Struct ComboBox 

pub struct ComboBox { /* private fields */ }

A single-selection dropdown.

Example

ComboBox::new(vec!["Option A", "Option B", "Option C"], 0, font)
    .on_change(|idx| println!("selected {idx}"))

Implementations

impl ComboBox

pub fn new( options: Vec<impl Into<String>>, selected: usize, font: Arc<Font>, ) -> Self

Create a new ComboBox.

options is the full list of choices; selected is the initial index (clamped to a valid range).

pub fn with_selected_cell(self, cell: Rc<Cell<usize>>) -> Self

Bind this combo’s selection to an external Rc<Cell<usize>>. layout() reads the cell each frame so a sibling combo (e.g. the matching font picker in another window) sharing the same cell stays in lock-step; user selections here write back. Mirrors the Slider::with_value_cell / RadioGroup::with_selected_cell pattern.

pub fn with_font_size(self, size: f64) -> Self

pub fn with_margin(self, m: Insets) -> Self

pub fn with_h_anchor(self, h: HAnchor) -> Self

pub fn with_v_anchor(self, v: VAnchor) -> Self

pub fn with_min_size(self, s: Size) -> Self

pub fn with_max_size(self, s: Size) -> Self

pub fn on_change(self, cb: impl FnMut(usize) + 'static) -> Self

Set the callback called when the user selects a new option.

pub fn with_item_fonts(self, fonts: Vec<Arc<Font>>) -> Self

Override the font used for EACH dropdown entry individually — one font per option. Intended for font-preview UI (the System window’s font picker renders each name in its own face). Each item label is rebuilt with the matching Arc<Font> and marked to ignore the system-wide font override (otherwise changing the global font would overwrite all the per-entry faces).

Lengths must match: fonts.len() should equal the number of options. Extra fonts are ignored; missing entries keep the default self.font. The SELECTED label (shown when the dropdown is closed) is also rebuilt with the currently-selected font so the closed combo reflects the live face.

pub fn set_item_fonts(&mut self, fonts: Vec<Arc<Font>>)

Replace per-item preview fonts after construction for lazy font UIs.

pub fn selected(&self) -> usize

pub fn set_selected(&mut self, idx: usize)

Trait Implementations

impl Widget for ComboBox

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

A static name for this widget type, used by the inspector. Default: “Widget”.

fn bounds(&self) -> Rect

Bounding rectangle in parent-local Y-up coordinates.

fn set_bounds(&mut self, b: Rect)

Set the bounding rectangle. Called by the parent during layout.

fn children(&self) -> &[Box<dyn Widget>]

Immutable access to child widgets.

fn children_mut(&mut self) -> &mut Vec<Box<dyn Widget>>

Mutable access to child widgets (required for event dispatch + layout).

fn is_focusable(&self) -> bool

Whether this widget can receive keyboard focus. Default: false.

fn needs_draw(&self) -> bool

Return true if this widget, or any visible descendant, has an ongoing draw need that should keep the host drawing.

fn hit_test(&self, local_pos: Point) -> bool

Return true if local_pos (in this widget’s local coordinates) falls inside this widget’s interactive area. Default: axis-aligned rect test.

fn hit_test_global_overlay(&self, local_pos: Point) -> bool

Return true when local_pos hits an app-level overlay owned by this widget. Unlike normal hit testing, ancestors may be missed because the overlay is painted outside their bounds.

fn margin(&self) -> Insets

Outer margin around this widget in logical units.

fn widget_base(&self) -> Option<&WidgetBase>

Direct read access to the widget’s embedded WidgetBase.

fn widget_base_mut(&mut self) -> Option<&mut WidgetBase>

Mutable counterpart of widget_base.

fn h_anchor(&self) -> HAnchor

Horizontal anchor: how this widget sizes/positions itself horizontally within the slot the parent assigns. Default: HAnchor::FIT (take natural content width).

fn v_anchor(&self) -> VAnchor

Vertical anchor: how this widget sizes/positions itself vertically within the slot the parent assigns. Default: VAnchor::FIT (take natural content height).

fn min_size(&self) -> Size

Minimum size constraint (logical units).

fn max_size(&self) -> Size

Maximum size constraint (logical units).

fn layout(&mut self, available: Size) -> Size

Compute desired size given available space, and update internal layout.

fn paint(&mut self, ctx: &mut dyn DrawCtx)

Paint this widget’s own content into ctx.

fn paint_overlay(&mut self, _ctx: &mut dyn DrawCtx)

Paint decorations that must appear on top of all children.

fn paint_global_overlay(&mut self, ctx: &mut dyn DrawCtx)

Paint app-level overlays after the entire widget tree has been painted.

fn on_event(&mut self, event: &Event) -> EventResult

Handle an event. The event’s positions are already in local Y-up coordinates. Return EventResult::Consumed to stop bubbling.

fn properties(&self) -> Vec<(&'static str, String)>

Return type-specific properties for the inspector properties pane.

fn claims_pointer_exclusively(&self, _local_pos: Point) -> bool

When true, hit_test_subtree stops recursing into this widget’s children and returns this widget as the hit target. Used for floating overlays (e.g. a scrollbar painted above its content) that must claim the pointer before children that happen to share the same pixels. Default: false.

fn has_active_modal(&self) -> bool

Whether this widget currently owns an app-modal interaction layer.

fn on_unconsumed_key( &mut self, _key: &Key, _modifiers: Modifiers, ) -> EventResult

Handle a key that was not consumed by the focused widget path.

fn id(&self) -> Option<&str>

Optional human-readable identifier for this widget instance.

fn is_visible(&self) -> bool

Return false to suppress painting this widget and all its children. The widget’s own paint() will not be called. Default: true.

fn set_label_color(&mut self, _color: Color)

If this widget is text-bearing (e.g. Label), update its foreground colour. Default is a no-op. Composite widgets call this on their children to retint labels without rebuilding them — used by Button when toggling between active (white text on accent) and inactive (theme text on subtle bg) appearances.

fn set_label_text(&mut self, _text: &str)

If this widget is text-bearing (e.g. Label), update its displayed text. Default is a no-op. Composite widgets that own a Label child use this to push live values (e.g. an FPS counter) into the child without bypassing the standard backbuffered glyph cache — calling this on a Label only invalidates the cache when the text actually changed.

fn as_reflect(&self) -> Option<&dyn Reflect>

Opt-in reflection accessor for the inspector’s typed property editors.

fn as_reflect_mut(&mut self) -> Option<&mut dyn Reflect>

Mutable counterpart of as_reflect. Used by the inspector to write edits back into the live widget.

fn has_backbuffer(&self) -> bool

Whether this widget renders into its own offscreen buffer before compositing into the parent.

fn compositing_layer(&mut self) -> Option<CompositingLayer>

Request that this widget subtree be painted into a transient transparent compositing layer before being blended into its parent.

fn backbuffer_spec(&mut self) -> BackbufferSpec

Unified widget-owned backbuffer request.

fn backbuffer_state_mut(&mut self) -> Option<&mut BackbufferState>

Mutable retained backbuffer state for widgets that request a BackbufferSpec other than BackbufferKind::None.

fn mark_dirty(&mut self)

Mark this widget’s own retained surface dirty, if it owns one.

fn backbuffer_cache_mut(&mut self) -> Option<&mut BackbufferCache>

Opt into per-widget CPU bitmap caching with a dirty flag.

fn backbuffer_mode(&self) -> BackbufferMode

Storage format for this widget’s backbuffer. Ignored unless [backbuffer_cache_mut] returns Some. Default BackbufferMode::Rgba — correct for any widget. Opt into BackbufferMode::LcdCoverage only when the widget paints opaque content covering its full bounds.

fn contributes_children_to_inspector(&self) -> bool

Whether the inspector should recurse into this widget’s children.

fn show_in_inspector(&self) -> bool

Return false to hide this widget (and its subtree) from the inspector node snapshot entirely. Intended for zero-size utility widgets such as layout-time watchers / tickers / invisible composers — they bloat the inspector tree without providing user-relevant information and, at scale, can make the inspector’s per-frame tree rebuild expensive.

fn lcd_preference(&self) -> Option<bool>

Per-widget LCD subpixel preference for backbuffered text rendering.

fn finish_paint(&mut self, _ctx: &mut dyn DrawCtx)

Called after paint, child painting, and optional overlay painting.

fn clip_children_rect(&self) -> Option<(f64, f64, f64, f64)>

Return a clip rectangle (in local coordinates) that constrains all child painting. paint_subtree applies this clip before recursing into children, then restores the previous clip state afterward. The clip does not affect paint_overlay, which runs after the clip is removed.

fn padding(&self) -> Insets

Inner padding — space the widget reserves between its own bounds and its child layout area. Only container widgets carry padding; leaf widgets default to Insets::ZERO.

fn enforce_integer_bounds(&self) -> bool

Whether paint_subtree should snap this widget’s incoming translation to the physical pixel grid.

fn measure_min_height(&self, _available_w: f64) -> f64

Report the minimum height this widget needs to fully render its content when given the supplied available_w for width.

fn take_raise_request(&mut self) -> bool

Container widgets (notably crate::widgets::Stack) call this on each child at the start of layout(). A widget that returns true is moved to the END of its parent’s child list — painted last, i.e. raised to the top of the z-order. take_ semantics: the call is also expected to clear the request so the child doesn’t keep getting raised every frame.

fn next_draw_deadline(&self) -> Option<Instant>

Return the earliest wall-clock instant at which this widget (or any visible descendant) wants the next draw. None = no scheduled wake. The host loop turns a Some(t) into ControlFlow::WaitUntil(t) so e.g. a cursor blink fires without continuous polling.