use-eye-dropper

useEyeDropper

👀🩸🧫 Browser color picker hook for React.

Implements the EyeDropper API into an easy-to-use React hook. This API is currently only available in Chromium based browsers.

Features

• Supports Server-Side rendering.
• Test coverage with unit and integration tests.
• TypeScript support
• Under 670 bytes GZipped
• Safely detect and fallback on unsupported browsers using isSupported method.
• Closes eye dropper when corresponding component is unmounted.
• Provides explicit close method to cancel eye dropper (signals can still be used).

Installation

pnpm

pnpm add use-eye-dropper

Yarn

yarn add use-eye-dropper

npm

npm install use-eye-dropper

Usage

import React, { useState, useCallback } from 'react'
import useEyeDropper from 'use-eye-dropper'

const App = () => {
  const { open, close, isSupported } = useEyeDropper()
  const [color, setColor] = useState('#fff')
  const [error, setError] = useState()
  // useEyeDropper will reject/cleanup the open() promise on unmount,
  // so setState never fires when the component is unmounted.
  const pickColor = useCallback(() => {
    // Using async/await (can be used as a promise as-well)
    const openPicker = async () => {
      try {
        const color = await open()
        setColor(color.sRGBHex)
      } catch (e) {
        console.log(e)
        // Ensures component is still mounted
        // before calling setState
        if (!e.canceled) setError(e)
      }
    }
    openPicker()
  }, [open])
  return (
    <>
      <div style={{ padding: '64px', background: color }}>Selected color</div>
      {isSupported() ?
          <button onClick={pickColor}>Pick color</button>
        : <span>EyeDropper API not supported in this browser</span>
      }
      {!!error && <div>{error.message}</div>}
    </>
  )
}

Usage with TypeScript

With TypeScript all of the types will be inferred where possible, however if you need to use error handling some type-guard functions can be used to narrow down the type of the error from the catch block. Otherwise it will be unknown.

Here is one approach to deal with this when working with TypeScript and dropper errors:

type DropperError = { 
  message: string
  canceled?: boolean
}

const isError = <T, >(err: DropperError | T): err is DropperError => 
  !!err && err instanceof Error && !!err.message

const isNotCanceled = <T, >(err: DropperError | T): err is DropperError =>
  isError(err) && !err.canceled

and then !e.canceled can be replaced with isNotCanceled(e), the type-guard will enforce a proper type when using setError.

This will also work for isError.

Methods

• open({ signal?: AbortSignal }) => Promise<{ sRGBHex: string }>'

  Opens the EyeDropper API in supported browsers and returns a promise which will resolve with the selected color. Alternatively the promise will be rejected if the user cancels the operation, for instance by hitting escape. Additionally if the browser does not support the API, the promise is rejected. While the spec currently indicates that a 6-digit HEX value is returned, the current Chrome implementation returns a rgba value.

• close() => void

  This method closes the EyeDropper API selector if it is open and rejects the promise from open. Otherwise this performs a no-op.

• isSupported() => boolean

  Determines if the EyeDropper API is supported in the current browser.