Crate alpha2_text 

Text shaping and rasterization for alpha2 hosts.

Produces the engine’s TextTexture in pure Rust from caller-supplied fonts. Paragraphs are split by direction (UAX #9), script and font, shaped with rustybuzz, broken per UAX #14 and rasterized with ab_glyph_rasterizer (color glyphs in color). The same request and fonts give the same pixels natively and in wasm, so browser preview and native export match.

Structs

ClusterInfo

One cluster of a TextLayout.

ClusterState

Animation state of one cluster.

ColorMix

A color change base * keep + add in premultiplied linear light. Mixing toward a target by w is keep = 1 - w, add = w * target; mixes compose.

LineInfo

One line of a TextLayout.

LineMetrics

Lines of a shaped text at one wrapping width (ShapedText::lines_at).

ShapedText

Text shaped once (TextRasterizer::shape) so lines can be broken at any width without reshaping.

TextBackground

A box behind each non-empty line (advance by one em, grown by padding). Touching boxes merge.

TextFont

One caller-owned font registered in fallback order.

TextGradient

A gradient over a text’s layout box. Points are fractions of the box ((0, 0) top-left) and a radius is a fraction of its shorter side.

TextGradientStop

One color of a TextGradient.

TextLayout

Cluster and line positions, matching TextRasterizer::rasterize.

TextMeasure

Text geometry from TextRasterizer::measure. Rectangles are [left, top, right, bottom] in pixels from the layout box’s top-left, which sits at (TextTexture::layout_x, TextTexture::layout_y) in the rasterized texture.

TextRasterRequest

One text layout request.

TextRasterResult

Rasterized pixels and their text-specific layout descriptor.

TextRasterizer

Deterministic text host with version-key result caching.

TextStroke

An outline band drawn behind the glyphs and earlier strokes.

Enums

TextFill

What paints a text’s glyphs.

TextGradientKind

Where a gradient’s offsets lie.

TextRasterError

Typed text-host failure.

TextSpread

What a linear or radial gradient shows past its first and last stops.

Constants

DEFAULT_TEXT_CACHE_BYTES

Default result cache budget in bytes: a few full-frame 4K titles.

Functions

check_font

Checks that bytes hold an OpenType face at face_index, as TextRasterizer::add_font would, so a host can reject a file at import.

face_count

Number of faces in a font collection (.ttc, .otc), else 1.

fold_family

Normalizes a family name for comparison: NFC, then Unicode lowercase.

font_family

The face’s typographic family (name ID 16), else family (name ID 1), preferring US English. None for unparsable bytes or no family name.

font_family_names

Every distinct name ID 16 and 1 family name in every language, in table order. A project may name a family by any of them. Empty for unparsable bytes.

half_leading

CSS half-leading above the em box, or zero when lines are closer than an em.