IMPORTANT NOTICE

While this package continues to work, and was even migrated to null safety, there is a new, official tool to generate dart ffi bindings: ffigen

Overview

This library helps developers to generate dart:ffi bindings. You can contribute at github.com/dart-interop/ffi_tool.

The advantages over handwritten dart:ffi code are:

Less boilerplate
- You don't have to define multiple types for each C function.
- You can require the generated code to use cupertino_ffi reference counting methods (arcPush, arcPop, arcReturn).
Possibly better readability
- You can use the original identifiers (such as *size_t instead of Pointer<IntPtr>).
- You can define aliases, e.g. const len_t = 'int32';.
- You can configure how a shared library is loaded at runtime.

Getting started

1.Add dependency

The version of this package hosted on pub is outdated, use the newest version from github! In 'pubspec.yaml':

dev_dependencies:
  ffi_tool:
    git:
      url: git://github.com/dart-interop/ffi_tool.git
      ref: v0.4.0

Run pub get.

2.Write a script

Create 'tool/generate_example.dart'.

Example

import 'package:ffi_tool/c.dart';
import 'dart:io';

void main() {
  // Generates source code and runs 'dartfmt'
  generateFile(File('generated.dart'), library);
}

final library = Library.platformAware(
  // Configure, how the dynamic library should be loaded depending on the platform
  dynamicLibraryConfig: DynamicLibraryConfig(
      windows: DynamicLibraryPlatformConfig.open('path/to/library.dll'),
      android: DynamicLibraryPlatformConfig.open('path/to/library.so'),
      iOS: DynamicLibraryPlatformConfig.process()),

  // Optional library preamble
  preamble: '// Licensed under MIT license\r\n// AUTOMATICALLY GENERATED. DO NOT EDIT.',
  
  // Optional imports
  importedUris: {
    ImportedUri('package:example/library.dart'),
  },

  /// List of generated functions, structs, and global variables
  elements: <Element>[
    // A definition for a function in C
    Func(
      name: 'Example',
      documentation: 'Takes parameters and does stuff.',
      parameterTypes: ['int32', 'float32', '*void'],
      returnType: 'void',
    ),

    // A definition for a struct in C
    // structs must at lease have one field, for
    // structs without fields use Opaque
    Struct(
      name: 'ExampleStruct',
      fields: [
        StructField(
          name: 'length',
          type: 'size_t',
        ),
      ],
    ),

    // Opaque structs are structs without fields
    Opaque(
      name: 'ExampleOpaqueStruct'
    ),

    // A definition for a global variable in C
    Global(
      name: 'ExampleGlobal',
      type: 'Int32',
    ),
  ],
);

3.Run the script

With Dart SDK:

pub run tool/generate_example.dart

With Flutter SDK:

flutter pub run tool/generate_example.dart

4.About Null safty

Since version 0.4.0 the code generated by this package and this package itself are null safe. To achive this, functions and globals needed to be encapsulated in a container class. This on the other hand causes the newly generated code to have an other API than older versions of this package produced.