ScrollBarRenderable — scroll bar

A track-and-thumb scroll bar showing position within a scrollable document. Focusable. Pair it with a ScrollBoxRenderable or any widget exposing scroll state.

ScrollBarRenderable::new(orientation: ScrollBarOrientation) -> Self
pub enum ScrollBarOrientation { Vertical, Horizontal }

Scroll model

set_scroll_size and set_viewport_size re-clamp the current position, so the thumb always stays in range.

Colors

set_track_color(Option<ColorInput>)   // default #252527
set_thumb_color(Option<ColorInput>)   // default #9a9ea3
set_show_arrows(bool)                 // draw ▲/▼ (or ◄/►) at the ends

The arrow color is fixed at its default (#9a9ea3) — there is no public setter for it in this version.

Rendering

render_self fills the track across the area, then draws the thumb at the position proportional to scroll_position / (scroll_size - viewport_size). The thumb size is proportional to viewport_size / scroll_size (a large viewport = long thumb), clamped to at least 1 cell. Thumb characters: █ for the body, ▲/▼ (or ◄/►) at the ends, ■ when the thumb is a single cell.

Example

use cosh_tui::core::renderables::scroll_bar::{ScrollBarRenderable, ScrollBarOrientation};

let mut bar = ScrollBarRenderable::new(ScrollBarOrientation::Vertical);
bar.set_scroll_size(100.0);
bar.set_viewport_size(20.0);
bar.set_scroll_position(30.0);    // clamps to max 80
assert_eq!(bar.scroll_position(), 30.0);
bar.scroll_by(1.0, true);         // +20 → 50
assert_eq!(bar.scroll_position(), 50.0);

Next: scroll_box — the scrollable viewport.