Struct Dropdown 

pub struct Dropdown<'a, C: PixelColor, M: Clone> { /* private fields */ }

A drop-down selector. The host owns the open flag and selected index; the widget renders the field, draws the option list as an overlay while open, and emits on_toggle / on_select.

Implementations

impl<'a, C: PixelColor + 'a, M: Clone + 'a> Dropdown<'a, C, M>

pub fn new() -> Self

New drop-down. Position and size are assigned by the parent container via arrange. Defaults: no options, selection 0, closed, fill width, 36px field height.

pub fn width(self, width: impl Into<Length>) -> Self

Width sizing intent (default Length::Fill).

pub fn height(self, height: impl Into<Length>) -> Self

Height sizing intent of the field (default 36px). The option list always uses one fixed-height row per option.

pub fn options(self, options: &[&str]) -> Self

The option labels. They are copied into owned Strings so the widget can outlive the borrowed slice.

pub fn selected(self, index: usize) -> Self

The currently-selected option index (host-owned).

pub fn open(self, open: bool) -> Self

Whether the option list is currently shown (host-owned).

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

Text shown on the field when the selected index is out of range (e.g. nothing selected yet).

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

Set a stable base id so the field and option rows can participate in focus traversal.

pub fn on_toggle<F: Fn(bool) -> M + 'a>(self, f: F) -> Self

Callback invoked when the field is tapped, receiving the negated open flag. Without it the field does not toggle.

pub fn on_select<F: Fn(usize) -> M + 'a>(self, f: F) -> Self

Callback invoked when an option is tapped, receiving that option’s index. Without it the options are inert.

Trait Implementations

impl<'a, C: PixelColor + 'a, M: Clone + 'a> Default for Dropdown<'a, C, M>

fn default() -> Self

Returns the “default value” for a type.

impl<'a, C: PixelColor + 'a, M: Clone + 'a> Widget<C, M> for Dropdown<'a, C, M>

fn measure(&mut self, constraints: Constraints) -> Size

Report the size this widget wants within constraints.

fn preferred_size(&self) -> (Length, Length)

Per-axis sizing intent set via .width(...) / .height(...). Containers consult this during layout to allocate fixed slots, query intrinsic sizes, and split residual space among Fill / FillPortion children. Default is Length::Fill on both axes.

fn arrange(&mut self, rect: Rectangle)

Commit the final rectangle, recursively arranging any children.

fn rect(&self) -> Rectangle

The current arranged rectangle.

fn handle_touch(&mut self, point: Point, phase: TouchPhase) -> Option<M>

Dispatch a touch event. Returns a message if consumed.

fn mark_pressed(&mut self, point: Point)

Set this widget’s pressed flag if point hits. No message emit. Containers forward to children. Default no-op.

fn collect_focusable(&self, out: &mut Vec<WidgetId>)

Append focusable widget ids in traversal order.

fn sync_focus(&mut self, focused: Option<WidgetId>)

Synchronize focused state against the runtime’s currently-focused id.

fn route_action(&mut self, target: WidgetId, action: UiAction) -> Option<M>

Route a semantic action to the widget with id target.

fn focus_rect(&self, target: WidgetId) -> Option<Rectangle>

Rectangle currently occupied by the focusable target, if any.

fn focus_at(&self, point: Point) -> Option<WidgetId>

Focusable widget id at point, if any.

fn draw<'t>( &self, renderer: &mut dyn Renderer<C>, theme: &Theme<'t, C>, ) -> Result<(), RenderError>

Paint into renderer at rect.

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

Stable id of this widget, if it participates in focus.

fn is_focusable(&self) -> bool

True if this widget should appear in focus traversal.

fn handle_action(&mut self, action: UiAction) -> Option<M>

Handle a semantic action directed at this widget.

fn navigate_focus(&self, target: WidgetId, action: UiAction) -> Option<WidgetId>

Request a focus movement relative to target for directional actions.