rn-pretext

@chenglou/pretext for React Native — multiline text measurement and layout without the DOM.

What it does

Re-exports all @chenglou/pretext APIs with a native measurement polyfill applied. Pretext's prepare() uses platform-native text measurement (CoreText on iOS, Paint on Android) via expo-text-measure, so measurements match RN's <Text> rendering with zero drift.

Install

npm install rn-pretext expo-text-measure

Requires native rebuild (expo prebuild or pod install).

Usage

import { prepare, layout, prepareWithSegments, layoutWithLines } from 'rn-pretext'

// One-time measurement
const prepared = prepare('Hello world', '16px System')

// Pure arithmetic on every resize — no native calls
const { height, lineCount } = layout(prepared, containerWidth, 24)

// Line-by-line data for custom rendering
const result = layoutWithLines(prepareWithSegments(text, font), width, lineHeight)
result.lines.forEach(line => {
  console.log(line.text, line.width)
})

API

All APIs from @chenglou/pretext are re-exported:

• prepare() / prepareWithSegments() — one-time text measurement
• layout() — compute height + line count (pure arithmetic)
• layoutWithLines() — per-line text, width, and cursor data
• layoutNextLine() — iterator-style, for variable-width layouts
• walkLineRanges() — line geometry without materializing text
• clearCache() / setLocale() — cache and locale management

See @chenglou/pretext README for full documentation.