Struct ScrollState 

pub struct ScrollState {

    pub offset: Point,
    pub accum: (f32, f32),
    pub phase: GesturePhase,
    pub press_origin: Point,
    pub offset_at_press: Point,
    pub last_point: Point,
    pub velocity: (f32, f32),
    pub last_sample_point: Point,
    pub last_sample_ms: u64,
    pub spring_target: Point,
    pub max_offset: Point,
    pub content: Size,
    pub viewport: Size,
}

Cross-frame scroll/gesture/velocity state owned by the host screen.

Copy so the scroll_core engine can take it by value (see this module’s header for why).

Fields

offset: Point

Current committed scroll offset in pixels (subtracted from children).

accum: (f32, f32)

Sub-pixel integrator for smooth fling/spring motion.

phase: GesturePhase

Current gesture/animation phase.

press_origin: Point

Screen point where the active press began.

offset_at_press: Point

offset captured at the moment of press (drag is relative to this).

last_point: Point

Most recent point seen during the gesture.

velocity: (f32, f32)

Current velocity in px/s, sampled at release.

last_sample_point: Point

Point of the last velocity sample.

last_sample_ms: u64

Millisecond timestamp of the last velocity sample.

spring_target: Point

Spring destination while GesturePhase::Springing.

max_offset: Point

Cached maximum scrollable offset (max(content - viewport, 0)).

content: Size

Cached content size from the last layout pass.

viewport: Size

Cached viewport size from the last layout pass.

Implementations

impl ScrollState

pub const fn new() -> Self

A fresh, idle scroll state at offset zero.

pub fn is_animating(&self) -> bool

True while coasting (GesturePhase::Flinging) or settling (GesturePhase::Springing) — i.e. the host should keep ticking.

pub fn is_active(&self) -> bool

True while any interaction is in progress (phase is not idle).

pub fn clamp_offset(&self, offset: Point) -> Point

Clamp offset into the valid [0, max_offset] range on both axes.

pub fn rubber_band(&self, offset: Point) -> Point

Apply rubber-band resistance to a raw drag offset: any overshoot past [0, max_offset] is compressed by resist(o, dim) = o*dim/(dim+o*C).

pub fn nearest_snap( &self, offset: Point, snap: SnapMode, snap_lines: &[i32], ) -> Point

Nearest snap line to offset among lines, clamped to range. Empty lines (or SnapMode::None) returns the clamped offset.

pub fn apply(&mut self, msg: ScrollMsg, now_ms: u64)

Single dispatch over a ScrollMsg; now_ms is the caller’s millisecond clock (from embassy_time::Instant) used for velocity sampling. Mutates the state in place.

pub fn tick(&mut self, dt_ms: u32, snap: SnapMode, snap_lines: &[i32])

Advance one animation frame. dt_ms is elapsed milliseconds since the last tick; snap/snap_lines describe the settle target. Transitions Flinging → Springing → Idle and updates offset in place.

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 Copy for ScrollState