event loop: Decouple event timeout from event type

src/event_loop/mod.rs

@@ -44,11 +44,15 @@ pub mod driver;
 // and the loop parametrized over them.
 use crate::main::Commands;
 use crate::state;
-use crate::state::Event;
 use std::cmp;
 use std::time::{ Duration, Instant };
 
 
+pub trait Event: Clone {
+    fn get_timeout_reached(&self) -> Option<Instant>;
+}
+
+
 /// This keeps the state of the tracker loop between iterations
 #[derive(Clone)]
 struct State {
@@ -75,7 +79,7 @@ impl State {
 /// It returns the new state, and the message to send onwards.
 fn handle_event(
     mut loop_state: State,
-    event: Event,
+    event: state::Event,
     now: Instant,
 ) -> (State, Commands) {
     // Calculate changes to send to the consumer,
@@ -93,8 +97,8 @@ fn handle_event(
         .get_commands_to_reach(&new_outcome);
     
     // Timeout events are special: they affect the scheduled timeout.
-    loop_state.scheduled_wakeup = match event {
-        Event::TimeoutReached(when) => {
+    loop_state.scheduled_wakeup = match event.get_timeout_reached() {
+        Some(when) => {
             if when > now {
                 // Special handling for scheduled events coming in early.
                 // Wait at least 10 ms to avoid Zeno's paradox.
@@ -112,7 +116,7 @@ fn handle_event(
                 None
             }
         },
-        _ => loop_state.scheduled_wakeup.clone(),
+        None => loop_state.scheduled_wakeup.clone(),
     };
     
     // Reschedule timeout if the new state calls for it.

src/state.rs

@@ -7,6 +7,7 @@
 
 use crate::animation;
 use crate::debug;
+use crate::event_loop;
 use crate::imservice::{ ContentHint, ContentPurpose };
 use crate::layout::ArrangementKind;
 use crate::main;
@@ -80,6 +81,15 @@ pub enum Event {
     TimeoutReached(Instant),
 }
 
+impl event_loop::Event for Event {
+    fn get_timeout_reached(&self) -> Option<Instant> {
+        match self {
+            Self::TimeoutReached(when) => Some(*when),
+            _ => None,
+        }
+    }
+}
+
 impl From<InputMethod> for Event {
     fn from(im: InputMethod) -> Self {
         Self::InputMethod(im)