ffi

Note there are two ffi packages:

Doc for dart:io:

Doc for dart:ffi: https://api.dart.dev/stable/3.4.0/dart-ffi/dart-ffi-library.html

Examples for ffi: https://github.com/dart-lang/samples/tree/main/ffi

types

  • char -> Char

  • double -> Double

  • float -> Float

  • int -> Int

  • int8 -> Int8

  • int16 -> Int16

  • int32 -> Int32

  • int64 -> Int64

  • intptr_t -> IntPtr

  • long -> Long

// void xxx();
typedef HelloWorldFunc = ffi.Void Function();

# create a pluggin
flutter create --template=plugin --platforms=android,ios mybatteryplugin
./code/ffi/a.h
1extern "C" int add(int a, int b);
./code/ffi/a.cc
1#include "a.h"
2int add(int a, int b) { return a + b; }
./code/ffi/hello.dart
 1import 'dart:ffi' as ffi;
 2import 'dart:io' show Platform, Directory;
 3import 'package:path/path.dart' as path;
 4
 5typedef HelloWorldFunc = ffi.Int Function(ffi.Int, ffi.Int);
 6
 7typedef HelloWorld = int Function(int, int);
 8
 9void main() {
10  var libraryPath = path.join(Directory.current.path, 'libfoo.so');
11  if (Platform.isMacOS) {
12    libraryPath = path.join(Directory.current.path, 'libfoo.dylib');
13  }
14  final dylib = ffi.DynamicLibrary.open(libraryPath);
15
16  // Look up the C function 'hello_world'
17  final HelloWorld hello =
18      dylib.lookup<ffi.NativeFunction<HelloWorldFunc>>('add').asFunction();
19  print(hello(2, 3));
20}
./code/ffi/pubspec.yaml
1name: hello_ffi
2
3environment:
4  sdk: ^3.4.0
5
6dependencies:
7  path: ^1.8.0
./code/ffi/run.sh
1#!/usr/bin/env bash
2
3g++ -c -fPIC -o a.o a.cc
4g++ -shared -o libfoo.dylib ./a.o
5ls -lh
6nm libfoo.dylib