Crate lumen_text 

Text shaping backend trait.

Implementations (e.g. lumen-text-cosmic) take a UTF-8 string + size and return positioned glyphs plus the resolved font data. Backend-agnostic so the WGPU/vello renderer and any future renderer can both consume the output.

Multi-segment output (W5.6)

A real paragraph can mix scripts (Latin + Arabic), fonts (SansSerif falling back to a CJK face), and BiDi levels (LTR runs of even level, RTL runs of odd level). cosmic-text already emits the right itemisation internally; the W5.6 work surfaces it through ShapedRun::segments. Each ShapedSegment is a maximal slice with one font + one BiDi level, so the renderer can call draw_glyphs once per font and the caret/selection math can split logical ranges at segment boundaries to reproduce the BiDi-correct visual rectangles.

Re-exports

pub use geometry::CaretGeometry;

pub use geometry::SelectionBand;

pub use geometry::TextGeometry;

pub use hit_test::hit_test_text;

pub use hit_test::select_line_at_byte;

pub use hit_test::select_word_at_byte;

pub use shaped::ShapedText;

pub use shaped::TextViewport;

pub use shaped::build_shaped_text;

pub use undo::UndoEntry;

pub use undo::UndoKind;

pub use undo::UndoStack;

pub use edit::*;

Modules

edit

W3.2-W3.4: Lumen text-editing systems.

geometry

D4: byte<->pixel geometry derived from a shaped run.

hit_test

W3.4: pointer -> caret hit-test + word/line expansion.

shaped

D4: the shaped-once main-world store.

undo

W3.3: Undo / redo stack with typing coalesce.

Structs

GlyphPosition

One positioned glyph within a shaped run.

NullShaper

The shaper that shapes nothing.

ShapeOptions

Extension shape parameters. Backends that don’t override [TextShaper::shape_wrapped] fall through to the no-wrap path so old callers keep working.

ShapedRun

A shaped paragraph of text.

ShapedSegment

One maximal (font_id, BiDi level) slice within a shaped run.

ShaperService

The text shaper an app runs, held as a NonSend resource (font databases are rarely Send).

Enums

WrapMode

Wrap policy passed to [TextShaper::shape_wrapped].

Constants

DEFAULT_LINE_HEIGHT_MULTIPLIER

Re-export of lumen_core::components::DEFAULT_LINE_HEIGHT_MULTIPLIER for crates (e.g. lumen-text-cosmic) that depend on lumen-text but not directly on lumen-core. Default CSS line-height: normal multiplier - the single Rust fallback used wherever no line-height value reaches the layout / shaping / paint path. Common browsers use ~1.2; Lumen matches that. This is the sole line-height ratio in the codebase; text_block_top and text_baseline_in_line take the resolved line height (see resolve_line_height) rather than re-deriving it from size_px and a hardcoded factor, so an authored CSS line-height moves the text block and baseline the same way it moves everything else.

Traits

FontDB

Marker trait for a font database / system-font accessor. Currently empty.

TextShaper

Backend that turns strings into ShapedRuns.