Struct JagTextProvider 

pub struct JagTextProvider { /* private fields */ }

Text provider backed by jag-text (HarfBuzz) for shaping and swash for rasterization.

This uses a primary jag-text FontFace for text and an optional emoji font for color emoji fallback. Delegates shaping to TextShaper::shape_ltr, then rasterizes glyphs via swash bitmap images.

Supports CSS font-family stack resolution: when a TextRun specifies a family string (e.g. "Georgia, 'Times New Roman', serif"), the provider parses the stack and resolves candidates against the system font database, caching loaded fonts for subsequent requests.

Implementations

impl JagTextProvider

pub fn from_bytes( bytes: &[u8], orientation: SubpixelOrientation, ) -> Result<Self>

pub fn from_bytes_with_emoji( bytes: &[u8], emoji_bytes: &[u8], orientation: SubpixelOrientation, ) -> Result<Self>

Create a provider with a primary font and an emoji font for fallback.

pub fn from_system_fonts(orientation: SubpixelOrientation) -> Result<Self>

Construct from a reasonable system sans-serif font using fontdb. Also attempts to load a system emoji font for color emoji fallback.

pub fn register_web_font( &self, family: &str, data: Vec<u8>, weight: u16, style: FontStyle, ) -> Result<bool>

Register a web font from raw TTF/OTF bytes.

Idempotent: returns Ok(false) if a font with the same family + weight + style is already registered.

Thread-safe: font_cache is Mutex-protected.

The data must be raw TTF or OTF — WOFF/WOFF2 must be decompressed before calling this method.

pub fn layout_paragraph( &self, text: &str, size_px: f32, max_width: Option<f32>, ) -> TextLayout

Layout a paragraph using jag-text’s TextLayout with optional width-based wrapping.

This exposes jag-text’s multi-line layout (including per-line baselines) so that callers can build GPU-ready glyph batches without relying on PassManager baseline heuristics.

Trait Implementations

impl TextProvider for JagTextProvider

fn rasterize_run(&self, run: &TextRun) -> Vec<RasterizedGlyph>

fn shape_paragraph(&self, text: &str, size_px: f32) -> Option<ShapedParagraph>

Optional paragraph shaping hook for advanced wrappers.

fn line_metrics(&self, px: f32) -> Option<LineMetrics>

fn measure_run(&self, run: &TextRun) -> f32

Measure the total advance width of a styled text run (in the same pixel units as run.size). The default delegates to shape_paragraph, ignoring weight/style/family. Providers that support multiple font faces should override this to select the correct face.

fn register_web_font( &self, family: &str, data: Vec<u8>, weight: u16, style: FontStyle, ) -> Result<bool>

Register a web font from raw TTF/OTF bytes. Returns Ok(true) if newly registered, Ok(false) if already present. Default implementation returns Ok(false) (no-op).

fn cache_tag(&self) -> u64

Optional cache tag to distinguish providers in text caches. The default implementation returns 0, which is sufficient when a single provider is used with a given PassManager.