Struct GlyphAtlas 

pub struct GlyphAtlas { /* private fields */ }

A cache of rasterised glyphs, packed into a single texture.

The GPU backends cannot draw text directly: WebGPU and WebGL2 have no text API. The atlas solves that by rasterising each glyph once into an offscreen canvas and then drawing the glyphs as textured quads. The canvas is handed to the GPU as a texture source, so no pixel read-back is ever needed.

The Canvas2D backend does not use the atlas at all — it has a real text API — but it shares the measurer, so the three backends lay text out identically.

Implementations

impl GlyphAtlas

Inherent implementation of GlyphAtlas.

pub fn new(width: u32, height: u32) -> Option<Self>

Creates an atlas of the given size, in pixels.

Returns None when the host has no DOM.

Arguments

• u32 - A 32-bit unsigned integer (u32).

Returns

• Option<Self> - Some(...) on success, None otherwise.

pub fn canvas(&self) -> &HtmlCanvasElement

Returns the canvas the glyphs are rasterised into.

The GPU backends upload this canvas straight into a texture.

Returns

• &HtmlCanvasElement - A HtmlCanvasElement value.

pub fn width(&self) -> u32

Returns the width of the atlas, in pixels.

Returns

• u32 - A 32-bit unsigned integer.

pub fn height(&self) -> u32

Returns the height of the atlas, in pixels.

Returns

• u32 - A 32-bit unsigned integer.

pub fn is_dirty(&self) -> bool

Returns true when the atlas changed since the last upload.

Returns

• bool - A boolean.

pub fn mark_clean(&mut self)

Marks the atlas as uploaded.

pub fn len(&self) -> usize

Returns the number of rasterised glyphs.

Returns

• usize - A non-negative integer.

pub fn is_empty(&self) -> bool

Returns true when the atlas holds no glyphs.

Returns

• bool - A boolean.

pub fn glyph(&mut self, character: char, font: &str) -> GlyphEntry

Returns the entry for the given character and font, rasterising it on first use.

Arguments

• char - A char parameter.
• &str - Shared reference to a str.

Returns

• GlyphEntry - A GlyphEntry value.

Trait Implementations

impl Clone for GlyphAtlas

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for GlyphAtlas

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

Formats the value using the given formatter.