mattuy/text-frame

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TextFrame

中文版 | English

A javascript tool to split long text into frames, with typesetting prohibition processed and unicode full support.

Introduction

It's difficute to compute how many characters a DOM element can show, because diffrent User Agents have diffrent typesetting rules. So for that, we have to draw text on a canvas with our own rules to know how to split text into several text frames, since we can compute character width through CanvasRenderingContext2D.measureText().

refering to W3C draft for Chinese typesetting, following are my rules:

Prohibition Rules for Line Start

Punctuation Name	The Punctuation Marks
Pause or Stop	、,，.．。:：;；!！?？
Closing Quotation	'"」』”’
Closing Parentheses	)]}）】〗〕］｝
Closing Angle Brackets	》〉
Connectors	–~～—
Interpuncts	·．‧•・
Solidi	/／

Prohibition Rules for Line End

Punctuation Name	The Punctuation Marks
Opening Quotation	「『“‘
opening Parentheses	([{（【〖〔［〔
Opening Angle Brackets	《〈
Solidi	/／

Prohibition Rules for Unbreakable Marks

Name	Mark
Em dash and long dash	──
Ellipsis	……

This library take the above as default rules, but it can be configued with options.

Here is an online demo.

Usage

Browser environment is required, and canvas support is needed. This library CANNOT work under web worker.

API

// compute text frames
function computeTextFrames(options: FrameOptions): TextFrame[];
// render text frame
function renderFrame(context: CanvasRenderingContext2D, frame: TextFrame, clear: boolean): void;

npm

npm install @mattuy/text-frame --save

ES2015 & CommonJS

// cjs
// const { computeTextFrames, renderFrame } = require('@mattuy/text-frame');
// or esm
import { computeTextFrames, renderFrame } from '@mattuy/text-frame/esm';

const frames = computeTextFrames({
    viewWidth: 320,
    viewHeight: 640,
    fontSize: 16,
    margin: 8,
    color: '#000',
    fragments: [
        {
            color: 'green',
            fontSize: 20,
            margin: 32,
            textAlign: 'center',
            text: "Caption"
        },
        {
            textIndent: 32,
            fontFamily: 'serif',
            margin: { bottom: 32 },
            marginCollapse: true,
            textAlign: 'justify',
            text: "This is a multi-line text. Pass your text paragraph as this."
        }
    ]
});
const canvas = document.createElement('canvas');
canvas.style.width = '320px';
canvas.style.height = '640px';
document.body.append(canvas);
renderFrame(canvas.getContext('2d'), frames[0], true);

Globally Script

<script src="text-frame/dist/umd/text-frame-min.js"></script>
<script>
    const frames = TextFrame.computeTextFrames({
        // ...options
    });
    console.log(frames)
    // ...render
</script>

Option reference sits here.

Build from Source

clone the repo git clone https://github.com/mattuylee/text-frame.git
install dependences cd text-frame
npm install

Distribution

npm run dist

Start a demo serve

npm run example

Debug

Run npm run debug, then open example/index.html in your browser, rollup will watch your code changes and automatically rebuild.

Licence

MIT

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