Desktop: Use multithreaded CEF event loop on Windows and Linux (#3076)

* Prototype multi threaded event loop

* Fix input event dispatch

* Remove dead code

* Reenable do_message_loop_work for macos targets

* Cleanup

* Review cleanup

* Remove outdated comment

* Attempt to fix texture import errors

---------

Co-authored-by: Timon Schelling <me@timon.zip>

desktop/src/app.rs

@@ -24,7 +24,7 @@ use winit::window::WindowId;
 use crate::cef;
 
 pub(crate) struct WinitApp {
-	cef_context: cef::Context<cef::Initialized>,
+	cef_context: Box<dyn cef::CefContext>,
 	window: Option<Arc<Window>>,
 	cef_schedule: Option<Instant>,
 	window_size_sender: Sender<WindowSize>,
@@ -38,7 +38,7 @@ pub(crate) struct WinitApp {
 }
 
 impl WinitApp {
-	pub(crate) fn new(cef_context: cef::Context<cef::Initialized>, window_size_sender: Sender<WindowSize>, wgpu_context: WgpuContext, event_loop_proxy: EventLoopProxy<CustomEvent>) -> Self {
+	pub(crate) fn new(cef_context: Box<dyn cef::CefContext>, window_size_sender: Sender<WindowSize>, wgpu_context: WgpuContext, event_loop_proxy: EventLoopProxy<CustomEvent>) -> Self {
 		let rendering_loop_proxy = event_loop_proxy.clone();
 		let (start_render_sender, start_render_receiver) = std::sync::mpsc::sync_channel(1);
 		std::thread::spawn(move || {
@@ -71,7 +71,7 @@ impl WinitApp {
 					tracing::error!("Failed to serialize frontend messages");
 					return;
 				};
-				self.cef_context.send_web_message(bytes.as_slice());
+				self.cef_context.send_web_message(bytes);
 			}
 			DesktopFrontendMessage::OpenFileDialog { title, filters, context } => {
 				let event_loop_proxy = self.event_loop_proxy.clone();
@@ -254,7 +254,7 @@ impl ApplicationHandler<CustomEvent> for WinitApp {
 	}
 
 	fn window_event(&mut self, event_loop: &ActiveEventLoop, _window_id: WindowId, event: WindowEvent) {
-		let Some(event) = self.cef_context.handle_window_event(event) else { return };
+		self.cef_context.handle_window_event(&event);
 
 		match event {
 			WindowEvent::CloseRequested => {

desktop/src/cef.rs

@@ -20,6 +20,7 @@ use std::sync::mpsc::Receiver;
 use std::sync::{Arc, Mutex};
 use std::time::Instant;
 
+mod consts;
 mod context;
 mod dirs;
 mod input;
@@ -34,7 +35,7 @@ mod texture_import;
 #[cfg(feature = "accelerated_paint")]
 use texture_import::SharedTextureHandle;
 
-pub(crate) use context::{Context, InitError, Initialized, Setup, SetupError};
+pub(crate) use context::{CefContext, CefContextBuilder, InitError};
 use winit::event_loop::EventLoopProxy;
 
 pub(crate) trait CefEventHandler: Clone {

desktop/src/cef/consts.rs

@@ -0,0 +1,2 @@
+pub(crate) const GRAPHITE_SCHEME: &str = "graphite-static";
+pub(crate) const FRONTEND_DOMAIN: &str = "frontend";

desktop/src/cef/context.rs

@@ -1,164 +1,15 @@
-use cef::sys::{CEF_API_VERSION_LAST, cef_resultcode_t};
-use cef::{App, BrowserSettings, Client, DictionaryValue, ImplBrowser, ImplBrowserHost, ImplCommandLine, RenderHandler, RequestContext, WindowInfo, browser_host_create_browser_sync, initialize};
-use cef::{Browser, CefString, Settings, api_hash, args::Args, execute_process};
-use thiserror::Error;
-use winit::event::WindowEvent;
+mod multithreaded;
+mod singlethreaded;
 
-use crate::cef::dirs::{cef_cache_dir, cef_data_dir};
+mod builder;
+pub(crate) use builder::{CefContextBuilder, InitError};
 
-use super::input::InputState;
-use super::ipc::{MessageType, SendMessage};
-use super::scheme_handler::{FRONTEND_DOMAIN, GRAPHITE_SCHEME};
-use super::{CefEventHandler, input};
+pub(crate) trait CefContext {
+	fn work(&mut self);
 
-use super::internal::{BrowserProcessAppImpl, BrowserProcessClientImpl, RenderHandlerImpl, RenderProcessAppImpl};
+	fn handle_window_event(&mut self, event: &winit::event::WindowEvent);
 
-pub(crate) struct Setup {}
-pub(crate) struct Initialized {}
-pub(crate) trait ContextState {}
-impl ContextState for Setup {}
-impl ContextState for Initialized {}
+	fn notify_of_resize(&self);
 
-pub(crate) struct Context<S: ContextState> {
-	args: Args,
-	pub(crate) browser: Option<Browser>,
-	pub(crate) input_state: InputState,
-	marker: std::marker::PhantomData<S>,
-}
-
-impl Context<Setup> {
-	pub(crate) fn new() -> Result<Context<Setup>, SetupError> {
-		#[cfg(target_os = "macos")]
-		let _loader = {
-			let loader = library_loader::LibraryLoader::new(&std::env::current_exe().unwrap(), false);
-			assert!(loader.load());
-			loader
-		};
-		let _ = api_hash(CEF_API_VERSION_LAST, 0);
-
-		let args = Args::new();
-		let cmd = args.as_cmd_line().unwrap();
-		let switch = CefString::from("type");
-		let is_browser_process = cmd.has_switch(Some(&switch)) != 1;
-
-		if !is_browser_process {
-			let process_type = CefString::from(&cmd.switch_value(Some(&switch)));
-			let mut app = RenderProcessAppImpl::app();
-			let ret = execute_process(Some(args.as_main_args()), Some(&mut app), std::ptr::null_mut());
-			if ret >= 0 {
-				return Err(SetupError::SubprocessFailed(process_type.to_string()));
-			} else {
-				return Err(SetupError::Subprocess);
-			}
-		}
-
-		Ok(Context {
-			args,
-			browser: None,
-			input_state: InputState::default(),
-			marker: std::marker::PhantomData::<Setup>,
-		})
-	}
-
-	pub(crate) fn init(self, event_handler: impl CefEventHandler) -> Result<Context<Initialized>, InitError> {
-		let settings = Settings {
-			windowless_rendering_enabled: 1,
-			multi_threaded_message_loop: 0,
-			external_message_pump: 1,
-			root_cache_path: cef_data_dir().to_str().map(CefString::from).unwrap(),
-			cache_path: cef_cache_dir().to_str().map(CefString::from).unwrap(),
-			..Default::default()
-		};
-
-		// Attention! Wrapping this in an extra App is necessary, otherwise the program still compiles but segfaults
-		let mut cef_app = App::new(BrowserProcessAppImpl::new(event_handler.clone()));
-
-		let result = initialize(Some(self.args.as_main_args()), Some(&settings), Some(&mut cef_app), std::ptr::null_mut());
-		if result != 1 {
-			let cef_exit_code = cef::get_exit_code() as u32;
-			if cef_exit_code == cef_resultcode_t::CEF_RESULT_CODE_NORMAL_EXIT_PROCESS_NOTIFIED as u32 {
-				return Err(InitError::AlreadyRunning);
-			}
-			return Err(InitError::InitializationFailed(cef_exit_code));
-		}
-
-		let render_handler = RenderHandler::new(RenderHandlerImpl::new(event_handler.clone()));
-		let mut client = Client::new(BrowserProcessClientImpl::new(render_handler, event_handler.clone()));
-
-		let url = CefString::from(format!("{GRAPHITE_SCHEME}://{FRONTEND_DOMAIN}/").as_str());
-		// let url = CefString::from("chrome://gpu");
-
-		let window_info = WindowInfo {
-			windowless_rendering_enabled: 1,
-			#[cfg(feature = "accelerated_paint")]
-			shared_texture_enabled: if crate::cef::platform::should_enable_hardware_acceleration() { 1 } else { 0 },
-			..Default::default()
-		};
-
-		let settings = BrowserSettings {
-			windowless_frame_rate: crate::consts::CEF_WINDOWLESS_FRAME_RATE,
-			background_color: 0x0,
-			..Default::default()
-		};
-
-		let browser = browser_host_create_browser_sync(
-			Some(&window_info),
-			Some(&mut client),
-			Some(&url),
-			Some(&settings),
-			Option::<&mut DictionaryValue>::None,
-			Option::<&mut RequestContext>::None,
-		);
-
-		Ok(Context {
-			args: self.args.clone(),
-			browser,
-			input_state: self.input_state.clone(),
-			marker: std::marker::PhantomData::<Initialized>,
-		})
-	}
-}
-
-impl Context<Initialized> {
-	pub(crate) fn work(&mut self) {
-		cef::do_message_loop_work();
-	}
-
-	pub(crate) fn handle_window_event(&mut self, event: WindowEvent) -> Option<WindowEvent> {
-		input::handle_window_event(self, event)
-	}
-
-	pub(crate) fn notify_of_resize(&self) {
-		if let Some(browser) = &self.browser {
-			browser.host().unwrap().was_resized();
-		}
-	}
-
-	pub(crate) fn send_web_message(&self, message: &[u8]) {
-		self.send_message(MessageType::SendToJS, message);
-	}
-}
-
-impl<S: ContextState> Drop for Context<S> {
-	fn drop(&mut self) {
-		if self.browser.is_some() {
-			cef::shutdown();
-		}
-	}
-}
-
-#[derive(Error, Debug)]
-pub(crate) enum SetupError {
-	#[error("this is the sub process should exit immediately")]
-	Subprocess,
-	#[error("subprocess returned non zero exit code")]
-	SubprocessFailed(String),
-}
-
-#[derive(Error, Debug)]
-pub(crate) enum InitError {
-	#[error("initialization failed")]
-	InitializationFailed(u32),
-	#[error("Another instance is already running")]
-	AlreadyRunning,
+	fn send_web_message(&self, message: Vec<u8>);
 }

desktop/src/cef/context/builder.rs

@@ -0,0 +1,171 @@
+use cef::args::Args;
+use cef::sys::{CEF_API_VERSION_LAST, cef_resultcode_t};
+use cef::{
+	App, BrowserSettings, CefString, Client, DictionaryValue, ImplCommandLine, RenderHandler, RequestContext, Settings, WindowInfo, api_hash, browser_host_create_browser_sync, execute_process,
+};
+
+use super::CefContext;
+use super::singlethreaded::SingleThreadedCefContext;
+use crate::cef::CefHandler;
+use crate::cef::consts::{FRONTEND_DOMAIN, GRAPHITE_SCHEME};
+use crate::cef::dirs::{cef_cache_dir, cef_data_dir};
+use crate::cef::input::InputState;
+use crate::cef::internal::{BrowserProcessAppImpl, BrowserProcessClientImpl, RenderHandlerImpl, RenderProcessAppImpl};
+
+pub(crate) struct CefContextBuilder {
+	pub(crate) args: Args,
+	pub(crate) is_sub_process: bool,
+}
+
+unsafe impl Send for CefContextBuilder {}
+
+impl CefContextBuilder {
+	pub(crate) fn new() -> Self {
+		#[cfg(target_os = "macos")]
+		let _loader = {
+			let loader = library_loader::LibraryLoader::new(&std::env::current_exe().unwrap(), false);
+			assert!(loader.load());
+			loader
+		};
+		let _ = api_hash(CEF_API_VERSION_LAST, 0);
+
+		let args = Args::new();
+		let cmd = args.as_cmd_line().unwrap();
+		let switch = CefString::from("type");
+		let is_sub_process = cmd.has_switch(Some(&switch)) == 1;
+
+		Self { args, is_sub_process }
+	}
+
+	pub(crate) fn is_sub_process(&self) -> bool {
+		self.is_sub_process
+	}
+
+	pub(crate) fn execute_sub_process(&self) -> SetupError {
+		let cmd = self.args.as_cmd_line().unwrap();
+		let switch = CefString::from("type");
+		let process_type = CefString::from(&cmd.switch_value(Some(&switch)));
+		let mut app = RenderProcessAppImpl::app();
+		let ret = execute_process(Some(self.args.as_main_args()), Some(&mut app), std::ptr::null_mut());
+		if ret >= 0 {
+			SetupError::SubprocessFailed(process_type.to_string())
+		} else {
+			SetupError::Subprocess
+		}
+	}
+
+	#[cfg(target_os = "macos")]
+	pub(crate) fn initialize(self, event_handler: CefHandler) -> Result<impl CefContext, InitError> {
+		let settings = Settings {
+			windowless_rendering_enabled: 1,
+			multi_threaded_message_loop: 0,
+			external_message_pump: 1,
+			root_cache_path: cef_data_dir().to_str().map(CefString::from).unwrap(),
+			cache_path: cef_cache_dir().to_str().map(CefString::from).unwrap(),
+			..Default::default()
+		};
+
+		self.initialize_inner(&event_handler, settings)?;
+
+		create_browser(event_handler)
+	}
+
+	#[cfg(not(target_os = "macos"))]
+	pub(crate) fn initialize(self, event_handler: CefHandler) -> Result<impl CefContext, InitError> {
+		let settings = Settings {
+			windowless_rendering_enabled: 1,
+			multi_threaded_message_loop: 1,
+			root_cache_path: cef_data_dir().to_str().map(CefString::from).unwrap(),
+			cache_path: cef_cache_dir().to_str().map(CefString::from).unwrap(),
+			..Default::default()
+		};
+
+		self.initialize_inner(&event_handler, settings)?;
+
+		super::multithreaded::run_on_ui_thread(move || match create_browser(event_handler) {
+			Ok(context) => {
+				super::multithreaded::CONTEXT.with(|b| {
+					*b.borrow_mut() = Some(context);
+				});
+			}
+			Err(e) => {
+				tracing::error!("Failed to initialize CEF context: {:?}", e);
+				std::process::exit(1);
+			}
+		});
+
+		Ok(super::multithreaded::MultiThreadedCefContextProxy)
+	}
+
+	fn initialize_inner(self, event_handler: &CefHandler, settings: Settings) -> Result<(), InitError> {
+		let mut cef_app = App::new(BrowserProcessAppImpl::new(event_handler.clone()));
+		let result = cef::initialize(Some(self.args.as_main_args()), Some(&settings), Some(&mut cef_app), std::ptr::null_mut());
+		// Attention! Wrapping this in an extra App is necessary, otherwise the program still compiles but segfaults
+
+		if result != 1 {
+			let cef_exit_code = cef::get_exit_code() as u32;
+			if cef_exit_code == cef_resultcode_t::CEF_RESULT_CODE_NORMAL_EXIT_PROCESS_NOTIFIED as u32 {
+				return Err(InitError::AlreadyRunning);
+			}
+			return Err(InitError::InitializationFailed(cef_exit_code));
+		}
+		Ok(())
+	}
+}
+
+fn create_browser(event_handler: CefHandler) -> Result<SingleThreadedCefContext, InitError> {
+	let render_handler = RenderHandler::new(RenderHandlerImpl::new(event_handler.clone()));
+	let mut client = Client::new(BrowserProcessClientImpl::new(render_handler, event_handler.clone()));
+
+	let url = CefString::from(format!("{GRAPHITE_SCHEME}://{FRONTEND_DOMAIN}/").as_str());
+
+	let window_info = WindowInfo {
+		windowless_rendering_enabled: 1,
+		#[cfg(feature = "accelerated_paint")]
+		shared_texture_enabled: if crate::cef::platform::should_enable_hardware_acceleration() { 1 } else { 0 },
+		..Default::default()
+	};
+
+	let settings = BrowserSettings {
+		windowless_frame_rate: crate::consts::CEF_WINDOWLESS_FRAME_RATE,
+		background_color: 0x0,
+		..Default::default()
+	};
+
+	let browser = browser_host_create_browser_sync(
+		Some(&window_info),
+		Some(&mut client),
+		Some(&url),
+		Some(&settings),
+		Option::<&mut DictionaryValue>::None,
+		Option::<&mut RequestContext>::None,
+	);
+
+	if let Some(browser) = browser {
+		Ok(SingleThreadedCefContext {
+			browser,
+			input_state: InputState::default(),
+		})
+	} else {
+		tracing::error!("Failed to create browser");
+		Err(InitError::BrowserCreationFailed)
+	}
+}
+
+#[derive(thiserror::Error, Debug)]
+pub(crate) enum SetupError {
+	#[error("This is the sub process should exit immediately")]
+	Subprocess,
+	#[error("Subprocess returned non zero exit code")]
+	SubprocessFailed(String),
+}
+
+#[derive(thiserror::Error, Debug)]
+pub(crate) enum InitError {
+	#[error("Initialization failed")]
+	InitializationFailed(u32),
+	#[error("Browser creation failed")]
+	BrowserCreationFailed,
+	#[error("Another instance is already running")]
+	AlreadyRunning,
+}

desktop/src/cef/context/multithreaded.rs

@@ -0,0 +1,67 @@
+use cef::sys::cef_thread_id_t;
+use cef::{Task, ThreadId, post_task};
+use std::cell::RefCell;
+use winit::event::WindowEvent;
+
+use crate::cef::internal::task::ClosureTask;
+
+use super::CefContext;
+use super::singlethreaded::SingleThreadedCefContext;
+
+thread_local! {
+	pub(super) static CONTEXT: RefCell<Option<SingleThreadedCefContext>> = const { RefCell::new(None) };
+}
+
+pub(super) struct MultiThreadedCefContextProxy;
+
+impl CefContext for MultiThreadedCefContextProxy {
+	fn work(&mut self) {
+		// CEF handles its own message loop in multi-threaded mode
+	}
+
+	fn handle_window_event(&mut self, event: &WindowEvent) {
+		let event_clone = event.clone();
+		run_on_ui_thread(move || {
+			CONTEXT.with(|b| {
+				if let Some(context) = b.borrow_mut().as_mut() {
+					context.handle_window_event(&event_clone);
+				}
+			});
+		});
+	}
+
+	fn notify_of_resize(&self) {
+		run_on_ui_thread(move || {
+			CONTEXT.with(|b| {
+				if let Some(context) = b.borrow_mut().as_mut() {
+					context.notify_of_resize();
+				}
+			});
+		});
+	}
+
+	fn send_web_message(&self, message: Vec<u8>) {
+		run_on_ui_thread(move || {
+			CONTEXT.with(|b| {
+				if let Some(context) = b.borrow_mut().as_mut() {
+					context.send_web_message(message);
+				}
+			});
+		});
+	}
+}
+
+impl Drop for MultiThreadedCefContextProxy {
+	fn drop(&mut self) {
+		cef::shutdown();
+	}
+}
+
+pub(super) fn run_on_ui_thread<F>(closure: F)
+where
+	F: FnOnce() + Send + 'static,
+{
+	let closure_task = ClosureTask::new(closure);
+	let mut task = Task::new(closure_task);
+	post_task(ThreadId::from(cef_thread_id_t::TID_UI), Some(&mut task));
+}

desktop/src/cef/context/singlethreaded.rs

@@ -0,0 +1,48 @@
+use cef::{Browser, ImplBrowser, ImplBrowserHost};
+use winit::event::WindowEvent;
+
+use crate::cef::input;
+use crate::cef::input::InputState;
+use crate::cef::ipc::{MessageType, SendMessage};
+
+use super::CefContext;
+
+pub(super) struct SingleThreadedCefContext {
+	pub(super) browser: Browser,
+	pub(super) input_state: InputState,
+}
+
+impl CefContext for SingleThreadedCefContext {
+	fn work(&mut self) {
+		cef::do_message_loop_work();
+	}
+
+	fn handle_window_event(&mut self, event: &WindowEvent) {
+		input::handle_window_event(&self.browser, &mut self.input_state, event)
+	}
+
+	fn notify_of_resize(&self) {
+		self.browser.host().unwrap().was_resized();
+	}
+
+	fn send_web_message(&self, message: Vec<u8>) {
+		self.send_message(MessageType::SendToJS, &message);
+	}
+}
+
+impl Drop for SingleThreadedCefContext {
+	fn drop(&mut self) {
+		cef::shutdown();
+	}
+}
+
+impl SendMessage for SingleThreadedCefContext {
+	fn send_message(&self, message_type: MessageType, message: &[u8]) {
+		let Some(frame) = self.browser.main_frame() else {
+			tracing::error!("Main frame is not available, cannot send message");
+			return;
+		};
+
+		frame.send_message(message_type, message);
+	}
+}

desktop/src/cef/input.rs

@@ -1,164 +1,153 @@
 use cef::sys::{cef_event_flags_t, cef_key_event_type_t, cef_mouse_button_type_t};
-use cef::{ImplBrowser, ImplBrowserHost, KeyEvent, KeyEventType, MouseEvent};
+use cef::{Browser, ImplBrowser, ImplBrowserHost, KeyEvent, KeyEventType, MouseEvent};
 use winit::dpi::PhysicalPosition;
 use winit::event::{ElementState, MouseButton, MouseScrollDelta, WindowEvent};
 
-use super::context::{Context, Initialized};
-
 mod keymap;
 use keymap::{ToDomBits, ToVKBits};
 
-pub(crate) fn handle_window_event(context: &mut Context<Initialized>, event: WindowEvent) -> Option<WindowEvent> {
+pub(crate) fn handle_window_event(browser: &Browser, input_state: &mut InputState, event: &WindowEvent) {
 	match event {
 		WindowEvent::CursorMoved { position, .. } => {
-			if let Some(browser) = &context.browser {
-				if let Some(host) = browser.host() {
-					host.set_focus(1);
-				}
-
-				context.input_state.update_mouse_position(&position);
-				let mouse_event: MouseEvent = (&context.input_state).into();
-				browser.host().unwrap().send_mouse_move_event(Some(&mouse_event), 0);
+			if let Some(host) = browser.host() {
+				host.set_focus(1);
 			}
+
+			input_state.update_mouse_position(position);
+			let mouse_event: MouseEvent = (input_state).into();
+			browser.host().unwrap().send_mouse_move_event(Some(&mouse_event), 0);
 		}
 		WindowEvent::MouseInput { state, button, .. } => {
-			if let Some(browser) = &context.browser {
-				if let Some(host) = browser.host() {
-					host.set_focus(1);
+			if let Some(host) = browser.host() {
+				host.set_focus(1);
 
-					let mouse_up = match state {
-						ElementState::Pressed => 0,
-						ElementState::Released => 1,
-					};
+				let mouse_up = match state {
+					ElementState::Pressed => 0,
+					ElementState::Released => 1,
+				};
 
-					let cef_button = match button {
-						MouseButton::Left => Some(cef::MouseButtonType::from(cef_mouse_button_type_t::MBT_LEFT)),
-						MouseButton::Right => Some(cef::MouseButtonType::from(cef_mouse_button_type_t::MBT_RIGHT)),
-						MouseButton::Middle => Some(cef::MouseButtonType::from(cef_mouse_button_type_t::MBT_MIDDLE)),
-						MouseButton::Forward => None, //TODO: Handle Forward button
-						MouseButton::Back => None,    //TODO: Handle Back button
-						_ => None,
-					};
+				let cef_button = match button {
+					MouseButton::Left => Some(cef::MouseButtonType::from(cef_mouse_button_type_t::MBT_LEFT)),
+					MouseButton::Right => Some(cef::MouseButtonType::from(cef_mouse_button_type_t::MBT_RIGHT)),
+					MouseButton::Middle => Some(cef::MouseButtonType::from(cef_mouse_button_type_t::MBT_MIDDLE)),
+					MouseButton::Forward => None, //TODO: Handle Forward button
+					MouseButton::Back => None,    //TODO: Handle Back button
+					_ => None,
+				};
 
-					let mut mouse_state = context.input_state.mouse_state.clone();
-					match button {
-						MouseButton::Left => {
-							mouse_state.left = match state {
-								ElementState::Pressed => true,
-								ElementState::Released => false,
-							}
+				let mut mouse_state = input_state.mouse_state.clone();
+				match button {
+					MouseButton::Left => {
+						mouse_state.left = match state {
+							ElementState::Pressed => true,
+							ElementState::Released => false,
 						}
-						MouseButton::Right => {
-							mouse_state.right = match state {
-								ElementState::Pressed => true,
-								ElementState::Released => false,
-							}
-						}
-						MouseButton::Middle => {
-							mouse_state.middle = match state {
-								ElementState::Pressed => true,
-								ElementState::Released => false,
-							}
-						}
-						_ => {}
-					};
-					context.input_state.update_mouse_state(mouse_state);
-
-					let mouse_event: MouseEvent = (&context.input_state).into();
-
-					if let Some(button) = cef_button {
-						host.send_mouse_click_event(
-							Some(&mouse_event),
-							button,
-							mouse_up,
-							1, // click count
-						);
 					}
+					MouseButton::Right => {
+						mouse_state.right = match state {
+							ElementState::Pressed => true,
+							ElementState::Released => false,
+						}
+					}
+					MouseButton::Middle => {
+						mouse_state.middle = match state {
+							ElementState::Pressed => true,
+							ElementState::Released => false,
+						}
+					}
+					_ => {}
+				};
+				input_state.update_mouse_state(mouse_state);
+
+				let mouse_event: MouseEvent = input_state.into();
+
+				if let Some(button) = cef_button {
+					host.send_mouse_click_event(
+						Some(&mouse_event),
+						button,
+						mouse_up,
+						1, // click count
+					);
 				}
 			}
 		}
 		WindowEvent::MouseWheel { delta, phase: _, device_id: _, .. } => {
-			if let Some(browser) = &context.browser {
-				if let Some(host) = browser.host() {
-					let mouse_event = (&context.input_state).into();
-					let line_width = 40; //feels about right, TODO: replace with correct value
-					let line_height = 30; //feels about right, TODO: replace with correct value
-					let (delta_x, delta_y) = match delta {
-						MouseScrollDelta::LineDelta(x, y) => (x * line_width as f32, y * line_height as f32),
-						MouseScrollDelta::PixelDelta(physical_position) => (physical_position.x as f32, physical_position.y as f32),
-					};
-					host.send_mouse_wheel_event(Some(&mouse_event), delta_x as i32, delta_y as i32);
-				}
+			if let Some(host) = browser.host() {
+				let mouse_event = input_state.into();
+				let line_width = 40; //feels about right, TODO: replace with correct value
+				let line_height = 30; //feels about right, TODO: replace with correct value
+				let (delta_x, delta_y) = match delta {
+					MouseScrollDelta::LineDelta(x, y) => (x * line_width as f32, y * line_height as f32),
+					MouseScrollDelta::PixelDelta(physical_position) => (physical_position.x as f32, physical_position.y as f32),
+				};
+				host.send_mouse_wheel_event(Some(&mouse_event), delta_x as i32, delta_y as i32);
 			}
 		}
 		WindowEvent::ModifiersChanged(modifiers) => {
-			context.input_state.update_modifiers(&modifiers.state());
+			input_state.update_modifiers(&modifiers.state());
 		}
 		WindowEvent::KeyboardInput { device_id: _, event, is_synthetic: _ } => {
-			if let Some(browser) = &context.browser {
-				if let Some(host) = browser.host() {
-					host.set_focus(1);
+			if let Some(host) = browser.host() {
+				host.set_focus(1);
 
-					let (named_key, character) = match &event.logical_key {
-						winit::keyboard::Key::Named(named_key) => (
-							Some(named_key),
-							match named_key {
-								winit::keyboard::NamedKey::Space => Some(' '),
-								winit::keyboard::NamedKey::Enter => Some('\u{000d}'),
-								_ => None,
-							},
-						),
-						winit::keyboard::Key::Character(str) => {
-							let char = str.chars().next().unwrap_or('\0');
-							(None, Some(char))
-						}
-						_ => return None,
-					};
-
-					let mut key_event = KeyEvent {
-						size: size_of::<KeyEvent>(),
-						focus_on_editable_field: 1,
-						modifiers: context.input_state.cef_modifiers(&event.location, event.repeat).raw(),
-						is_system_key: 0,
-						..Default::default()
-					};
-
-					if let Some(named_key) = named_key {
-						key_event.native_key_code = named_key.to_dom_bits();
-						key_event.windows_key_code = named_key.to_vk_bits();
-					} else if let Some(char) = character {
-						key_event.native_key_code = char.to_dom_bits();
-						key_event.windows_key_code = char.to_vk_bits();
+				let (named_key, character) = match &event.logical_key {
+					winit::keyboard::Key::Named(named_key) => (
+						Some(named_key),
+						match named_key {
+							winit::keyboard::NamedKey::Space => Some(' '),
+							winit::keyboard::NamedKey::Enter => Some('\u{000d}'),
+							_ => None,
+						},
+					),
+					winit::keyboard::Key::Character(str) => {
+						let char = str.chars().next().unwrap_or('\0');
+						(None, Some(char))
 					}
+					_ => return,
+				};
 
-					match event.state {
-						ElementState::Pressed => {
-							key_event.type_ = KeyEventType::from(cef_key_event_type_t::KEYEVENT_RAWKEYDOWN);
-							host.send_key_event(Some(&key_event));
+				let mut key_event = KeyEvent {
+					size: size_of::<KeyEvent>(),
+					focus_on_editable_field: 1,
+					modifiers: input_state.cef_modifiers(&event.location, event.repeat).raw(),
+					is_system_key: 0,
+					..Default::default()
+				};
 
-							if let Some(char) = character {
-								let mut buf = [0; 2];
-								char.encode_utf16(&mut buf);
-								key_event.character = buf[0];
-								let mut buf = [0; 2];
-								char.to_lowercase().next().unwrap().encode_utf16(&mut buf);
-								key_event.unmodified_character = buf[0];
-
-								key_event.type_ = KeyEventType::from(cef_key_event_type_t::KEYEVENT_CHAR);
-								host.send_key_event(Some(&key_event));
-							}
-						}
-						ElementState::Released => {
-							key_event.type_ = KeyEventType::from(cef_key_event_type_t::KEYEVENT_KEYUP);
-							host.send_key_event(Some(&key_event));
-						}
-					};
+				if let Some(named_key) = named_key {
+					key_event.native_key_code = named_key.to_dom_bits();
+					key_event.windows_key_code = named_key.to_vk_bits();
+				} else if let Some(char) = character {
+					key_event.native_key_code = char.to_dom_bits();
+					key_event.windows_key_code = char.to_vk_bits();
 				}
+
+				match event.state {
+					ElementState::Pressed => {
+						key_event.type_ = KeyEventType::from(cef_key_event_type_t::KEYEVENT_RAWKEYDOWN);
+						host.send_key_event(Some(&key_event));
+
+						if let Some(char) = character {
+							let mut buf = [0; 2];
+							char.encode_utf16(&mut buf);
+							key_event.character = buf[0];
+							let mut buf = [0; 2];
+							char.to_lowercase().next().unwrap().encode_utf16(&mut buf);
+							key_event.unmodified_character = buf[0];
+
+							key_event.type_ = KeyEventType::from(cef_key_event_type_t::KEYEVENT_CHAR);
+							host.send_key_event(Some(&key_event));
+						}
+					}
+					ElementState::Released => {
+						key_event.type_ = KeyEventType::from(cef_key_event_type_t::KEYEVENT_KEYUP);
+						host.send_key_event(Some(&key_event));
+					}
+				};
 			}
 		}
-		e => return Some(e),
+		_ => {}
 	}
-	None
 }
 
 #[derive(Default, Clone)]
@@ -227,6 +216,15 @@ impl From<&InputState> for MouseEvent {
 		}
 	}
 }
+impl From<&mut InputState> for MouseEvent {
+	fn from(val: &mut InputState) -> Self {
+		MouseEvent {
+			x: val.mouse_position.x as i32,
+			y: val.mouse_position.y as i32,
+			modifiers: val.cef_modifiers_mouse_event().raw(),
+		}
+	}
+}
 
 struct CefModifiers(u32);
 

desktop/src/cef/internal.rs

@@ -2,11 +2,13 @@ mod browser_process_app;
 mod browser_process_client;
 mod browser_process_handler;
 mod browser_process_life_span_handler;
-pub mod render_handler;
 mod render_process_app;
 mod render_process_handler;
 mod render_process_v8_handler;
 
+pub(super) mod render_handler;
+pub(super) mod task;
+
 pub(super) use browser_process_app::BrowserProcessAppImpl;
 pub(super) use browser_process_client::BrowserProcessClientImpl;
 pub(super) use render_handler::RenderHandlerImpl;

desktop/src/cef/internal/browser_process_app.rs

@@ -1,3 +1,4 @@
+#[cfg(target_os = "linux")]
 use std::env;
 
 use cef::rc::{Rc, RcImpl};

desktop/src/cef/internal/browser_process_handler.rs

@@ -5,7 +5,8 @@ use cef::sys::{_cef_browser_process_handler_t, cef_base_ref_counted_t, cef_brows
 use cef::{CefString, ImplBrowserProcessHandler, SchemeHandlerFactory, WrapBrowserProcessHandler};
 
 use crate::cef::CefEventHandler;
-use crate::cef::scheme_handler::{GRAPHITE_SCHEME, GraphiteSchemeHandlerFactory};
+use crate::cef::consts::GRAPHITE_SCHEME;
+use crate::cef::scheme_handler::GraphiteSchemeHandlerFactory;
 
 pub(crate) struct BrowserProcessHandlerImpl<H: CefEventHandler> {
 	object: *mut RcImpl<cef_browser_process_handler_t, Self>,

desktop/src/cef/internal/task.rs

@@ -0,0 +1,61 @@
+use cef::rc::{Rc, RcImpl};
+use cef::sys::{_cef_task_t, cef_base_ref_counted_t};
+use cef::{ImplTask, WrapTask};
+use std::cell::RefCell;
+
+// Closure-based task wrapper following CEF patterns
+pub struct ClosureTask<F> {
+	pub(crate) object: *mut RcImpl<_cef_task_t, Self>,
+	pub(crate) closure: RefCell<Option<F>>,
+}
+
+impl<F: FnOnce() + Send + 'static> ClosureTask<F> {
+	pub fn new(closure: F) -> Self {
+		Self {
+			object: std::ptr::null_mut(),
+			closure: RefCell::new(Some(closure)),
+		}
+	}
+}
+
+impl<F: FnOnce() + Send + 'static> ImplTask for ClosureTask<F> {
+	fn execute(&self) {
+		if let Some(closure) = self.closure.borrow_mut().take() {
+			closure();
+		}
+	}
+
+	fn get_raw(&self) -> *mut _cef_task_t {
+		self.object.cast()
+	}
+}
+
+impl<F: FnOnce() + Send + 'static> Clone for ClosureTask<F> {
+	fn clone(&self) -> Self {
+		unsafe {
+			if !self.object.is_null() {
+				let rc_impl = &mut *self.object;
+				rc_impl.interface.add_ref();
+			}
+		}
+		Self {
+			object: self.object,
+			closure: RefCell::new(None), // Closure can only be executed once
+		}
+	}
+}
+
+impl<F: FnOnce() + Send + 'static> Rc for ClosureTask<F> {
+	fn as_base(&self) -> &cef_base_ref_counted_t {
+		unsafe {
+			let base = &*self.object;
+			std::mem::transmute(&base.cef_object)
+		}
+	}
+}
+
+impl<F: FnOnce() + Send + 'static> WrapTask for ClosureTask<F> {
+	fn wrap_rc(&mut self, object: *mut RcImpl<_cef_task_t, Self>) {
+		self.object = object;
+	}
+}

desktop/src/cef/ipc.rs

@@ -1,6 +1,4 @@
-use cef::{CefString, Frame, ImplBinaryValue, ImplBrowser, ImplFrame, ImplListValue, ImplProcessMessage, ImplV8Context, ProcessId, V8Context, sys::cef_process_id_t};
-
-use super::{Context, Initialized};
+use cef::{CefString, Frame, ImplBinaryValue, ImplFrame, ImplListValue, ImplProcessMessage, ImplV8Context, ProcessId, V8Context, sys::cef_process_id_t};
 
 pub(crate) enum MessageType {
 	SendToJS,
@@ -39,21 +37,6 @@ pub(crate) struct MessageInfo {
 pub(crate) trait SendMessage {
 	fn send_message(&self, message_type: MessageType, message: &[u8]);
 }
-impl SendMessage for Context<Initialized> {
-	fn send_message(&self, message_type: MessageType, message: &[u8]) {
-		let Some(browser) = &self.browser else {
-			tracing::error!("Browser is not initialized, cannot send message");
-			return;
-		};
-
-		let Some(frame) = browser.main_frame() else {
-			tracing::error!("Main frame is not available, cannot send message");
-			return;
-		};
-
-		frame.send_message(message_type, message);
-	}
-}
 impl SendMessage for Option<V8Context> {
 	fn send_message(&self, message_type: MessageType, message: &[u8]) {
 		let Some(context) = self else {

desktop/src/cef/scheme_handler.rs

@@ -11,8 +11,7 @@ use cef::{
 };
 use include_dir::{Dir, include_dir};
 
-pub(crate) const GRAPHITE_SCHEME: &str = "graphite-static";
-pub(crate) const FRONTEND_DOMAIN: &str = "frontend";
+use super::consts::{FRONTEND_DOMAIN, GRAPHITE_SCHEME};
 
 pub(crate) struct GraphiteSchemeHandlerFactory {
 	object: *mut RcImpl<_cef_scheme_handler_factory_t, Self>,

desktop/src/cef/texture_import/d3d11.rs

@@ -87,22 +87,15 @@ impl D3D11Importer {
 				// Wrap D3D12 resource in wgpu-hal texture
 				let hal_texture = <api::Dx12 as wgpu::hal::Api>::Device::texture_from_raw(
 					d3d12_resource,
-					&wgpu::hal::TextureDescriptor {
-						label: Some("CEF D3D11→D3D12 Shared Texture"),
-						size: wgpu::Extent3d {
-							width: self.width,
-							height: self.height,
-							depth_or_array_layers: 1,
-						},
-						mip_level_count: 1,
-						sample_count: 1,
-						dimension: wgpu::TextureDimension::D2,
-						format: format::cef_to_wgpu(self.format)?,
-						usage: wgpu::TextureUses::COPY_DST | wgpu::TextureUses::RESOURCE,
-						memory_flags: wgpu::hal::MemoryFlags::empty(),
-						view_formats: vec![],
+					format::cef_to_wgpu(self.format)?,
+					wgpu::TextureDimension::D2,
+					wgpu::Extent3d {
+						width: self.width,
+						height: self.height,
+						depth_or_array_layers: 1,
 					},
-					None, // drop_callback
+					1, // mip_level_count
+					1, // sample_count
 				);
 
 				Ok(hal_texture)
@@ -286,7 +279,7 @@ impl D3D11Importer {
 		unsafe {
 			let mut shared_resource: Option<ID3D12Resource> = None;
 			d3d12_device
-				.OpenSharedHandle(windows::Win32::Foundation::HANDLE(self.handle as isize), &ID3D12Resource::IID, &mut shared_resource as *mut _ as *mut _)
+				.OpenSharedHandle(windows::Win32::Foundation::HANDLE(self.handle), &mut shared_resource)
 				.map_err(|e| TextureImportError::PlatformError {
 					message: format!("Failed to open D3D11 shared handle on D3D12: {:?}", e),
 				})?;

desktop/src/main.rs

@@ -7,7 +7,6 @@ use winit::event_loop::EventLoop;
 pub(crate) mod consts;
 
 mod cef;
-use cef::Setup;
 
 mod render;
 
@@ -29,21 +28,24 @@ pub(crate) enum CustomEvent {
 fn main() {
 	tracing_subscriber::fmt().with_env_filter(EnvFilter::from_default_env()).init();
 
-	let cef_context = match cef::Context::<Setup>::new() {
-		Ok(c) => c,
-		Err(cef::SetupError::Subprocess) => exit(0),
-		Err(cef::SetupError::SubprocessFailed(t)) => {
-			tracing::error!("Subprocess of type {t} failed");
-			exit(1);
-		}
-	};
+	let cef_context_builder = cef::CefContextBuilder::new();
+
+	if cef_context_builder.is_sub_process() {
+		// We are in a CEF subprocess
+		// This will block until the CEF subprocess quits
+		let error = cef_context_builder.execute_sub_process();
+		tracing::error!("Cef subprocess failed with error: {error}");
+		return;
+	}
+
+	let wgpu_context = futures::executor::block_on(WgpuContext::new()).unwrap();
 
 	let event_loop = EventLoop::<CustomEvent>::with_user_event().build().unwrap();
 
 	let (window_size_sender, window_size_receiver) = std::sync::mpsc::channel();
 
-	let wgpu_context = futures::executor::block_on(WgpuContext::new()).unwrap();
-	let cef_context = match cef_context.init(cef::CefHandler::new(window_size_receiver, event_loop.create_proxy(), wgpu_context.clone())) {
+	let cef_handler = cef::CefHandler::new(window_size_receiver, event_loop.create_proxy(), wgpu_context.clone());
+	let cef_context = match cef_context_builder.initialize(cef_handler) {
 		Ok(c) => c,
 		Err(cef::InitError::AlreadyRunning) => {
 			tracing::error!("Another instance is already running, Exiting.");
@@ -53,11 +55,15 @@ fn main() {
 			tracing::error!("Cef initialization failed with code: {code}");
 			exit(1);
 		}
+		Err(cef::InitError::BrowserCreationFailed) => {
+			tracing::error!("Failed to create CEF browser");
+			exit(1);
+		}
 	};
 
-	tracing::info!("Cef initialized successfully");
+	tracing::info!("CEF initialized successfully");
 
-	let mut winit_app = WinitApp::new(cef_context, window_size_sender, wgpu_context, event_loop.create_proxy());
+	let mut winit_app = WinitApp::new(Box::new(cef_context), window_size_sender, wgpu_context, event_loop.create_proxy());
 
 	event_loop.run_app(&mut winit_app).unwrap();
 }