From 1bf1e33317b8da299ffd9a620e7e0e099c0c3478 Mon Sep 17 00:00:00 2001
From: Ashley Wulber <ashley@system76.com>
Date: Tue, 14 Apr 2026 14:47:25 -0400
Subject: [PATCH] improv(wayland): handle capabilities for
 ext_background_effect

---
 .../wayland/event_loop/state.rs               |  7 +++
 .../wayland/handlers/ext_background_effect.rs | 50 +++++++++++++++++--
 2 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/winit/src/platform_specific/wayland/event_loop/state.rs b/winit/src/platform_specific/wayland/event_loop/state.rs
index 68de367f..f99e48ba 100644
--- a/winit/src/platform_specific/wayland/event_loop/state.rs
+++ b/winit/src/platform_specific/wayland/event_loop/state.rs
@@ -1647,6 +1647,13 @@ impl SctkState {
                 }
             }
             Action::BlurSurface(id, rectangles) => {
+                use wayland_protocols::ext::background_effect::v1::client::ext_background_effect_manager_v1;
+
+                if let Some(bg_effect_mgr) = self.ext_background_effect_manager.as_mut() && !bg_effect_mgr.capabilities().contains(ext_background_effect_manager_v1::Capability::Blur) {
+                    bg_effect_mgr.enqueue(id, rectangles.clone());
+                    return Ok(());
+                }
+                
                 let s = if let Some(s) = self.popups.iter().find(|s| s.data.id == id) {
                     s.popup.wl_surface()
                 } else if let Some(s) = self.layer_surfaces.iter().find(|s| s.id == id) {
diff --git a/winit/src/platform_specific/wayland/handlers/ext_background_effect.rs b/winit/src/platform_specific/wayland/handlers/ext_background_effect.rs
index 3e33d9a1..03a80da9 100644
--- a/winit/src/platform_specific/wayland/handlers/ext_background_effect.rs
+++ b/winit/src/platform_specific/wayland/handlers/ext_background_effect.rs
@@ -1,16 +1,23 @@
+use std::collections::HashMap;
+
 use cctk::sctk;
+use iced_runtime::core::Rectangle;
+use iced_runtime::platform_specific::wayland::Action;
 use sctk::globals::GlobalData;
 use sctk::reexports::client::globals::{BindError, GlobalList};
 use sctk::reexports::client::protocol::wl_surface::WlSurface;
 use sctk::reexports::client::{Connection, Dispatch, Proxy, QueueHandle, delegate_dispatch};
-use wayland_protocols::ext::background_effect::v1::client::ext_background_effect_manager_v1::ExtBackgroundEffectManagerV1;
+use wayland_protocols::ext::background_effect::v1::client::ext_background_effect_manager_v1::{Capability, Event, ExtBackgroundEffectManagerV1};
 use wayland_protocols::ext::background_effect::v1::client::ext_background_effect_surface_v1::ExtBackgroundEffectSurfaceV1;
 
 use crate::event_loop::state::SctkState;
+use crate::window;
 
 #[derive(Debug, Clone)]
 pub struct ExtBackgroundEffectManager {
     manager: ExtBackgroundEffectManagerV1,
+    capabilities: Capability,
+    queued_blur_actions: HashMap<window::Id, Option<Vec<Rectangle>>>,
 }
 
 impl ExtBackgroundEffectManager {
@@ -19,7 +26,11 @@ impl ExtBackgroundEffectManager {
         queue_handle: &QueueHandle<SctkState>,
     ) -> Result<Self, BindError> {
         let manager = globals.bind(queue_handle, 1..=1, GlobalData)?;
-        Ok(Self { manager })
+        Ok(Self {
+            manager,
+            capabilities: Capability::empty(),
+            queued_blur_actions: HashMap::new(),
+        })
     }
 
     pub fn blur(
@@ -30,19 +41,50 @@ impl ExtBackgroundEffectManager {
         self.manager
             .get_background_effect(surface, queue_handle, ())
     }
+
+    pub fn enqueue(&mut self, id: window::Id, rects: Option<Vec<Rectangle>>) {
+        _ = self.queued_blur_actions.insert(id, rects);
+    }
+
+    pub fn capabilities(&self) -> Capability {
+        self.capabilities
+    }
 }
 
 impl Dispatch<ExtBackgroundEffectManagerV1, GlobalData, SctkState>
     for ExtBackgroundEffectManager
 {
     fn event(
-        _: &mut SctkState,
+        state: &mut SctkState,
         _: &ExtBackgroundEffectManagerV1,
-        _: <ExtBackgroundEffectManagerV1 as Proxy>::Event,
+        event: <ExtBackgroundEffectManagerV1 as Proxy>::Event,
         _: &GlobalData,
         _: &Connection,
         _: &QueueHandle<SctkState>,
     ) {
+        match event {
+            Event::Capabilities { flags } => match flags {
+                wayland_client::WEnum::Value(capability) => {
+                    let mut queued_actions = Vec::new();
+                    if let Some(bg_effect_mgr) =
+                        state.ext_background_effect_manager.as_mut()
+                    {
+                        bg_effect_mgr.capabilities = capability;
+                        queued_actions =
+                            bg_effect_mgr.queued_blur_actions.drain().collect();
+                    }
+                    for (id, rects) in queued_actions {
+                        _ = state.handle_action(Action::BlurSurface(id, rects));
+                    }
+                }
+                wayland_client::WEnum::Unknown(u) => {
+                    log::warn!("Unknown value: {u:?}");
+                }
+            },
+            e => {
+                log::warn!("Ignored event {e:?}");
+            }
+        }
     }
 }