Struct ComboBox 

pub struct ComboBox<T: Clone + PartialEq + 'static> { /* private fields */ }

A dropdown selection widget.

// Simple: list of strings.
let selected = ctx.signal(None::<String>);
ComboBox::new(["Apple", "Banana", "Cherry"], selected)
    .placeholder(lit!("Select a fruit..."))

// Typed items: any T: Clone + PartialEq, plus a label extractor.
#[derive(Clone, PartialEq)] struct Fruit { name: String, emoji: &'static str }
let selected = ctx.signal(None::<Fruit>);
ComboBox::from_items(fruits, selected)
    .item_label(|f: &Fruit| lit!(format!("{} {}", f.emoji, f.name)))

// Model-backed: reactive.
let model = ListModel::from_vec(fruits);
ComboBox::from_model(model, selected)
    .item_label(|f: &Fruit| lit!(f.name.clone()))
    .max_visible_items(6)

Implementations

impl ComboBox<String>

pub fn new( items: impl IntoIterator<Item = impl Into<String>>, selected: Signal<Option<String>>, ) -> Self

Create a ComboBox from a list of strings.

Accepts any impl Into<String> — string literals (&str), owned Strings, resolved LocalizedStrings, etc. For translated items, resolve translations before passing in, e.g. vec![tr!(apple()).resolve_now(), ...].

impl<T: Clone + PartialEq + 'static> ComboBox<T>

pub fn from_items<F>( items: impl IntoIterator<Item = T>, selected: Signal<Option<T>>, item_label: F, ) -> Self

where F: Fn(&T) -> LocalizedString + 'static,

Static list of typed items. item_label is the display extractor — it’s required at construction so the compiler enforces it rather than a runtime check. For T = String, use ComboBox::new which defaults to the identity label.

pub fn from_model<F>( model: ListModel<T>, selected: Signal<Option<T>>, item_label: F, ) -> Self

where F: Fn(&T) -> LocalizedString + 'static,

Backed by a reactive ListModel<T>. Inserts, removes, and reorders propagate into the dropdown automatically. If the currently-selected value disappears from the model, selected becomes None.

pub fn from_source<S, F>( source: S, selected: Signal<Option<T>>, item_label: F, ) -> Self

where S: ListDataSource<Item = T> + 'static, F: Fn(&T) -> LocalizedString + 'static,

Backed by a custom ListDataSource — for external or paged data.

pub fn item_label(self, f: impl Fn(&T) -> LocalizedString + 'static) -> Self

Override the display-label extractor. Rarely needed — prefer passing item_label to the constructor. Useful for the ComboBox<String> path when you want a non-identity projection.

pub fn render_item( self, f: impl Fn(&T, bool) -> Box<dyn Widget> + 'static, ) -> Self

Custom cell rendering. The closure receives the item and a flag indicating whether it is the currently-selected value.

The framework wraps the returned widget with the correct Role::ListBoxOption accessibility and tap handler, so callers do not need to manage a11y or selection dispatch themselves.

Reactivity. The bool argument is a snapshot at build time. If the selection flips after the dropdown is open, the user’s subtree is not automatically re-rendered; the framework-managed highlight background (behind the custom widget) does update, and closing and re-opening the dropdown picks up the new state. If you need a reactive appearance that tracks selection, close over a Signal<Option<T>> in your closure and compare against the item value inside a .map() / bind_* on primitives.

Accessibility. The wrapper’s set_name(label) (from item_label) is what screen readers announce. If the returned widget includes its own text nodes (e.g. a bare TextWidget), the label may be announced twice — one from the wrapper, one from the inner text. Wrap primary text nodes in .a11y_hidden() to avoid duplication, and reserve visible widgets for presentation only.

pub fn render_selected( self, f: impl Fn(&T) -> Box<dyn Widget> + 'static, ) -> Self

Custom renderer for the trigger’s selected value — the widget shown when the combo is closed. The parallel of render_item for the trigger rather than the dropdown rows.

When set, the closed combo shows f(&value) for the current selection instead of the plain text label (item_label). The canonical use is a FontPicker rendering the selected family name in its own typeface. The subtree is rebuilt whenever the selection changes and whenever the locale changes (so a None-state placeholder re-translates), without rebuilding the whole ComboBox.

Accessibility. The rendered subtree is excluded from the accessibility tree — the ComboBox’s own accessibility(builder) already announces the selected value via set_value, so the custom visual can never double-announce. When nothing is selected the trigger shows the placeholder text.

pub fn on_select(self, f: impl Fn(&T, &mut EventContext<'_>) + 'static) -> Self

Register a callback fired when the user commits a selection — by tapping a dropdown row or picking one with the keyboard (arrows / type-ahead / Home / End). The callback receives the chosen value and a live EventContext, so it can run context-bearing actions that observing the bound selected signal cannot — e.g. ctx.set_locale(...), navigation, or opening another overlay.

It fires only on user-driven commits, not on external writes to the selected signal (those are observed via ctx.effect). The selected signal is updated before the callback runs.

pub fn max_visible_items(self, n: usize) -> Self

Maximum number of items shown before the dropdown becomes scrollable. Defaults to 8. Clamped to at least 1.

pub fn type_ahead_timeout(self, d: Duration) -> Self

Reset window for keyboard type-ahead. Keystrokes more than d apart begin a fresh prefix; within d they extend it. Defaults to 500 ms, matching MenuList::type_ahead_timeout. Pass Duration::ZERO to treat each keystroke independently.

pub fn placeholder(self, text: impl Into<LocalizedString>) -> Self

Placeholder text shown in the trigger when selected is None. Accepts a tr!(...) directly (resolved at build); use placeholder_literal for an untranslated string.

pub fn label(self, label: impl Into<LocalizedString>) -> Self

Accessible label describing what this combo box is for (e.g. “Fruit”, “Font family”). Independent of the visible placeholder and of the current selection — screen readers announce this as the name of the control.

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

Set the enabled state, statically or reactively. Forwarded to the arena at build time.

pub fn variant(self, variant: ComboBoxVariant) -> Self

Pick a Tier-1 design-language variant (ComboBoxVariant::Outlined / Filled / Underline / Plain). The active ComboBoxStyle decides what to do with the hint — IntUI’s default impl honours Outlined (default) and Plain; a custom impl (Material 3, macOS, etc.) might paint differently.

pub fn style(self, style: impl ComboBoxStyle) -> Self

Override the active ComboBoxStyle for this widget instance only. The default IntUI chrome (crate::styles::RecipeComboBoxStyle) resolves its dimensions from theme.input (the density InputTokens); custom impls can paint anything they want around the selected-label slot.

pub fn text_style(self, style: impl Into<TextStyleProp>) -> Self

Override the selected-value text style (font, size, weight). Accepts a TextStyleRole, a TextStyle, or a Signal of either. Default (unset) is TextStyleRole::Body.

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

Override the selected-value text color. Accepts Color, a role, or a Signal of either. Default (unset) is enabled-derived (Primary / Disabled); setting this replaces that cascade.

pub fn tooltip(self, text: impl Into<LocalizedString>) -> Self

Attach a plain tooltip that appears after a hover delay. The tooltip is anchored to the trigger only — with the framework’s overlay-boundary gate it does not re-trigger while the pointer is over the open dropdown’s option rows.

Mutually exclusive with rich_tooltip / rich_tooltip_content / composite_tooltip — last call wins.

pub fn rich_tooltip(self, key: impl Into<String>) -> Self

Attach a rich tooltip resolved from the app-wide tooltip registry. The key is looked up via TooltipRegistry at build time; the resolved body supports inline markup, a shortcut chip, and a “more” disclosure. Overrides any previously set tooltip.

pub fn rich_tooltip_content(self, content: TooltipContent) -> Self

Attach a rich tooltip driven by inline TooltipContent — for one-off tooltips that aren’t worth registering centrally. Overrides any previously set tooltip.

pub fn composite_tooltip(self, content: impl Widget + 'static) -> Self

Attach a composite tooltip — third tier, hosting an arbitrary widget tree (tabbed sections, charts, conditional rows). Promotes to a focusable Role::Dialog after the standard dwell. Overrides any plain or rich tooltip previously set.

impl<T: Clone + PartialEq + 'static> ComboBox<T>

Searchable-mode builders. The search field is a TextInput, which shares the RichTextEditor engine and therefore the teksilo-text dependency.

pub fn searchable(self, enabled: bool) -> Self

Show a search field at the top of the dropdown panel and filter the list live against the user’s query. When true, items are matched by the closure passed to filter, or — if no filter is set — by a case-insensitive substring match on the item_label.

The search input becomes a child of the dropdown panel only, not of the trigger: the closed combo box looks identical whether searchable or not.

The query signal is created internally. Use search_query to supply your own if you want to observe or drive the query externally.

pub fn search_query(self, query: Signal<String>) -> Self

Bind the search field to an external Signal<String>. Implies searchable(true). Useful for observing or programmatically setting the query from outside the widget (e.g. a “Clear” button, persistence across sessions).

pub fn filter(self, f: impl Fn(&str, &T) -> bool + 'static) -> Self

Custom match predicate for searchable mode. Called on every visible-item pass with the current query string (as typed, not normalized) and a reference to the item; return true to keep the item in the filtered list. Only consulted when searchable is true. Ignored otherwise.

Trait Implementations

impl<T: Clone + PartialEq + 'static> Debug for ComboBox<T>

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

Formats the value using the given formatter.

impl<T: Clone + PartialEq + 'static> Widget for ComboBox<T>

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

Compose child widgets. Called once after the widget is placed in the arena, and again whenever the widget is marked for rebuild — a BindingLevel::Rebuild binding, rebuild_single_widget, or a density switch. A theme or locale switch does not rebuild: set_theme and set_locale mark layout + paint dirty and leave the built subtree standing, so anything derived from the theme or the locale must be read per pass or bound to a signal rather than captured here. 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 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 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 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 culls_children(&self) -> bool

Whether this widget decides, on every layout pass, which of its children exist at all.

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 accessible_title_node(&self) -> Option<WidgetId>

The widget that paints this one’s title, when it has one.

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 context_menu_key_target(&self) -> Option<WidgetId>

Which descendant a keyboard request for a context menu should target.

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 accepts_child_hit(&self, _child: WidgetId, _point: Point) -> bool

Veto a hit on one of this widget’s direct children, per point.

fn hit_outset(&self, _kind: PointerKind, _tokens: &InputTokens) -> EdgeInsets

How far outside its own bounds this widget still absorbs a press, per edge, for the pointer that is asking.

fn hit_slop(&self, _kind: PointerKind, _tokens: &InputTokens) -> Option<HitSlop>

This widget’s own say in the miss-only slop pass, overriding the density default for its node.

fn hit_distance(&self, local_point: Point, bounds: Rect) -> Option<f32>

How far a missed press is from this widget’s actual silhouette, in the widget’s own bounds space.

fn target_regions(&self, _bounds: Rect) -> Vec<TargetRegion>

The interactive sub-regions this widget paints inside its own single node — a scroll bar’s thumb, a slider’s knob, a header cell’s filter affordance.

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).

impl WidgetCatalog for ComboBox<String>

fn id() -> &'static str

Stable, ASCII id (e.g. "button", "tag_chip"). Used in CLI args, navigator URLs, and persistence keys.

fn group() -> &'static str

Group label for navigator organisation ("Controls", "Containers", "Composites", …).

fn display_name() -> &'static str

Human-readable label shown in the navigator.

fn knobs() -> KnobSpec

Optional knob declarations. Empty by default — composite widgets that build via Scenario variants leave this empty.

fn variants() -> Vec<PreviewVariant>

Named variants. At least one is required — typically a “default”.

fn build(_variant: &str, knobs: &KnobValues) -> Box<dyn Widget>

Construct a fresh widget instance for the named variant, given runtime knob values. The implementation typically dispatches on the variant name to handle Scenario paths and otherwise builds via the knob values for Knobs variants.

fn icon() -> Option<Box<dyn Widget>>

An icon widget for the navigator palette and the designer’s outline tree. None (the default) leaves the consumer to substitute a generic fallback. Returns a Box<dyn Widget> (not an IconWidget) so this crate stays free of any widgets-crate dependency.

fn category() -> WidgetCategory

How this widget accepts children. The default, WidgetCategory::Leaf, is correct for every control; container widgets override it.

fn slots() -> &'static [&'static str]

Named slots for a WidgetCategory::ContainerB widget (e.g. Card → ["header", "content", "footer"]). Empty for Leaf and ContainerA.

fn build_with_children( variant: &str, knobs: &KnobValues, children: Vec<SlottedChild>, ) -> Box<dyn Widget>

Build with pre-registered children injected. ContainerA folds children as ordered bare children; ContainerB routes each by its slot name; Leaf ignores them. The default ignores children and delegates to build, so non-container widgets need no override.