refactor: event-driven state mutation

adapters/src/wayland/surfaces/event_bus.rs

@@ -0,0 +1,42 @@
+use super::window_events::WindowStateEvent;
+use std::cell::RefCell;
+use std::rc::Rc;
+
+type EventHandlerFn = Box<dyn Fn(&WindowStateEvent)>;
+
+#[derive(Clone)]
+pub struct EventBus {
+    handlers: Rc<RefCell<Vec<EventHandlerFn>>>,
+}
+
+impl Default for EventBus {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl EventBus {
+    pub fn new() -> Self {
+        Self {
+            handlers: Rc::new(RefCell::new(Vec::new())),
+        }
+    }
+
+    pub fn subscribe<F>(&self, handler: F)
+    where
+        F: Fn(&WindowStateEvent) + 'static,
+    {
+        self.handlers.borrow_mut().push(Box::new(handler));
+    }
+
+    pub fn publish(&self, event: &WindowStateEvent) {
+        let handlers = self.handlers.borrow();
+        for handler in handlers.iter() {
+            handler(event);
+        }
+    }
+
+    pub fn clear(&self) {
+        self.handlers.borrow_mut().clear();
+    }
+}

adapters/src/wayland/surfaces/interaction_state.rs

@@ -1,7 +1,9 @@
 use crate::wayland::managed_proxies::ManagedWlPointer;
 use crate::wayland::services::popup_service::PopupService;
+use crate::wayland::surfaces::event_bus::EventBus;
 use crate::wayland::surfaces::event_router::EventRouter;
 use crate::wayland::surfaces::scale_coordinator::{ScaleCoordinator, SharedPointerSerial};
+use crate::wayland::surfaces::window_events::{ScaleSource, WindowStateEvent};
 use slint::LogicalPosition;
 use slint::platform::WindowEvent;
 use std::rc::Rc;
@@ -12,6 +14,7 @@ pub struct InteractionState {
     pointer: ManagedWlPointer,
     event_router: EventRouter,
     scale_coordinator: ScaleCoordinator,
+    event_bus: EventBus,
 }
 
 impl InteractionState {
@@ -25,13 +28,24 @@ impl InteractionState {
             pointer,
             event_router,
             scale_coordinator,
+            event_bus: EventBus::new(),
         }
     }
 
+    pub fn set_event_bus(&mut self, event_bus: EventBus) {
+        self.event_bus = event_bus;
+    }
+
     #[allow(clippy::cast_possible_truncation)]
     pub fn set_current_pointer_position(&mut self, physical_x: f64, physical_y: f64) {
         self.scale_coordinator
             .set_current_pointer_position(physical_x, physical_y);
+
+        self.event_bus
+            .publish(&WindowStateEvent::PointerPositionChanged {
+                physical_x,
+                physical_y,
+            });
     }
 
     pub fn current_pointer_position(&self) -> LogicalPosition {
@@ -44,6 +58,9 @@ impl InteractionState {
 
     pub fn set_last_pointer_serial(&mut self, serial: u32) {
         self.scale_coordinator.set_last_pointer_serial(serial);
+
+        self.event_bus
+            .publish(&WindowStateEvent::PointerSerialUpdated { serial });
     }
 
     pub fn set_shared_pointer_serial(&mut self, shared_serial: Rc<SharedPointerSerial>) {
@@ -65,6 +82,14 @@ impl InteractionState {
 
     #[allow(clippy::cast_precision_loss)]
     pub fn update_scale_factor(&mut self, scale_120ths: u32) -> f32 {
-        self.scale_coordinator.update_scale_factor(scale_120ths)
+        let new_scale = self.scale_coordinator.update_scale_factor(scale_120ths);
+
+        self.event_bus
+            .publish(&WindowStateEvent::ScaleFactorChanged {
+                new_scale,
+                source: ScaleSource::FractionalScale,
+            });
+
+        new_scale
     }
 }

adapters/src/wayland/surfaces/mod.rs

@@ -1,5 +1,6 @@
 pub mod component_state;
 pub mod dimensions;
+pub mod event_bus;
 pub mod event_router;
 pub mod interaction_state;
 pub mod layer_surface;
@@ -10,4 +11,5 @@ pub mod rendering_state;
 pub mod scale_coordinator;
 pub mod surface_builder;
 pub mod surface_state;
+pub mod window_events;
 pub mod window_renderer;

adapters/src/wayland/surfaces/popup_state.rs

@@ -1,11 +1,14 @@
 use crate::wayland::services::popup_service::PopupService;
+use crate::wayland::surfaces::event_bus::EventBus;
 use crate::wayland::surfaces::popup_manager::PopupManager;
+use crate::wayland::surfaces::window_events::WindowStateEvent;
 use slint::PhysicalSize;
 use std::rc::Rc;
 use wayland_protocols::wp::fractional_scale::v1::client::wp_fractional_scale_v1::WpFractionalScaleV1;
 
 pub struct PopupState {
     popup_service: Option<Rc<PopupService>>,
+    event_bus: EventBus,
 }
 
 impl Default for PopupState {
@@ -16,24 +19,36 @@ impl Default for PopupState {
 
 impl PopupState {
     #[must_use]
-    pub const fn new() -> Self {
+    pub fn new() -> Self {
         Self {
             popup_service: None,
+            event_bus: EventBus::new(),
         }
     }
 
+    pub fn set_event_bus(&mut self, event_bus: EventBus) {
+        self.event_bus = event_bus;
+    }
+
     pub fn set_popup_service(&mut self, popup_service: Rc<PopupService>) {
         self.popup_service = Some(popup_service);
+        self.event_bus
+            .publish(&WindowStateEvent::PopupConfigurationChanged);
     }
 
     pub fn set_popup_manager(&mut self, popup_manager: Rc<PopupManager>) {
         self.popup_service = Some(Rc::new(PopupService::new(popup_manager)));
+        self.event_bus
+            .publish(&WindowStateEvent::PopupConfigurationChanged);
     }
 
     pub fn update_output_size(&self, output_size: PhysicalSize) {
         if let Some(popup_service) = &self.popup_service {
             popup_service.update_output_size(output_size);
         }
+
+        self.event_bus
+            .publish(&WindowStateEvent::OutputSizeChanged { output_size });
     }
 
     pub fn update_scale_factor(&self, scale_factor: f32) {

adapters/src/wayland/surfaces/rendering_state.rs

@@ -2,12 +2,15 @@ use std::rc::Rc;
 use crate::errors::Result;
 use crate::rendering::femtovg::main_window::FemtoVGWindow;
 use crate::wayland::surfaces::window_renderer::{WindowRenderer, WindowRendererParams};
+use crate::wayland::surfaces::event_bus::EventBus;
+use crate::wayland::surfaces::window_events::WindowStateEvent;
 use slint::PhysicalSize;
 use smithay_client_toolkit::reexports::protocols_wlr::layer_shell::v1::client::zwlr_layer_surface_v1::ZwlrLayerSurfaceV1;
 use crate::wayland::managed_proxies::ManagedWpFractionalScaleV1;
 
 pub struct RenderingState {
     renderer: WindowRenderer,
+    event_bus: EventBus,
 }
 
 impl RenderingState {
@@ -15,15 +18,25 @@ impl RenderingState {
     pub fn new(params: WindowRendererParams) -> Self {
         Self {
             renderer: WindowRenderer::new(params),
+            event_bus: EventBus::new(),
         }
     }
 
+    pub fn set_event_bus(&mut self, event_bus: EventBus) {
+        self.event_bus = event_bus;
+    }
+
     pub fn render_frame_if_dirty(&self) -> Result<()> {
         self.renderer.render_frame_if_dirty()
     }
 
     pub fn update_size(&mut self, width: u32, height: u32, scale_factor: f32) {
         self.renderer.update_size(width, height, scale_factor);
+
+        self.event_bus.publish(&WindowStateEvent::SizeChanged {
+            logical_width: width,
+            logical_height: height,
+        });
     }
 
     pub const fn size(&self) -> PhysicalSize {

adapters/src/wayland/surfaces/surface_state.rs

@@ -9,6 +9,7 @@ use super::popup_state::PopupState;
 use super::popup_manager::PopupManager;
 use super::scale_coordinator::{ScaleCoordinator, SharedPointerSerial};
 use super::window_renderer::WindowRendererParams;
+use super::event_bus::EventBus;
 use crate::wayland::managed_proxies::{
     ManagedWlPointer, ManagedWlSurface, ManagedZwlrLayerSurfaceV1,
     ManagedWpFractionalScaleV1, ManagedWpViewport,
@@ -35,6 +36,8 @@ pub struct WindowState {
     output_size: PhysicalSize,
     active_popup_key: RefCell<Option<usize>>,
     main_surface: Rc<WlSurface>,
+    #[allow(dead_code)]
+    event_bus: EventBus,
 }
 
 impl WindowState {
@@ -91,7 +94,21 @@ impl WindowState {
         let has_fractional_scale = fractional_scale.is_some();
         let size = builder.size.unwrap_or_default();
 
-        let rendering = RenderingState::new(WindowRendererParams {
+        let main_surface_id = (*surface_rc).id();
+        let event_router = EventRouter::new(Rc::clone(&window), main_surface_id);
+        let scale_coordinator = ScaleCoordinator::new(builder.scale_factor, has_fractional_scale);
+
+        let mut interaction = InteractionState::new(pointer, event_router, scale_coordinator);
+
+        let mut popup = PopupState::new();
+
+        let event_bus = EventBus::new();
+
+        let event_bus_clone_for_rendering = event_bus.clone();
+        let event_bus_clone_for_interaction = event_bus.clone();
+        let event_bus_clone_for_popup = event_bus.clone();
+
+        let mut rendering = RenderingState::new(WindowRendererParams {
             window: Rc::clone(&window),
             surface,
             layer_surface,
@@ -102,15 +119,11 @@ impl WindowState {
             size,
         });
 
-        let main_surface_id = (*surface_rc).id();
-        let event_router = EventRouter::new(Rc::clone(&window), main_surface_id);
-        let scale_coordinator = ScaleCoordinator::new(builder.scale_factor, has_fractional_scale);
+        rendering.set_event_bus(event_bus_clone_for_rendering);
+        interaction.set_event_bus(event_bus_clone_for_interaction);
+        popup.set_event_bus(event_bus_clone_for_popup);
 
-        let interaction = InteractionState::new(pointer, event_router, scale_coordinator);
-
-        let popup = PopupState::new();
-
-        Ok(Self {
+        let mut instance = Self {
             component,
             rendering,
             interaction,
@@ -118,9 +131,17 @@ impl WindowState {
             output_size: builder.output_size.unwrap_or_default(),
             active_popup_key: RefCell::new(None),
             main_surface: surface_rc,
-        })
+            event_bus,
+        };
+
+        instance.setup_event_handlers();
+
+        Ok(instance)
     }
 
+    #[allow(clippy::unused_self)]
+    fn setup_event_handlers(&mut self) {}
+
     pub fn update_size(&mut self, width: u32, height: u32) {
         let scale_factor = self.interaction.scale_factor();
         self.rendering.update_size(width, height, scale_factor);

adapters/src/wayland/surfaces/window_events.rs

@@ -0,0 +1,52 @@
+use slint::PhysicalSize;
+use wayland_client::backend::ObjectId;
+
+#[derive(Debug, Clone)]
+pub enum WindowStateEvent {
+    ScaleFactorChanged {
+        new_scale: f32,
+        source: ScaleSource,
+    },
+
+    SizeChanged {
+        logical_width: u32,
+        logical_height: u32,
+    },
+
+    OutputSizeChanged {
+        output_size: PhysicalSize,
+    },
+
+    PointerPositionChanged {
+        physical_x: f64,
+        physical_y: f64,
+    },
+
+    PointerSerialUpdated {
+        serial: u32,
+    },
+
+    SurfaceEntered {
+        surface_id: ObjectId,
+    },
+
+    SurfaceExited,
+
+    RenderRequested,
+
+    PopupConfigurationChanged,
+}
+
+#[derive(Debug, Clone, Copy)]
+pub enum ScaleSource {
+    FractionalScale,
+    IntegerScale,
+}
+
+pub trait WindowStateEventHandler {
+    fn handle_event(&mut self, event: &WindowStateEvent);
+}
+
+pub trait WindowStateEventEmitter {
+    fn emit_event(&self, event: WindowStateEvent);
+}