Struct ScrollState 

pub struct ScrollState { /* private fields */ }

Scroll state for smooth, momentum-based scrolling with rubber-banding.

Keeps track of the current fractional scroll offset, velocity, and drag-to-scroll gestures. Completely separate from drawing, and generic over time: takes a time delta step to decay velocity or animate snap-back, making it deterministic and suitable for unit tests.

Implementations

impl ScrollState

pub const fn new() -> Self

Create a new ScrollState at offset 0.0 with default physics.

pub const fn with_physics(physics: ScrollPhysics) -> Self

Create a new ScrollState with custom physics.

pub const fn offset(&self) -> f32

The current fractional scroll offset.

pub const fn set_offset(&mut self, offset: f32, max_offset: f32)

Set the offset directly, clamping it to bounds.

pub const fn velocity(&self) -> f32

The current velocity in items/second.

pub const fn dragging(&self) -> bool

Whether a drag gesture is currently active.

pub fn integer_offset(&self) -> usize

Returns the integer part of the offset, clamped to positive.

pub fn fractional_offset(&self) -> f32

Returns the fractional remainder of the offset (0.0..1.0).

pub fn tick(&mut self, dt: Duration, max_offset: f32)

Update physics for a single frame step.

Decays momentum if in bounds, or animates the rubber-band spring back to boundaries if out of bounds. Has no effect if dragging is active.

pub const fn begin_drag(&mut self, y: f32)

Begin a drag gesture at pointer coordinate y.

pub fn update_drag(&mut self, y: f32, max_offset: f32)

Update the drag gesture with a new pointer coordinate y.

pub fn end_drag(&mut self)

End the current drag gesture, initiating a fling if pointer speed was sufficient.

pub fn scroll_by_wheel(&mut self, delta: f32)

Apply a scroll wheel impulse directly to velocity.

Trait Implementations

impl Clone for ScrollState

fn clone(&self) -> ScrollState

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ScrollState

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for ScrollState

fn default() -> Self

Returns the “default value” for a type.

impl PartialEq for ScrollState

fn eq(&self, other: &ScrollState) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for ScrollState