Struct Dropdown 

pub struct Dropdown;

A searchable dropdown selection component.

This component provides a filterable dropdown menu for selecting a single option from a list. Users can type to filter options, then navigate and select using keyboard controls.

Features

• Case-insensitive “contains” matching
• Keyboard navigation through filtered results
• Selection from existing options only
• Filter clears on close/confirm

Keyboard Navigation

The dropdown itself doesn’t handle keyboard events directly. Your application should map:

• Characters to DropdownMessage::Insert
• Backspace to DropdownMessage::Backspace
• Down arrow to DropdownMessage::Down
• Up arrow to DropdownMessage::Up
• Enter to DropdownMessage::Confirm
• Escape to DropdownMessage::Close

Visual States

Closed (no selection):

┌──────────────────────┐
│ Search...          ▼ │
└──────────────────────┘

Closed (with selection):

┌──────────────────────┐
│ Apple              ▼ │
└──────────────────────┘

Open (with filter):

┌──────────────────────┐
│ app█               ▲ │
├──────────────────────┤
│ > Apple              │  ← highlighted
│   Pineapple          │
└──────────────────────┘

Example

use envision::component::{Dropdown, DropdownMessage, DropdownOutput, DropdownState, Component};

let mut state = DropdownState::new(vec!["Apple", "Banana", "Cherry"]);

// Open and filter
Dropdown::update(&mut state, DropdownMessage::Open);
Dropdown::update(&mut state, DropdownMessage::Insert('a'));

// Navigate and select
Dropdown::update(&mut state, DropdownMessage::Down);
let output = Dropdown::update(&mut state, DropdownMessage::Confirm);
assert_eq!(output, Some(DropdownOutput::Selected("Banana".to_string()))); // Banana

Trait Implementations

impl Component for Dropdown

type State = DropdownState

The component’s internal state type.

type Message = DropdownMessage

Messages this component can receive.

type Output = DropdownOutput

Messages this component can emit to its parent.

fn init() -> Self::State

Initialize the component state.

fn update(state: &mut Self::State, msg: Self::Message) -> Option<Self::Output>

Update component state based on a message.

fn handle_event(state: &Self::State, event: &Event) -> Option<Self::Message>

Maps an input event to a component message.

fn view(state: &Self::State, frame: &mut Frame<'_>, area: Rect, theme: &Theme)

Render the component to the given area.

fn traced_view( state: &Self::State, frame: &mut Frame<'_>, area: Rect, theme: &Theme, )

Renders the component with optional tracing instrumentation.

fn dispatch_event( state: &mut Self::State, event: &Event, ) -> Option<Self::Output>

Dispatches an event by mapping it to a message and updating state.

impl Focusable for Dropdown

fn is_focused(state: &Self::State) -> bool

Returns true if this component is currently focused.

fn set_focused(state: &mut Self::State, focused: bool)

Sets the focus state of this component.

fn focus(state: &mut Self::State)

Gives focus to this component.

fn blur(state: &mut Self::State)

Removes focus from this component.