next-sanity-image

Utility for using images hosted on the Sanity.io CDN with the Next.js image component. This library:

- Supports all layout options from the next/image component.
- Implements the loader callback to resolve the corresponding Sanity CDN URL's.
- Respects the image sizes and device sizes as specified in your Next config.
- Respects the quality as specified in the next/image props.
- Allows transforming the image using the @sanity/image-url builder.
- Automatically sets the width and the height of the Next image component to the corresponding aspect ratio.
- Supports Webp formats using automatic content negotation.
- Is fully typed and exposes relevant types.

Installation

``
npm install --save next-sanity-image
`

This library also expects you to pass in a SanityClient instance, if you haven't installed this already:

`
npm install --save @sanity/client
`

Upgrading

$3

Version 5.0.0 of this library has removed support for the blur options. The reason for this is that this could not be correctly standardised from the library, the only way to support blur up was to request a low quality placeholder image from the Sanity CDN. Sanity already provides a base 64 lqip from the asset's metadata (https://www.sanity.io/docs/image-metadata#74bfd1db9b97).

Checkout the Responsive layout example on how to use the lqip in your Image component.

Usage

All next/image component layouts are supported. Below you can find a usage example for each of the supported layouts.

$3

It's recommended to use the responsive layout for the best compatibility with different devices and resolutions. It's required to set the sizes attribute using this layout (https://developer.mozilla.org/en-US/docs/Web/HTML/Element/img#attr-sizes).

`jsx
import { createClient } from '@sanity/client';
import Img from 'next/image';
import { useNextSanityImage } from 'next-sanity-image';

// If you're using a private dataset you probably have to configure a separate write/read client.
// https://www.sanity.io/help/js-client-usecdn-token
const configuredSanityClient = createClient({
projectId: process.env.NEXT_PUBLIC_SANITY_PROJECT_ID,
dataset: process.env.NEXT_PUBLIC_SANITY_DATASET,
useCdn: true
});

const Page = ({ mySanityData }) => {
const imageProps = useNextSanityImage(configuredSanityClient, mySanityData.image);

return (
{...imageProps}
style={{ width: '100%', height: 'auto' }} // layout="responsive" prior to Next 13.0.0
sizes="(max-width: 800px) 100vw, 800px"
placeholder="blur"
blurDataURL={mySanityData.image.asset.metadata.lqip}
/>
);
};

// Replace this with your logic for fetching data from the Sanity API.
export const getServerSideProps = async function (context) {
const { slug = '' } = context.query;

const data = await configuredSanityClient.fetch(
{
"mySanityData": *[_type == "mySanityType" && slug.current == $slug][0] {
image {
asset->{
...,
metadata
}
}
}
},
{ slug }
);

return { props: data };
};

export default Page;
`

$3

`jsx
// ... see "Responsive layout"

const Page = ({ mySanityData }) => {
const imageProps = useNextSanityImage(configuredSanityClient, mySanityData.image);

return (
{...imageProps}
style={{ maxWidth: '100%', height: 'auto' }} // layout="intrinsic" prior to Next 13.0.0
placeholder="blur"
blurDataURL={mySanityData.image.asset.metadata.lqip}
/>
);
};

// ... see "Responsive layout"
`

$3

`jsx
// ... see "Responsive layout"

const Page = ({ mySanityData }) => {
const imageProps = useNextSanityImage(configuredSanityClient, mySanityData.image);

return (
{...imageProps}
placeholder="blur"
blurDataURL={mySanityData.image.asset.metadata.lqip}
/>
);
};

// ... see "Responsive layout"
`

$3

Omit the width and height props returned from useNextSanityImage when using a fill layout, as this fills the available space of the parent container. You probably also want to set the objectFit prop to specify how the object resizes inside the container.

`jsx
// ... see "Responsive layout"

const Page = ({ mySanityData }) => {
const imageProps = useNextSanityImage(configuredSanityClient, mySanityData.image);

return (
src={imageProps.src}
loader={imageProps.loader}
fill // layout="fill" prior to Next 13.0.0
objectFit="contain"
/>
);
};

// ... see "Responsive layout"
`

API

$3

React hook which handles generating a URL for each of the defined sizes in the image sizes and device sizes Next.js options.

#### sanityClient: SanityClient

Pass in a configured instance of the SanityClient, used for building the URL using the @sanity/image-url builder.

#### image: SanityImageSource | null

A reference to a Sanity image asset, can be retrieved by using the Sanity API. You can pass in any asset that is also supported by the image() method of @sanity/image-url. This parameter can be set to null in order to not load any image.

#### options: UseNextSanityImageOptions

##### imageBuilder?: function(/ see below /)

| property | type | description |
| --------------------------------- | --------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------- |
| imageUrlBuilder | ImageUrlBuilder | @sanity/image-url builder to apply image transformations. |
| options | UseNextSanityImageBuilderOptions | Options object with relevant context passed to the callback, see properties below. |
| options.width | number | null | The width for the current srcSet entry, if set to null this is the entry for the src fallback attribute. |
| options.originalImageDimensions | { width: number, height: number, aspectRatio: number } : UseNextSanityImageDimensions | Object containing dimensions of the original image passed to the image parameter. |
| options.croppedImageDimensions | { width: number, height: number, aspectRatio: number } : UseNextSanityImageDimensions | The cropped dimensions of the image, if a crop is supplied. Otherwise, the same as originalImageDimensions. |
| options.quality | number | null | The quality of the image as passed to the quality prop of the next/image component. |

An optional function callback which allows you to customize the image using the ImageUrlBuilder. This function is called for every entry in the image sizes and device sizes, and is used to define the URL's outputted in the srcSet attribute of the image.

Defaults to:

`javascript
(imageUrlBuilder, options) => {
return imageUrlBuilder
.width(options.width || Math.min(options.originalImageDimensions.width, 1920))
.quality(options.quality || 75)
.fit('clip');
};
`

For an example on how to use this, read the chapter on Image transformations.

#### Return value: UseNextSanityImageProps | null

If the image parameter is set to null, the return value of this hook will also be null. This allows you to handle any conditional rendering when no image is loaded. If an image is set, to following result (UseNextSanityImageProps) will be returned:

`javascript
{
src: string,
width: number,
height: number,
// https://nextjs.org/docs/api-reference/next/image#loader
loader: ImageLoader
}
`

Image transformations

Custom transformations to the resulting image can be made by implementing the imageBuilder callback function. Note that it's recommended to implement a memoized callback, either by implementing the function outside of the component function scope or by making use of useCallback. Otherwise the props will be recomputed for every render.

`jsx
//...

const myCustomImageBuilder = (imageUrlBuilder, options) => {
return imageUrlBuilder
.width(options.width || Math.min(options.originalImageDimensions.width, 800))
.blur(20)
.flipHorizontal()
.saturation(-100)
.fit('clip');
};

const Page = ({ mySanityData }) => {
const imageProps = useNextSanityImage(configuredSanityClient, mySanityData.image, {
imageBuilder: myCustomImageBuilder
});

return ;
};

//...
`

$3

- Because next/image only renders a single element with a srcSet attribute, the width and height prop being returned by the React hook is uniform for each size. Cropping an image is possible using the ImageUrlBuilder, however you have to return an image with the same aspect ratio for each of the defined sizes. Art direction is currently not supported (both by next/image and this library).

If the functionality mentioned above is desired, please file an issue stating your specific use case so we can look at the desired behavior and possibilities.

Types

The following types are exposed from the library:

- ImageUrlBuilder
- UseNextSanityImageProps
- UseNextSanityImageOptions
- UseNextSanityImageBuilder
- UseNextSanityImageBuilderOptions
- UseNextSanityImageDimensions`