An interactive typography demonstration built with Next.js and PreText, showcasing real-time multilingual text layout without DOM reflows.
Experience the application live at: https://pre-text-web-app.vercel.app/
A massive shoutout to Cheng Lou and the incredible work on PreText. This application is fundamentally built upon the capabilities of the PreText layout engine. By measuring and flowing text using pure arithmetic, PreText eliminates the need for expensive browser layout passes. Thank you for developing and sharing such a powerful tool with the open-source community.
This project serves as a showcase for high-performance text rendering techniques. It demonstrates how text can be manipulated and laid out smoothly without relying on conventional DOM reads.
An animated character moves within a stage while surrounding paragraph text dynamically reflows around its body in real-time at 60 FPS. The character is fully interactive and draggable, with text reshaping instantly upon movement.
- The layout handling is performed entirely via arithmetic.
- Circular obstacle carving computes clear text slots per line band.
- An imperative DOM element pool handles updates, bypassing standard React render cycles during the animation loop to maintain performance.
- Live performance statistics are displayed, including lines rendered, reflow time in milliseconds, and frames per second.
The project includes support for various languages and scripts to demonstrate precise cross-script layout accuracy:
| Language | Script |
|---|---|
| English | Latin |
| Mixed | Mixed CJK, Arabic, and Symbols |
| Japanese | Hiragana and Kanji |
| Arabic | Arabic (Right-to-Left) |
| Hindi | Devanagari |
| Korean | Hangul |
| Thai | Thai |
| Greek | Greek |
| Hebrew | Hebrew (Right-to-Left) |
| Russian | Cyrillic |
| Bengali | Bengali |
The application demonstrates precise methods for measuring and laying out multi-line text on a Canvas element. This approach ensures accuracy across all supported languages without triggering any browser layout recalculations.
To run this project locally on your machine, follow these steps:
npm install
npm run devNavigate to http://localhost:3000 in your web browser to view the application.
- Next.js: React framework
- @chenglou/pretext: Zero-reflow text measurement and layout
- TypeScript: Static typing for JavaScript
- Tailwind CSS: Utility classes for styling
The continuous reflow mechanism operates using the following sequence on each animation frame:
- The character position is updated via a physics simulation or pointer drag events.
- Circle obstacles are computed around the character's central point.
- The blocked horizontal range is calculated for each text line band.
- Obstacles are subtracted from the full line width to generate free horizontal layout slots.
- Each slot is subsequently filled with the maximum amount of text that fits its specific width.
- DOM elements are updated imperatively to ensure maximum efficiency.
These highly optimized layout computations complete in under one millisecond per frame.
The project has been refactored utilizing the Separation of Concerns (SoC) principle, heavily segregating logical elements into distinct focused directories:
src/
app/
page.tsx Main application orchestrator
components/
CanvasRenderer.tsx Canvas-based text rendering component
CodeBlock.tsx Syntax highlighting layout block
DragonTextReflow.tsx Core dynamic reflow simulation engine
Metric.tsx Performance tracking visualization UI
Slider.tsx Input variable controls component
constants/
index.ts Global string configurations and fallback layouts
types/
index.ts Application typescript interfaces and bounds
utils/
dragonHelpers.ts Geometric bounds algorithms and carving utilities
public/
tenor.gif Animated character asset