Struct TitleBar 

pub struct TitleBar { /* private fields */ }

A custom window title bar.

Layout (left to right):

[leading inset] [leading slot] [drag region (flexible)] [trailing slot] [trailing inset] [window controls]

The leading inset reserves space for the OS-drawn traffic lights on macOS. The drag region is a Spacer-style flex child that absorbs all leftover horizontal space and forwards pointer / drag / double-tap gestures to the platform host. The window controls (minimize / maximize / close) are rendered only when the host advertises [PlatformTitleBarHost::renders_custom_controls] — i.e. on Windows and Wayland but not on macOS.

This widget builds exactly once

build consumes the leading / center / trailing slots with take(), so a second pass finds them all None and produces a bar containing nothing but window controls — no menu, no title, no tools. Nothing here may therefore carry a BindingLevel::Rebuild binding. Reactive state on this widget is expressed either as a RepaintOnly colour prop or, for structure, as dormancy via [teksilo_core::BuildContext::visible_when] on an always-built child — which is how controls_visible works. Memoising the resolved slot ids is not a workaround: a rebuild replaces the inner row and prunes its subtree, so the cached ids dangle and re-adding them yields an empty bar just the same.

Implementations

impl TitleBar

pub fn new(host: Rc<dyn PlatformTitleBarHost>) -> Self

Construct a TitleBar bound to the given platform host.

The maximize/restore glyph follows WindowState::placement via ctx.window() at build time — the host no longer owns the maximize signal.

pub fn controls_visible(self, visible: impl Into<Prop<bool>>) -> Self

Show or hide the minimize / maximize / close cluster. Default true.

Accepts a plain bool or a Signal<bool>. Applied through the framework’s own dormancy ([teksilo_core::BuildContext::visible_when]), so a flip costs a relayout and never a rebuild of the bar: a dormant node is skipped by layout, hit-test, focus and paint, so a hidden cluster takes no space and receives no input. A derived (.map) signal is fine — binding resolves through to the mutable roots and never calls observe.

The case this exists for is fullscreen. WindowPlacement::Fullscreen is documented as “covers the entire display, title bar and all chrome hidden”, and every desktop convention agrees: macOS hides the traffic lights, Windows fullscreen has no caption buttons, browsers and editors hide their chrome outright. Minimize and maximize are meaningless for a window with no frame. An app drawing custom chrome (DecorationsMode::CustomChrome) owns that decision itself, because the framework cannot hide a title bar the app composed — so it gates it here.

An app that hides these must keep some other visible way out of fullscreen: a menu item, an on-screen button, or a documented shortcut.

pub fn height(self, height: f32) -> Self

Set the title bar’s logical-pixel height. Default: 40.

pub fn background(self, color: impl Into<ColorProp>) -> Self

Fill the title bar with a solid background color. Default: transparent (the window’s clear color shows through).

Accepts a Color, a Signal<Color>, or any of the role types (SurfaceRole, TextRole, BorderRole, or their Signal<…> variants). Role values resolve at paint time, so the title bar retints live across ctx.set_theme(...) switches.

pub fn border(self, color: impl Into<ColorProp>, width: f32) -> Self

Draw a 1px-or-thicker bottom border separating the title bar from the body.

Color accepts the same range as Self::background; pair with BorderRole::Default for a theme-tracking divider.

pub fn leading(self, widget: impl Widget + 'static) -> Self

Set the leading-edge content (e.g. app icon, menus). Rendered to the right of the macOS traffic-light inset.

pub fn leading_id(self, id: WidgetId) -> Self

Set the leading-edge content by pre-registered ID.

pub fn center(self, widget: impl Widget + 'static) -> Self

Set the center content (e.g. search box, breadcrumbs). Wrapped in a flexible drag region: clicks that are not consumed by the child initiate a window drag.

pub fn center_id(self, id: WidgetId) -> Self

Set the center content by pre-registered ID.

pub fn trailing(self, widget: impl Widget + 'static) -> Self

Set the trailing-edge content (e.g. user avatar, notification bell). Rendered before the window controls.

pub fn trailing_id(self, id: WidgetId) -> Self

Set the trailing-edge content by pre-registered ID.

pub fn close_action( self, action: impl Fn(&mut EventContext<'_>) + 'static, ) -> Self

Override the close-button action. When set, the close button calls this closure instead of host.close(). Required on Wayland where the host’s close() is a no-op (winit 0.30 has no Window::request_close); the application typically wires this to call EventContext::close_window directly, or to send an Intent whose root-level Action handler calls it.

Trait Implementations

impl Debug for TitleBar

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Widget for TitleBar

fn build(&mut self, ctx: &mut BuildContext<'_>) -> Vec<WidgetId>

Compose child widgets. Called once after the widget is placed in the arena, and again on environment change (theme switch, locale switch). Takes &mut self — store child IDs, signal handles, any state needed later. Returns the list of root child IDs (empty for leaf widgets).

fn layout_response( &self, proposal: SizeProposal, _ctx: &LayoutContext<'_>, ) -> LayoutResponse

Respond to the parent’s size proposal with this widget’s wanted size, grow/shrink weights, and compression floor (see [LayoutResponse]).

fn place_children( &self, bounds: Rect, _proposal: SizeProposal, children: &mut [WidgetPlacement], _ctx: &LayoutContext<'_>, )

Position children within the allocated bounds.

fn paint(&self, bounds: Rect, canvas: &mut Canvas, ctx: &PaintContext<'_>)

Draw the widget’s visual representation.

fn wants_after_paint(&self) -> bool

Whether this widget wants its after_paint hook to fire each frame. Returning false (the default) saves a virtual call per widget per frame for the vast majority of widgets that don’t aggregate descendant geometry.

fn after_paint(&self, view: &WidgetTreeView<'_>, _ctx: &PaintContext<'_>)

Called once per frame after this widget’s subtree has finished painting. Receives a read-only view of the layout-resolved arena so a parent can read its descendants’ final bounds — e.g. TitleBar aggregates its drag region and control-button rects into a single HitRegions payload for the Windows backend’s WM_NCHITTEST.

fn accessibility(&self, builder: &mut AccessNodeBuilder)

Declare this widget’s accessibility identity.

fn children(&self) -> Vec<WidgetId>

Return the child widget IDs that this widget manages.

fn type_name(&self) -> &'static str

Concrete type name of this widget (e.g. "teksilo_widgets::button::Button"). The default implementation resolves at the impl site via std::any::type_name::<Self>(), so calls through &dyn Widget correctly dispatch to the monomorphized fn for the concrete type — getting the concrete name through the vtable without per-impl boilerplate.

fn cacheable_layout(&self) -> bool

Whether this widget’s layout_response may be memoized by the per-pass layout cache. Defaults to true.

fn wants_post_paint(&self) -> bool

Whether this widget wants its post_paint hook to fire each frame. Returning false (the default) saves a virtual call per widget per frame for the vast majority of widgets that don’t draw a foreground over their children.

fn post_paint( &self, _bounds: Rect, _canvas: &mut Canvas, _ctx: &PaintContext<'_>, )

Draw a foreground layer over this widget’s children.

fn wants_descendant_redirects(&self) -> bool

Whether this widget wants the AT walker to consult its a11y_redirect_descendant hook for every descendant during AT tree emission, not just its direct arena children.

fn a11y_redirect_descendant( &self, _self_id: WidgetId, _descendant: WidgetId, ) -> Option<NodeId>

Optional redirection hook for AT-tree placement of a child.

fn accessible_title_hint(&self) -> Option<String>

Suggest an accessible title to an enclosing container that wraps this widget as content — typically a modal / dialog shell that wants to propagate the inner content’s visible title as the shell’s own accessible name.

fn initial_focus_hint(&self) -> Option<WidgetId>

Optional hint that directs initial focus to a specific descendant when this widget is the root of a deferred-built modal surface.

fn accessibility_children(&self) -> Option<Vec<WidgetId>>

Optional override for the child ORDER presented to assistive technology, when it must differ from the paint / z-order child order returned by children.

fn as_any(&self) -> Option<&(dyn Any + 'static)>

Downcast hook. Default implementation returns None; concrete widgets override with Some(self) when they want to expose their concrete type to test-level introspection or reflection. The trait already bounds on std::any::Any so concrete types satisfy the 'static requirement.

fn as_any_mut(&mut self) -> Option<&mut (dyn Any + 'static)>

Mutable counterpart of as_any. Default returns None; widgets that want to expose mutable state to tests (e.g. so a test can mutate a Scene inside a SceneView post-layout) override with Some(self). Should follow the same opt-in pattern as as_any: only widgets that opt into & introspection should opt into &mut.

fn clips_children(&self) -> bool

Whether this widget clips its children to its bounds.

fn focus_reveal_rect(&self, _bounds: Rect) -> Option<Rect>

The rectangle (in absolute tree coordinates) that best represents this widget when the framework reveals it into an ancestor scroll area on focus gain. Returning None (the default) reveals the widget’s whole bounds — correct for most controls.

fn hit_shape(&self, _local_point: Point, _bounds: Rect) -> bool

Whether the point lies inside this widget’s actual shape, not just its rectangular bounds. Consulted by hit-testing right after the bounds check: returning false for a point that is inside the bounding box makes the widget transparent to the click there, so it falls through to whatever sibling is painted underneath (the same machinery as a fully pass-through node, but shape-aware).

fn preserves_children_on_rebuild(&self) -> bool

How rebuild_single_widget treats this widget’s existing children when re-running its build().

fn tooltip_has_content(&self) -> bool

Whether this widget, used as tooltip content, currently has anything worth showing.

fn declare_shortcuts(&self) -> Vec<Shortcut>

Declare the rebindable keyboard shortcuts this widget exposes, without installing handlers. The framework calls this at arena insertion time (before build()) and at certain lazy boundaries (e.g. Switcher walks declarations on its not-yet-mounted Pending slots), so settings UIs and the ShortcutRegistry see the keystrokes the moment the owning container mounts — even if build() hasn’t run.

fn take_handler_set(&mut self) -> Option<HandlerSet>

Extract attached handler set from a WidgetWithHandlers wrapper. Called during arena insertion to transfer handlers to the WidgetNode. Default: returns None (no attached handlers).