all: add support for hy3 like tiling

src/tree/container.rs

@@ -12,20 +12,24 @@ use {
         },
         rect::Rect,
         renderer::Renderer,
+        scale::Scale,
         state::State,
+        text::TextTexture,
         tree::{
             ContainingNode, Direction, FindTreeResult, FindTreeUsecase, FloatNode, FoundNode, Node,
             NodeId, NodeLayerLink, NodeLocation, OutputNode, TddType, TileDragDestination,
             ToplevelData, ToplevelNode, ToplevelNodeBase, ToplevelType, WorkspaceNode,
-            default_tile_drag_bounds, toplevel_set_workspace,
+            default_tile_drag_bounds, tab_bar::{TabBar, TabBarEntry}, toplevel_set_workspace,
             walker::NodeVisitor,
         },
         utils::{
             clonecell::CloneCell,
+            errorfmt::ErrorFmt,
             event_listener::LazyEventSource,
             hash_map_ext::HashMapExt,
             linkedlist::{LinkedList, LinkedNode, NodeRef},
             numcell::NumCell,
+            on_drop_event::OnDropEvent,
             rc_eq::rc_eq,
             threshold_counter::ThresholdCounter,
         },
@@ -85,6 +89,28 @@ pub enum ContainerFocus {
 
 tree_id!(ContainerNodeId);
 
+/// Ephemeral group state (hy3-style auto-collapse).
+///
+/// An ephemeral container is a transient grouping that auto-collapses back to
+/// its single child when all but one child is removed.
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Default)]
+pub enum Ephemeral {
+    /// Normal container — never auto-collapses.
+    #[default]
+    Off,
+    /// Ephemeral container — when child count drops to 1, collapse.
+    On,
+}
+
+/// Actions for the `changegroup` operation.
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum ChangeGroupAction {
+    /// Toggle between Horizontal and Vertical.
+    Opposite,
+    /// Toggle between tabbed (mono) and split mode.
+    ToggleTab,
+}
+
 #[derive(Default)]
 pub struct ContainerRenderData {
     pub border_rects: Vec<Rect>,
@@ -120,6 +146,9 @@ pub struct ContainerNode {
     pub child_added: Rc<LazyEventSource>,
     pub child_removed: Rc<LazyEventSource>,
     pub all_children_resized: Rc<LazyEventSource>,
+    pub tab_bar: RefCell<Option<TabBar>>,
+    pub update_tab_textures_scheduled: Cell<bool>,
+    pub ephemeral: Cell<Ephemeral>,
 }
 
 impl Debug for ContainerNode {
@@ -231,6 +260,9 @@ impl ContainerNode {
             child_added: state.lazy_event_sources.create_source(),
             child_removed: state.lazy_event_sources.create_source(),
             all_children_resized: state.post_layout_event_sources.create_source(),
+            tab_bar: RefCell::new(None),
+            update_tab_textures_scheduled: Cell::new(false),
+            ephemeral: Cell::new(Ephemeral::Off),
         });
         child.tl_set_parent(slf.clone());
         slf.pull_child_properties(&child_node_ref);
@@ -335,6 +367,8 @@ impl ContainerNode {
         self.sum_factors.set(sum_factors);
         if self.mono_child.is_some() {
             self.activate_child(&new_ref);
+            self.rebuild_tab_bar();
+            self.damage();
         }
         // log::info!("add_child");
         self.schedule_layout();
@@ -549,11 +583,19 @@ impl ContainerNode {
                 self.content_width.set(self.width.get());
             }
         }
+        let tab_bar_height = if self.mono_child.is_some() {
+            // Tab bar sits above the window with a configurable gap.
+            let tbh = self.state.theme.sizes.tab_bar_height.get();
+            let gap = self.state.theme.sizes.tab_bar_gap.get();
+            tbh + gap
+        } else {
+            0
+        };
         self.mono_body.set(Rect::new_sized_saturating(
             0,
-            0,
+            tab_bar_height,
             self.width.get(),
-            self.height.get(),
+            (self.height.get() - tab_bar_height).max(0),
         ));
     }
 
@@ -588,7 +630,9 @@ impl ContainerNode {
                     dist_left,
                     dist_right,
                 } => {
-                    let prev = op.child.prev().unwrap();
+                    let Some(prev) = op.child.prev() else {
+                        return;
+                    };
                     let prev_body = prev.body.get();
                     let child_body = op.child.body.get();
                     let (prev_factor, child_factor) = match self.split.get() {
@@ -656,6 +700,14 @@ impl ContainerNode {
         }
     }
 
+    fn schedule_update_tab_textures(self: &Rc<Self>) {
+        if !self.update_tab_textures_scheduled.replace(true) {
+            self.state
+                .pending_container_tab_render_textures
+                .push(self.clone());
+        }
+    }
+
     fn compute_render_positions(&self) {
         self.compute_render_positions_scheduled.set(false);
         let mut rd = self.render_data.borrow_mut();
@@ -713,6 +765,13 @@ impl ContainerNode {
                 }
             }
             self.mono_child.set(Some(child.clone()));
+            // Keep focus_history in sync with mono_child so that
+            // toggle_tab and other operations that use focus_history.last()
+            // return the correct child.
+            child
+                .focus_history
+                .set(Some(self.focus_history.add_last(child.clone())));
+            self.rebuild_tab_bar();
             if self.toplevel_data.visible.get() {
                 self.perform_layout();
                 child.node.tl_set_visible(true);
@@ -764,9 +823,25 @@ impl ContainerNode {
                 }
             }
         }
-        self.mono_child.set(child);
-        // log::info!("set_mono");
+        self.mono_child.set(child.clone());
+        if child.is_some() {
+            self.rebuild_tab_bar();
+        } else {
+            *self.tab_bar.borrow_mut() = None;
+        }
+        self.update_content_size();
+        self.damage();
         self.schedule_layout();
+        // Notify parent to rebuild its tab bar if we're a child of a mono container.
+        // Our tab title prefix changes when we enter/leave mono mode ([T] vs [H]/[V]).
+        if let Some(parent) = self.toplevel_data.parent.get() {
+            if let Some(pc) = parent.node_into_container() {
+                if pc.mono_child.is_some() {
+                    pc.rebuild_tab_bar();
+                    pc.damage();
+                }
+            }
+        }
     }
 
     pub fn set_split(self: &Rc<Self>, split: ContainerSplit) {
@@ -777,6 +852,233 @@ impl ContainerNode {
         }
     }
 
+    /// Rebuild the tab bar entries from the current children.
+    ///
+    /// Called when entering mono mode or when children change while in mono mode.
+    fn rebuild_tab_bar(self: &Rc<Self>) {
+        self.rebuild_tab_bar_with_override(None, None);
+    }
+
+    /// Generate a tab title for a child node. For windows this is the window
+    /// title or app_id. For container (group) children, we show a layout
+    /// prefix like hy3: `[H] child_title`, `[V] child_title`, `[T] child_title`.
+    fn get_child_tab_title(
+        &self,
+        child: &ContainerChild,
+        override_id: Option<NodeId>,
+        override_title: Option<&str>,
+    ) -> String {
+        let child_id = child.node.node_id();
+        // If this child is a container (group), show layout prefix + focused child title.
+        if let Some(cn) = child.node.clone().node_into_container() {
+            let prefix = if cn.mono_child.is_some() {
+                "[T]"
+            } else {
+                match cn.split.get() {
+                    ContainerSplit::Horizontal => "[H]",
+                    ContainerSplit::Vertical => "[V]",
+                }
+            };
+            // Get the focused child's title recursively.
+            let inner = if let Some(focused) = cn.focus_history.last() {
+                let inner_child = ContainerChild {
+                    node: focused.node.clone(),
+                    active: Cell::new(false),
+                    body: Default::default(),
+                    content: Default::default(),
+                    factor: Cell::new(0.0),
+                    focus_history: Default::default(),
+                    attention_requested: Cell::new(false),
+                    border_color_is_focused: Default::default(),
+                };
+                cn.get_child_tab_title(&inner_child, override_id, override_title)
+            } else {
+                "Group".to_string()
+            };
+            return format!("{} {}", prefix, inner);
+        }
+        // Window node: use override, title, app_id, or "untitled".
+        let raw_title = if override_id == Some(child_id) && override_title.is_some() {
+            override_title.unwrap().to_string()
+        } else {
+            child.node.tl_data().title.borrow().clone()
+        };
+        if !raw_title.is_empty() {
+            return raw_title;
+        }
+        if override_id == Some(child_id) {
+            let app = child.node.tl_data().app_id.borrow().clone();
+            if !app.is_empty() {
+                return app;
+            }
+        } else {
+            let app = child.node.tl_data().app_id.borrow().clone();
+            if !app.is_empty() {
+                return app;
+            }
+        }
+        "untitled".to_string()
+    }
+
+    /// Rebuild the tab bar. If `override_id` and `override_title` are provided,
+    /// use the override title for that child instead of borrowing it (avoids
+    /// RefCell double-borrow when called from node_child_title_changed).
+    fn rebuild_tab_bar_with_override(
+        self: &Rc<Self>,
+        override_id: Option<NodeId>,
+        override_title: Option<&str>,
+    ) {
+        let mono = self.mono_child.get();
+        if mono.is_none() {
+            *self.tab_bar.borrow_mut() = None;
+            return;
+        }
+        let mono_ref = mono.as_ref().unwrap();
+        let active_id = mono_ref.node.node_id();
+        let height = self.state.theme.sizes.tab_bar_height.get();
+        let render_scale = self.workspace.get().output.get().global.persistent.scale.get();
+        let mut bar = TabBar::new(height, render_scale);
+        for child in self.children.iter() {
+            let child_id = child.node.node_id();
+            let title = self.get_child_tab_title(&child, override_id, override_title);
+            bar.entries.push(TabBarEntry {
+                child_id,
+                title,
+                title_texture: Rc::new(RefCell::new(None)),
+                active: child_id == active_id,
+                attention_requested: child.attention_requested.get(),
+                x: Cell::new(0),
+                width: Cell::new(0),
+            });
+        }
+        let padding = self.state.theme.sizes.tab_bar_padding.get();
+        bar.layout_entries(self.width.get(), padding);
+        *self.tab_bar.borrow_mut() = Some(bar);
+        self.schedule_update_tab_textures();
+    }
+
+    /// Wrap the focused child in a new sub-container with the given split direction.
+    ///
+    /// This is hy3's `makegroup` operation.
+    pub fn make_group(self: &Rc<Self>, split: ContainerSplit, ephemeral: bool) {
+        let Some(focused) = self.focus_history.last() else {
+            return;
+        };
+        if self.num_children.get() <= 1 {
+            return;
+        }
+        let focused_node = focused.node.clone();
+        // Record the sibling that comes AFTER the focused child so we can
+        // insert the new group at the same position.
+        let next_sibling: Option<Rc<dyn ToplevelNode>> = {
+            let nodes = self.child_nodes.borrow();
+            nodes
+                .get(&focused_node.node_id())
+                .and_then(|ln| ln.next())
+                .map(|n| n.node.clone())
+        };
+        // Temporarily disable ephemeral collapse during make_group so
+        // removing the focused child doesn't destroy this container.
+        let was_ephemeral = self.ephemeral.replace(Ephemeral::Off);
+        self.clone().cnode_remove_child2(&*focused_node, true);
+        self.ephemeral.set(was_ephemeral);
+        let sub = ContainerNode::new(
+            &self.state,
+            &self.workspace.get(),
+            focused_node,
+            split,
+        );
+        if ephemeral {
+            sub.ephemeral.set(Ephemeral::On);
+        }
+        // Insert at the original position instead of appending to the end.
+        if let Some(ref next) = next_sibling {
+            self.add_child_before(&**next, sub);
+        } else {
+            // Was the last child — append.
+            self.append_child(sub);
+        }
+    }
+
+    /// Change this container's split direction (hy3's `changegroup`).
+    ///
+    /// `opposite` toggles H↔V, `toggletab` toggles between mono and split.
+    pub fn change_group(self: &Rc<Self>, action: ChangeGroupAction) {
+        match action {
+            ChangeGroupAction::Opposite => {
+                let new_split = match self.split.get() {
+                    ContainerSplit::Horizontal => ContainerSplit::Vertical,
+                    ContainerSplit::Vertical => ContainerSplit::Horizontal,
+                };
+                self.set_split(new_split);
+            }
+            ChangeGroupAction::ToggleTab => {
+                if self.mono_child.is_some() {
+                    // Exit mono/tabbed mode.
+                    self.set_mono(None);
+                } else if let Some(focused) = self.focus_history.last() {
+                    // Enter mono/tabbed mode with the focused child.
+                    self.set_mono(Some(&*focused.node));
+                }
+            }
+        }
+    }
+
+    /// Reset all children's factors to equal (hy3's `equalize`).
+    pub fn equalize(self: &Rc<Self>) {
+        let n = self.num_children.get();
+        if n == 0 {
+            return;
+        }
+        let factor = 1.0 / n as f64;
+        let mut sum = 0.0;
+        for child in self.children.iter() {
+            child.factor.set(factor);
+            sum += factor;
+        }
+        self.sum_factors.set(sum);
+        self.schedule_layout();
+    }
+
+    /// Recursively equalize all descendant containers.
+    pub fn equalize_recursive(self: &Rc<Self>) {
+        self.equalize();
+        for child in self.children.iter() {
+            if let Some(cn) = child.node.clone().node_into_container() {
+                cn.equalize_recursive();
+            }
+        }
+    }
+
+    /// Move the currently active tab left or right within the tab bar.
+    ///
+    /// This is the equivalent of hy3's `movewindow` within a tabbed group.
+    pub fn move_tab(self: &Rc<Self>, right: bool) {
+        let mc = match self.mono_child.get() {
+            Some(mc) => mc,
+            None => return,
+        };
+        let child_nodes = self.child_nodes.borrow();
+        let Some(link) = child_nodes.get(&mc.node.node_id()) else {
+            return;
+        };
+        let active_ref = link.to_ref();
+        if right {
+            if let Some(next) = active_ref.next() {
+                // Move active tab after the next sibling (moves right).
+                next.append_existing(&active_ref);
+            }
+        } else {
+            if let Some(prev) = active_ref.prev() {
+                // Move active tab before the previous sibling (moves left).
+                prev.prepend_existing(&active_ref);
+            }
+        }
+        drop(child_nodes);
+        self.rebuild_tab_bar();
+        self.damage();
+    }
+
     fn parent_container(&self) -> Option<Rc<ContainerNode>> {
         self.toplevel_data
             .parent
@@ -955,6 +1257,42 @@ impl ContainerNode {
     }
 
     pub fn insert_child(self: &Rc<Self>, node: Rc<dyn ToplevelNode>, direction: Direction) {
+        // Autotile: if the container would become too narrow/tall, wrap the
+        // focused child and new node in a perpendicular sub-container.
+        if self.state.theme.autotile_enabled.get() && self.mono_child.is_none() {
+            let (pw, ph) = self.predict_child_body_size();
+            let opposite = match self.split.get() {
+                ContainerSplit::Horizontal if pw > 0 && ph > 0 && pw < ph => {
+                    Some(ContainerSplit::Vertical)
+                }
+                ContainerSplit::Vertical if pw > 0 && ph > 0 && ph < pw => {
+                    Some(ContainerSplit::Horizontal)
+                }
+                _ => None,
+            };
+            if let Some(opp_split) = opposite {
+                if let Some(focused) = self.focus_history.last() {
+                    if self.num_children.get() <= 1 {
+                        // Single child, autotile not applicable.
+                    } else {
+                        let focused_node = focused.node.clone();
+                        let was_ephemeral = self.ephemeral.replace(Ephemeral::Off);
+                        self.clone().cnode_remove_child2(&*focused_node, true);
+                        self.ephemeral.set(was_ephemeral);
+                        let sub = ContainerNode::new(
+                            &self.state,
+                            &self.workspace.get(),
+                            focused_node,
+                            opp_split,
+                        );
+                        sub.ephemeral.set(Ephemeral::On);
+                        sub.append_child(node);
+                        self.append_child(sub);
+                        return;
+                    }
+                }
+            }
+        }
         let (split, right) = direction_to_split(direction);
         if split != self.split.get() || right {
             self.append_child(node);
@@ -1050,16 +1388,39 @@ impl ContainerNode {
             if !pressed {
                 return;
             }
+            // Handle tab bar clicks in mono mode.
+            if self.mono_child.is_some() {
+                let tab_bar = self.tab_bar.borrow();
+                if let Some(tb) = tab_bar.as_ref() {
+                    if seat_data.y >= 0 && seat_data.y < tb.height {
+                        if let Some(idx) = tb.entry_at_x(seat_data.x) {
+                            let child_id = tb.entries[idx].child_id;
+                            drop(tab_bar);
+                            drop(seat_datas);
+                            let children = self.child_nodes.borrow();
+                            if let Some(child) = children.get(&child_id) {
+                                let child_ref = child.to_ref();
+                                drop(children);
+                                self.activate_child(&child_ref);
+                            }
+                            return;
+                        }
+                    }
+                }
+            }
             let (kind, child) = 'res: {
                 let mono = self.mono_child.is_some();
                 for child in self.children.iter() {
                     if !mono {
                         if self.split.get() == ContainerSplit::Horizontal {
                             if seat_data.x < child.body.get().x1() {
+                                let Some(prev) = child.prev() else {
+                                    continue;
+                                };
                                 break 'res (
                                     SeatOpKind::Resize {
                                         dist_left: seat_data.x
-                                            - child.prev().unwrap().body.get().x2(),
+                                            - prev.body.get().x2(),
                                         dist_right: child.body.get().x1() - seat_data.x,
                                     },
                                     child,
@@ -1067,10 +1428,13 @@ impl ContainerNode {
                             }
                         } else {
                             if seat_data.y < child.body.get().y1() {
+                                let Some(prev) = child.prev() else {
+                                    continue;
+                                };
                                 break 'res (
                                     SeatOpKind::Resize {
                                         dist_left: seat_data.y
-                                            - child.prev().unwrap().body.get().y2(),
+                                            - prev.body.get().y2(),
                                         dist_right: child.body.get().y1() - seat_data.y,
                                     },
                                     child,
@@ -1285,6 +1649,78 @@ pub async fn container_render_positions(state: Rc<State>) {
     }
 }
 
+pub async fn container_tab_render_textures(state: Rc<State>) {
+    loop {
+        let container = state.pending_container_tab_render_textures.pop().await;
+        container.update_tab_textures_scheduled.set(false);
+        let (event, textures) = container.update_tab_textures_phase1();
+        event.triggered().await;
+        container.update_tab_textures_phase2(&textures);
+    }
+}
+
+impl ContainerNode {
+    fn update_tab_textures_phase1(
+        self: &Rc<Self>,
+    ) -> (Rc<crate::utils::asyncevent::AsyncEvent>, Vec<Rc<RefCell<Option<TextTexture>>>>) {
+        let on_completed = Rc::new(OnDropEvent::default());
+        let (entries, bar_height, render_scale) = {
+            let tab_bar = self.tab_bar.borrow();
+            let Some(tb) = tab_bar.as_ref() else {
+                return (on_completed.event(), vec![]);
+            };
+            let entries: Vec<_> = tb.entries.iter().map(|e| {
+                (e.title.clone(), TabBar::entry_colors(&self.state, e), e.title_texture.clone())
+            }).collect();
+            (entries, tb.height, tb.render_scale)
+        };
+        let Some(ctx) = self.state.render_ctx.get() else {
+            log::warn!("tab text phase1: no render context");
+            return (on_completed.event(), vec![]);
+        };
+        let font = self.state.theme.title_font();
+        let scale = if render_scale != Scale::from_int(1) {
+            Some(render_scale.to_f64())
+        } else {
+            None
+        };
+        let mut texture_height = bar_height;
+        if let Some(s) = scale {
+            texture_height = (bar_height as f64 * s).round() as _;
+        }
+        let mut scheduled = 0;
+        let mut texture_refs = Vec::new();
+        for (title, (_, _, text_color), title_texture) in &entries {
+            let mut tex_ref = title_texture.borrow_mut();
+            let tex = tex_ref.get_or_insert_with(|| TextTexture::new(&self.state, &ctx));
+            tex.schedule_render_fitting(
+                on_completed.clone(),
+                Some(texture_height),
+                &font,
+                title,
+                *text_color,
+                false,
+                scale,
+            );
+            texture_refs.push(title_texture.clone());
+            scheduled += 1;
+        }
+        (on_completed.event(), texture_refs)
+    }
+
+    fn update_tab_textures_phase2(&self, textures: &[Rc<RefCell<Option<TextTexture>>>]) {
+        for title_texture in textures {
+            let tex_ref = title_texture.borrow();
+            if let Some(tex) = tex_ref.as_ref() {
+                if let Err(e) = tex.flip() {
+                    log::warn!("Could not render tab text: {}", ErrorFmt(e));
+                }
+            }
+        }
+        self.damage();
+    }
+}
+
 impl Node for ContainerNode {
     fn node_id(&self) -> NodeId {
         self.id.into()
@@ -1329,8 +1765,9 @@ impl Node for ContainerNode {
         self.toplevel_data.node_layer()
     }
 
-    fn node_child_title_changed(self: Rc<Self>, _child: &dyn Node, _title: &str) {
-        // Titlebars removed; no title tracking needed
+    fn node_child_title_changed(self: Rc<Self>, child: &dyn Node, title: &str) {
+        self.rebuild_tab_bar_with_override(Some(child.node_id()), Some(title));
+        self.damage();
     }
 
     fn node_do_focus(self: Rc<Self>, seat: &Rc<WlSeatGlobal>, direction: Direction) {
@@ -1433,8 +1870,31 @@ impl Node for ContainerNode {
         self.button(id, seat, time_usec, state == ButtonState::Pressed, button);
     }
 
-    fn node_on_axis_event(self: Rc<Self>, _seat: &Rc<WlSeatGlobal>, _event: &PendingScroll) {
-        // Scroll-to-switch-tabs was a title bar feature; no-op without titles
+    fn node_on_axis_event(self: Rc<Self>, _seat: &Rc<WlSeatGlobal>, event: &PendingScroll) {
+        if self.mono_child.is_none() {
+            return;
+        }
+        // Use vertical scroll (index 1) to switch tabs.
+        let v = match event.v120[1].get() {
+            Some(v) if v != 0 => v,
+            _ => return,
+        };
+        let mono = match self.mono_child.get() {
+            Some(m) => m,
+            None => return,
+        };
+        let next = if v > 0 {
+            // Scroll down → next tab.
+            mono.next().or_else(|| self.children.first())
+        } else {
+            // Scroll up → previous tab.
+            mono.prev().or_else(|| self.children.last())
+        };
+        if let Some(next) = next {
+            if next.node.node_id() != mono.node.node_id() {
+                self.activate_child(&next);
+            }
+        }
     }
 
     fn node_on_leave(&self, seat: &WlSeatGlobal) {
@@ -1644,7 +2104,27 @@ impl ContainingNode for ContainerNode {
             }
         }
         self.sum_factors.set(sum);
+        // Ephemeral collapse: if this container is ephemeral and has exactly
+        // one child remaining, replace this container with that child in the parent.
+        if self.ephemeral.get() == Ephemeral::On
+            && num_children == 1
+            && !self.toplevel_data.is_fullscreen.get()
+        {
+            if let Some(parent) = self.toplevel_data.parent.get() {
+                if let Some(only_child) = self.children.first() {
+                    let child_node = only_child.node.clone();
+                    if parent.cnode_accepts_child(&*child_node) {
+                        parent.cnode_replace_child(self.deref(), child_node);
+                        self.toplevel_data.parent.take();
+                        self.child_nodes.borrow_mut().clear();
+                        self.tl_destroy();
+                        return;
+                    }
+                }
+            }
+        }
         // log::info!("cnode_remove_child2");
+        self.rebuild_tab_bar();
         self.schedule_layout();
         self.cancel_seat_ops();
         self.child_removed.trigger();
@@ -1664,6 +2144,8 @@ impl ContainingNode for ContainerNode {
             return;
         }
         self.mod_attention_requests(set);
+        drop(children);
+        self.rebuild_tab_bar();
         self.schedule_compute_render_positions();
     }
 
@@ -1882,6 +2364,13 @@ impl ToplevelNodeBase for ContainerNode {
         size_changed |= self.height.replace(rect.height()) != rect.height();
         if size_changed {
             self.update_content_size();
+            // Re-layout tab bar entries when container size changes in mono mode.
+            if self.mono_child.is_some() {
+                if let Some(bar) = self.tab_bar.borrow().as_ref() {
+                    let padding = self.state.theme.sizes.tab_bar_padding.get();
+                    bar.layout_entries(rect.width(), padding);
+                }
+            }
             // log::info!("tl_change_extents");
             self.perform_layout();
             self.cancel_seat_ops();

src/tree/tab_bar.rs

@@ -0,0 +1,113 @@
+use {
+    crate::{
+        scale::Scale,
+        state::State,
+        text::TextTexture,
+        theme::Color,
+        tree::NodeId,
+    },
+    std::{cell::{Cell, RefCell}, rc::Rc},
+};
+
+/// A single entry (tab) within a tab bar.
+pub struct TabBarEntry {
+    /// The node ID of the child this tab represents.
+    pub child_id: NodeId,
+    /// The display title of the tab.
+    pub title: String,
+    /// Pre-rendered text texture for the tab title.
+    pub title_texture: Rc<RefCell<Option<TextTexture>>>,
+    /// Whether this is the active (visible) tab.
+    pub active: bool,
+    /// Whether this tab's window has requested attention.
+    pub attention_requested: bool,
+    /// X offset of this tab within the tab bar (relative to tab bar start).
+    pub x: Cell<i32>,
+    /// Width of this tab in pixels.
+    pub width: Cell<i32>,
+}
+
+/// A tab bar rendered above a container in mono (tabbed) mode.
+pub struct TabBar {
+    /// The individual tab entries.
+    pub entries: Vec<TabBarEntry>,
+    /// Height of the tab bar in pixels (from theme).
+    pub height: i32,
+    /// The output scale at which text textures were rendered.
+    pub render_scale: Scale,
+}
+
+impl TabBar {
+    /// Create a new empty tab bar.
+    pub fn new(height: i32, render_scale: Scale) -> Self {
+        Self {
+            entries: Vec::new(),
+            height,
+            render_scale,
+        }
+    }
+
+    /// Recompute the positions and widths of all tab entries.
+    ///
+    /// `total_width` is the available width for the entire tab bar.
+    pub fn layout_entries(&self, total_width: i32, padding: i32) {
+        let n = self.entries.len() as i32;
+        if n == 0 {
+            return;
+        }
+        let total_padding = padding * (n + 1);
+        let available = (total_width - total_padding).max(0);
+        let per_tab = available / n;
+        let mut remainder = available - per_tab * n;
+        let mut x = padding;
+        for entry in &self.entries {
+            let w = if remainder > 0 {
+                remainder -= 1;
+                per_tab + 1
+            } else {
+                per_tab
+            };
+            entry.x.set(x);
+            entry.width.set(w);
+            x += w + padding;
+        }
+    }
+
+    /// Find the tab entry index at the given x coordinate (relative to tab bar).
+    ///
+    /// Returns `None` if the coordinate is in padding between tabs or out of bounds.
+    pub fn entry_at_x(&self, x: i32) -> Option<usize> {
+        for (i, entry) in self.entries.iter().enumerate() {
+            let ex = entry.x.get();
+            let ew = entry.width.get();
+            if x >= ex && x < ex + ew {
+                return Some(i);
+            }
+        }
+        None
+    }
+
+    /// Get the colors for a tab entry based on its state.
+    pub fn entry_colors(state: &State, entry: &TabBarEntry) -> (Color, Color, Color) {
+        let theme = &state.theme;
+        if entry.attention_requested {
+            (
+                theme.colors.tab_attention_background.get(),
+                theme.colors.tab_inactive_border.get(),
+                theme.colors.tab_active_text.get(),
+            )
+        } else if entry.active {
+            (
+                theme.colors.tab_active_background.get(),
+                theme.colors.tab_active_border.get(),
+                theme.colors.tab_active_text.get(),
+            )
+        } else {
+            (
+                theme.colors.tab_inactive_background.get(),
+                theme.colors.tab_inactive_border.get(),
+                theme.colors.tab_inactive_text.get(),
+            )
+        }
+    }
+}