Module measure 

Text measurement, abstracted.

This trait is the reason the rest of the crate has no dependencies. Shaping text genuinely needs a font stack, but everything around shaping — wrapping, height indexing, scroll anchoring, the message model — does not, and keeping the font stack behind a trait is what lets the whole engine run under cargo test on display-less CI.

The view supplies a Pango-backed implementation. The tests here supply FixedMeasure, where every character is exactly N pixels wide, which makes wrap assertions exact and readable instead of font-dependent and brittle.

It is also a hedge against xtext’s worst performance bug. Its find_next_wrap (xtext.c:3685) called backend_get_text_width_emph per character, and that did a pango_layout_set_text + pango_layout_get_pixel_size round trip each time. The trait’s unit of work is a run, never a character, so an implementation physically cannot repeat that mistake.

Structs

FixedMeasure

Deterministic measurer for tests: every character is char_width pixels wide regardless of style.

FontMetrics

Font metrics the layout engine needs before it measures anything.

Traits

TextMeasure

Measures runs of styled text.