Function compute_vertical_scrollbar_geometry

src/engine.rs:903–943

(
    bbox: BoundingBox,
    content_height: f32,
    scroll_position_positive: f32,
    config: ScrollbarConfig,
)

}

fn compute_vertical_scrollbar_geometry(
    bbox: BoundingBox,
    content_height: f32,
    scroll_position_positive: f32,
    config: ScrollbarConfig,
) -> Option<ScrollbarAxisGeometry> {
    let viewport = bbox.height;
    let max_scroll = (content_height - viewport).max(0.0);
    if viewport <= 0.0 || max_scroll <= 0.0 {
        return None;
    }

    let thickness = config.width.max(1.0);
    let track_len = viewport;
    let thumb_len = (track_len * (viewport / content_height.max(viewport)))
        .max(config.min_thumb_size.max(1.0))
        .min(track_len);
    let thumb_travel = (track_len - thumb_len).max(0.0);
    let thumb_offset = if thumb_travel <= 0.0 {
        0.0
    } else {
        (scroll_position_positive.clamp(0.0, max_scroll) / max_scroll) * thumb_travel
    };

    Some(ScrollbarAxisGeometry {
        track_bbox: BoundingBox::new(
            bbox.x + bbox.width - thickness,
            bbox.y,
            thickness,
            track_len,
        ),
        thumb_bbox: BoundingBox::new(
            bbox.x + bbox.width - thickness,
            bbox.y + thumb_offset,
            thickness,
            thumb_len,
        ),
        max_scroll,
        thumb_travel,
    })
}

fn compute_horizontal_scrollbar_geometry(
    bbox: BoundingBox,