Struct ScrollbarGeometry

Source

pub struct ScrollbarGeometry {
    pub axis: ScrollbarAxis,
    pub track: Rect,
    pub thumb: Rect,
    pub hit_track: Rect,
    pub viewport_extent: f32,
    pub max_offset: f32,
}

Expand description

Resolved proportional scrollbar geometry in one coordinate space.

track and thumb are paint rectangles. hit_track may be wider than the paint while remaining clipped to the original viewport.

§Examples

use ailloli_ui_core::{Rect, ScrollMetrics, ScrollState, ScrollbarAxis, ScrollbarGeometrySpec, Size};
let geometry = ScrollbarGeometrySpec::new(
    ScrollbarAxis::Horizontal,
    Rect::new(0.0, 0.0, 100.0, 60.0),
    ScrollMetrics::new(Size::new(100.0, 60.0), Size::new(300.0, 60.0)),
    ScrollState::new(),
).resolve().unwrap();
assert!(geometry.hit_track.h >= geometry.track.h);

Fields§

§axis: ScrollbarAxis

Controlled axis.

§track: Rect

Painted track bounds.

§thumb: Rect

Painted proportional thumb bounds.

§hit_track: Rect

Pointer target containing the track and expanded cross-axis area.

§viewport_extent: f32

Visible content extent along Self::axis.

§max_offset: f32

Greatest valid content offset along Self::axis.

Implementations§

Source §

impl ScrollbarGeometry

Source

pub fn hit_test(self, point: Point) -> Option<ScrollbarPart>

Returns the thumb or the track side containing point.

§Examples

use ailloli_ui_core::{Point, Rect, ScrollMetrics, ScrollState, ScrollbarAxis, ScrollbarGeometrySpec, ScrollbarPart, Size};
let geometry = ScrollbarGeometrySpec::new(
    ScrollbarAxis::Vertical,
    Rect::new(0.0, 0.0, 100.0, 100.0),
    ScrollMetrics::new(Size::new(100.0, 100.0), Size::new(100.0, 300.0)),
    ScrollState::new(),
).resolve().unwrap();
assert_eq!(geometry.hit_test(Point::new(geometry.track.x, geometry.track.bottom())), Some(ScrollbarPart::TrackAfter));

Source

pub fn page_target(self, current_offset: f32, part: ScrollbarPart) -> f32

Computes a one-viewport page target for a track hit.

Thumb hits leave the current offset unchanged. All results are finite and clamped to 0.0..=max_offset.

§Examples

use ailloli_ui_core::{Rect, ScrollMetrics, ScrollState, ScrollbarAxis, ScrollbarGeometrySpec, ScrollbarPart, Size};
let geometry = ScrollbarGeometrySpec::new(
    ScrollbarAxis::Vertical,
    Rect::new(0.0, 0.0, 100.0, 100.0),
    ScrollMetrics::new(Size::new(100.0, 100.0), Size::new(100.0, 400.0)),
    ScrollState::new(),
).resolve().unwrap();
assert_eq!(geometry.page_target(40.0, ScrollbarPart::TrackAfter), 140.0);

Source

pub fn track_target(self, point: Point) -> f32

Maps a track position to an offset with the thumb centered on the point.

The result is clamped at both track ends. Callers normally use this for a press outside the thumb; thumb presses should retain their exact grab offset through Self::begin_drag instead.

§Examples

use ailloli_ui_core::{Point, Rect, ScrollMetrics, ScrollState, ScrollbarAxis, ScrollbarGeometrySpec, Size};
let geometry = ScrollbarGeometrySpec::new(
    ScrollbarAxis::Vertical,
    Rect::new(0.0, 0.0, 80.0, 100.0),
    ScrollMetrics::new(Size::new(80.0, 100.0), Size::new(80.0, 400.0)),
    ScrollState::new(),
).resolve().unwrap();
let point = Point::new(geometry.track.x, geometry.track.y + geometry.track.h * 0.5);
assert!(geometry.track_target(point) > 0.0);

Source

pub fn begin_drag(self, point: Point) -> Option<ScrollbarDrag>

Begins a drag only when point hits the thumb.

The retained logical grab offset keeps the exact pressed point attached to the pointer instead of recentering the thumb at drag start.

§Examples

use ailloli_ui_core::{Point, Rect, ScrollMetrics, ScrollState, ScrollbarAxis, ScrollbarGeometrySpec, Size};
let geometry = ScrollbarGeometrySpec::new(
    ScrollbarAxis::Horizontal,
    Rect::new(0.0, 0.0, 100.0, 60.0),
    ScrollMetrics::new(Size::new(100.0, 60.0), Size::new(300.0, 60.0)),
    ScrollState::new(),
).resolve().unwrap();
let center = Point::new(geometry.thumb.x + geometry.thumb.w * 0.5, geometry.thumb.y);
assert!(geometry.begin_drag(center).is_some());