wayland/decoration: Make default decoration mode configurable

cosmic-comp-config/src/lib.rs

@@ -66,6 +66,13 @@ impl Default for AppearanceConfig {
     }
 }
 
+#[derive(Copy, Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
+pub enum DecorationPreference {
+    #[default]
+    ClientSide,
+    ServerSide,
+}
+
 #[derive(Clone, Debug, PartialEq, CosmicConfigEntry)]
 #[version = 1]
 pub struct CosmicCompConfig {
@@ -104,6 +111,7 @@ pub struct CosmicCompConfig {
     /// Briefly magnify the cursor when the pointer is shaken, to help locate it
     pub cursor_shake_to_find: bool,
     pub activation_policy: ActivationPolicy,
+    pub decoration_preference: DecorationPreference,
 }
 
 impl Default for CosmicCompConfig {
@@ -143,6 +151,7 @@ impl Default for CosmicCompConfig {
             cursor_hide_timeout: None,
             cursor_shake_to_find: true,
             activation_policy: ActivationPolicy::default(),
+            decoration_preference: DecorationPreference::default(),
         }
     }
 }

src/config/mod.rs

@@ -49,8 +49,8 @@ mod types;
 use cosmic::config::CosmicTk;
 pub use cosmic_comp_config::EdidProduct;
 use cosmic_comp_config::{
-    ActivationPolicy, AppearanceConfig, CosmicCompConfig, KeyboardConfig, TileBehavior, XkbConfig,
+    ActivationPolicy, AppearanceConfig, CosmicCompConfig, DecorationPreference, KeyboardConfig,
-    XwaylandDescaling, XwaylandEavesdropping, ZoomConfig,
+    TileBehavior, XkbConfig, XwaylandDescaling, XwaylandEavesdropping, ZoomConfig,
     input::{DeviceState as InputDeviceState, InputConfig, TouchpadOverride},
     output::comp::{
         OutputConfig, OutputInfo, OutputState, OutputsConfig, TransformDef, load_outputs,
@@ -1000,6 +1000,13 @@ fn config_changed(config: cosmic_config::Config, keys: Vec<String>, state: &mut
                     state.common.config.cosmic_conf.activation_policy = new;
                 }
             }
+            "decoration_preference" => {
+                let new = get_config::<DecorationPreference>(&config, "decoration_preference");
+                if new != state.common.config.cosmic_conf.decoration_preference {
+                    state.common.config.cosmic_conf.decoration_preference = new;
+                    state.update_decorations();
+                }
+            }
             _ => {}
         }
     }

src/wayland/handlers/decoration.rs

@@ -1,5 +1,6 @@
 use std::{cell::RefCell, sync::Mutex};
 
+use cosmic_comp_config::DecorationPreference;
 use smithay::{
     desktop::Window,
     reexports::{
@@ -20,7 +21,7 @@ use smithay::{
 };
 use wayland_backend::protocol::WEnum;
 
-use crate::state::State;
+use crate::{shell::CosmicMapped, state::State};
 
 pub struct PreferredDecorationMode(RefCell<Option<XdgMode>>);
 
@@ -29,7 +30,7 @@ impl PreferredDecorationMode {
         window
             .user_data()
             .get::<PreferredDecorationMode>()
-            .is_none()
+            .is_none_or(|mode| mode.0.borrow().is_none())
     }
 
     pub fn mode(window: &Window) -> Option<XdgMode> {
@@ -53,6 +54,73 @@ impl PreferredDecorationMode {
     }
 }
 
+impl State {
+    pub fn default_decoration(&self) -> DecorationPreference {
+        self.common.config.cosmic_conf.decoration_preference
+    }
+
+    pub fn update_decorations(&self) {
+        let shell = self.common.shell.read();
+
+        let update = |mapped: &CosmicMapped| {
+            let mode = if mapped.is_stack() {
+                XdgMode::ServerSide
+            } else {
+                XdgMode::from_preference(self.default_decoration())
+            };
+            for (window, _) in mapped.windows() {
+                if PreferredDecorationMode::is_unset(&window.0) {
+                    if let Some(toplevel) = window.0.toplevel() {
+                        if toplevel.with_committed_state(|state| {
+                            state.is_some_and(|state| state.decoration_mode.is_some())
+                        }) {
+                            toplevel.with_pending_state(|state| {
+                                state.decoration_mode = Some(mode);
+                            });
+                            toplevel.send_configure();
+                        }
+                    }
+                }
+            }
+        };
+
+        for set in shell.workspaces.sets.values() {
+            set.sticky_layer.mapped().for_each(update);
+        }
+
+        for space in shell.workspaces.spaces() {
+            space.mapped().for_each(update);
+            space
+                .minimized_windows
+                .iter()
+                .filter_map(|m| m.mapped())
+                .for_each(update);
+        }
+    }
+}
+
+trait FromDecorationPreference {
+    fn from_preference(preference: DecorationPreference) -> Self;
+}
+
+impl FromDecorationPreference for XdgMode {
+    fn from_preference(preference: DecorationPreference) -> Self {
+        match preference {
+            DecorationPreference::ClientSide => XdgMode::ClientSide,
+            DecorationPreference::ServerSide => XdgMode::ServerSide,
+        }
+    }
+}
+
+impl FromDecorationPreference for KdeMode {
+    fn from_preference(preference: DecorationPreference) -> Self {
+        match preference {
+            DecorationPreference::ClientSide => KdeMode::Client,
+            DecorationPreference::ServerSide => KdeMode::Server,
+        }
+    }
+}
+
 pub type KdeDecorationData = Mutex<KdeDecorationSurfaceState>;
 #[derive(Debug, Default)]
 pub struct KdeDecorationSurfaceState {
@@ -67,7 +135,7 @@ impl XdgDecorationHandler for State {
             let mode = if mapped.is_stack() {
                 XdgMode::ServerSide
             } else {
-                XdgMode::ClientSide
+                XdgMode::from_preference(self.default_decoration())
             };
 
             if let Some((window, _)) = mapped
@@ -80,6 +148,10 @@ impl XdgDecorationHandler for State {
                 });
                 toplevel.send_configure();
             }
+        } else {
+            toplevel.with_pending_state(|state| {
+                state.decoration_mode = Some(XdgMode::from_preference(self.default_decoration()))
+            })
         }
     }
 
@@ -99,6 +171,13 @@ impl XdgDecorationHandler for State {
             }
         } else {
             toplevel.with_pending_state(|state| state.decoration_mode = Some(mode));
+            if let Some(pending) = shell
+                .pending_windows
+                .iter()
+                .find(|pending| pending.surface.0.toplevel().is_some_and(|t| t == &toplevel))
+            {
+                PreferredDecorationMode::update(&pending.surface.0, Some(mode));
+            }
         }
     }
 
@@ -110,11 +189,28 @@ impl XdgDecorationHandler for State {
                 .find(|(window, _)| window.wl_surface().as_deref() == Some(toplevel.wl_surface()))
             && let Some(toplevel) = window.0.toplevel()
         {
+            let mode = if mapped.is_stack() {
+                XdgMode::ServerSide
+            } else {
+                XdgMode::from_preference(self.default_decoration())
+            };
+
             PreferredDecorationMode::update(&window.0, None);
             toplevel.with_pending_state(|state| {
-                state.decoration_mode = None;
+                state.decoration_mode = Some(mode);
             });
             toplevel.send_configure();
+        } else {
+            toplevel.with_pending_state(|state| {
+                state.decoration_mode = Some(XdgMode::from_preference(self.default_decoration()))
+            });
+            if let Some(pending) = shell
+                .pending_windows
+                .iter()
+                .find(|pending| pending.surface.0.toplevel().is_some_and(|t| t == &toplevel))
+            {
+                PreferredDecorationMode::update(&pending.surface.0, None);
+            }
         }
     }
 }
@@ -129,10 +225,10 @@ impl KdeDecorationHandler for State {
             if mapped.is_stack() {
                 KdeMode::Server
             } else {
-                KdeMode::Client
+                KdeMode::from_preference(self.default_decoration())
             }
         } else {
-            KdeMode::Client
+            KdeMode::from_preference(self.default_decoration())
         };
 
         with_states(surface, |states| {