flutter_smartface #

A new Flutter FFI plugin project.

Getting Started #

This project is a starting point for a Flutter FFI plugin, a specialized package that includes native code directly invoked with Dart FFI.

Project structure #

This template uses the following structure:

• src: Contains the native source code, and a CmakeFile.txt file for building that source code into a dynamic library.

• lib: Contains the Dart code that defines the API of the plugin, and which calls into the native code using dart:ffi.

• platform folders (android, ios, windows, etc.): Contains the build files for building and bundling the native code library with the platform application.

Building and bundling native code #

The pubspec.yaml specifies FFI plugins as follows:

  plugin:
    platforms:
      some_platform:
        ffiPlugin: true

This configuration invokes the native build for the various target platforms and bundles the binaries in Flutter applications using these FFI plugins.

This can be combined with dartPluginClass, such as when FFI is used for the implementation of one platform in a federated plugin:

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

A plugin can have both FFI and method channels:

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

The native build systems that are invoked by FFI (and method channel) plugins are:

• For Android: Gradle, which invokes the Android NDK for native builds.
  • See the documentation in android/build.gradle.
• For iOS and MacOS: Xcode, via CocoaPods.
  • See the documentation in ios/flutter_smartface.podspec.
  • See the documentation in macos/flutter_smartface.podspec.
• For Linux and Windows: CMake.
  • See the documentation in linux/CMakeLists.txt.
  • See the documentation in windows/CMakeLists.txt.

Binding to native code #

To use the native code, bindings in Dart are needed. To avoid writing these by hand, they are generated from the header file (wrapper/flutter_smartface.h) by package:ffigen. Regenerate the bindings by running flutter pub run ffigen --config ffigen.yaml.

Invoking native code #

Very short-running native functions can be directly invoked from any isolate. For example, see sum in lib/flutter_smartface.dart.

Longer-running functions should be invoked on a helper isolate to avoid dropping frames in Flutter applications. For example, see sumAsync in lib/flutter_smartface.dart.

Flutter help #

For help getting started with Flutter, view our online documentation, which offers tutorials, samples, guidance on mobile development, and a full API reference.

Building native libraries #

cd ./src
cmake .
make

brew install libomp libsqlite3

Flutter Smartface Library #

This library provides the core functionality of the Flutter Smartface application. It is designed to be built for both Android and macOS platforms.

Prerequisites #

• Make sure you have CMake installed. The minimum required version is 3.10.

Build Instructions #

1. Configure the build. The build process is platform-dependent.

   macOS #

   For macOS, you need to specify the architecture (x86_64 or arm64) when running CMake.

   For x86_64:

   cmake -DCMAKE_OSX_ARCHITECTURES=x86_64 ..
   

   For arm64:

   cmake -DCMAKE_OSX_ARCHITECTURES=arm64 ..
   

   Android #

   For Android, no special configuration flags are necessary:

   cmake .
   

2. Build the project:

   cmake --build .
   

The build process will generate a shared library (.so for Android and .dylib for macOS) which is used in the Flutter Smartface application.