feat: auto-generate blurDataURL property when placeholder=blur

example/pages/index.tsx

@@ -5,15 +5,21 @@ import { FC } from 'react';
 import styles from '../styles/Home.module.css';
 
 type CodeProps = {
-  [key: string]: any
-}
-const Code: FC<CodeProps> = (p) => 
+  [key: string]: any;
+};
+const Code: FC<CodeProps> = (p) => (
   <code className={styles.inlineCode} {...p} />
+);
 
 const Home: NextPage = () => (
   <div className={styles.container}>
     <div className={styles.card}>
-      <h1>Uploadcare custom loader for Image Component <a href="https://github.com/uploadcare/nextjs-loader">@uploadcare/nextjs-loader</a></h1>
+      <h1>
+        Uploadcare custom loader for Image Component{' '}
+        <a href="https://github.com/uploadcare/nextjs-loader">
+          @uploadcare/nextjs-loader
+        </a>
+      </h1>
       <p>
         The following is an example of a reference to an image from the{' '}
         Uploadcare CDN at <Code>ucarecdn.com</Code>
@@ -31,7 +37,8 @@ const Home: NextPage = () => (
       />
       <hr className={styles.hr} />
       <p>
-        The following is an example of use of the <Code>UploadcareImage</Code> helper component.
+        The following is an example of use of the <Code>UploadcareImage</Code>{' '}
+        helper component.
       </p>
       <UploadcareImage
         alt="Vercel logo"
@@ -40,6 +47,19 @@ const Home: NextPage = () => (
         height={500}
       />
       <hr className={styles.hr} />
+      <p>
+        The following is an example of use of the <Code>UploadcareImage</Code>{' '}
+        helper component with <Code>placeholder=blur</Code> property. It&apos;s
+        better to enable network throttling in dev tools to see the blurred placeholder.
+      </p>
+      <UploadcareImage
+        alt="Vercel logo"
+        src="https://ucarecdn.com/c768f1c2-891a-4f54-8e1e-7242df218b51/pinewatt2Hzmz15wGikunsplash.jpg"
+        width={500}
+        height={500}
+        placeholder="blur"
+      />
+      <hr className={styles.hr} />
       <p>
         The following is an example of a reference to an external image at{' '}
         <Code>assets.vercel.com</Code>.
@@ -68,8 +88,11 @@ const Home: NextPage = () => (
         height={64}
         loader={uploadcareLoader}
       />
-       <hr className={styles.hr} />
-      <p>Local image will be served AS IS in Development, and converted to the absolute URL and passed to the proxy in Production</p>
+      <hr className={styles.hr} />
+      <p>
+        Local image will be served AS IS in Development, and converted to the
+        absolute URL and passed to the proxy in Production
+      </p>
       <Image
         alt="A local image"
         src="/local_image.png"
@@ -78,9 +101,13 @@ const Home: NextPage = () => (
         loader={uploadcareLoader}
       />
       <hr className={styles.hr} />
-      Checkout the project documentation on Github <a href="https://github.com/uploadcare/nextjs-loader">@uploadcare/nextjs-loader</a>.
+      Checkout the project documentation on Github{' '}
+      <a href="https://github.com/uploadcare/nextjs-loader">
+        @uploadcare/nextjs-loader
+      </a>
+      .
     </div>
   </div>
-)
+);
 
-export default Home
+export default Home;

jest-setup.js

@@ -0,0 +1 @@
+import '@testing-library/jest-dom'

jest.config.ts

@@ -1,4 +1,5 @@
 export default {
   testPathIgnorePatterns: ["<rootDir>/build/", "<rootDir>/src/__tests__/utils"],
-  collectCoverageFrom: ["src/**/*.{ts,js,tsx}"]
+  collectCoverageFrom: ["src/**/*.{ts,js,tsx}"],
+  setupFilesAfterEnv: ['<rootDir>/jest-setup.js']
 }

package.json

@@ -43,6 +43,7 @@
     "@babel/preset-env": "^7.15.6",
     "@babel/preset-react": "^7.14.5",
     "@babel/preset-typescript": "^7.15.0",
+    "@testing-library/jest-dom": "^5.16.4",
     "@testing-library/react": "^12.1.2",
     "@testing-library/react-hooks": "^7.0.2",
     "@types/jest": "^27.0.2",

src/__tests__/uploadcare-image.spec.tsx

@@ -17,7 +17,7 @@ describe('UploadcareImage', () => {
     removeEnvVar('NEXT_PUBLIC_UPLOADCARE_PUBLIC_KEY');
   });
 
-  test('The UploadcareImage component renders passed image with default settings properly', () => {
+  it('should render passed image with default settings properly', () => {
     const src =
       'https://ucarecdn.com/a6f8abc8-f92e-460a-b7a1-c5cd70a18cdb/vercel.png';
 
@@ -38,7 +38,7 @@ describe('UploadcareImage', () => {
     );
   });
 
-  test('The UploadcareImage component should accept src without filename', () => {
+  it('should accept src without filename', () => {
     const src = 'https://ucarecdn.com/a6f8abc8-f92e-460a-b7a1-c5cd70a18cdb/';
 
     render(
@@ -56,4 +56,43 @@ describe('UploadcareImage', () => {
       'https://ucarecdn.com/a6f8abc8-f92e-460a-b7a1-c5cd70a18cdb/-/format/auto/-/stretch/off/-/progressive/yes/-/resize/1080x/-/quality/normal/'
     );
   });
+
+  it('should generate blurDataURL when placeholder=blur passed', () => {
+    const src =
+      'https://ucarecdn.com/a6f8abc8-f92e-460a-b7a1-c5cd70a18cdb/image.png';
+
+    render(
+      <UploadcareImage
+        src={src}
+        width={500}
+        height={500}
+        quality={80}
+        placeholder="blur"
+      />
+    );
+
+    expect(screen.getByRole('img')).toHaveStyle(
+      'background-image: url(https://ucarecdn.com/a6f8abc8-f92e-460a-b7a1-c5cd70a18cdb/-/format/auto/-/stretch/off/-/progressive/yes/-/resize/10x/-/quality/lightest/image.png)'
+    );
+  });
+
+  it('should not override passed blurDataURL', () => {
+    const src =
+      'https://ucarecdn.com/a6f8abc8-f92e-460a-b7a1-c5cd70a18cdb/image.png';
+
+    render(
+      <UploadcareImage
+        src={src}
+        width={500}
+        height={500}
+        quality={80}
+        placeholder="blur"
+        blurDataURL={src}
+      />
+    );
+
+    expect(screen.getByRole('img')).toHaveStyle(
+      `background-image: url(${src})`
+    );
+  });
 });

src/components/UploadcareImage.tsx

@@ -1,7 +1,26 @@
 import Image, { ImageProps } from 'next/image';
 import React from 'react';
+import { getInt } from '../utils/helpers';
 import { uploadcareLoader } from '../utils/loader';
 
-export function UploadcareImage(props: ImageProps): JSX.Element {
-  return <Image loader={uploadcareLoader} {...props} />;
+export function UploadcareImage({
+  blurDataURL,
+  ...props
+}: ImageProps): JSX.Element {
+  if (
+    props.placeholder === 'blur' &&
+    !blurDataURL &&
+    typeof props.src === 'string'
+  ) {
+    const imageWidth = getInt(props.width);
+    const blurImageWidth = imageWidth ? Math.ceil(imageWidth * 0.01) : 10;
+    blurDataURL = uploadcareLoader({
+      src: props.src,
+      width: blurImageWidth,
+      quality: 0
+    });
+  }
+  return (
+    <Image loader={uploadcareLoader} blurDataURL={blurDataURL} {...props} />
+  );
 }

src/utils/helpers.ts

@@ -143,6 +143,16 @@ export function isJpegExtension(extension: string): boolean {
   return ['jpg', 'jpeg'].includes(extension.toLowerCase());
 }
 
+export function getInt(x: unknown): number | undefined {
+  if (typeof x === 'number') {
+    return x;
+  }
+  if (typeof x === 'string') {
+    return parseInt(x, 10);
+  }
+  return undefined;
+}
+
 function _parseUploadcareTransformationParam(param: string): string[] {
   return param.split('/');
 }