Overhaul resize presentation and wallpaper rendering

Coordinate native-pixel resize handoffs, fractional geometry and shared animation timing. Delegate wallpaper rendering to the compositor, advertise DMA-BUF device feedback, and improve callback pacing and render metrics.

Handle monitor-local shell surfaces, lid-driven output evacuation and workspace restoration.

compositor/src/resize_transaction.rs

@@ -0,0 +1,78 @@
+//! A presentation barrier, not an event-loop or client-commit blocker.
+//! Grouping barriers by workspace keeps viewport and neighboring tiles on the
+//! same clock. A serial identifies readiness even for cell-grid clients whose
+//! committed size is smaller than the configure, and after rapid reversals.
+use std::time::Duration;
+
+use smithay::utils::{Logical, Rectangle, Serial};
+
+const DEADLINE: Duration = Duration::from_millis(300);
+
+#[derive(Clone, Copy, Debug)]
+pub(crate) struct ResizeTransaction {
+    serial: Serial,
+    started: Duration,
+    source_geometry: Option<Rectangle<i32, Logical>>,
+}
+
+impl ResizeTransaction {
+    pub(crate) fn new(serial: Serial, started: Duration) -> Self {
+        Self {
+            serial,
+            started,
+            source_geometry: None,
+        }
+    }
+
+    pub(crate) fn with_source_geometry(mut self, geometry: Rectangle<i32, Logical>) -> Self {
+        self.source_geometry = Some(geometry);
+        self
+    }
+    pub(crate) fn source_geometry(self) -> Option<Rectangle<i32, Logical>> {
+        self.source_geometry
+    }
+
+    pub(crate) fn accepts(self, committed: Option<Serial>) -> bool {
+        committed.is_some_and(|serial| serial >= self.serial)
+    }
+
+    pub(crate) fn expired(self, now: Duration) -> bool {
+        now.saturating_sub(self.started) >= DEADLINE
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn acknowledgement_alone_or_stale_commit_does_not_release_resize() {
+        let transaction = ResizeTransaction::new(12.into(), Duration::ZERO);
+        assert!(!transaction.accepts(None));
+        assert!(!transaction.accepts(Some(11.into())));
+        assert!(transaction.accepts(Some(12.into())));
+        assert!(transaction.accepts(Some(13.into())));
+    }
+
+    #[test]
+    fn serial_comparison_handles_wraparound() {
+        let transaction = ResizeTransaction::new(u32::MAX.into(), Duration::ZERO);
+        assert!(transaction.accepts(Some(0.into())));
+        assert!(!transaction.accepts(Some((u32::MAX - 1).into())));
+    }
+
+    #[test]
+    fn unresponsive_client_has_bounded_wait() {
+        let transaction = ResizeTransaction::new(1.into(), Duration::from_millis(10));
+        assert!(!transaction.expired(Duration::from_millis(309)));
+        assert!(transaction.expired(Duration::from_millis(310)));
+    }
+
+    #[test]
+    fn shrinking_commit_retains_the_previous_full_frame_geometry() {
+        let source = Rectangle::new((4, 8).into(), (1200, 800).into());
+        let transaction =
+            ResizeTransaction::new(1.into(), Duration::ZERO).with_source_geometry(source);
+        assert_eq!(transaction.source_geometry(), Some(source));
+    }
+}