Struct ScrollState

Source

pub struct ScrollState {
    pub offset: Offset,
}

Expand description

Persistent logical scroll offset. Positive values move the viewport into content.

§Examples

use ailloli_ui_core::{Offset, ScrollState};
assert_eq!(ScrollState::with_offset(Offset::new(4.0, 5.0)).offset.x, 4.0);

Fields§

§offset: Offset

Logical content-space offset from the content origin.

Implementations§

Source §

impl ScrollState

Source

pub fn new() -> Self

Creates a state at the content origin.

§Examples

use ailloli_ui_core::{Offset, ScrollState};
assert_eq!(ScrollState::new().offset, Offset::default());

Source

pub fn with_offset(offset: Offset) -> Self

Creates a state whose components are at least zero.

This does not know the content bounds. Use Self::clamp_to once ScrollMetrics are available. Negative values and NaN become zero; positive infinity remains infinite until a bounded operation such as Self::clamp_to maps it to zero.

§Examples

use ailloli_ui_core::{Offset, ScrollState};
assert_eq!(ScrollState::with_offset(Offset::new(-1.0, 2.0)).offset, Offset::new(0.0, 2.0));

Source

pub fn clamp_to(self, metrics: ScrollMetrics, axes: ScrollAxes) -> ScrollOutcome

Clamps the current state to the enabled axes and content bounds.

Disabled axes are reset to zero rather than preserving a latent offset.

§Examples

use ailloli_ui_core::{Offset, ScrollAxes, ScrollMetrics, ScrollState, Size};
let metrics = ScrollMetrics::new(Size::new(10.0, 10.0), Size::new(20.0, 20.0));
let out = ScrollState::with_offset(Offset::new(50.0, 5.0)).clamp_to(metrics, ScrollAxes::BOTH);
assert_eq!(out.after, Offset::new(10.0, 5.0));

Source

pub fn scroll_by( self, delta: Offset, metrics: ScrollMetrics, axes: ScrollAxes, ) -> ScrollOutcome

Adds a logical-pixel delta, filters disabled axes, and clamps the result.

Positive deltas move the viewport farther into the content.

§Examples

use ailloli_ui_core::{Offset, ScrollAxes, ScrollMetrics, ScrollState, Size};
let metrics = ScrollMetrics::new(Size::new(10.0, 10.0), Size::new(30.0, 30.0));
assert_eq!(ScrollState::new().scroll_by(Offset::new(4.0, 5.0), metrics, ScrollAxes::BOTH).after, Offset::new(4.0, 5.0));

Source

pub fn scroll_to( self, target: Offset, metrics: ScrollMetrics, axes: ScrollAxes, ) -> ScrollOutcome

Moves directly to a logical content offset and clamps it to valid bounds.

Disabled axes and non-finite target components become zero.

§Examples

use ailloli_ui_core::{Offset, ScrollAxes, ScrollMetrics, ScrollState, Size};
let metrics = ScrollMetrics::new(Size::new(10.0, 10.0), Size::new(30.0, 30.0));
assert_eq!(ScrollState::new().scroll_to(Offset::new(8.0, 9.0), metrics, ScrollAxes::BOTH).after, Offset::new(8.0, 9.0));

Source

pub fn reveal_rect( self, rect: Rect, metrics: ScrollMetrics, axes: ScrollAxes, ) -> ScrollOutcome

Moves the minimum distance needed to expose rect in the viewport.

rect uses content coordinates in logical pixels. Already visible axes remain unchanged. If a rectangle is larger than the viewport, the first violated edge chosen by the algorithm is aligned before final clamping.

§Examples

use ailloli_ui_core::{Offset, Rect, ScrollAxes, ScrollMetrics, ScrollState, Size};
let metrics = ScrollMetrics::new(Size::new(100.0, 100.0), Size::new(300.0, 300.0));
let out = ScrollState::new().reveal_rect(Rect::new(120.0, 0.0, 20.0, 20.0), metrics, ScrollAxes::BOTH);
assert_eq!(out.after, Offset::new(40.0, 0.0));