Struct ShadowCache 

pub struct ShadowCache { /* private fields */ }

Rendered shadows, most recently used last.

Implementations

impl ShadowCache

pub fn new(capacity: usize) -> Self

A cache holding capacity shadows.

Zero is treated as DEFAULT_CAPACITY: a cache that held nothing would re-blur every shadow every frame, which is the cost this type exists to remove.

pub fn len(&self) -> usize

How many shadows are cached.

pub fn is_empty(&self) -> bool

Whether nothing is cached.

pub const fn capacity(&self) -> usize

How many it will hold.

pub fn contains(&self, key: &ShadowKey) -> bool

Whether this shadow is already rendered.

pub fn clear(&mut self)

Forget everything.

For a theme change that invalidates every shadow at once, where evicting one at a time would blur each of them again on the way out.

pub fn blit_into( &mut self, key: ShadowKey, theme: &Theme, dst: &mut ShadowDest<'_>, ) -> bool

Blit this shadow into dst, rendering it first if it is not cached.

Returns whether anything was written. A zero-sized key or an undersized destination writes nothing rather than failing: a window being resized passes through both, and a decoration that errored on the way would flicker.

A destination smaller than the patch is clipped, not refused — the alternative is reading past the caller’s buffer.

pub fn blit_cross_fade( &mut self, a: ShadowKey, b: ShadowKey, theme: &Theme, dst: &mut ShadowDest<'_>, t: f32, ) -> bool

Blit a blend of two shadows, t of the way from a to b.

What a focus change animates through. Both patches are cached, so the transition costs a per-pixel lerp rather than a blur per frame.

t is clamped to 0..=1: an animation that overshoots is a caller bug, and extrapolating a colour past its endpoints produces values that are not a shadow at all.

Trait Implementations

impl Debug for ShadowCache

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

Formats the value using the given formatter.

impl Default for ShadowCache

fn default() -> Self

Returns the “default value” for a type.