Struct GlyphCache 

pub struct GlyphCache { /* private fields */ }

Memoized glyph outlines in 1000/em text space.

A miss is cached too: a glyph that produced no outline is stored as None so it is not recomputed, which is what PDFium’s own null-result memoization does.

The outlines are held behind an Arc so a caller that wants one for longer than the borrow — the renderer’s per-glyph placement record, which cannot hold a borrow because placing the next glyph needs the cache mutably again — takes a refcount rather than a copy of the path. Copying instead was 2891 BezPath clones and 3.3 MiB per render of one corpus page, on a document where the copies were then never read.

Implementations

impl GlyphCache

pub fn new() -> Self

An empty cache.

pub fn shared(&mut self, font: &Font, key: GlyphKey) -> Option<Arc<BezPath>>

The same outline, as a handle that outlives the borrow.

For a caller that needs the outline after asking the cache for the next glyph. Cloning the returned Arc is a refcount bump; cloning a borrowed path copies every element.

pub fn shared_fallback( &mut self, fallback: &GlyphFallback, vertical: bool, key: GlyphKey, ) -> Option<Arc<BezPath>>

The outline of a glyph drawn from the Arial ShouldUseFont stand-in.

The key must name crate::GlyphFallback::id; the host font’s identity would collide with Arial on any shared glyph index.

Trait Implementations

impl Debug for GlyphCache

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

Formats the value using the given formatter.

impl Default for GlyphCache

fn default() -> GlyphCache

Returns the “default value” for a type.