Open Graph Image Generation

About Generate Open Graph Images dynamically from HTML/CSS without a browser in SvelteKit.

v1.0.0 Update (Breaking Changes)

Finally, We have added html to react like element like object converter out of the box and with svelte compiler. Now you can use { toReactElement } with "@ethercorps/sveltekit-og" like:

// +page.server.js

import { toReactElement, satori } from '@ethercorps/sveltekit-og';

const htmlString = `
        <div tw="bg-gray-50 flex w-full">
        <div tw="flex flex-col md:flex-row w-full py-12 px-4 md:items-center justify-between p-8">
          <h2 tw="flex flex-col text-3xl sm:text-4xl font-bold tracking-tight text-gray-900 text-left">
            <span>Ready to dive in?</span>
            <span tw="text-indigo-600">Start your free trial today.</span>
          </h2>
          <div tw="mt-8 flex md:mt-0">
            <div tw="flex rounded-md shadow">
              <a tw="flex items-center justify-center rounded-md border border-transparent bg-indigo-600 px-5 py-3 text-base font-medium text-white">Get started</a>
            </div>
            <div tw="ml-3 flex rounded-md shadow">
              <a tw="flex items-center justify-center rounded-md border border-transparent bg-white px-5 py-3 text-base font-medium text-indigo-600">Learn more</a>
            </div>
          </div>
        </div>
        </div>
        `;
const newNode = toReactElement(htmlString);

/** @type {import('./$types').PageServerLoad} */
export async function load() {
	const fontFile400 = await fetch(
		'https://og-playground.vercel.app/inter-latin-ext-400-normal.woff'
	);
	const fontData400 = await fontFile400.arrayBuffer();
	const svg = await satori(newNode, {
		height: 350,
		width: 500,
		fonts: [
			{
				name: 'sans serif',
				data: fontData400,
				style: 'normal',
				weight: 700
			}
		]
	});

	return { svg };
}

• We have changed to function based instead of class based ImageResponse and componentToImageResponse.
• Removed @resvg/resvg-wasm with @resvg/resvg-js because of internal errors.
• Removed satori-html because now we have toReactElement out of the box with svelte compiler.

  If you find a problem related to undefined a please check vite.config.js and add define: { _a: 'undefined' } in config.

If you find any issue and have suggestion for this project please open a ticket and if you want to contribute please create a new discussion.

Quick Start

Install @ethercorps/sveltekit-og, then use it inside a server endpoint route (+server.ts or +server.js):

// /routes/og/+server.ts
import { ImageResponse } from '@ethercorps/sveltekit-og';
import { RequestHandler } from './$types';

const template = `
 <div tw="bg-gray-50 flex w-full h-full items-center justify-center">
    <div tw="flex flex-col md:flex-row w-full py-12 px-4 md:items-center justify-between p-8">
      <h2 tw="flex flex-col text-3xl sm:text-4xl font-bold tracking-tight text-gray-900 text-left">
        <span>Ready to dive in?</span>
        <span tw="text-indigo-600">Start your free trial today.</span>
      </h2>
      <div tw="mt-8 flex md:mt-0">
        <div tw="flex rounded-md shadow">
          <a href="#" tw="flex items-center justify-center rounded-md border border-transparent bg-indigo-600 px-5 py-3 text-base font-medium text-white">Get started</a>
        </div>
        <div tw="ml-3 flex rounded-md shadow">
          <a href="#" tw="flex items-center justify-center rounded-md border border-transparent bg-white px-5 py-3 text-base font-medium text-indigo-600">Learn more</a>
        </div>
      </div>
    </div>
  </div>
`;
const fontFile = await fetch('https://og-playground.vercel.app/inter-latin-ext-400-normal.woff');
const fontData: ArrayBuffer = await fontFile.arrayBuffer();

export const GET: RequestHandler = async () => {
	return await ImageResponse(template, {
		height: 250,
		width: 500,
		fonts: [
			{
				name: 'Inter Latin',
				data: fontData,
				weight: 400
			}
		]
	});
};

Then run pnpm dev and access localhost:5173/og, the api/route endpoint be rendered and responded as a PNG from that api/endpoint:

Read more about the API, supported features and check out the examples on Satori Playground.

Examples:

• ImageResponse · source · demo
• componentToImageResponse · source · demo

API Reference

The package exposes an ImageResponse and componentToImageResponse constructors, with the following options available:

import {ImageResponse, componentToImageResponse} from '@ethercorps/sveltekit-og'
import {SvelteComponent} from "svelte";

// ...
ImageResponse(
    element : string,
    options : {
    width ? : number = 1200
    height ? : number = 630
    fonts ? : {
        name: string,
        data: ArrayBuffer,
        weight: number,
        style: 'normal' | 'italic'
    }[]
    debug ? : boolean = false
    graphemeImages ? : Record<string, string>;
    loadAdditionalAsset ? : (languageCode: string, segment: string) => Promise<SatoriOptions["fonts"] | string | undefined>;
    // Options that will be passed to the HTTP response
    status ? : number = 200
    statusText ? : string
    headers ? : Record<string, string>
    })

componentToImageResponse(
    component : typeof SvelteComponent,
    props : {}, // All export let example inside prop dictionary
    options : {
    width ? : number = 1200
    height ? : number = 630
    fonts ? : {
        name: string,
        data: ArrayBuffer,
        weight: number,
        style: 'normal' | 'italic'
    }[]
    debug ? : boolean = false
    graphemeImages ? : Record<string, string>;
    loadAdditionalAsset ? : (languageCode: string, segment: string) => Promise<SatoriOptions["fonts"] | string | undefined>;
    // Options that will be passed to the HTTP response
    status ? : number = 200
    statusText ? : string
    headers ? : Record<string, string>
    })

When running in production, these headers will be included by @ethercorps/sveltekit-og:

'content-type': 'image/png',
'cache-control': 'public, immutable, no-transform, max-age=31536000',

During development, the cache-control: no-cache, no-store header is used instead.

Supported HTML and CSS Features

Please refer to Satori’s documentation for a list of supported HTML and CSS features.

By default, @ethercorps/sveltekit-og only has the 'Noto Sans' font included. If you need to use other fonts, you can pass them in the fonts option.

Acknowledgements

This project will not be possible without the following projects:

• Satori & @vercel/og
• Noto by Google Fonts
• Resvg.js

Authors

• @theetherGit
• @etherCorps