Astro + eleventy-img

A tiny script and component intended to be used with Astro for generating images with eleventy-img. It also supports creating blurry placeholders for said images

It was mostly made for my own website and I do not intend to really support this outside of my own needs as more modern and generalist solutions are in the work for Astro

Installation

npm install astro-eleventy-img

Due to an issue in the current version of Vite used by Astro, you need to add the following to your astro project config file:

vite: {
    ssr: {
      external: ["@11ty/eleventy-img"],
    },
},

Usage

The best way to use this in my opinion is to use it to generate images in the public folder. That way, they're copied directly to the result website. This is the default behavior.

Javascript Usage

Generating images

---
import { generateImage } from 'astro-eleventy-img';

const myImage = await generateImage('src/assets/my_image.png', {
  // The options here are passed directly to eleventy-img
  widths: [300],
  formats: ['webp', 'avif'],
});
---

<img src={myImage.webp[0].url} />

generateImage returns an object containing all the formats generated and metadata you can use in your HTML, so myImage is equal to:

{
  webp: [
    {
      format: 'webp',
      width: 300,
      height: 240,
      url: '/assets/images/RfSNa8TCUW-300.webp',
      sourceType: 'image/webp',
      srcset: '/assets/images/RfSNa8TCUW-300.webp 300w',
      filename: 'RfSNa8TCUW-300.webp',
      outputPath: 'public/assets/images/RfSNa8TCUW-300.webp'
    }
  ],
  avif: [
    {
      format: 'avif',
      width: 300,
      height: 240,
      url: '/assets/images/RfSNa8TCUW-300.avif',
      sourceType: 'image/avif',
      srcset: '/assets/images/RfSNa8TCUW-300.avif 300w',
      filename: 'RfSNa8TCUW-300.avif',
      outputPath: 'public/assets/images/RfSNa8TCUW-300.avif'
    }
  ]
}

The following files will be generated in the public/assets/images folder:

RfSNa8TCUW-300.webp
RfSNa8TCUW-300.avif

Generating placeholders

---
import { generatePlaceholder } from 'astro-eleventy-img';

const myPlaceholder = generatePlaceholder('src/assets/my_image.png');
---

<img src={myPlaceholder.dataURI} width={myPlaceholder.width} height={myPlaceholder.height} />

generatePlaceholder return an object containing all the properties needed for showing the image. So myPlaceholder in this example is equal to:

{
  dataURI: 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAkAAAAHCAIAAABV+fA3AAAACXBIWXMAAAsTAAALEwEAmpwYAAAAz0lEQVQImQHEADv/AJ7Ho7PYwTt5UhdkNjmLSUOPUCB4MSFzMkGMNACixqksb04WUy4wdz9cnFxPnksbaS0HTCo3hDUAnLmcRnFLQ289ZpZXn7Z9MpA+OYU9EFstVZpHAJ3GaqnPbJXFW5iyZNzLqZWvco+9YHeqVlKXSACu1myt13Cc1GW6ynnFrIjK4ouSzFZ/vlNsskgAytqD1d6Q3+Kevsl/xb951+OXyt6FstVytNRzAIS0S4i2S5u8TK3NXrPOZ57CYqLGXWiqOoi4Rz9UYMGpm241AAAAAElFTkSuQmCC';
  width: 640;
  height: 514;
  quality: 60;
}

Component Usage

Alternatively, it can also be used through a provided component to automatically generate the proper HTML for including the image and its placeholder:

---
import { Image } from 'astro-eleventy-img';
---

<Image src="src/assets/my_image.png" alt="My super image!" caption="This is my favorite image." />

will generate the following HTML:

<figure>
  <picture>
    <source type="image/avif" srcset="/assets/images/4dWK95ygTq-640.avif 640w" />
    <source type="image/webp" srcset="/assets/images/4dWK95ygTq-640.webp 640w" />
    <img
      alt="My super image!"
      loading="lazy"
      decoding="async"
      style="
      background-size: cover;
      background-image: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAkAAAAHCAIAAABV+fA3AAAACXBIWXMAAAsTAAALEwEAmpwYAAAAz0lEQVQImQHEADv/AJ7Ho7PYwTt5UhdkNjmLSUOPUCB4MSFzMkGMNACixqksb04WUy4wdz9cnFxPnksbaS0HTCo3hDUAnLmcRnFLQ289ZpZXn7Z9MpA+OYU9EFstVZpHAJ3GaqnPbJXFW5iyZNzLqZWvco+9YHeqVlKXSACu1myt13Cc1GW6ynnFrIjK4ouSzFZ/vlNsskgAytqD1d6Q3+Kevsl/xb951+OXyt6FstVytNRzAIS0S4i2S5u8TK3NXrPOZ57CYqLGXWiqOoi4Rz9UYMGpm241AAAAAElFTkSuQmCC);
    "
      onload="this.style.backgroundImage='none'"
      src="/assets/images/4dWK95ygTq-640.png"
      width="640"
      height="514"
    />
  </picture>
  <figcaption>
    <p>This is my favorite image.</p>
  </figcaption>
</figure>

and the following files will be generated in the public/assets/images folder:

4dWK95ygTq-640.avif
4dWK95ygTq-640.webp
4dWK95ygTq-640.png

The included Image component is a thin wrapper around generateImage and generatePlaceholder, it works for most needs but do not hesitate to build your own!

Complete Docs available here

Troubleshooting

require is not defined

Make sure to add the following to your astro.config.js config:

vite: {
    ssr: {
      external: ["@11ty/eleventy-img"],
    },
},