satori

What is satori?

Satori is an npm package designed to generate SVG images from HTML and CSS. It is particularly useful for creating dynamic, server-side rendered graphics that can be used in various applications such as social media previews, charts, and more.

What are satori's main functionalities?

Generate SVG from HTML

This feature allows you to convert HTML content into an SVG image. The code sample demonstrates how to generate an SVG from a simple HTML string.

const satori = require('satori');
const html = '<div>Hello, World!</div>';
const svg = satori(html, { width: 200, height: 100 });
console.log(svg);

Support for CSS Styling

Satori supports CSS styling within the HTML content. The code sample shows how to apply CSS styles to the HTML content before converting it to an SVG.

const satori = require('satori');
const html = '<div style="color: red;">Hello, World!</div>';
const svg = satori(html, { width: 200, height: 100 });
console.log(svg);

Custom Fonts

You can use custom fonts in your HTML content when generating SVGs. The code sample demonstrates how to include a custom font in the SVG generation process.

const satori = require('satori');
const html = '<div style="font-family: CustomFont;">Hello, World!</div>';
const svg = satori(html, { width: 200, height: 100, fonts: [{ name: 'CustomFont', data: 'base64-encoded-font-data' }] });
console.log(svg);

Other packages similar to satori

html-to-image

The 'html-to-image' package allows you to convert HTML content to various image formats, including PNG and JPEG. Unlike Satori, which focuses on SVG generation, 'html-to-image' provides more flexibility in terms of output formats.

puppeteer

Puppeteer is a Node library that provides a high-level API to control Chrome or Chromium over the DevTools Protocol. It can be used to generate screenshots and PDFs of web pages, making it a more versatile but heavier alternative to Satori for generating images from HTML content.

dom-to-image

The 'dom-to-image' package allows you to convert DOM nodes to images in various formats. It is similar to Satori in that it can generate images from HTML content, but it supports more output formats like PNG and JPEG.

README

Satori

API

satori is a function that takes a JSX element and returns a SVG string:

import satori from 'satori'

satori(
  <div style={{ color: 'black' }}>hello, world</div>,
  {
    width: 600,
    height: 400,
    fonts: [
      {
        name: 'Roboto',
        data: robotoArrayBuffer,
        weight: 400,
        style: 'normal',
      },
      ...
    ],
    embedFont: true, // Embed the font in SVG as path data
    debug: false,    // Show/hide the bounding box
  }
)

Which yields:

'<svg ...><path d="..." fill="black"></path></svg>'

Text will be embedded in the SVG as path.

Playground

https://satori-playground.vercel.app

Documentation

JSX

Satori only accepts JSX elements that are pure and stateless. You can use a subset of HTML elements (see section below), or custom React components, but React APIs such as useState and useEffect are not supported.

HTML Elements

Satori supports a limited subset of HTML and CSS features, due to its special use cases. In general, only these static and visible elements and properties that are implemented.

For example, the <input> HTML element, the cursor CSS property are not in consideration. And you can't use <style> tags or external resources via <link> or <script>.

Also, Satori does not guarantee that the SVG will 100% match the browser-rendered HTML output since Satori implements its own rendering engine based on the SVG 1.1 spec.

CSS Properties

Property	Supported Values
display	none, flex
position	relative, absolute
margin, padding	Supported
top, right, bottom, left	Supported
width, height	Supported
max-width, max-height	Supported
min-width, min-height	Supported
border	Supported
flex-direction	Supported
flex-wrap	Supported
flex-grow	Supported
flex-shrink	Supported
flex-basis	Supported except for auto
align-items	Supported
align-content	Supported
align-self	Supported
justify-content	Supported
font-family	Support single value
font-size	Supported
font-weight	Supported
font-style	Supported
text-align	Supported
letter-spacing	Supported
box-shadow	All supported except spread-radius (works like drop-shadow)
border-radius	Supported
overflow	visible, hidden
color	Supported
transform	Support absolute values
object-fit	contain, cover, none
opacity	Supported
background-color	Supported
background-image	Support linear-gradient, url
word-break	Supported
background-clip	TBD
background-size	TBD
background-position	TBD
background-repeat	TBD
background-origin	TBD
text-decoration	TBD
text-shadow	TBD
text-transform	TBD
transform-origin	TBD

Note:

1. Three-dimensional transforms are not supported.
2. There is no z-index support in SVG. Elements that come later in the document will be painted on top.
3. box-sizing is set to border-box for all elements.

Contribute

This project uses pnpm. To install dependencies, run:

pnpm install

To start the playground locally, run:

cd playground
pnpm dev

And visit localhost:3000/test.

To start the development mode, run pnpm dev in the root directory (can be used together with the playground to view it in live).

To start and live-watch the tests, run:

pnpm dev:test

Author

• Shu Ding (@shuding_)

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