Struct Scrollbar 

pub struct Scrollbar { /* private fields */ }

A vertical scrollbar (typically one cell wide) covering total_len items in a visible_len-row viewport.

offset defaults to 0; track_style/thumb_style default to Theme::DARK (as if Scrollbar::theme had been called). Set whichever a caller needs via Scrollbar::offset/Scrollbar::track_style/Scrollbar::thumb_style.

track_style fills the whole strip, then crate::draw::thumb_geometry’s span (if any) is redrawn with thumb_style on top. Draws just the plain track, with no thumb, if there’s nothing to scroll: see crate::draw::thumb_geometry.

As a plain Widget, Scrollbar is purely a display: offset is whatever the caller last set, unaffected by the pointer. InteractiveWidget’s type State = ScrollState makes it draggable and wheel-scrollable instead: sense() is Sense::drag | Sense::CLICK | Sense::SCROLL, and its render reads the thumb’s position from state.integer_offset(), drives a drag via offset_for_pos/ScrollState::update_drag/ ScrollState::end_drag using Response::pointer_pos, and applies wheel input via ScrollState::apply.

Examples

use retroglyph_core::grid::{Grid, Rect};
use retroglyph_ui::{Scrollbar, Surface, Widget};

let area = Rect::new(0, 0, 1, 10);
let mut grid = Grid::new(1, 10);
let scrollbar = Scrollbar::new(100, 10).offset(20);
Widget::render(&scrollbar, &mut Surface::new(&mut grid, area, 0));

Implementations

impl Scrollbar

pub fn new(total_len: usize, visible_len: usize) -> Self

A scrollbar covering total_len items in a visible_len-row viewport, starting at offset 0, styled from Theme::DARK (as if Scrollbar::theme had been called).

pub const fn offset(self, offset: usize) -> Self

Set the scroll offset the thumb is drawn at.

pub const fn track_style(self, style: Style) -> Self

Set the track’s style.

pub const fn thumb_style(self, style: Style) -> Self

Set the thumb’s style.

pub fn theme(self, theme: Theme) -> Self

Applies theme’s named roles to this scrollbar: track_style becomes theme.panel_bg (the same surface the scrolled content sits on), and thumb_style becomes theme.border: a subtle divider-like color rather than theme.accent, so a themed scrollbar doesn’t compete with an actually-selected/focused control for attention.

Call before any manual Scrollbar::track_style/Scrollbar::thumb_style override you want to keep.

pub fn theme_on(self, theme: Theme, bg: Color) -> Self

Same as Scrollbar::theme, but track_style is drawn on bg instead of theme.panel_bg: for a scrollbar drawn directly on a backdrop other than a themed super::Panel/super::Modal’s fill. Scrollbar::theme is exactly theme_on(theme, theme.panel_bg).

Trait Implementations

impl AnimatedWidget for Scrollbar

fn render( &self, surface: &mut Surface<'_>, state: &mut Self::State, frame: &Frame, )

Ticks state’s momentum/rubber-band physics forward by frame.delta (a no-op while ScrollState::dragging is true, per ScrollState::tick’s own docs), then draws the thumb at the resulting integer_offset: the Widget::render this type already has, just with self.offset replaced by state’s current one. max_offset is total_len - visible_len (floored at 0), matching thumb_geometry’s own definition, so the physics and the drawn thumb position are always in terms of the same bound.

type State = ScrollState

The externally owned, time-evolving state this widget reads and/or updates while rendering, e.g. crate::ScrollState.

impl Clone for Scrollbar

fn clone(&self) -> Scrollbar

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Scrollbar

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

Formats the value using the given formatter.

impl<Id> InteractiveWidget<Id> for Scrollbar

fn sense(&self) -> Sense

Draggable (thumb or track, click-to-jump then continues as a smooth drag) and wheel-scrollable.

type State = ScrollState

State that outlives one render call, e.g. a selection index or scroll offset. () for widgets that have none.

fn render( &self, surface: &mut Surface<'_>, state: &mut Self::State, response: Response<Id>, )

Draw into surface, styled by response, which the caller already resolved (via Interaction::interact) for surface.area() and sense.

impl Widget for Scrollbar

fn render(&self, surface: &mut Surface<'_>)

Draw this widget into surface, filling surface.area().

impl Copy for Scrollbar