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gatsby-image

Speedy, optimized images without the work.

gatsby-image is a React component specially designed to work seamlessly with Gatsby’s GraphQL queries. It combines Gatsby’s native image processing capabilities with advanced image loading techniques to easily and completely optimize image loading for your sites. gatsby-image uses gatsby-plugin-sharp to power its image transformations.

Note: gatsby-image is not a drop-in replacement for <img />. It’s optimized for fixed width/height images and images that stretch the full-width of a container. Some ways you can use <img /> won’t work with gatsby-image.

Demo

Table of Contents

Problem

Large, unoptimized images dramatically slow down your site.

But creating optimized images for websites has long been a thorny problem. Ideally you would:

  • Resize large images to the size needed by your design
  • Generate multiple smaller images so smartphones and tablets don’t download desktop-sized images
  • Strip all unnecessary metadata and optimize JPEG and PNG compression
  • Efficiently lazy load images to speed initial page load and save bandwidth
  • Use the “blur-up” technique or a ”traced placeholder” SVG to show a preview of the image while it loads
  • Hold the image position so your page doesn’t jump while images load

Doing this consistently across a site feels like sisyphean labor. You manually optimize your images and then… several images are swapped in at the last minute or a design-tweak shaves 100px of width off your images.

Most solutions involve a lot of manual labor and bookkeeping to ensure every image is optimized.

This isn’t ideal. Optimized images should be easy and the default.

Solution

With Gatsby, we can make images way way better.

gatsby-image is designed to work seamlessly with Gatsby’s native image processing capabilities powered by GraphQL and Sharp. To produce perfect images, you need only:

  1. Import gatsby-image and use it in place of the built-in img
  2. Write a GraphQL query using one of the included GraphQL “fragments” which specify the fields needed by gatsby-image.

The GraphQL query creates multiple thumbnails with optimized JPEG and PNG compression. The gatsby-image component automatically sets up the “blur-up” effect as well as lazy loading of images further down the screen.

Install

npm install --save gatsby-image

Depending on the gatsby starter you used, you may need to include gatsby-transformer-sharp and gatsby-plugin-sharp as well, and make sure they are installed and included in your gatsby-config.

npm install --save gatsby-transformer-sharp gatsby-plugin-sharp

Then in your gatsby-config.js:

plugins: [`gatsby-transformer-sharp`, `gatsby-plugin-sharp`]

Also, make sure you have set up a source plugin, so your images are available in graphql queries. For example, if your images live in a project folder on the local filesystem, you would set up gatsby-source-filesystem in gatsby-config.js like so:

const path = require(`path`)

module.exports = {
  plugins: [
    {
      resolve: `gatsby-source-filesystem`,
      options: {
        name: `images`,
        path: path.join(__dirname, `src`, `images`),
      },
    },
    `gatsby-plugin-sharp`,
    `gatsby-transformer-sharp`,
  ],
}

How to use

This is what a component using gatsby-image looks like:

import React from "react"
import { graphql } from "gatsby"
import Img from "gatsby-image"

export default ({ data }) => (
  <div>
    <h1>Hello gatsby-image</h1>
    <Img fixed={data.file.childImageSharp.fixed} />
  </div>
)

export const query = graphql`
  query {
    file(relativePath: { eq: "blog/avatars/kyle-mathews.jpeg" }) {
      childImageSharp {
        # Specify the image processing specifications right in the query.
        # Makes it trivial to update as your page's design changes.
        fixed(width: 125, height: 125) {
          ...GatsbyImageSharpFixed
        }
      }
    }
  }
`

For other explanations of how to get started with gatsby-image, see this blog post by community member Kyle Gill Image Optimization Made Easy with Gatsby.js, this post by Hunter Chang (which also includes some details about changes to gatsby-image for Gatsby v2): An Intro To Gatsby Image V2, or this free playlist on egghead.io with examples for using gatsby-image.

Polyfilling object-fit/object-position for IE

If you’d like to include a polyfill for the object-fit/object-position CSS properties (which aren’t supported by default in Internet Explorer), import from gatsby-image/withIEPolyfill instead:

// Other imports...
import Img from "gatsby-image/withIEPolyfill"

export default ({ data }) => (
  <div>
    <h1>Hello gatsby-image</h1>
    <Img
      fixed={data.file.childImageSharp.fixed}
      objectFit="cover"
      objectPosition="50% 50%"
      alt=""
    />
  </div>
)

// GraphQL query...

Importing from gatsby-image/withIEPolyfill tells Gatsby to automatically apply the object-fit-images polyfill to your image. To make your object-fit/object-position values work in IE, be sure to use the objectFit and objectPosition props (rather than the imgStyle prop or a CSS or CSS-in-JS solution) so the polyfill will recognize them.

Two types of responsive images

There are two types of responsive images supported by gatsby-image.

  1. Images that have a fixed width and height
  2. Images that stretch across a fluid container

In the first scenario, you want to vary the image’s size for different screen resolutions — in other words, create retina images.

For the second scenario, you want to create multiple sizes of thumbnails for devices with widths stretching from smartphone to wide desktop monitors.

To decide between the two, ask yourself: “do I know the exact size this image will be?” If yes, it’s the first type. If no and its width and/or height need to vary depending on the size of the screen, then it’s the second type.

In Gatsby’s GraphQL implementation, you query for the first type by querying a child object of an image called fixed — which you can see in the sample component above. For the second type, you do a similar query but for a child object called fluid.

Fragments

GraphQL includes a concept called “query fragments”. Which, as the name suggests, are a part of a query that can be used in multiple queries. To ease building with gatsby-image, Gatsby image processing plugins which support gatsby-image ship with fragments which you can easily include in your queries.

Note, due to a limitation of GraphiQL, you can not currently use these fragments in the GraphiQL IDE.

Plugins supporting gatsby-image currently include gatsby-transformer-sharp, gatsby-source-contentful, gatsby-source-datocms and gatsby-source-sanity.

Their fragments are:

gatsby-transformer-sharp

  • GatsbyImageSharpFixed
  • GatsbyImageSharpFixed_noBase64
  • GatsbyImageSharpFixed_tracedSVG
  • GatsbyImageSharpFixed_withWebp
  • GatsbyImageSharpFixed_withWebp_noBase64
  • GatsbyImageSharpFixed_withWebp_tracedSVG
  • GatsbyImageSharpFluid
  • GatsbyImageSharpFluid_noBase64
  • GatsbyImageSharpFluid_tracedSVG
  • GatsbyImageSharpFluid_withWebp
  • GatsbyImageSharpFluid_withWebp_noBase64
  • GatsbyImageSharpFluid_withWebp_tracedSVG

gatsby-source-contentful

  • GatsbyContentfulFixed
  • GatsbyContentfulFixed_noBase64
  • GatsbyContentfulFixed_tracedSVG
  • GatsbyContentfulFixed_withWebp
  • GatsbyContentfulFixed_withWebp_noBase64
  • GatsbyContentfulFluid
  • GatsbyContentfulFluid_noBase64
  • GatsbyContentfulFluid_tracedSVG
  • GatsbyContentfulFluid_withWebp
  • GatsbyContentfulFluid_withWebp_noBase64

gatsby-source-datocms

  • GatsbyDatoCmsFixed
  • GatsbyDatoCmsFixed_noBase64
  • GatsbyDatoCmsFluid
  • GatsbyDatoCmsFluid_noBase64

gatsby-source-sanity

  • GatsbySanityImageFixed
  • GatsbySanityImageFixed_noBase64
  • GatsbySanityImageFluid
  • GatsbySanityImageFluid_noBase64

Links to source code for fragment fields of official Gatsby plugins can be found in the Gatsby GraphQL API

If you don’t want to use the blur-up effect, choose the fragment with noBase64 at the end. If you want to use the traced placeholder SVGs, choose the fragment with tracedSVG at the end.

If you want to automatically use WebP images when the browser supports the file format, use the withWebp fragments. If the browser doesn’t support WebP, gatsby-image will fall back to the default image format.

Please see the gatsby-plugin-sharp documentation for more information on tracedSVG and its configuration options.

“Fixed” queries

Component

Pass in the data returned from the fixed object in your query via the fixed prop. e.g. <Img fixed={fixed} />

Query

{
  imageSharp {
    # Other options include height (set both width and height to crop),
    # grayscale, duotone, rotate, etc.
    fixed(width: 400) {
      # Choose either the fragment including a small base64ed image, a traced placeholder SVG, or one without.
      ...GatsbyImageSharpFixed
    }
  }
}

“Fluid” queries

Component

Pass in the data returned from the fluid object in your query via the fluid prop. e.g. <Img fluid={fluid} />

Query

{
  imageSharp {
    # i.e. the max width of your container is 700 pixels.
    #
    # Other options include maxHeight (set both maxWidth and maxHeight to crop),
    # grayscale, duotone, rotate, etc.
    fluid(maxWidth: 700) {
      # Choose either the fragment including a small base64ed image, a traced placeholder SVG, or one without.
      ...GatsbyImageSharpFluid_noBase64
    }
  }
}

Avoiding stretched images using the fluid type

As mentioned previously, images using the fluid type are stretched to match the container’s width. In the case where the image’s width is smaller than the available viewport, the image will stretch to match the container, potentially leading to unwanted problems and worsened image quality.

To counter this edge case one could wrap the Img component in order to set a better, for that case, maxWidth:

const NonStretchedImage = props => {
  let normalizedProps = props
  if (props.fluid && props.fluid.presentationWidth) {
    normalizedProps = {
      ...props,
      style: {
        ...(props.style || {}),
        maxWidth: props.fluid.presentationWidth,
        margin: "0 auto", // Used to center the image
      },
    }
  }

  return <Img {...normalizedProps} />
}

Note: The GatsbyImageSharpFluid fragment does not include presentationWidth. You will need to add it in your graphql query as is shown in the following snippet:

{
  childImageSharp {
    fluid(maxWidth: 500, quality: 100) {
      ...GatsbyImageSharpFluid
      presentationWidth
    }
  }
}

Art-directing multiple images

gatsby-image supports showing different images at different breakpoints, which is known as art direction. To do this, you can define your own array of fixed or fluid images, along with a media key per image, and pass it to gatsby-image’s fixed or fluid props. The media key that is set on an image can be any valid CSS media query.

import React from "react"
import { graphql } from "gatsby"
import Img from "gatsby-image"

export default ({ data }) => {
  // Set up the array of image data and `media` keys.
  // You can have as many entries as you'd like.
  const sources = [
    data.mobileImage.childImageSharp.fluid,
    {
      ...data.desktopImage.childImageSharp.fluid,
      media: `(min-width: 768px)`,
    },
  ]

  return (
    <div>
      <h1>Hello art-directed gatsby-image</h1>
      <Img fluid={sources} />
    </div>
  )
}

export const query = graphql`
  query {
    mobileImage: file(relativePath: { eq: "blog/avatars/kyle-mathews.jpeg" }) {
      childImageSharp {
        fluid(maxWidth: 1000, quality: 100) {
          ...GatsbyImageSharpFluid
        }
      }
    }
    desktopImage: file(
      relativePath: { eq: "blog/avatars/kyle-mathews-desktop.jpeg" }
    ) {
      childImageSharp {
        fluid(maxWidth: 2000, quality: 100) {
          ...GatsbyImageSharpFluid
        }
      }
    }
  }
`

While you could achieve a similar effect with plain CSS media queries, gatsby-image accomplishes this using the <picture> tag, which ensures that browsers only download the image they need for a given breakpoint.

gatsby-image props

Name Type Description
fixed object / array Data returned from the fixed query. When prop is an array it has to be combined with media keys, allows for art directing fixed images.
fluid object / array Data returned from the fluid query. When prop is an array it has to be combined with media keys, allows for art directing fluid images.
fadeIn bool Defaults to fading in the image on load
durationFadeIn number fading duration is set up to 500ms by default
title string Passed to the img element
alt string Passed to the img element. Defaults to an empty string alt=""
crossOrigin string Passed to the img element
className string / object Passed to the wrapper element. Object is needed to support Glamor’s css prop
style object Spread into the default styles of the wrapper element
imgStyle object Spread into the default styles of the actual img element
placeholderStyle object Spread into the default styles of the placeholder img element
placeholderClassName string A class that is passed to the placeholder img element
backgroundColor string / bool Set a colored background placeholder. If true, uses “lightgray” for the color. You can also pass in any valid color string.
onLoad func A callback that is called when the full-size image has loaded.
onStartLoad func A callback that is called when the full-size image starts loading, it gets the parameter { wasCached: boolean } provided.
onError func A callback that is called when the image fails to load.
Tag string Which HTML tag to use for wrapping elements. Defaults to div.
objectFit string Passed to the object-fit-images polyfill when importing from gatsby-image/withIEPolyfill. Defaults to cover.
objectPosition string Passed to the object-fit-images polyfill when importing from gatsby-image/withIEPolyfill. Defaults to 50% 50%.
loading string Set the browser’s native lazy loading attribute. One of lazy, eager or auto. Defaults to lazy.
critical bool Opt-out of lazy-loading behavior. Defaults to false. Deprecated, use loading instead.
draggable bool Set the img tag draggable to either false, true
itemProp string Add an itemprop schema.org structured data attribute on the image.

Image processing arguments

gatsby-plugin-sharp supports many additional arguments for transforming your images like quality, sizeByPixelDensity, pngCompressionLevel, cropFocus, grayscale and many more. See its documentation for more.

Some other stuff to be aware of

  • If you want to set display: none; on a component using a fixed prop, you need to also pass in to the style prop { display: 'inherit' }.
  • Be aware that from a SEO perspective it is advisable not to change the image parameters lightheartedly once the website has been published. Every time you change properties within fluid or fixed (like quality or maxWidth), the absolute path of the image changes. These properties generate the hash we use in our absolute path. This happens even if the image didn’t change its name. As a result, the image could appear on the image SERP as “new” one. (more details can be found on this issue)
  • By default, images don’t load until JavaScript is loaded. Gatsby’s automatic code splitting generally makes this fine but if images seem slow coming in on a page, check how much JavaScript is being loaded there.
  • Images marked as critical will start loading immediately as the DOM is parsed, but unless fadeIn is set to false, the transition from placeholder to final image will not occur until after the component is mounted.
  • gatsby-image is now backed by the newer <picture> tag. This newer standard allows for media types to be chosen by the browser without using JavaScript. It also is backward compatible to older browsers (IE 11, etc)
  • Gifs can’t be resized the same way as pngs and jpegs, unfortunately—if you try to use a gif with gatsby-image, it won’t work. For now, the best workaround is to import the gif directly.
  • Lazy loading behavior is dependent on IntersectionObserver which is not available in IE. A polyfill is recommended.

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