tree: don't nest redundant containers on repeated split

book/src/configuration/misc.md

@@ -214,6 +214,19 @@ window-management-key = "Alt_L"
 The value should be a keysym name from
 [KBVM](https://docs.rs/kbvm/latest/kbvm/syms/index.html).
 
+## Split Reuses Container
+
+Controls whether splitting a window that is the only window in its container
+reuses that container.
+
+If this is disabled, splitting such a window wraps it in another container,
+creating a redundant nesting level. If this is enabled, the split direction of
+the existing container is changed instead.
+
+```toml
+split-reuses-container = false  # default
+```
+
 ## Middle-Click Paste
 
 Controls whether middle-clicking pastes the primary selection. Changing this

jay-config/src/_private/client.rs

@@ -1125,6 +1125,16 @@ impl ConfigClient {
         above
     }
 
+    pub fn set_split_reuses_container(&self, reuse: bool) {
+        self.send(&ClientMessage::SetSplitReusesContainer { reuse });
+    }
+
+    pub fn get_split_reuses_container(&self) -> bool {
+        let res = self.send_with_response(&ClientMessage::GetSplitReusesContainer);
+        get_response!(res, false, GetSplitReusesContainer { reuse });
+        reuse
+    }
+
     pub fn set_show_bar(&self, show: bool) {
         self.send(&ClientMessage::SetShowBar { show });
     }

jay-config/src/_private/ipc.rs

@@ -1008,6 +1008,10 @@ pub enum ClientMessage<'a> {
     GetPlaneColorPipelinesEnabled {
         device: DrmDevice,
     },
+    SetSplitReusesContainer {
+        reuse: bool,
+    },
+    GetSplitReusesContainer,
 }
 
 #[derive(Serialize, Deserialize, Debug)]
@@ -1282,6 +1286,9 @@ pub enum Response {
     GetPlaneColorPipelinesEnabled {
         enabled: bool,
     },
+    GetSplitReusesContainer {
+        reuse: bool,
+    },
 }
 
 #[derive(Serialize, Deserialize, Debug)]

jay-config/src/lib.rs

@@ -473,6 +473,30 @@ pub fn set_show_float_pin_icon(show: bool) {
     get!().set_show_float_pin_icon(show);
 }
 
+/// Sets whether splitting a window that is the only child of its container reuses
+/// that container.
+///
+/// If disabled, splitting such a window wraps it in another container. If enabled, the split direction of the existing container
+/// is changed instead.
+///
+/// The default is `false`.
+pub fn set_split_reuses_container(reuse: bool) {
+    get!().set_split_reuses_container(reuse)
+}
+
+/// Returns whether splitting a window that is the only child of its container reuses
+/// that container.
+pub fn get_split_reuses_container() -> bool {
+    get!(false).get_split_reuses_container()
+}
+
+/// Toggles whether splitting a window that is the only child of its container reuses
+/// that container.
+pub fn toggle_split_reuses_container() {
+    let get = get!();
+    get.set_split_reuses_container(!get.get_split_reuses_container());
+}
+
 /// Sets whether the built-in bar is shown.
 ///
 /// The default is `true`.

src/compositor.rs

@@ -449,6 +449,7 @@ fn start_compositor2(
         backend_connector_state_serials: Default::default(),
         head_names: Default::default(),
         show_bar: Cell::new(true),
+        split_reuses_container: Cell::new(false),
         enable_primary_selection: Cell::new(true),
         workspace_display_order: Cell::new(WorkspaceDisplayOrder::Manual),
         outputs_without_hc: Default::default(),

src/config/handler.rs

@@ -1816,6 +1816,16 @@ impl ConfigProxyHandler {
         });
     }
 
+    fn handle_set_split_reuses_container(&self, reuse: bool) {
+        self.state.set_split_reuses_container(reuse);
+    }
+
+    fn handle_get_split_reuses_container(&self) {
+        self.respond(Response::GetSplitReusesContainer {
+            reuse: self.state.split_reuses_container.get(),
+        });
+    }
+
     fn handle_set_show_bar(&self, show: bool) {
         self.state.set_show_bar(show);
     }
@@ -3832,6 +3842,10 @@ impl ConfigProxyHandler {
             ClientMessage::GetContentType { window } => self
                 .handle_get_content_type(window)
                 .wrn("get_content_type")?,
+            ClientMessage::SetSplitReusesContainer { reuse } => {
+                self.handle_set_split_reuses_container(reuse)
+            }
+            ClientMessage::GetSplitReusesContainer => self.handle_get_split_reuses_container(),
             ClientMessage::SetShowBar { show } => self.handle_set_show_bar(show),
             ClientMessage::GetShowBar => self.handle_get_show_bar(),
             ClientMessage::SetShowTitles { show } => self.handle_set_show_titles(show),

src/control_center/cc_look_and_feel.rs

@@ -119,6 +119,21 @@ impl LookAndFeelPane {
                 self.state.float_above_fullscreen.get(),
                 |v| self.state.set_float_above_fullscreen(v),
             );
+            bool_ui(
+                ui,
+                "Split Reuses Container",
+                |ui| {
+                    tip(ui, |ui| {
+                        ui.label(concat!(
+                            "Splitting the only window in a container changes the split ",
+                            "direction of that container.",
+                        ));
+                        ui.label("Otherwise the window is wrapped in a new container.");
+                    });
+                },
+                self.state.split_reuses_container.get(),
+                |v| self.state.set_split_reuses_container(v),
+            );
             row(ui, "Font", |ui| {
                 let mut v = self.state.theme.font.get().to_string();
                 if text_edit(ui, &mut v).changed() {

src/it/test_config.rs

@@ -324,6 +324,16 @@ impl TestConfig {
         self.send(ClientMessage::SetBarPosition { position })
     }
 
+    pub fn set_split_reuses_container(&self, reuse: bool) -> TestResult {
+        self.send(ClientMessage::SetSplitReusesContainer { reuse })
+    }
+
+    pub fn get_split_reuses_container(&self) -> Result<bool, TestError> {
+        let reply = self.send_with_reply(ClientMessage::GetSplitReusesContainer)?;
+        get_response!(reply, GetSplitReusesContainer { reuse });
+        Ok(reuse)
+    }
+
     pub fn set_show_bar(&self, show: bool) -> TestResult {
         self.send(ClientMessage::SetShowBar { show })
     }

src/state.rs

@@ -402,6 +402,7 @@ pub struct State {
     pub backend_connector_state_serials: BackendConnectorStateSerials,
     pub head_names: HeadNames,
     pub show_bar: Cell<bool>,
+    pub split_reuses_container: Cell<bool>,
     pub enable_primary_selection: Cell<bool>,
     pub workspace_display_order: Cell<WorkspaceDisplayOrder>,
     pub outputs_without_hc: NumCell<usize>,
@@ -2612,6 +2613,11 @@ impl State {
         let initial = config.initial_output_for_workspace(name)?;
         Some(initial.map(|o| o.id))
     }
+
+    pub fn set_split_reuses_container(&self, v: bool) {
+        self.split_reuses_container.set(v);
+        self.trigger_cci(CCI_LOOK_AND_FEEL);
+    }
 }
 
 #[derive(Debug, Error)]

src/tree/container.rs

@@ -1231,6 +1231,10 @@ impl ContainerNode {
         self.update_title();
     }
 
+    pub fn num_children(&self) -> usize {
+        self.num_children.get()
+    }
+
     pub fn set_split(self: &Rc<Self>, split: ContainerSplit) {
         if self.set_ns_split(split) != split {
             self.update_content_size();

src/tree/toplevel.rs

@@ -1181,6 +1181,13 @@ pub fn toplevel_create_split(state: &Rc<State>, tl: Rc<dyn ToplevelNode>, axis:
         Some(pn) => pn,
         _ => return,
     };
+    if state.split_reuses_container.get()
+        && let Some(pn) = toplevel_parent_container(&*tl)
+        && pn.num_children() == 1
+    {
+        pn.set_split(axis);
+        return;
+    }
     if let Some(pn) = pn.node_into_containing_node() {
         let cn = ContainerNode::new(state, &ws, tl.clone(), axis);
         pn.cnode_replace_child(&*tl, cn);

toml-config/src/config.rs

@@ -609,6 +609,7 @@ pub struct Config {
     pub pointer_revert_key: Option<KeySym>,
     pub use_hardware_cursor: Option<bool>,
     pub show_bar: Option<bool>,
+    pub split_reuses_container: Option<bool>,
     pub show_titles: Option<bool>,
     pub focus_history: Option<FocusHistory>,
     pub middle_click_paste: Option<bool>,

toml-config/src/config/parsers/config.rs

@@ -174,6 +174,7 @@ impl Parser for ConfigParser<'_, '_> {
                 transactions_val,
                 cursor_size,
                 device_config_filter,
+                split_reuses_container,
             ),
         ) = ext.extract((
             (
@@ -242,6 +243,7 @@ impl Parser for ConfigParser<'_, '_> {
                 opt(val("transactions")),
                 recover(opt(s32("cursor-size"))),
                 recover(opt(str("device-config-filter"))),
+                recover(opt(bol("split-reuses-container"))),
             ),
         ))?;
         let mut keymap = None;
@@ -679,6 +681,7 @@ impl Parser for ConfigParser<'_, '_> {
             pointer_revert_key,
             use_hardware_cursor: use_hardware_cursor.despan(),
             show_bar: show_bar.despan(),
+            split_reuses_container: split_reuses_container.despan(),
             show_titles: show_titles.despan(),
             focus_history,
             middle_click_paste: middle_click_paste.despan(),

toml-config/src/lib.rs

@@ -79,6 +79,7 @@ use jay_config::set_session_management_enabled;
 use jay_config::set_show_bar;
 use jay_config::set_show_float_pin_icon;
 use jay_config::set_show_titles;
+use jay_config::set_split_reuses_container;
 use jay_config::set_transaction_timeout;
 use jay_config::set_ui_drag_enabled;
 use jay_config::set_ui_drag_threshold;
@@ -1840,6 +1841,9 @@ fn load_config(initial_load: bool, auto_reload: bool, persistent: &Rc<Persistent
     if let Some(v) = config.show_bar {
         set_show_bar(v);
     }
+    if let Some(v) = config.split_reuses_container {
+        set_split_reuses_container(v);
+    }
     if let Some(v) = config.show_titles {
         set_show_titles(v);
     }

toml-spec/spec/spec.generated.json

@@ -1237,6 +1237,10 @@
           "type": "boolean",
           "description": "Configures whether the default seat uses hardware cursors.\n\nThe default is `true`.\n"
         },
+        "split-reuses-container": {
+          "type": "boolean",
+          "description": "Configures whether splitting a window that is the only window in its container\nreuses that container.\n\nIf this is disabled, splitting such a window wraps it in another container. If this is enabled, the split direction of\nthe existing container is changed instead.\n\nThe default is `false`.\n"
+        },
         "show-bar": {
           "type": "boolean",
           "description": "Configures whether the built-in bar is shown.\n\nThe default is `true`.\n"

toml-spec/spec/spec.generated.md

@@ -2489,6 +2489,18 @@ The table has the following fields:
 
   The value of this field should be a boolean.
 
+- `split-reuses-container` (optional):
+
+  Configures whether splitting a window that is the only window in its container
+  reuses that container.
+
+  If this is disabled, splitting such a window wraps it in another container. If this is enabled, the split direction of
+  the existing container is changed instead.
+
+  The default is `false`.
+
+  The value of this field should be a boolean.
+
 - `show-bar` (optional):
 
   Configures whether the built-in bar is shown.

toml-spec/spec/spec.yaml

@@ -3304,6 +3304,17 @@ Config:
         Configures whether the default seat uses hardware cursors.
 
         The default is `true`.
+    split-reuses-container:
+      kind: boolean
+      required: false
+      description: |
+        Configures whether splitting a window that is the only window in its container
+        reuses that container.
+
+        If this is disabled, splitting such a window wraps it in another container. If this is enabled, the split direction of
+        the existing container is changed instead.
+
+        The default is `false`.
     show-bar:
       kind: boolean
       required: false