Implement support for Flutter Plugins (#8)

* plugins WIP

* Add flutter plugins support for macOS

#6

* Add flutter plugins support for windows

* Move macOS resources to res/macos

* Short-circuit to empty registrar if there are no plugins

* Add flutter plugin support for linux

* Update XCode project file to specify SWIFT_VERSION

* Handle FFI only plugins

nativeshell/src/shell/context.rs

@@ -3,13 +3,13 @@ use std::rc::Rc;
 use crate::{util::LateRefCell, Error, Result};
 
 use super::{
-    platform::{drag_data::DragDataAdapter, init::init_platform},
+    platform::{drag_data::DragDataAdapter, engine::PlatformPlugin, init::init_platform},
     EngineManager, MenuManager, MessageManager, RunLoop, WindowManager, WindowMethodChannel,
 };
 
 pub struct ContextOptions {
     pub app_namespace: String,
-
+    pub flutter_plugins: Vec<PlatformPlugin>,
     pub on_last_engine_removed: Box<dyn Fn(Rc<Context>)>,
     pub custom_drag_data_adapters: Vec<Box<dyn DragDataAdapter>>,
 }
@@ -18,6 +18,7 @@ impl Default for ContextOptions {
     fn default() -> Self {
         Self {
             app_namespace: Default::default(),
+            flutter_plugins: Vec::new(),
             on_last_engine_removed: Box::new(|context| context.run_loop.borrow().stop()),
             custom_drag_data_adapters: Vec::new(),
         }

nativeshell/src/shell/engine.rs

@@ -1,4 +1,7 @@
-use super::{platform::engine::PlatformEngine, BinaryMessenger};
+use super::{
+    platform::engine::{PlatformEngine, PlatformPlugin},
+    BinaryMessenger,
+};
 use crate::Result;
 
 pub struct FlutterEngine {
@@ -7,8 +10,8 @@ pub struct FlutterEngine {
 }
 
 impl FlutterEngine {
-    pub fn create() -> Self {
-        let platform_engine = PlatformEngine::new();
+    pub fn create(plugins: &[PlatformPlugin]) -> Self {
+        let platform_engine = PlatformEngine::new(plugins);
 
         let messenger = BinaryMessenger::new(platform_engine.new_binary_messenger());
         FlutterEngine {

nativeshell/src/shell/engine_manager.rs

@@ -26,7 +26,7 @@ impl EngineManager {
     }
 
     pub fn create_engine(&mut self) -> EngineHandle {
-        let engine = FlutterEngine::create();
+        let engine = FlutterEngine::create(&self.context.options.flutter_plugins);
         let handle = self.next_handle;
         self.next_handle.0 += 1;
         self.engines.insert(handle, Box::new(RefCell::new(engine)));

nativeshell/src/shell/macros.rs

@@ -0,0 +1,9 @@
+#[macro_export]
+macro_rules! include_flutter_plugins {
+    () => {
+        ::std::include!(::std::concat!(
+            ::std::env!("OUT_DIR"),
+            "/generated_plugins_registrar.rs"
+        ));
+    };
+}

nativeshell/src/shell/mod.rs

@@ -5,6 +5,7 @@ mod context;
 mod engine;
 mod engine_manager;
 mod geometry;
+mod macros;
 mod menu_manager;
 mod message_manager;
 mod observatory;
@@ -19,6 +20,7 @@ pub use context::*;
 pub use engine::*;
 pub use engine_manager::*;
 pub use geometry::*;
+pub use macros::*;
 pub use menu_manager::*;
 pub use message_manager::*;
 pub use observatory::*;

nativeshell/src/shell/platform/linux/engine.rs

@@ -29,10 +29,23 @@ struct _FlEngine {
     _engine: isize,
 }
 
+pub struct PlatformPlugin {
+    pub name: String,
+    pub register_func: Option<unsafe extern "C" fn(registrar: *mut std::os::raw::c_void)>,
+}
+
 impl PlatformEngine {
-    pub fn new() -> Self {
+    pub fn new(plugins: &[PlatformPlugin]) -> Self {
         let project = flutter::DartProject::new();
         let view = flutter::View::new(&project);
+        for plugin in plugins {
+            let registrar = view.get_registrar_for_plugin(&plugin.name);
+            if let Some(func) = plugin.register_func {
+                unsafe {
+                    func(registrar);
+                }
+            }
+        }
         PlatformEngine { view }
     }
 

nativeshell/src/shell/platform/linux/flutter.rs

@@ -1,6 +1,9 @@
 #![allow(clippy::from_over_into)]
 
-use std::{mem::ManuallyDrop, os::raw::c_char};
+use std::{
+    mem::ManuallyDrop,
+    os::raw::{c_char, c_void},
+};
 
 use super::flutter_sys;
 use glib::{glib_wrapper, Object};
@@ -46,6 +49,7 @@ impl View {
 
 pub trait ViewExt: 'static {
     fn get_engine(&self) -> Engine;
+    fn get_registrar_for_plugin(&self, plugin: &str) -> *mut c_void;
 }
 
 impl<O: IsA<View>> ViewExt for O {
@@ -57,6 +61,15 @@ impl<O: IsA<View>> ViewExt for O {
             .unsafe_cast()
         }
     }
+
+    fn get_registrar_for_plugin(&self, plugin: &str) -> *mut c_void {
+        unsafe {
+            flutter_sys::fl_plugin_registry_get_registrar_for_plugin(
+                self.as_ref().to_glib_none().0,
+                plugin.to_glib_none().0,
+            )
+        }
+    }
 }
 
 glib_wrapper! {

nativeshell/src/shell/platform/linux/flutter_sys.rs

@@ -1,7 +1,7 @@
 extern crate gobject_sys;
 extern crate gtk_sys;
 
-use std::os::raw::c_char;
+use std::os::raw::{c_char, c_void};
 
 use gobject_sys::{GObject, GObjectClass};
 use gtk_sys::{GtkContainer, GtkContainerClass, GtkWidget};
@@ -113,4 +113,9 @@ extern "C" {
         result: *mut gio_sys::GAsyncResult,
         error: *mut *mut glib_sys::GError,
     ) -> *mut glib_sys::GBytes;
+
+    pub fn fl_plugin_registry_get_registrar_for_plugin(
+        registry: *mut FlView,
+        name: *const c_char,
+    ) -> *mut c_void;
 }

nativeshell/src/shell/platform/macos/engine.rs

@@ -1,9 +1,13 @@
 use std::ffi::c_void;
 
 use cocoa::base::{id, nil, BOOL, NO};
+use log::warn;
 use objc::rc::{autoreleasepool, StrongPtr};
 
-use crate::shell::platform::key_interceptor::override_key_event;
+use crate::shell::platform::{
+    key_interceptor::override_key_event,
+    platform_impl::utils::{class_from_string, to_nsstring},
+};
 
 use super::{
     binary_messenger::PlatformBinaryMessenger,
@@ -15,14 +19,35 @@ pub struct PlatformEngine {
     pub(super) view_controller: StrongPtr,
 }
 
+pub struct PlatformPlugin {
+    pub name: String,
+    pub class: String,
+}
+
 impl PlatformEngine {
-    pub fn new() -> Self {
+    pub fn new(plugins: &[PlatformPlugin]) -> Self {
         autoreleasepool(|| unsafe {
             let class = class!(FlutterViewController);
             let view_controller: id = msg_send![class, alloc];
             let view_controller = StrongPtr::new(msg_send![view_controller, initWithProject: nil]);
             let engine: id = msg_send![*view_controller, engine];
             let embedder_api: *mut c_void = msg_send![engine, embedderAPI];
+
+            // register plugins with this engine
+            for plugin in plugins {
+                let class = class_from_string(&plugin.class);
+                if class.is_null() {
+                    warn!(
+                        "Plugin {} for plugin {} not found",
+                        plugin.name, plugin.class
+                    );
+                } else {
+                    let registrar: id =
+                        msg_send![engine, registrarForPlugin: *to_nsstring(&plugin.name)];
+                    let () = msg_send![class, registerWithRegistrar: registrar];
+                }
+            }
+
             override_key_event(embedder_api);
             Self {
                 handle: StrongPtr::retain(engine),

nativeshell/src/shell/platform/macos/utils.rs

@@ -168,3 +168,9 @@ pub(super) fn class_decl_from_name(name: &str) -> ManuallyDrop<ClassDecl> {
     // class, and it's now worth replicating the entire functionality here
     ManuallyDrop::new(unsafe { std::mem::transmute(res) })
 }
+
+pub(super) fn class_from_string(name: &str) -> *mut Class {
+    let name = CString::new(name).unwrap();
+    let class = unsafe { objc_getClass(name.as_ptr() as *const _) as *mut _ };
+    return class;
+}

nativeshell/src/shell/platform/null/engine.rs

@@ -2,8 +2,10 @@ use super::{binary_messenger::PlatformBinaryMessenger, error::PlatformResult};
 
 pub struct PlatformEngine {}
 
+pub type PlatformPlugin = isize;
+
 impl PlatformEngine {
-    pub fn new() -> Self {
+    pub fn new(_plugins: &[PlatformPlugin]) -> Self {
         PlatformEngine {}
     }
 

nativeshell/src/shell/platform/win32/engine.rs

@@ -1,4 +1,4 @@
-use std::{mem::size_of, ptr};
+use std::{ffi::CString, mem::size_of, ptr};
 
 use crate::shell::platform::key_interceptor::override_key_event;
 
@@ -7,7 +7,8 @@ use super::{
     error::PlatformResult,
     flutter_sys::{
         FlutterDesktopEngineCreate, FlutterDesktopEngineDestroy, FlutterDesktopEngineGetMessenger,
-        FlutterDesktopEngineProperties, FlutterDesktopEngineRef,
+        FlutterDesktopEngineGetPluginRegistrar, FlutterDesktopEngineProperties,
+        FlutterDesktopEngineRef,
     },
     util::to_utf16,
 };
@@ -16,8 +17,13 @@ pub struct PlatformEngine {
     pub(super) handle: FlutterDesktopEngineRef,
 }
 
+pub struct PlatformPlugin {
+    pub name: String,
+    pub register_func: Option<unsafe extern "C" fn(registrar: *mut std::os::raw::c_void)>,
+}
+
 impl PlatformEngine {
-    pub fn new() -> Self {
+    pub fn new(plugins: &[PlatformPlugin]) -> Self {
         let assets = to_utf16("data\\flutter_assets");
         let icu = to_utf16("data\\icudtl.dat");
         let aot = to_utf16("data\\app.so");
@@ -31,6 +37,18 @@ impl PlatformEngine {
 
         let engine = unsafe { FlutterDesktopEngineCreate(&properties) };
 
+        // register plugins
+        for plugin in plugins {
+            let name = CString::new(plugin.name.as_str()).unwrap();
+            let registrar =
+                unsafe { FlutterDesktopEngineGetPluginRegistrar(engine, name.as_ptr()) };
+            if let Some(register_func) = plugin.register_func {
+                unsafe {
+                    register_func(registrar as *mut _);
+                }
+            }
+        }
+
         unsafe {
             // TODO: This makes assumption about internal engine layout and will possibly
             // break in future;

nativeshell_build/Cargo.toml

@@ -16,3 +16,14 @@ pathdiff = "0.2.0"
 path-slash = "0.1.4"
 dunce = "1.0.1"
 copy_dir = "0.1.2"
+yaml-rust = "0.4"
+
+[target.'cfg(target_os = "macos")'.dependencies]
+tar = "0.4"
+
+[target.'cfg(target_os = "windows")'.dependencies]
+cmake = "0.1"
+
+[target.'cfg(target_os = "linux")'.dependencies]
+cmake = "0.1"
+convert_case = "0.4.0"