Pretext

Pretext is a deterministic text preparation and line-layout engine for any SkiaSharp-based UI. It prepares text once, exposes segment and break metadata, and lets you compute line counts, materialized lines, or streamed line geometry without relying on control reflow.

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What This Library Does

Prepare once, reuse often

`Prepare` and `PrepareWithSegments` precompute widths, break opportunities, and whitespace behavior so repeated layout passes stay cheap.

Batch and streaming layout

Use `Layout` for quick metrics, `LayoutWithLines` for materialized lines, or `LayoutNextLine` and `WalkLineRanges` for incremental custom layout engines.

Real text behavior

The engine handles grapheme-aware breaks, discretionary hyphens, tabs, preserved whitespace, bidi text, and locale-aware segmentation on desktop targets.

Scope

Pretext is a layout engine, not a text renderer. It answers questions such as:

  • how many lines fit in a given width
  • what text ends up on each line
  • where the next line should start for a custom flow algorithm
  • which whitespace, punctuation, and discretionary break opportunities should stay visible

You still own:

  • drawing the text in your host UI
  • choosing the line height and baseline policy
  • arranging lines into columns, cards, obstacles, or custom panels
  • invalidating or repainting your UI when layout inputs change

Documentation Map

Getting Started

Install the packages, learn the font string contract, and build the first useful `Prepare` + `Layout` flow.

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Concepts

Understand the prepared-text lifecycle, whitespace modes, break kinds, locale-aware segmentation, bidi, and line fitting.

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Guides

Integrate `Pretext` into Uno or any SkiaSharp-based host, and reuse the sample app patterns for shrinkwrap, editorial, and obstacle-aware layouts.

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Reference

Browse every public type and operation, the `Pretext.Uno` companion helpers, platform notes, and repository structure.

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Repository Layout

Path Purpose
src/Pretext The packable library project containing PretextLayout and the text preparation/layout pipeline.
src/Pretext.Uno The source for the Pretext.Uno package, with Uno-specific reusable controls and layout helpers.
tests/Pretext.Uno.Tests Deterministic parity tests for whitespace handling, break behavior, bidi text, and line walking.
samples/PretextSamples A Uno sample app with layout demos including bubbles, masonry, editorial, and justification views.

Published Packages

Package Purpose
Pretext Core SkiaSharp-based text preparation and layout engine.
Pretext.Uno Uno-specific controls and helpers layered on top of Pretext.

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