@arco-design/web-react/es/_hooks/useWatermark/utils.js

Arco Design React UI Library.

// canvas渲染图片会导致图片失焦模糊，
// 需要对图片进行缩放保证可读性
// polyfill 提供了这个方法用来获取设备的 pixel ratio
export function getPixelRatio(context) {
    if (!context)
        return 1;
    var backingStore = context.backingStorePixelRatio ||
        context.webkitBackingStorePixelRatio ||
        context.mozBackingStorePixelRatio ||
        context.msBackingStorePixelRatio ||
        context.oBackingStorePixelRatio ||
        context.backingStorePixelRatio ||
        1;
    return (window.devicePixelRatio || 1) / backingStore;
}