Struct ParleyTextSystem 

pub struct ParleyTextSystem { /* private fields */ }

Experimental flat-LTR backend with an opt-in paragraph path. Select fonts before constructing GPUI; GPUI owns the font-metric, line-layout, wrapping and final raster caches.

Implementations

impl ParleyTextSystem

pub fn new( fonts: FontContext, default_family: impl Into<String>, ) -> Result<Self>

Use an existing Parley font context and an explicit application default. .SystemUIFont maps to this family; native system-family discovery is not implied. FontContext system discovery requires the system-fonts feature.

pub fn set_layout_error_handler(&self, handler: LayoutErrorHandler)

Replace the rejection diagnostic (default: stderr). Rejections remain fallible through try_layout_line; only GPUI’s infallible hook substitutes.

pub fn try_layout_line( &self, text: &str, size: Pixels, runs: &[FontRun], ) -> Result<LineLayout>

Fallible equivalent of the infallible GPUI layout hook. Validate unsupported input here before using the backend through GPUI (RTL, synthetic styles, paragraph breaks and invalid style ranges return errors).

pub fn prepare_paragraph( &self, text: &str, size: Pixels, runs: &[FontRun], ) -> Result<ParagraphShape>

Extension-only prototype, automatic base direction, one logical paragraph. U+2028 is a hard line break; document/paragraph separators are rejected. Reuses backend contexts/face registry. GPUI owns paragraph caching through the optional PlatformTextSystem hook; this method itself adds no cache.

pub fn prepare_paragraph_with_options( &self, text: &str, size: Pixels, runs: &[FontRun], options: ParagraphOptions, ) -> Result<ParagraphShape>

Like Self::prepare_paragraph, with an explicit base direction and content language. The language applies to the whole paragraph and selects language-specific shaping and line breaking where fonts support it.

Trait Implementations

impl PlatformTextSystem for ParleyTextSystem

fn add_fonts(&self, fonts: Vec<Cow<'static, [u8]>>) -> Result<()>

fn set_missing_glyph_sink(&self, sink: Option<Arc<dyn MissingGlyphSink>>)

Installs a nonblocking sink for unresolved grapheme clusters.

fn all_font_names(&self) -> Vec<String>

Get all available font names.

fn font_id(&self, descriptor: &Font) -> Result<FontId>

Get the font ID for a font descriptor.

fn font_capabilities(&self) -> FontCapabilities

Reports support for font inspection and explicit static variations.

fn font_table( &self, id: FontId, tag: FontTag, ) -> Result<FontQuery<Option<Vec<u8>>>>

Reads one OpenType table from the resolved face identified by font_id.

fn font_metrics(&self, id: FontId) -> FontMetrics

Get metrics for a font.

fn typographic_bounds(&self, id: FontId, glyph: GlyphId) -> Result<Bounds<f32>>

Get typographic bounds for a glyph.

fn advance(&self, id: FontId, glyph: GlyphId) -> Result<Size<f32>>

Get the advance width for a glyph.

fn glyph_for_char(&self, id: FontId, ch: char) -> Option<GlyphId>

Get the glyph ID for a character.

fn glyph_raster_bounds( &self, params: &RenderGlyphParams, ) -> Result<Bounds<DevicePixels>>

Get raster bounds for a glyph.

fn rasterize_glyph( &self, params: &RenderGlyphParams, bounds: Bounds<DevicePixels>, ) -> Result<(Size<DevicePixels>, Vec<u8>)>

Rasterize a glyph.

fn layout_line(&self, text: &str, size: Pixels, runs: &[FontRun]) -> LineLayout

Layout a line of text with the given font runs.

fn shape_paragraph( &self, request: ParagraphRequest<'_>, ) -> Result<Arc<dyn PlatformParagraphShape>>

Optional paragraph capability; native implementations need not opt in.

fn recommended_rendering_mode(&self, _: FontId, _: Pixels) -> TextRenderingMode

Returns the recommended text rendering mode for the given font and size.

fn font_axes( &self, font_id: FontId, ) -> Result<FontQuery<Vec<VariationAxisInfo>>, Error>

Queries axis ranges on a resolved face, distinguishing unsupported queries. By default, reads fvar through font_table and parses it in core.

fn opentype_features( &self, font_id: FontId, ) -> Result<FontQuery<Vec<OpenTypeFeatureInfo>>, Error>

Queries feature metadata for a resolved face. Backends that cannot inspect the face must return Unsupported, rather than a successful empty list. The default reads GSUB/GPOS through font_table and parses them in core. Invalid IDs, failed reads, and malformed metadata return errors.

fn prewarm_fonts(&self, _font_ids: &[FontId])

Prewarm any system font caches needed to shape text.

fn glyph_dilation_for_color(&self, _color: Hsla) -> u8

Returns the dilation level to use for a glyph painted in the given color.