Struct ThumbLength 

pub struct ThumbLength { /* private fields */ }

The thumb’s length, and the fact that Wear only measures it once.

ScalingLazyColumnStateAdapter holds currentSizeFraction and recomputes it only when totalItemsCount changes, guarded by previousItemsCount. That is not a cache in the sense of an optimisation, it is the behaviour: the thumb keeps the length it was given by the list’s first layout and does not breathe as rows of different heights scroll past. Recomputing it every frame gives a thumb that grows and shrinks while you turn the crown, which the shipping build does not do.

One of these belongs to one list. Give a screen its own, and drop it (or call ThumbLength::forget) when the screen goes away, the way Wear drops the adapter with the ScreenScaffold that made it.

Implementations

impl ThumbLength

pub fn of(&mut self, list: ScalingList<'_>) -> f32

getSizeFraction: the share of the track the thumb covers.

pub fn forget(&mut self)

Forget the measured length, so the next list measures itself again.

Trait Implementations

impl Clone for ThumbLength

fn clone(&self) -> ThumbLength

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for ThumbLength

impl Debug for ThumbLength

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

Formats the value using the given formatter.

impl Default for ThumbLength

fn default() -> ThumbLength

Returns the “default value” for a type.

impl PartialEq for ThumbLength

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for ThumbLength