Struct ScrollbarGeometrySpec

Source

pub struct ScrollbarGeometrySpec {
    pub axis: ScrollbarAxis,
    pub bounds: Rect,
    pub metrics: ScrollMetrics,
    pub state: ScrollState,
    pub thickness: f32,
    pub min_thumb_len: f32,
    pub inset: f32,
    pub end_reserve: f32,
    pub hit_thickness: f32,
}

Expand description

Inputs used to resolve one proportional scrollbar.

Geometry is expressed in logical pixels. Self::resolve rejects non-finite values, non-positive extents, and axes without meaningful overflow instead of constructing partially valid rectangles.

§Examples

use ailloli_ui_core::{
    Rect, ScrollMetrics, ScrollState, ScrollbarAxis, ScrollbarGeometrySpec, Size,
};
let geometry = ScrollbarGeometrySpec::new(
    ScrollbarAxis::Vertical,
    Rect::new(0.0, 0.0, 100.0, 80.0),
    ScrollMetrics::new(Size::new(100.0, 80.0), Size::new(100.0, 240.0)),
    ScrollState::new(),
)
.resolve()
.expect("vertical overflow");
assert_eq!(geometry.axis, ScrollbarAxis::Vertical);

Fields§

§axis: ScrollbarAxis

Controlled axis.

§bounds: Rect

Complete viewport bounds in the coordinate space used for hit testing.

§metrics: ScrollMetrics

Visible and full content extents.

§state: ScrollState

Current logical content offset.

§thickness: f32

Painted cross-axis thickness.

§min_thumb_len: f32

Minimum painted thumb length, capped to the resolved track.

§inset: f32

Distance between the track and viewport edges.

§end_reserve: f32

Main-axis space reserved at the trailing end, normally for another bar.

§hit_thickness: f32

Minimum cross-axis thickness of the pointer hit region.

Implementations§

Source §

impl ScrollbarGeometrySpec

Source

pub const DEFAULT_HIT_THICKNESS: f32 = 16f32

Default pointer hit thickness used by framework scrollbars.

Source

pub const fn new( axis: ScrollbarAxis, bounds: Rect, metrics: ScrollMetrics, state: ScrollState, ) -> Self

Creates a specification with the framework’s neutral geometry defaults.

The painted bar is six pixels thick, inset by three pixels, with a 24-pixel minimum thumb and a 16-pixel pointer target.

§Examples

use ailloli_ui_core::{Rect, ScrollMetrics, ScrollState, ScrollbarAxis, ScrollbarGeometrySpec, Size};
let spec = ScrollbarGeometrySpec::new(
    ScrollbarAxis::Horizontal,
    Rect::new(0.0, 0.0, 120.0, 60.0),
    ScrollMetrics::new(Size::new(120.0, 60.0), Size::new(360.0, 60.0)),
    ScrollState::new(),
);
assert_eq!(spec.hit_thickness, 16.0);

Source

pub fn with_paint_metrics( self, thickness: f32, min_thumb_len: f32, inset: f32, ) -> Self

Replaces painted geometry while retaining the standard hit thickness.

§Examples

use ailloli_ui_core::{Rect, ScrollMetrics, ScrollState, ScrollbarAxis, ScrollbarGeometrySpec, Size};
let spec = 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, 300.0)),
    ScrollState::new(),
).with_paint_metrics(4.0, 18.0, 2.0);
assert_eq!((spec.thickness, spec.min_thumb_len, spec.inset), (4.0, 18.0, 2.0));

Source

pub fn with_end_reserve(self, end_reserve: f32) -> Self

Reserves main-axis space at the trailing end of the track.

§Examples

use ailloli_ui_core::{Rect, ScrollMetrics, ScrollState, ScrollbarAxis, ScrollbarGeometrySpec, Size};
let spec = 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, 300.0)),
    ScrollState::new(),
).with_end_reserve(10.0);
assert_eq!(spec.end_reserve, 10.0);

Source

pub fn with_hit_thickness(self, hit_thickness: f32) -> Self

Replaces the minimum pointer-target thickness.

Values smaller than the painted thickness are promoted to the painted thickness during resolution.

§Examples

use ailloli_ui_core::{Rect, ScrollMetrics, ScrollState, ScrollbarAxis, ScrollbarGeometrySpec, Size};
let spec = 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, 300.0)),
    ScrollState::new(),
).with_hit_thickness(20.0);
assert_eq!(spec.hit_thickness, 20.0);

Source

pub fn resolve(self) -> Option<ScrollbarGeometry>

Resolves proportional track, thumb, and pointer geometry.

Overflow of at most half a logical pixel is treated as absent. This avoids flickering bars for floating-point layout noise.

§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, 400.0)),
    ScrollState::new(),
).resolve().unwrap();
let center = Point::new(geometry.thumb.x + geometry.thumb.w * 0.5, geometry.thumb.y + geometry.thumb.h * 0.5);
assert_eq!(geometry.hit_test(center), Some(ScrollbarPart::Thumb));