Struct LineLayoutCache 

pub struct LineLayoutCache { /* private fields */ }

A per-window cache of shaped and wrapped line layouts, retaining the previous frame so reused layouts survive a frame boundary.

Implementations

impl LineLayoutCache

pub fn new( platform_text_system: Arc<dyn PlatformTextSystem>, font_generation: Arc<Atomic<usize>>, ) -> LineLayoutCache

Creates an empty cache backed by platform_text_system.

pub fn layout_index(&self) -> LineLayoutIndex

Saves the current cache position so it can be reused or truncated later.

pub fn reuse_layouts(&self, range: Range<LineLayoutIndex>)

Re-inserts layouts from the previous frame created before range.

pub fn truncate_layouts(&self, index: LineLayoutIndex)

Drops layouts created after index, keeping the cache consistent.

pub fn finish_frame(&self)

Ages the current frame into the previous frame and clears the current one.

pub fn layout_wrapped_line<Text>( &self, text: Text, font_size: Pixels, runs: &[FontRun], wrap_width: Option<Pixels>, max_lines: Option<usize>, ) -> Arc<WrappedLineLayout>

where Text: AsRef<str>, SharedString: From<Text>,

Shapes and wraps text, reusing a cached layout when the inputs match.

pub fn layout_line<Text>( &self, text: Text, font_size: Pixels, runs: &[FontRun], force_width: Option<Pixels>, ) -> Arc<LineLayout>

where Text: AsRef<str>, SharedString: From<Text>,

Shapes a single line of text, reusing a cached layout when the inputs match.

pub fn try_layout_line_by_hash( &self, text_hash: u64, text_len: usize, font_size: Pixels, runs: &[FontRun], force_width: Option<Pixels>, ) -> Option<Arc<LineLayout>>

Try to retrieve a previously-shaped line layout using a caller-provided content hash.

This is a non-allocating cache probe: it does not materialize any text. If the layout is not already cached in either the current frame or previous frame, returns None.

Contract (caller enforced):

• Same text_hash implies identical text content (collision risk accepted by caller).
• text_len should be the UTF-8 byte length of the text (helps reduce accidental collisions).

pub fn layout_line_by_hash( &self, text_hash: u64, text_len: usize, font_size: Pixels, runs: &[FontRun], force_width: Option<Pixels>, materialize_text: impl FnOnce() -> SharedString, ) -> Arc<LineLayout>

Layout a line of text using a caller-provided content hash as the cache key.

This enables cache hits without materializing a contiguous SharedString for text. If the cache misses, materialize_text is invoked to produce the SharedString for shaping.

Contract (caller enforced):

• Same text_hash implies identical text content (collision risk accepted by caller).
• text_len should be the UTF-8 byte length of the text (helps reduce accidental collisions).