chore: reduce component overhead (#3)

Reviewed-on: #3

crates/layout/src/dock.rs

@@ -192,10 +192,8 @@ impl DockState {
     }
 
     /// Registers a panel descriptor, replacing any earlier one with its id.
-    pub fn register_panel(&mut self, panel: PanelDescriptor, cx: &mut Context<Self>) {
-        if self.panels.insert(panel.id.clone(), panel).is_none() {
-            cx.notify();
-        }
+    pub fn register_panel(&mut self, panel: PanelDescriptor) {
+        self.panels.insert(panel.id.clone(), panel);
     }
 
     /// Opens a panel into the active pane and activates its tab.
@@ -330,6 +328,17 @@ impl DockState {
         };
 
         if changed {
+            // The kept tab may have no right view, show the first remaining one.
+            self.right_view = self
+                .locate(id)
+                .and_then(|(pane_key, _)| self.pane(pane_key))
+                .and_then(|pane| {
+                    pane.active.as_deref().and_then(|active| {
+                        pane.tabs.iter().find(|tab| tab.panel.as_ref() == active)
+                    })
+                })
+                .and_then(|tab| tab.right_view.clone())
+                .or_else(|| first_right_view(&self.root));
             cx.notify();
         }
     }
@@ -354,10 +363,14 @@ impl DockState {
         }
 
         self.detach_pane(pane_key);
+
         if self.active_pane == pane_key {
             self.active_pane = self.first_pane_key().unwrap_or(0);
         }
 
+        // The closed pane's views are gone; show the first remaining one.
+        self.right_view = first_right_view(&self.root);
+
         cx.notify();
     }
 
@@ -526,6 +539,19 @@ impl DockState {
         }
     }
 
+    fn pane(&self, key: u64) -> Option<&Pane> {
+        Self::pane_in(&self.root, key)
+    }
+
+    fn pane_in(node: &Node, key: u64) -> Option<&Pane> {
+        match node {
+            Node::Pane(pane) => (pane.key == key).then_some(pane),
+            Node::Split(split) => {
+                Self::pane_in(&split.a, key).or_else(|| Self::pane_in(&split.b, key))
+            }
+        }
+    }
+
     fn pane_mut(&mut self, key: u64) -> Option<&mut Pane> {
         Self::pane_mut_in(&mut self.root, key)
     }
@@ -969,15 +995,10 @@ fn render_pane(
         .map(|tab| tab.view.clone());
 
     // The cache keeps an un-notified panel from re-rendering on dock frames.
+    let content_id = SharedString::from(format!("{dock_id}-content-{}", pane.key));
     let content = div()
-        .id(SharedString::from(format!(
-            "{dock_id}-content-{}",
-            pane.key
-        )))
-        .debug_selector({
-            let id = SharedString::from(format!("{dock_id}-content-{}", pane.key));
-            move || id.to_string()
-        })
+        .id(content_id.clone())
+        .debug_selector(move || content_id.to_string())
         .flex_1()
         .min_h_0()
         .overflow_hidden()
@@ -999,6 +1020,7 @@ fn render_pane(
         let pane = pane.clone();
         let titlebar = *titlebar;
         let padding_x = metrics.dense_padding_x;
+
         move |window, cx| {
             let selected = pane
                 .active
@@ -1016,7 +1038,7 @@ fn render_pane(
                 move |_, _| {
                     tabs.iter()
                         .map(|tab| {
-                            let mut entry = Tab::new(tab.title.clone());
+                            let mut entry = Tab::new(tab.panel.clone(), tab.title.clone());
                             if let Some(role) = tab.icon {
                                 entry = entry.icon(role);
                             }
@@ -1065,21 +1087,17 @@ fn render_pane(
                 }
             });
 
+            let bar_id = SharedString::from(format!("{dock_id}-pane-{}-bar", pane.key));
+
             h_flex()
-                .id(SharedString::from(format!(
-                    "{dock_id}-pane-{}-bar",
-                    pane.key
-                )))
-                .debug_selector({
-                    let id = SharedString::from(format!("{dock_id}-pane-{}-bar", pane.key));
-                    move || id.to_string()
-                })
+                .id(bar_id.clone())
+                .debug_selector(move || bar_id.to_string())
                 .flex_none()
                 .w_full()
                 .h(titlebar.height)
                 .items_center()
                 .pl(if titlebar.traffic_light_pad {
-                    px(TRAFFIC_LIGHT_PAD)
+                    TRAFFIC_LIGHT_PAD
                 } else {
                     padding_x
                 })