Struct BreakpointTracker 

pub struct BreakpointTracker { /* private fields */ }

The class a surface holds while it lays out, re-derived from the rect of every pass (Widget::apply_layout).

Hysteresis is the point: a window dragged to rest exactly on a threshold would otherwise flicker between two layouts, a frame each, as the person lets go. A class that does not hold has to see a threshold pass by Metrics::layout_hysteresis before it changes, the same band NavShell uses for its own thresholds.

Implementations

impl BreakpointTracker

pub fn new() -> BreakpointTracker

A tracker that has not laid out yet.

pub fn derive(&mut self, width: f64, m: &Metrics) -> Breakpoint

Derive the class width asks for, holding the class of the last pass until the width is clear of its threshold by the hysteresis band.

pub fn held(&self) -> Option<Breakpoint>

The class of the last pass, None before the first.

pub fn forget(&mut self)

Forget the held class: the surface has no rect to speak of (it was closed, or has not been laid out since its tree was rebuilt), so the next pass derives from its rect alone.

Trait Implementations

impl Clone for BreakpointTracker

fn clone(&self) -> BreakpointTracker

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for BreakpointTracker

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

Formats the value using the given formatter.

impl Default for BreakpointTracker

fn default() -> BreakpointTracker

Returns the “default value” for a type.

impl PartialEq for BreakpointTracker

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for BreakpointTracker

impl Eq for BreakpointTracker

impl StructuralPartialEq for BreakpointTracker