Struct ToolbarScrollHide 

pub struct ToolbarScrollHide { /* private fields */ }

Upstream’s M3EToolbarVisibilityController as a pure value: the scroll accumulation, clamp, and settle rule an app runs from its own on_scroll, with the ticker left to the widget (see the module docs’ scroll-hide section).

offset is always ≤ 0 and clamped into [offset_limit, 0].

use frust_material::{TOOLBAR_HEIGHT, ToolbarScrollHide, TOOLBAR_SCREEN_OFFSET};

// The measured limit is `-(extent + screenOffset)`.
let mut hide = ToolbarScrollHide::for_bar(TOOLBAR_HEIGHT);
assert_eq!(hide.offset_limit(), -(TOOLBAR_HEIGHT + TOOLBAR_SCREEN_OFFSET));

// Scrolling down hides; scrolling back up returns.
hide.scroll(40.0);
assert_eq!(hide.offset(), -40.0);
hide.scroll(-15.0);
assert_eq!(hide.offset(), -25.0);

// A fling past the velocity threshold commits to its direction.
assert!(!hide.settle(400.0));
assert!(hide.is_hidden());

Implementations

impl ToolbarScrollHide

pub fn new(exit_extent: f64) -> Self

A controller with a fixed exit distance — upstream’s exitExtent, which pins offsetLimit to -|extent|. A non-finite exit_extent (NaN or ±∞) degrades to a resting 0.0 exit distance rather than carrying a non-finite limit into Self::set_offset’s clamp — see the module docs’ clamp discipline.

pub fn for_bar(cross_extent: f64) -> Self

A controller whose exit distance is measured off the bar — upstream’s M3EToolbarMeasureSize rule, -(cross_extent + screenOffset). A non-finite cross_extent degrades the same way Self::new’s own guard does — this delegates to it, so the guard applies whether the non-finite value reaches new directly or through here.

pub fn offset(&self) -> f64

The current translation, in [offset_limit, 0].

pub fn offset_limit(&self) -> f64

The most negative translation this controller allows.

pub fn scroll(&mut self, delta: f64)

Consume a scroll delta (positive scrolling down) — upstream’s _updateOffset’s offset -= delta, clamped. A non-finite delta is ignored rather than propagated into the offset.

pub fn collapsed_fraction(&self) -> f64

How far hidden the bar is, 0.0 fully visible through 1.0 fully hidden — upstream’s collapsedFraction.

pub fn is_hidden(&self) -> bool

Whether the bar is fully off-screen — upstream’s isHidden.

pub fn show(&mut self)

Snap fully visible — upstream’s show() target.

pub fn hide(&mut self)

Snap fully hidden — upstream’s hide() target.

pub fn toggle(&mut self)

Flip about the halfway point — upstream’s toggle().

pub fn settle(&mut self, velocity: f64) -> bool

Settle after a fling at velocity (positive scrolling down), reporting whether the bar ends up visible — upstream’s settle: past TOOLBAR_SETTLE_VELOCITY the direction of travel wins, otherwise the nearer end does. Already-settled at either end, nothing moves.

Trait Implementations

impl Clone for ToolbarScrollHide

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for ToolbarScrollHide

impl Debug for ToolbarScrollHide

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

Formats the value using the given formatter.

impl PartialEq for ToolbarScrollHide

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for ToolbarScrollHide