Invalidate blur from per-output sampled backdrop damage

compositor/src/handlers/compositor.rs

@@ -14,29 +14,6 @@ use super::{layer_shell, xdg_shell};
 use crate::Ferese;
 use crate::state::ClientState;
 
-fn layer_affects_backdrop(layer: smithay::wayland::shell::wlr_layer::Layer) -> bool {
-    matches!(
-        layer,
-        smithay::wayland::shell::wlr_layer::Layer::Background | smithay::wayland::shell::wlr_layer::Layer::Bottom
-    )
-}
-
-impl Ferese {
-    fn surface_affects_backdrop(&self, surface: &WlSurface) -> bool {
-        let mut root = surface.clone();
-        while let Some(parent) = get_parent(&root) {
-            root = parent;
-        }
-        if matches!(&self.cursor_status, smithay::input::pointer::CursorImageStatus::Surface(cursor) if cursor == &root)
-        {
-            return false;
-        }
-        self.space
-            .layer_for_surface(&root, smithay::desktop::WindowSurfaceType::ALL)
-            .is_none_or(|layer| layer_affects_backdrop(layer.cached_state().layer))
-    }
-}
-
 impl CompositorHandler for Ferese {
     fn compositor_state(&mut self) -> &mut CompositorState {
         &mut self.compositor_state
@@ -60,9 +37,6 @@ impl CompositorHandler for Ferese {
     fn commit(&mut self, surface: &WlSurface) {
         self.update_surface_preferences(surface);
         self.capture_resize_before_commit(surface);
-        if self.surface_affects_backdrop(surface) {
-            self.backdrop_generation = self.backdrop_generation.wrapping_add(1);
-        }
         on_commit_buffer_handler::<Self>(surface);
         if !is_sync_subsurface(surface) {
             let mut root = surface.clone();
@@ -109,7 +83,7 @@ impl CompositorHandler for Ferese {
                 .retain(|_, lock| lock.wl_surface() != surface);
             self.focus_lock_surface();
         }
-        self.backdrop_generation = self.backdrop_generation.wrapping_add(1);
+
         crate::backends::direct::render_surface(self, surface);
         if self.idle_inhibitors.remove(surface).is_some() {
             self.refresh_idle_inhibition();
@@ -142,17 +116,3 @@ impl ShmHandler for Ferese {
         &self.shm_state
     }
 }
-
-#[cfg(test)]
-mod tests {
-    use smithay::wayland::shell::wlr_layer::Layer;
-
-    use super::*;
-    #[test]
-    fn panel_commits_do_not_invalidate_their_own_backdrop() {
-        assert!(!layer_affects_backdrop(Layer::Top));
-        assert!(!layer_affects_backdrop(Layer::Overlay));
-        assert!(layer_affects_backdrop(Layer::Bottom));
-        assert!(layer_affects_backdrop(Layer::Background));
-    }
-}

compositor/src/main.rs

@@ -115,9 +115,6 @@ fn main() -> Result<(), Box<dyn Error>> {
         // The decoder wakes the loop after publishing its result, including
         // when no output has a pending frame.
         let wallpaper_changed = state.wallpaper.poll();
-        if wallpaper_changed {
-            state.backdrop_generation = state.backdrop_generation.wrapping_add(1);
-        }
         // All input/Wayland callbacks have returned, releasing seat locks.
         if state.focus_cycle.is_some() && (state.session_lock.active || state.input_capture.captures(1)) {
             state.cancel_focus_cycle();

compositor/src/render/backdrop.rs

@@ -0,0 +1,228 @@
+use super::*;
+
+#[derive(Debug, Default)]
+pub(super) struct Backdrop {
+    pub commit: CommitCounter,
+    sources: Vec<Source>,
+    region: Option<Rectangle<i32, Physical>>,
+}
+
+#[derive(Debug)]
+struct Source {
+    id: Id,
+    commit: CommitCounter,
+    geometry: Rectangle<i32, Physical>,
+    alpha: f32,
+    src: Rectangle<f64, Buffer>,
+    transform: Transform,
+    visible: Vec<Rectangle<i32, Physical>>,
+}
+
+impl Backdrop {
+    fn update<E: Element>(
+        &mut self,
+        elements: &[E],
+        region: Rectangle<i32, Physical>,
+        scale: RenderScale<f64>,
+    ) -> bool {
+        let mut uncovered = vec![region];
+        let mut sources = Vec::new();
+        let mut changed = self.region != Some(region);
+
+        for element in elements {
+            let geometry = element.geometry(scale);
+            let visible = uncovered
+                .iter()
+                .filter_map(|rect| rect.intersection(geometry))
+                .collect::<Vec<_>>();
+            if visible.is_empty() || element.alpha() == 0.0 {
+                continue;
+            }
+
+            let previous = self.sources.iter().find(|source| &source.id == element.id());
+            changed |= previous.is_none_or(|source| {
+                source.geometry != geometry
+                    || source.alpha != element.alpha()
+                    || source.src != element.src()
+                    || source.transform != element.transform()
+                    || source.visible != visible
+            });
+            if let Some(previous) = previous {
+                changed |= element.damage_since(scale, Some(previous.commit)).iter().any(|damage| {
+                    let damage = Rectangle::new(damage.loc + geometry.loc, damage.size);
+                    visible.iter().any(|rect| rect.overlaps(damage))
+                });
+            }
+
+            sources.push(Source {
+                id: element.id().clone(),
+                commit: element.current_commit(),
+                geometry,
+                alpha: element.alpha(),
+                src: element.src(),
+                transform: element.transform(),
+                visible,
+            });
+            if element.alpha() == 1.0 {
+                for opaque in element.opaque_regions(scale).iter() {
+                    let opaque = Rectangle::new(opaque.loc + geometry.loc, opaque.size);
+                    uncovered = uncovered
+                        .into_iter()
+                        .flat_map(|rect| rect.subtract_rect(opaque))
+                        .collect();
+                }
+            }
+        }
+
+        // Membership and stacking changes matter even without buffer damage.
+        changed |= !self
+            .sources
+            .iter()
+            .map(|source| &source.id)
+            .eq(sources.iter().map(|source| &source.id));
+        self.sources = sources;
+        self.region = Some(region);
+        if changed {
+            self.commit.increment();
+        }
+
+        changed
+    }
+}
+
+pub(super) fn update(elements: &[AnimatedWindowRenderElement], scale: f64) {
+    // Resolve lower blurs first so their damage propagates to higher materials.
+    for (index, element) in elements.iter().enumerate().rev() {
+        if let AnimatedWindowRenderElement::Blur(blur) = element {
+            let changed =
+                blur.backdrop
+                    .lock()
+                    .unwrap()
+                    .update(&elements[index + 1..], blur.geometry(scale.into()), scale.into());
+            if changed {
+                blur.capture_dirty.store(true, Ordering::Relaxed);
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    struct TestElement {
+        id: Id,
+        commit: CommitCounter,
+        rect: Rectangle<i32, Physical>,
+        damage: Vec<Rectangle<i32, Physical>>,
+        opaque: bool,
+        alpha: f32,
+    }
+
+    impl TestElement {
+        fn new(rect: Rectangle<i32, Physical>) -> Self {
+            Self {
+                id: Id::new(),
+                commit: CommitCounter::default(),
+                rect,
+                damage: vec![],
+                opaque: false,
+                alpha: 1.0,
+            }
+        }
+
+        fn repaint(&mut self, damage: Vec<Rectangle<i32, Physical>>) {
+            self.commit.increment();
+            self.damage = damage;
+        }
+    }
+
+    impl Element for TestElement {
+        fn id(&self) -> &Id {
+            &self.id
+        }
+        fn current_commit(&self) -> CommitCounter {
+            self.commit
+        }
+        fn src(&self) -> Rectangle<f64, Buffer> {
+            Rectangle::from_size((100.0, 100.0).into())
+        }
+        fn geometry(&self, _: RenderScale<f64>) -> Rectangle<i32, Physical> {
+            self.rect
+        }
+        fn damage_since(&self, _: RenderScale<f64>, commit: Option<CommitCounter>) -> DamageSet<i32, Physical> {
+            if commit == Some(self.commit) {
+                DamageSet::default()
+            } else {
+                DamageSet::from_slice(&self.damage)
+            }
+        }
+        fn opaque_regions(&self, _: RenderScale<f64>) -> OpaqueRegions<i32, Physical> {
+            if self.opaque {
+                OpaqueRegions::from_slice(&[Rectangle::from_size(self.rect.size)])
+            } else {
+                OpaqueRegions::default()
+            }
+        }
+        fn alpha(&self) -> f32 {
+            self.alpha
+        }
+    }
+
+    fn rect(x: i32, y: i32, w: i32, h: i32) -> Rectangle<i32, Physical> {
+        Rectangle::new((x, y).into(), (w, h).into())
+    }
+
+    #[test]
+    fn only_damage_intersecting_the_sample_invalidates_its_output() {
+        let mut first = Backdrop::default();
+        let mut second = Backdrop::default();
+        let region = rect(20, 20, 30, 30);
+        let mut a = TestElement::new(rect(0, 0, 100, 100));
+        let b = TestElement::new(rect(0, 0, 100, 100));
+        assert!(first.update(&[&a], region, 1.0.into()));
+        assert!(second.update(&[&b], region, 1.0.into()));
+
+        a.repaint(vec![]);
+        assert!(!first.update(&[&a], region, 1.0.into()));
+        a.repaint(vec![rect(60, 60, 10, 10)]);
+        assert!(!first.update(&[&a], region, 1.0.into()));
+        a.repaint(vec![rect(25, 25, 1, 1)]);
+        assert!(first.update(&[&a], region, 1.0.into()));
+        assert!(!second.update(&[&b], region, 1.0.into()));
+        assert!(!first.update(&[&a], region, 1.0.into()));
+    }
+
+    #[test]
+    fn opaque_occlusion_hides_damage_but_fading_and_moving_reveal_it() {
+        let mut backdrop = Backdrop::default();
+        let region = rect(0, 0, 100, 100);
+        let mut front = TestElement::new(rect(0, 0, 50, 100));
+        front.opaque = true;
+        let mut back = TestElement::new(region);
+        assert!(backdrop.update(&[&front, &back], region, 1.0.into()));
+
+        back.repaint(vec![rect(10, 10, 10, 10)]);
+        assert!(!backdrop.update(&[&front, &back], region, 1.0.into()));
+        front.alpha = 0.5;
+        assert!(backdrop.update(&[&front, &back], region, 1.0.into()));
+        back.repaint(vec![rect(10, 10, 10, 10)]);
+        assert!(backdrop.update(&[&front, &back], region, 1.0.into()));
+        front.rect.loc.x = 20;
+        assert!(backdrop.update(&[&front, &back], region, 1.0.into()));
+        assert!(!backdrop.update(&[&front, &back], region, 1.0.into()));
+    }
+
+    #[test]
+    fn membership_and_stacking_changes_invalidate_without_buffer_damage() {
+        let mut backdrop = Backdrop::default();
+        let region = rect(0, 0, 100, 100);
+        let a = TestElement::new(region);
+        let b = TestElement::new(region);
+        assert!(backdrop.update(&[&a, &b], region, 1.0.into()));
+        assert!(backdrop.update(&[&b, &a], region, 1.0.into()));
+        assert!(backdrop.update(&[&a], region, 1.0.into()));
+        assert!(backdrop.update(&[&a, &b], region, 1.0.into()));
+        assert!(!backdrop.update(&[&a, &b], region, 1.0.into()));
+    }
+}

compositor/src/render/materials.rs

@@ -46,7 +46,8 @@ pub(super) fn append_material_surface(
         })
         .collect();
     if let Some(buffers) = state.render.surfaces.get_mut(surface) {
-        buffers.contexts.retain(|(_, index), _| *index < targets.len());
+        buffers.contexts.retain(|(_, _, index), _| *index < targets.len());
+        buffers.captures.retain(|(_, _, index), _| *index < targets.len());
     }
     let material = (!materials.is_empty() && regions.is_none()).then_some(());
     let clip = material.as_ref().and_then(|_| {
@@ -181,7 +182,6 @@ pub(super) fn material_element(
         presentation_alpha,
         background_opacity,
         blur: (blur * scale) as f32,
-        scene_generation: if blur > 0.0 { state.backdrop_generation } else { 0 },
         sample_geometry,
         sample_physical,
         sample_framebuffer: framebuffer_clip_rect(sample_physical, mode.size, transform),
@@ -202,11 +202,13 @@ pub(super) fn material_element(
         .flatten();
     let capture_rect = framebuffer_capture_rect(parameters.sample_framebuffer);
     let capture_size = Size::from((capture_rect[2], capture_rect[3]));
+    let output_id = state.output_id(output)?;
+    let capture_key = (context.clone(), output_id, index);
     let buffers = state.render.surfaces.entry(surface.clone()).or_default();
     let capture = if let Some(blur_program) = blur_program {
         if buffers
             .captures
-            .get(&context)
+            .get(&capture_key)
             .is_none_or(|c| c.geometry != sample_geometry || c.texture.size() != capture_size)
         {
             let texture = Offscreen::<GlesTexture>::create_buffer(renderer, Fourcc::Abgr8888, capture_size)
@@ -217,7 +219,7 @@ pub(super) fn material_element(
                 .ok();
             if let Some(texture) = texture {
                 buffers.captures.insert(
-                    context.clone(),
+                    capture_key.clone(),
                     BlurCapture {
                         texture,
                         dirty: Arc::new(AtomicBool::new(true)),
@@ -225,16 +227,16 @@ pub(super) fn material_element(
                     },
                 );
             } else {
-                buffers.captures.remove(&context);
+                buffers.captures.remove(&capture_key);
             }
         }
         buffers
             .captures
-            .get(&context)
+            .get(&capture_key)
             .cloned()
             .map(|capture| (capture, blur_program))
     } else {
-        buffers.captures.remove(&context);
+        buffers.captures.remove(&capture_key);
         None
     };
     if capture.is_some() {
@@ -261,7 +263,7 @@ pub(super) fn material_element(
     };
     let cached = buffers
         .contexts
-        .entry((context, index))
+        .entry((context, output_id, index))
         .or_insert_with(|| CachedMaterial {
             element: make_element(),
             parameters: parameters.clone(),
@@ -284,8 +286,15 @@ pub(super) fn material_element(
         cached.element = make_element();
     }
     if cached.parameters != parameters {
+        if cached.parameters.shadow_rect != parameters.shadow_rect
+            || cached.parameters.shadow_values != parameters.shadow_values
+            || cached.parameters.shadow_bounds != parameters.shadow_bounds
+            || cached.parameters.radius != parameters.radius
+            || cached.parameters.visible_framebuffer != parameters.visible_framebuffer
+        {
             cached.shadow.resize(parameters.shadow_bounds, None);
             cached.shadow.update_uniforms(decoration_uniforms(&parameters, 2.0));
+        }
         match &mut cached.element {
             MaterialElement::Fill(element) => {
                 element.resize(

compositor/src/render/mod.rs

@@ -1,3 +1,4 @@
+mod backdrop;
 mod capture;
 mod decorations;
 mod materials;
@@ -130,7 +131,7 @@ struct BlurRenderElement {
     texture: GlesTexture,
     program: GlesTexProgram,
     id: Id,
-    commit: CommitCounter,
+    backdrop: Arc<std::sync::Mutex<backdrop::Backdrop>>,
     geometry: Rectangle<i32, Logical>,
     capture_rect: [i32; 4],
     uniforms: Arc<[Uniform<'static>]>,
@@ -148,7 +149,7 @@ impl BlurRenderElement {
             texture,
             program,
             id: Id::new(),
-            commit: CommitCounter::default(),
+            backdrop: Arc::default(),
             geometry: parameters.sample_geometry,
             capture_rect: framebuffer_capture_rect(parameters.sample_framebuffer),
             uniforms: blur_uniforms(parameters).into(),
@@ -156,11 +157,13 @@ impl BlurRenderElement {
     }
 
     fn update(&mut self, parameters: &MaterialParameters) {
+        if self.capture_rect != framebuffer_capture_rect(parameters.sample_framebuffer) {
             self.capture_dirty.store(true, Ordering::Relaxed);
+        }
         self.geometry = parameters.sample_geometry;
         self.capture_rect = framebuffer_capture_rect(parameters.sample_framebuffer);
         self.uniforms = blur_uniforms(parameters).into();
-        self.commit.increment();
+        self.backdrop.lock().unwrap().commit.increment();
     }
 }
 
@@ -170,7 +173,7 @@ impl Element for BlurRenderElement {
     }
 
     fn current_commit(&self) -> CommitCounter {
-        self.commit
+        self.backdrop.lock().unwrap().commit
     }
 
     fn src(&self) -> Rectangle<f64, Buffer> {
@@ -182,7 +185,7 @@ impl Element for BlurRenderElement {
     }
 
     fn damage_since(&self, scale: RenderScale<f64>, commit: Option<CommitCounter>) -> DamageSet<i32, Physical> {
-        blur_damage(self.geometry(scale).size, self.commit, commit)
+        blur_damage(self.geometry(scale).size, self.current_commit(), commit)
     }
 
     fn opaque_regions(&self, _scale: RenderScale<f64>) -> OpaqueRegions<i32, Physical> {
@@ -311,7 +314,6 @@ struct MaterialParameters {
     presentation_alpha: f32,
     background_opacity: f32,
     blur: f32,
-    scene_generation: u64,
     sample_geometry: Rectangle<i32, Logical>,
     sample_physical: Rectangle<i32, Physical>,
     sample_framebuffer: [f32; 4],
@@ -341,8 +343,8 @@ struct CachedMaterial {
 
 #[derive(Debug, Default)]
 pub(crate) struct MaterialBuffers {
-    contexts: HashMap<(ErasedContextId, usize), CachedMaterial>,
+    contexts: HashMap<(ErasedContextId, ferese_core::OutputId, usize), CachedMaterial>,
-    captures: HashMap<ErasedContextId, BlurCapture>,
+    captures: HashMap<(ErasedContextId, ferese_core::OutputId, usize), BlurCapture>,
 }
 
 #[derive(Clone, Debug, PartialEq)]

compositor/src/render/resources.rs

@@ -38,6 +38,10 @@ impl RenderResources {
 
     pub fn remove_output(&mut self, id: OutputId) {
         self.outputs.remove(&id);
+        for surface in self.surfaces.values_mut() {
+            surface.contexts.retain(|(_, output, _), _| *output != id);
+            surface.captures.retain(|(_, output, _), _| *output != id);
+        }
     }
 
     pub fn snapshot(&self, id: &WindowId) -> Option<&ResizeSnapshot> {
@@ -105,8 +109,8 @@ impl RenderResources {
         }
 
         for surface in self.surfaces.values_mut() {
-            surface.contexts.retain(|(id, _), _| id != context);
+            surface.contexts.retain(|(id, _, _), _| id != context);
-            surface.captures.remove(context);
+            surface.captures.retain(|(id, _, _), _| id != context);
         }
     }
 }

compositor/src/render/scene.rs

@@ -340,6 +340,7 @@ pub(crate) fn sampled_output_elements(
         }
         elements.push(previous.into());
     }
+    backdrop::update(&elements, scale);
     elements
 }
 

compositor/src/state.rs

@@ -346,7 +346,6 @@ pub struct Ferese {
     pub(crate) pending_logout: Option<u32>,
     pub(crate) logout_query: Option<u32>,
     pub(crate) logout_owner: Option<ObjectId>,
-    pub(crate) backdrop_generation: u64,
     viewport_animations: HashMap<WorkspaceId, AnimatedValue>,
     paused_workspaces: HashSet<WorkspaceId>,
     #[cfg(feature = "resize-metrics")]
@@ -576,7 +575,6 @@ impl Ferese {
             pending_logout: None,
             logout_query: None,
             logout_owner: None,
-            backdrop_generation: 0,
             viewport_animations: HashMap::new(),
             paused_workspaces: HashSet::new(),
             #[cfg(feature = "resize-metrics")]
@@ -761,7 +759,7 @@ impl Ferese {
 
         self.overview.set_font_family(config.overview_font_family);
         self.wallpaper.reload(config.wallpaper);
-        self.backdrop_generation = self.backdrop_generation.wrapping_add(1);
+
         self.relayout();
         crate::backends::direct::render_all(self);
 

compositor/src/state/animation.rs

@@ -468,9 +468,7 @@ impl Ferese {
         self.refresh_workspace_slide_offsets();
         self.sync_window_stacking();
 
-        if active_animation || dim_changed {
+        active_animation |= dim_changed;
-            self.backdrop_generation = self.backdrop_generation.wrapping_add(1);
-        }
         active_animation
     }
 

compositor/src/state/layout.rs

@@ -238,7 +238,7 @@ impl Ferese {
             }
         }
 
-        let mut layout_changed = self.unmap_invisible_windows(&visible);
+        self.unmap_invisible_windows(&visible);
 
         let now = self.start_time.elapsed();
 
@@ -268,7 +268,6 @@ impl Ferese {
             } else {
                 PresentationMode::Normal
             };
-            layout_changed |= !had_geometry || geometry.logical != rect;
             let mut requested_size = geometry.set_presentation_mode(rect, mode, now);
             if !was_mapped && (had_geometry || is_fullscreen) {
                 geometry.settle_presentation();
@@ -405,10 +404,6 @@ impl Ferese {
             }
         }
 
-        if layout_changed {
-            self.backdrop_generation = self.backdrop_generation.wrapping_add(1);
-        }
-
         self.sync_window_stacking();
         self.retarget_overview();
         self.send_shell_snapshots();

compositor/src/state/navigation.rs

@@ -71,7 +71,7 @@ impl Ferese {
         if let Some(swipe) = &mut self.focus_swipe {
             swipe.progress = progress;
         }
-        self.backdrop_generation = self.backdrop_generation.wrapping_add(1);
+
         if let Some(output) = self
             .focus_swipe
             .as_ref()
@@ -440,7 +440,7 @@ impl Ferese {
                 .expect("gesture output exists")
                 .held_progress = Some(progress);
             self.refresh_workspace_slide_offsets();
-            self.backdrop_generation = self.backdrop_generation.wrapping_add(1);
+
             if let Some(output) = self.outputs_by_id.get(&output).cloned() {
                 self.defer_output_redraw(output);
             }
@@ -464,7 +464,7 @@ impl Ferese {
         slide.gesture = Some((from, to, direction));
         self.workspace_slides.insert(output, slide);
         self.swipe.mark_preview_started();
-        self.backdrop_generation = self.backdrop_generation.wrapping_add(1);
+
         self.relayout();
     }
 

compositor/src/theme.rs

@@ -565,7 +565,7 @@ impl Ferese {
             self.theme_settings = Config::resolved_theme_settings(&presented).expect("validated resolved theme");
             self.theme_engine.snapshot.presented = presented;
             self.theme_engine.publish();
-            self.backdrop_generation = self.backdrop_generation.wrapping_add(1);
+
             if complete {
                 self.theme_engine.transition = None;
             }

compositor/src/winit.rs

@@ -95,7 +95,6 @@ pub fn init(event_loop: &mut EventLoop<Ferese>, state: &mut Ferese) -> Result<()
             let mut backend = backend.borrow_mut();
             match event {
                 WinitEvent::Resized { size, scale_factor } => {
-                    state.backdrop_generation = state.backdrop_generation.wrapping_add(1);
                     let scale = normalized_scale(scale_factor);
                     let rate = backend
                         .window()