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images

あなたが Next.js の組み込みの Image Optimization API を使わずに、クラウドプロバイダを使って画像を最適化したい場合、次のようにnext.config.jsを設定できます。

next.config.js

module.exports = {
  images: {
    loader: 'custom',
    loaderFile: './my/image/loader.js',
  },
}

この loaderFile は、あなたの Next.js アプリケーションの root に対する相対的なファイルを指す必要があります。ファイルは、例えば、string を返す default 関数を export する必要があります。

export default function myImageLoader({ src, width, quality }) {
  return `https://example.com/${src}?w=${width}&q=${quality || 75}`;
}

あるいは、loader propを使用して、next/imageの各インスタンスに関数を渡すこともできます。

Akamai

// Docs: https://techdocs.akamai.com/ivm/reference/test-images-on-demand
export default function akamaiLoader({ src, width, quality }) {
  return `https://example.com/${src}?imwidth=${width}`;
}

Cloudinary

// Demo: https://res.cloudinary.com/demo/image/upload/w_300,c_limit,q_auto/turtles.jpg
export default function cloudinaryLoader({ src, width, quality }) {
  const params = ["f_auto", "c_limit", `w_${width}`, `q_${quality || "auto"}`];
  return `https://example.com/${params.join(",")}${src}`;
}

Cloudflare

// Docs: https://developers.cloudflare.com/images/url-format
export default function cloudflareLoader({ src, width, quality }) {
  const params = [`width=${width}`, `quality=${quality || 75}`, "format=auto"];
  return `https://example.com/cdn-cgi/image/${params.join(",")}/${src}`;
}

Contentful

// Docs: https://www.contentful.com/developers/docs/references/images-api/
export default function contentfulLoader({ src, width, quality }) {
  const url = new URL(`https://example.com${src}`);
  url.searchParams.set("fm", "webp");
  url.searchParams.set("w", width.toString());
  url.searchParams.set("q", (quality || 75).toString());
  return url.href;
}

Fastly

// Docs: https://developer.fastly.com/reference/io/
export default function fastlyLoader({ src, width, quality }) {
  const url = new URL(`https://example.com${src}`);
  url.searchParams.set("auto", "webp");
  url.searchParams.set("width", width.toString());
  url.searchParams.set("quality", (quality || 75).toString());
  return url.href;
}

Gumlet

// Docs: https://docs.gumlet.com/reference/image-transform-size
export default function gumletLoader({ src, width, quality }) {
  const url = new URL(`https://example.com${src}`);
  url.searchParams.set("format", "auto");
  url.searchParams.set("w", width.toString());
  url.searchParams.set("q", (quality || 75).toString());
  return url.href;
}

ImageEngine

// Docs: https://support.imageengine.io/hc/en-us/articles/360058880672-Directives
export default function imageengineLoader({ src, width, quality }) {
  const compression = 100 - (quality || 50)
  const params = [`w_${width}`, `cmpr_${compression}`)]
  return `https://example.com${src}?imgeng=/${params.join('/')`
}

Imgix

// Demo: https://static.imgix.net/daisy.png?format=auto&fit=max&w=300
export default function imgixLoader({ src, width, quality }) {
  const url = new URL(`https://example.com${src}`);
  const params = url.searchParams;
  params.set("auto", params.getAll("auto").join(",") || "format");
  params.set("fit", params.get("fit") || "max");
  params.set("w", params.get("w") || width.toString());
  params.set("q", (quality || 50).toString());
  return url.href;
}

Thumbor

// Docs: https://thumbor.readthedocs.io/en/latest/
export default function thumborLoader({ src, width, quality }) {
  const params = [`${width}x0`, `filters:quality(${quality || 75})`];
  return `https://example.com${params.join("/")}${src}`;
}

Sanity

// Docs: https://www.sanity.io/docs/image-urls
export default function sanityLoader({ src, width, quality }) {
  const prj = "zp7mbokg";
  const dataset = "production";
  const url = new URL(`https://cdn.sanity.io/images/${prj}/${dataset}${src}`);
  url.searchParams.set("auto", "format");
  url.searchParams.set("fit", "max");
  url.searchParams.set("w", width.toString());
  if (quality) {
    url.searchParams.set("q", quality.toString());
  }
  return url.href;
}

Sirv

// Docs: https://sirv.com/help/articles/dynamic-imaging/
export default function sirvLoader({ src, width, quality }) {
  const url = new URL(`https://example.com${src}`);
  const params = url.searchParams;
  params.set("format", params.getAll("format").join(",") || "optimal");
  params.set("w", params.get("w") || width.toString());
  params.set("q", (quality || 85).toString());
  return url.href;
}

Supabase

// Docs: https://supabase.com/docs/guides/storage/image-transformations#nextjs-loader
export default function supabaseLoader({ src, width, quality }) {
  const url = new URL(`https://example.com${src}`);
  url.searchParams.set("width", width.toString());
  url.searchParams.set("quality", (quality || 75).toString());
  return url.href;
}