use-device-pixel-ratio

useDevicePixelRatio() is a React hook (and utility) that will tell you what the current device has as its Device Pixel Ratio (DPR). The hook is reactive - if the browser window moves to a different display with a different DPR, it will update automatically. If you only need to get the DPR statically, there is a function (getDevicePixelRatio()) equivalent.

Installing

npm i use-device-pixel-ratio

Server rendering

When rendering on the server or in browsers that do not support the devicePixelRatio property, it will default to 1 unless overriden by using the defaultDpr option.

Rounding/limiting

The hook (by default) both rounds and limits the DPR - it will round down by default, and cap the number at 3. In other words, you should by default only have three values returned: 1, 2 or 3. To allow larger DPRs, pass a higher number to the maxDpr option. To prevent rounding, pass round: false.

Usage

Default usage

1import {useDevicePixelRatio} from 'use-device-pixel-ratio'
2
3async function MyComponent() {
4  const dpr = useDevicePixelRatio()
5  return <img src={`https://my.image.host/file.jpg?dpr=${dpr}`}>
6}

Setting higher limit

1import {useDevicePixelRatio} from 'use-device-pixel-ratio'
2
3async function MyComponent() {
4  const dpr = useDevicePixelRatio({maxDpr: 50})
5  return <div>DPR is {dpr}</div>
6}

Getting the "raw" DPR

1import {useDevicePixelRatio} from 'use-device-pixel-ratio'
2
3async function MyComponent() {
4  const dpr = useDevicePixelRatio({maxDpr: +Infinity, round: false})
5  return <div>DPR is {dpr}</div>
6}

Setting the default DPR

1import {useDevicePixelRatio} from 'use-device-pixel-ratio'
2
3async function MyComponent() {
4  const dpr = useDevicePixelRatio({defaultDpr: 2})
5
6  // Actual device DPR if available, 2 otherwise
7  return <div>DPR is {dpr}</div>
8}

Function usage

1import {getDevicePixelRatio} from 'use-device-pixel-ratio'
2
3console.log('Device pixel ratio is ', getDevicePixelRatio())
4
5// Or, with options (same options as hook):
6console.log('Device pixel ratio is ', getDevicePixelRatio({maxDpr: 5}))

License

MIT © Espen Hovlandsdal