shell: trigger re-render when surface disappears

src/main.rs

@@ -7,6 +7,7 @@ use smithay::reexports::{
 
 use anyhow::{Context, Result};
 use slog::Drain;
+use std::sync::atomic::Ordering;
 
 pub mod backend;
 pub mod input;
@@ -42,12 +43,18 @@ fn main() -> Result<()> {
             return;
         }
 
-        // trigger routines
-        state.common.spaces.refresh();
+        // do we need to trigger another render
+        if state.common.dirty_flag.swap(false, Ordering::SeqCst) {
+            for output in state.common.spaces.outputs() {
+                state.backend.schedule_render(output)
+            }
+        }
 
         // send out events
         let display = state.common.display.clone();
         display.borrow_mut().flush_clients(state);
+        // trigger routines
+        state.common.spaces.refresh();
     })?;
 
     Ok(())

src/shell/mod.rs

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-3.0-only
 
-use crate::{input::active_output, state::State};
+use crate::{input::active_output, state::State, utils::SurfaceDropNotifier};
 use smithay::{
     backend::renderer::utils::on_commit_buffer_handler,
     desktop::{
@@ -342,6 +342,11 @@ fn commit(surface: &WlSurface, state: &mut State) {
     }
 
     let state = &mut state.common;
+    let _ = with_states(surface, |states| {
+        states
+            .data_map
+            .insert_if_missing(|| SurfaceDropNotifier::from(&*state));
+    });
 
     if let Some(toplevel) = state.pending_toplevels.iter().find(|toplevel| {
         toplevel

src/state.rs

@@ -18,7 +18,12 @@ use smithay::{
     },
 };
 
-use std::{cell::RefCell, rc::Rc, time::Instant};
+use std::{
+    cell::RefCell,
+    rc::Rc,
+    sync::{atomic::AtomicBool, Arc},
+    time::Instant,
+};
 #[cfg(feature = "debug")]
 use std::{collections::VecDeque, time::Duration};
 
@@ -34,6 +39,7 @@ pub struct Common {
     pub spaces: Workspaces,
     pub shell: ShellStates,
     pub pending_toplevels: Vec<ToplevelSurface>,
+    pub dirty_flag: Arc<AtomicBool>,
 
     pub seats: Vec<Seat>,
     pub last_active_seat: Seat,
@@ -125,6 +131,7 @@ impl State {
                 spaces: Workspaces::new(),
                 shell: shell_handles,
                 pending_toplevels: Vec::new(),
+                dirty_flag: Arc::new(AtomicBool::new(false)),
 
                 seats: vec![initial_seat.clone()],
                 last_active_seat: initial_seat,

src/utils.rs

@@ -1,7 +1,13 @@
 // SPDX-License-Identifier: GPL-3.0-only
 
 use smithay::reexports::wayland_server::{Global, Interface, Resource};
-use std::convert::{AsRef, From};
+use std::{
+    convert::{AsRef, From},
+    sync::{
+        atomic::{AtomicBool, Ordering},
+        Arc,
+    },
+};
 
 pub struct GlobalDrop<I: Interface + AsRef<Resource<I>> + From<Resource<I>>>(Option<Global<I>>);
 
@@ -18,3 +24,20 @@ impl<I: Interface + AsRef<Resource<I>> + From<Resource<I>>> Drop for GlobalDrop<
         }
     }
 }
+
+// This hack will hopefully will be superseeded by a better solution, when smithay transitions to wayland-rs 0.30.
+// But until then there is not really a better way to schedule a repaint on surface destruction
+#[derive(Debug)]
+pub struct SurfaceDropNotifier(Arc<AtomicBool>);
+
+impl From<&crate::state::Common> for SurfaceDropNotifier {
+    fn from(state: &crate::state::Common) -> Self {
+        SurfaceDropNotifier(state.dirty_flag.clone())
+    }
+}
+
+impl Drop for SurfaceDropNotifier {
+    fn drop(&mut self) {
+        self.0.store(true, Ordering::SeqCst);
+    }
+}