feat: new generated flutter plugin

Author: mcmah309

frb_codegen/assets/integration_template/plugin/example/integration_test/simple_test.dart

@@ -1,6 +1,6 @@
+import 'package:integration_test/integration_test.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:REPLACE_ME_DART_PACKAGE_NAME/REPLACE_ME_DART_PACKAGE_NAME.dart';
-import 'package:integration_test/integration_test.dart';
 
 void main() {
   IntegrationTestWidgetsFlutterBinding.ensureInitialized();

frb_codegen/assets/integration_template/plugin/pubspec.yaml

@@ -15,9 +15,9 @@ pub fn flutter_create(name: &str, org: &Option<String>, template: Template) -> a
         Template::App => args.extend(["--template", "app"]),
         Template::Plugin => args.extend([
             "--template",
-            "plugin",
+            "plugin_ffi",
             "--platforms",
-            "android,ios,linux,macos,windows,web",
+            "android,ios,linux,macos,windows",
         ]),
     }
     info!(

frb_codegen/src/library/commands/flutter.rs

@@ -57,9 +57,8 @@ pub fn create(config: CreateConfig) -> anyhow::Result<()> {
 fn remove_unnecessary_app_files(dart_root: &Path) -> anyhow::Result<()> {
     // frb-coverage:ignore-end
     let lib_dir = dart_root.join("lib");
-    let test_dir = dart_root.join("test");
-
     remove_files_in_dir(&lib_dir)?;
+    let test_dir = dart_root.join("test");
     remove_files_in_dir(&test_dir)?;
 
     Ok(())
@@ -70,23 +69,39 @@ fn remove_unnecessary_app_files(dart_root: &Path) -> anyhow::Result<()> {
 fn remove_unnecessary_plugin_files(dart_root: &Path) -> anyhow::Result<()> {
     // frb-coverage:ignore-end
     let lib_dir = dart_root.join("lib");
-    let test_dir = dart_root.join("test");
-    let example_lib_dir = dart_root.join("example").join("lib");
-    let example_integration_test_dir = dart_root.join("example").join("integration_test");
-    let android_dir = dart_root.join("android");
-    let ios_dir = dart_root.join("ios");
-    let linux_dir = dart_root.join("linux");
-    let macos_dir = dart_root.join("macos");
-    let windows_dir = dart_root.join("windows");
-
     remove_files_in_dir(&lib_dir)?;
-    remove_files_in_dir(&test_dir)?;
+    let src_dir = dart_root.join("src");
+    remove_files_in_dir(&src_dir)?;
+    let ffi_gen_file = dart_root.join("ffigen.yaml");
+    fs::remove_file(ffi_gen_file)?;
+    fs::remove_dir(src_dir)?;
+    let example_lib_dir = dart_root.join("example").join("lib");
     remove_files_in_dir(&example_lib_dir)?;
-    remove_files_in_dir(&example_integration_test_dir)?;
+
+    let android_dir = dart_root.join("android");
+    let android_src_dir = &android_dir.join("src");
+    let android_src_main_dir = &android_src_dir.join("main");
+    remove_files_in_dir(&android_src_main_dir)?;
+    fs::remove_dir(&android_src_main_dir)?;
+    fs::remove_dir(&android_src_dir)?;
     remove_files_in_dir(&android_dir)?;
+
+    let ios_dir = dart_root.join("ios");
+    let ios_classes_dir = &ios_dir.join("Classes");
+    remove_files_in_dir(&ios_classes_dir)?;
+    fs::remove_dir(&ios_classes_dir)?;
     remove_files_in_dir(&ios_dir)?;
+
+    let linux_dir = dart_root.join("linux");
     remove_files_in_dir(&linux_dir)?;
+
+    let macos_dir = dart_root.join("macos");
+    let macos_classes_dir = &macos_dir.join("Classes");
+    remove_files_in_dir(&macos_classes_dir)?;
+    fs::remove_dir(&macos_classes_dir)?;
     remove_files_in_dir(&macos_dir)?;
+
+    let windows_dir = dart_root.join("windows");
     remove_files_in_dir(&windows_dir)?;
 
     Ok(())
@@ -99,7 +114,7 @@ fn remove_files_in_dir(dir: &Path) -> anyhow::Result<()> {
         if path.is_file() {
             fs::remove_file(&path)?;
         } else if path.is_dir() {
-            bail!("An unexpected directory was encountered: {:?}", path);
+            bail!("Directory '{:?}' was expected to contain only files but directory '{:?}' was encountered", dir.display(), path.display());
         }
     }
     Ok(())

frb_codegen/src/library/integration/creator.rs

@@ -60,17 +60,18 @@ pub fn integrate(config: IntegrateConfig) -> Result<()> {
     }
 
     info!("Modify file permissions");
-    modify_permissions(&dart_root)?;
+    modify_permissions(&dart_root, &config.template)?;
 
     info!("Add pub dependencies");
     pub_add_dependencies(
         config.enable_integration_test,
         config.enable_local_dependency,
         &rust_crate_name,
+        &config.template,
     )?;
 
     info!("Setup cargokit dependencies");
-    setup_cargokit_dependencies(&dart_root)?;
+    setup_cargokit_dependencies(&dart_root, &config.template)?;
 
     info!("Format Dart code");
     format_dart(&[dart_root.clone()], &dart_root, 80, &[])?;
@@ -133,9 +134,12 @@ fn compute_replacements(
     replacements
 }
 
-fn modify_permissions(dart_root: &Path) -> Result<()> {
+fn modify_permissions(dart_root: &Path, template: &Template) -> Result<()> {
     #[allow(unused_variables)] // unused when in windows
-    let dir_cargokit = dart_root.join("rust_builder").join("cargokit");
+    let dir_cargokit = match template {
+        Template::App => dart_root.join("rust_builder").join("cargokit"),
+        Template::Plugin => dart_root.join("cargokit"),
+    };
 
     #[cfg(unix)]
     {
@@ -147,11 +151,14 @@ fn modify_permissions(dart_root: &Path) -> Result<()> {
     Ok(())
 }
 
-fn setup_cargokit_dependencies(dart_root: &Path) -> Result<()> {
-    let build_tool_dir = dart_root
-        .join("rust_builder")
-        .join("cargokit")
-        .join("build_tool");
+fn setup_cargokit_dependencies(dart_root: &Path, template: &Template) -> Result<()> {
+    let build_tool_dir = match template {
+        Template::App => dart_root
+            .join("rust_builder")
+            .join("cargokit")
+            .join("build_tool"),
+        Template::Plugin => dart_root.join("cargokit").join("build_tool"),
+    };
 
     flutter_pub_get(&build_tool_dir)
 }
@@ -292,12 +299,15 @@ fn pub_add_dependencies(
     enable_integration_test: bool,
     enable_local_dependency: bool,
     rust_crate_name: &str,
+    template: &Template,
 ) -> Result<()> {
     // frb-coverage:ignore-end
-    flutter_pub_add(
-        &[rust_crate_name.into(), "--path=rust_builder".into()],
-        None,
-    )?;
+    if template == &Template::App {
+        flutter_pub_add(
+            &[rust_crate_name.into(), "--path=rust_builder".into()],
+            None,
+        )?;
+    }
 
     pub_add_dependency_frb(enable_local_dependency, None)?;
 

frb_codegen/src/library/integration/integrator.rs

@@ -7,7 +7,7 @@ version:
   revision: "5dcb86f68f239346676ceb1ed1ea385bd215fba1"
   channel: "stable"
 
-project_type: plugin
+project_type: plugin_ffi
 
 # Tracks metadata for the flutter migrate command
 migration:
@@ -27,9 +27,6 @@ migration:
     - platform: macos
       create_revision: 5dcb86f68f239346676ceb1ed1ea385bd215fba1
       base_revision: 5dcb86f68f239346676ceb1ed1ea385bd215fba1
-    - platform: web
-      create_revision: 5dcb86f68f239346676ceb1ed1ea385bd215fba1
-      base_revision: 5dcb86f68f239346676ceb1ed1ea385bd215fba1
     - platform: windows
       create_revision: 5dcb86f68f239346676ceb1ed1ea385bd215fba1
       base_revision: 5dcb86f68f239346676ceb1ed1ea385bd215fba1

frb_example/flutter_package/.metadata

@@ -1,15 +1,92 @@
 # flutter_package
 
-A new Flutter plugin project.
+A new Flutter FFI plugin project.
 
 ## Getting Started
 
 This project is a starting point for a Flutter
-[plug-in package](https://flutter.dev/developing-packages/),
-a specialized package that includes platform-specific implementation code for
-Android and/or iOS.
+[FFI plugin](https://docs.flutter.dev/development/platform-integration/c-interop),
+a specialized package that includes native code directly invoked with Dart FFI.
 
-For help getting started with Flutter development, view the
+## 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:
+
+```yaml
+  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:
+
+```yaml
+  plugin:
+    implements: some_other_plugin
+    platforms:
+      some_platform:
+        dartPluginClass: SomeClass
+        ffiPlugin: true
+```
+
+A plugin can have both FFI and method channels:
+
+```yaml
+  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_package.podspec.
+  * See the documentation in macos/flutter_package.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
+(`src/flutter_package.h`) by `package:ffigen`.
+Regenerate the bindings by running `dart 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_package.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_package.dart`.
+
+## Flutter help
+
+For help getting started with Flutter, view our
 [online documentation](https://flutter.dev/docs), which offers tutorials,
 samples, guidance on mobile development, and a full API reference.