use-device-pixel-ratio/dist/index.modern.js

React hook for finding device pixel ratio (DPR), optionally capping/rounding

import { useState, useEffect } from 'react';

/**
 * Get the device pixel ratio, potentially rounded and capped.
 * Will emit new values if it changes.
 *
 * @param options
 * @returns The current device pixel ratio, or the default if none can be resolved
 */

function useDevicePixelRatio(options) {
  const dpr = getDevicePixelRatio(options);
  const [currentDpr, setCurrentDpr] = useState(dpr);
  const {
    defaultDpr,
    maxDpr,
    round
  } = options || {};
  useEffect(() => {
    const canListen = typeof window !== 'undefined' && 'matchMedia' in window;

    if (!canListen) {
      return;
    }

    const updateDpr = () => setCurrentDpr(getDevicePixelRatio({
      defaultDpr,
      maxDpr,
      round
    }));

    const mediaMatcher = window.matchMedia(`screen and (resolution: ${currentDpr}dppx)`); // Safari 13.1 does not have `addEventListener`, but does have `addListener`

    if (mediaMatcher.addEventListener) {
      mediaMatcher.addEventListener('change', updateDpr);
    } else {
      mediaMatcher.addListener(updateDpr);
    }

    return () => {
      if (mediaMatcher.removeEventListener) {
        mediaMatcher.removeEventListener('change', updateDpr);
      } else {
        mediaMatcher.removeListener(updateDpr);
      }
    };
  }, [currentDpr, defaultDpr, maxDpr, round]);
  return currentDpr;
}
/**
 * Returns the current device pixel ratio (DPR) given the passed options
 *
 * @param options
 * @returns current device pixel ratio
 */

function getDevicePixelRatio(options) {
  const {
    defaultDpr = 1,
    maxDpr = 3,
    round = true
  } = options || {};
  const hasDprProp = typeof window !== 'undefined' && typeof window.devicePixelRatio === 'number';
  const dpr = hasDprProp ? window.devicePixelRatio : defaultDpr;
  const rounded = Math.min(Math.max(1, round ? Math.floor(dpr) : dpr), maxDpr);
  return rounded;
}

export { getDevicePixelRatio, useDevicePixelRatio };
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