
+| **Latency** | Higher (requires message loop scheduling) | Extremely low (direct execution) |
+| **Synchronous Host Calls** | Not supported | Fully supported |
+| **Setup Complexity** | Simple | Complex (requires external tools) |
+| **Code Generation Steps** | Single-step (running Pigeon generates everything) | Multi-step (requires running Pigeon, then running generated config scripts) |
+
+#### When to Choose Which Model
+
+- **Consider Method Channels if**:
+  - Your plugin targets Windows or Linux (Native Interop is not supported on these platforms).
+  - Your plugin primarily passes simple data objects or has low-frequency communication.
+  - You want a simpler setup with no external dependencies or additional command-line tools.
+  - Your data classes contain many nested fields or custom collections where conversion overhead might offset performance gains. There are plans to address this issue in the future.
+- **Consider Native Interop if**:
+  - Your plugin targets only Android, iOS, and/or macOS.
+  - Your plugin handles high-frequency messaging, large typed arrays (e.g., image processing, sensor data streams), or latency-sensitive communication where serialization overhead is a bottleneck.
+  - You need synchronous execution for platform APIs on the host thread.
+
+For detailed information on setup, prerequisites, and instructions on how to use Native Interop, see the [Native Interop Guide](./native_interop_guide.md).
+
 ### Constants
 
 Pigeon supports generating top-level constants in the generated files. Constants can be defined at the top level of the Pigeon file:

packages/pigeon/example/app/README.md

@@ -1,10 +1,10 @@
-# pigeon_example_app
+# Pigeon Method Channel Example Application
 
-This demonstrates using Pigeon for platform communication directly in an
-application, rather than in a plugin.
+This demonstrates using standard Method Channel-based platform communication generated by Pigeon directly in an application, rather than in a plugin.
 
 To update the generated code, run:
 ```sh
 cd ../..
 dart tool/generate.dart
 ```
+

packages/pigeon/example/app/android/app/src/main/kotlin/dev/flutter/pigeon_example_app/NativeInteropExample.kt

@@ -0,0 +1,11 @@
+// Copyright 2013 The Flutter Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package dev.flutter.pigeon_example_app
+
+// #docregion concurrency-style
+suspend fun echoAsync(value: String): String {
+  return value
+}
+// #enddocregion concurrency-style

packages/pigeon/example/app/android/settings.gradle.kts

@@ -21,7 +21,7 @@ pluginManagement {
 plugins {
     id("dev.flutter.flutter-plugin-loader") version "1.0.0"
     id("com.android.application") version "9.1.0" apply false
-    id("org.jetbrains.kotlin.android") version "2.4.0" apply false
+    id("org.jetbrains.kotlin.android") version "2.3.20" apply false
     id("com.google.cloud.artifactregistry.gradle-plugin") version "2.2.1"
 }
 

packages/pigeon/example/app/ios/Runner/EventChannelMessages.g.swift

@@ -55,19 +55,19 @@ enum EventChannelMessagesPigeonInternal {
     case is (Void, Void):
       return true
 
-    case (let lhsArray, let rhsArray) as ([Any?], [Any?]):
+    case (let lhsArray, let rhsArray) as ([Double], [Double]):
       guard lhsArray.count == rhsArray.count else { return false }
       for (index, element) in lhsArray.enumerated() {
-        if !deepEquals(element, rhsArray[index]) {
+        if !doubleEquals(element, rhsArray[index]) {
           return false
         }
       }
       return true
 
-    case (let lhsArray, let rhsArray) as ([Double], [Double]):
+    case (let lhsArray, let rhsArray) as ([Any?], [Any?]):
       guard lhsArray.count == rhsArray.count else { return false }
       for (index, element) in lhsArray.enumerated() {
-        if !doubleEquals(element, rhsArray[index]) {
+        if !deepEquals(element, rhsArray[index]) {
           return false
         }
       }

packages/pigeon/example/app/ios/Runner/Messages.g.swift

@@ -33,7 +33,7 @@ final class PigeonError: Error {
 
   var localizedDescription: String {
     return
-      "PigeonError(code: \(code), message: \(message ?? "<nil>"), details: \(details ?? "<nil>")"
+      "PigeonError(code: \(code), message: \(message ?? "<nil>"), details: \(details ?? "<nil>"))"
   }
 }
 
@@ -110,19 +110,19 @@ enum MessagesPigeonInternal {
     case is (Void, Void):
       return true
 
-    case (let lhsArray, let rhsArray) as ([Any?], [Any?]):
+    case (let lhsArray, let rhsArray) as ([Double], [Double]):
       guard lhsArray.count == rhsArray.count else { return false }
       for (index, element) in lhsArray.enumerated() {
-        if !deepEquals(element, rhsArray[index]) {
+        if !doubleEquals(element, rhsArray[index]) {
           return false
         }
       }
       return true
 
-    case (let lhsArray, let rhsArray) as ([Double], [Double]):
+    case (let lhsArray, let rhsArray) as ([Any?], [Any?]):
       guard lhsArray.count == rhsArray.count else { return false }
       for (index, element) in lhsArray.enumerated() {
-        if !doubleEquals(element, rhsArray[index]) {
+        if !deepEquals(element, rhsArray[index]) {
           return false
         }
       }

packages/pigeon/example/app/ios/Runner/NativeInteropExample.swift

@@ -0,0 +1,17 @@
+// Copyright 2013 The Flutter Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import Foundation
+
+// #docregion callback-style
+func echoAsync(_ value: String, completion: @escaping (Result<String, Error>) -> Void) {
+  completion(.success(value))
+}
+// #enddocregion callback-style
+
+// #docregion concurrency-style
+func echoAsync(_ value: String) async throws -> String {
+  return value
+}
+// #enddocregion concurrency-style

packages/pigeon/example/app/lib/src/messages.g.dart

@@ -210,8 +210,8 @@ class ExampleHostApi {
       pigeonVar_messageChannelSuffix = messageChannelSuffix.isNotEmpty
           ? '.$messageChannelSuffix'
           : '';
-  final BinaryMessenger? pigeonVar_binaryMessenger;
 
+  final BinaryMessenger? pigeonVar_binaryMessenger;
   static const MessageCodec<Object?> pigeonChannelCodec = _PigeonCodec();
 
   final String pigeonVar_messageChannelSuffix;

packages/pigeon/example/app/pubspec.yaml

@@ -26,3 +26,41 @@ dev_dependencies:
 
 flutter:
   uses-material-design: true
+
+dependency_overrides:
+  ffi: 
+    git:
+      url: https://github.com/dart-lang/native/
+      path: pkgs/ffi
+      ref: 27890daeab690209603a979c7fbb54b22a3c878f
+  ffigen: 
+    git:
+      url: https://github.com/dart-lang/native/
+      path: pkgs/ffigen
+      ref: 27890daeab690209603a979c7fbb54b22a3c878f
+  jni: 
+    git:
+      url: https://github.com/dart-lang/native/
+      path: pkgs/jni
+      ref: 27890daeab690209603a979c7fbb54b22a3c878f
+  jnigen: 
+    git:
+      url: https://github.com/dart-lang/native/
+      path: pkgs/jnigen
+      ref: 27890daeab690209603a979c7fbb54b22a3c878f
+  objective_c: 
+    git:
+      url: https://github.com/dart-lang/native/
+      path: pkgs/objective_c
+      ref: 27890daeab690209603a979c7fbb54b22a3c878f
+  swift2objc: 
+    git:
+      url: https://github.com/dart-lang/native/
+      path: pkgs/swift2objc
+      ref: 27890daeab690209603a979c7fbb54b22a3c878f
+  swiftgen: 
+    git:
+      url: https://github.com/dart-lang/native/
+      path: pkgs/swiftgen
+      ref: 27890daeab690209603a979c7fbb54b22a3c878f
+

packages/pigeon/example/native_interop_app/.gitignore

@@ -0,0 +1,46 @@
+# Miscellaneous
+*.class
+*.log
+*.pyc
+*.swp
+.DS_Store
+.atom/
+.build/
+.buildlog/
+.history
+.svn/
+.swiftpm/
+migrate_working_dir/
+
+# IntelliJ related
+*.iml
+*.ipr
+*.iws
+.idea/
+
+# The .vscode folder contains launch configuration and tasks you configure in
+# VS Code which you may wish to be included in version control, so this line
+# is commented out by default.
+#.vscode/
+
+# Flutter/Dart/Pub related
+**/doc/api/
+**/ios/Flutter/.last_build_id
+.dart_tool/
+.flutter-plugins
+.flutter-plugins-dependencies
+.packages
+.pub-cache/
+.pub/
+/build/
+
+# Symbolication related
+app.*.symbols
+
+# Obfuscation related
+app.*.map.json
+
+# Android Studio will place build artifacts here
+/android/app/debug
+/android/app/profile
+/android/app/release

packages/pigeon/example/native_interop_app/.metadata

@@ -0,0 +1,45 @@
+# This file tracks properties of this Flutter project.
+# Used by Flutter tool to assess capabilities and perform upgrades etc.
+#
+# This file should be version controlled.
+
+version:
+  revision: 4d9e56e694b656610ab87fcf2efbcd226e0ed8cf
+  channel: stable
+
+project_type: app
+
+# Tracks metadata for the flutter migrate command
+migration:
+  platforms:
+    - platform: root
+      create_revision: 4d9e56e694b656610ab87fcf2efbcd226e0ed8cf
+      base_revision: 4d9e56e694b656610ab87fcf2efbcd226e0ed8cf
+    - platform: android
+      create_revision: 4d9e56e694b656610ab87fcf2efbcd226e0ed8cf
+      base_revision: 4d9e56e694b656610ab87fcf2efbcd226e0ed8cf
+    - platform: ios
+      create_revision: 4d9e56e694b656610ab87fcf2efbcd226e0ed8cf
+      base_revision: 4d9e56e694b656610ab87fcf2efbcd226e0ed8cf
+    - platform: linux
+      create_revision: 4d9e56e694b656610ab87fcf2efbcd226e0ed8cf
+      base_revision: 4d9e56e694b656610ab87fcf2efbcd226e0ed8cf
+    - platform: macos
+      create_revision: 4d9e56e694b656610ab87fcf2efbcd226e0ed8cf
+      base_revision: 4d9e56e694b656610ab87fcf2efbcd226e0ed8cf
+    - platform: web
+      create_revision: 4d9e56e694b656610ab87fcf2efbcd226e0ed8cf
+      base_revision: 4d9e56e694b656610ab87fcf2efbcd226e0ed8cf
+    - platform: windows
+      create_revision: 4d9e56e694b656610ab87fcf2efbcd226e0ed8cf
+      base_revision: 4d9e56e694b656610ab87fcf2efbcd226e0ed8cf
+
+  # User provided section
+
+  # List of Local paths (relative to this file) that should be
+  # ignored by the migrate tool.
+  #
+  # Files that are not part of the templates will be ignored by default.
+  unmanaged_files:
+    - 'lib/main.dart'
+    - 'ios/Runner.xcodeproj/project.pbxproj'

packages/pigeon/example/native_interop_app/.pluginToolsConfig.yaml

@@ -0,0 +1,4 @@
+buildFlags:
+  _pluginToolsConfigGlobalKey:
+    - "--no-tree-shake-icons"
+    - "--dart-define=buildmode=testing"

packages/pigeon/example/native_interop_app/README.md

@@ -0,0 +1,10 @@
+# Pigeon Native Interop Example Application
+
+This demonstrates using Pigeon's Native Interop feature (direct FFI and JNI function calls) for platform communication directly in an application, rather than in a plugin.
+
+To update the generated code, run:
+```sh
+cd ../..
+dart tool/generate.dart
+```
+

packages/pigeon/example/native_interop_app/android/.gitignore

@@ -0,0 +1,13 @@
+gradle-wrapper.jar
+/.gradle
+/captures/
+/gradlew
+/gradlew.bat
+/local.properties
+GeneratedPluginRegistrant.java
+
+# Remember to never publicly share your keystore.
+# See https://flutter.dev/to/reference-keystore
+key.properties
+**/*.keystore
+**/*.jks

packages/pigeon/example/native_interop_app/android/app/build.gradle.kts

@@ -0,0 +1,39 @@
+plugins {
+    id("com.android.application")
+    id("dev.flutter.flutter-gradle-plugin")
+}
+
+android {
+    namespace = "dev.flutter.pigeon_example_app"
+    compileSdk = flutter.compileSdkVersion
+    ndkVersion = flutter.ndkVersion
+
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_17
+        targetCompatibility = JavaVersion.VERSION_17
+    }
+
+    defaultConfig {
+        applicationId = "dev.flutter.pigeon_example_app"
+        minSdk = flutter.minSdkVersion
+        targetSdk = flutter.targetSdkVersion
+        versionCode = flutter.versionCode
+        versionName = flutter.versionName
+    }
+
+    buildTypes {
+        release {
+            signingConfig = signingConfigs.getByName("debug")
+        }
+    }
+}
+
+kotlin {
+    compilerOptions {
+        jvmTarget = org.jetbrains.kotlin.gradle.dsl.JvmTarget.JVM_17
+    }
+}
+
+flutter {
+    source = "../.."
+}