Merge branch 'master' into dev

README.md

@@ -9,6 +9,7 @@
 
 [![CI](https://github.com/trekhleb/javascript-algorithms/workflows/CI/badge.svg)](https://github.com/trekhleb/javascript-algorithms/actions?query=workflow%3ACI+branch%3Amaster)
 [![codecov](https://codecov.io/gh/trekhleb/javascript-algorithms/branch/master/graph/badge.svg)](https://codecov.io/gh/trekhleb/javascript-algorithms)
+![repo size](https://img.shields.io/github/repo-size/trekhleb/javascript-algorithms.svg)
 
 This repository contains JavaScript based examples of many
 popular algorithms and data structures.

package.json

@@ -38,14 +38,14 @@
     "@babel/cli": "7.20.7",
     "@babel/preset-env": "7.20.2",
     "@types/jest": "29.4.0",
-    "canvas": "2.11.0",
     "eslint": "8.33.0",
     "eslint-config-airbnb": "19.0.4",
     "eslint-plugin-import": "2.27.5",
     "eslint-plugin-jest": "27.2.1",
     "eslint-plugin-jsx-a11y": "6.7.1",
     "husky": "8.0.3",
-    "jest": "29.4.1"
+    "jest": "29.4.1",
+    "pngjs": "^7.0.0"
   },
   "engines": {
     "node": ">=16.15.0",

src/algorithms/image-processing/seam-carving/__tests__/resizeImageWidth.node.js

@@ -0,0 +1,85 @@
+import fs from 'fs';
+import { PNG } from 'pngjs';
+
+import resizeImageWidth from '../resizeImageWidth';
+
+const testImageBeforePath = './src/algorithms/image-processing/seam-carving/__tests__/test-image-before.png';
+const testImageAfterPath = './src/algorithms/image-processing/seam-carving/__tests__/test-image-after.png';
+
+/**
+ * Compares two images and finds the number of different pixels.
+ *
+ * @param {ImageData} imgA - ImageData for the first image.
+ * @param {ImageData} imgB - ImageData for the second image.
+ * @param {number} threshold - Color difference threshold [0..255]. Smaller - stricter.
+ * @returns {number} - Number of different pixels.
+ */
+function pixelsDiff(imgA, imgB, threshold = 0) {
+  if (imgA.width !== imgB.width || imgA.height !== imgB.height) {
+    throw new Error('Images must have the same size');
+  }
+
+  let differentPixels = 0;
+  const numColorParams = 4; // RGBA
+
+  for (let pixelIndex = 0; pixelIndex < imgA.data.length; pixelIndex += numColorParams) {
+    // Get pixel's color for each image.
+    const [aR, aG, aB] = imgA.data.subarray(pixelIndex, pixelIndex + numColorParams);
+    const [bR, bG, bB] = imgB.data.subarray(pixelIndex, pixelIndex + numColorParams);
+
+    // Get average pixel's color for each image (make them greyscale).
+    const aAvgColor = Math.floor((aR + aG + aB) / 3);
+    const bAvgColor = Math.floor((bR + bG + bB) / 3);
+
+    // Compare pixel colors.
+    if (Math.abs(aAvgColor - bAvgColor) > threshold) {
+      differentPixels += 1;
+    }
+  }
+
+  return differentPixels;
+}
+
+const pngLoad = (path) => new Promise((resolve) => {
+  fs.createReadStream(path)
+    .pipe(new PNG())
+    .on('parsed', function Parsed() {
+      /** @type {ImageData} */
+      const imageData = {
+        colorSpace: 'srgb',
+        width: this.width,
+        height: this.height,
+        data: this.data,
+      };
+      resolve(imageData);
+    });
+});
+
+describe('resizeImageWidth', () => {
+  it('should perform content-aware image width reduction', async () => {
+    const imgBefore = await pngLoad(testImageBeforePath);
+    const imgAfter = await pngLoad(testImageAfterPath);
+
+    const toWidth = Math.floor(imgBefore.width / 2);
+
+    const {
+      img: imgResized,
+      size: resizedSize,
+    } = resizeImageWidth({ img: imgBefore, toWidth });
+
+    expect(imgResized).toBeDefined();
+    expect(resizedSize).toBeDefined();
+
+    expect(resizedSize).toEqual({ w: toWidth, h: imgBefore.height });
+    expect(imgResized.width).toBe(imgAfter.width);
+    expect(imgResized.height).toBe(imgAfter.height);
+
+    const colorThreshold = 50;
+    const differentPixels = pixelsDiff(imgResized, imgAfter, colorThreshold);
+
+    // Allow 10% of pixels to be different
+    const pixelsThreshold = Math.floor((imgAfter.width * imgAfter.height) / 10);
+
+    expect(differentPixels).toBeLessThanOrEqual(pixelsThreshold);
+  });
+});

src/algorithms/image-processing/seam-carving/__tests__/resizeImageWidth.test.js

@@ -1,91 +0,0 @@
-import { createCanvas, loadImage } from 'canvas';
-import resizeImageWidth from '../resizeImageWidth';
-
-const testImageBeforePath = './src/algorithms/image-processing/seam-carving/__tests__/test-image-before.jpg';
-const testImageAfterPath = './src/algorithms/image-processing/seam-carving/__tests__/test-image-after.jpg';
-
-/**
- * Compares two images and finds the number of different pixels.
- *
- * @param {ImageData} imgA - ImageData for the first image.
- * @param {ImageData} imgB - ImageData for the second image.
- * @param {number} threshold - Color difference threshold [0..255]. Smaller - stricter.
- * @returns {number} - Number of different pixels.
- */
-function pixelsDiff(imgA, imgB, threshold = 0) {
-  if (imgA.width !== imgB.width || imgA.height !== imgB.height) {
-    throw new Error('Images must have the same size');
-  }
-
-  let differentPixels = 0;
-  const numColorParams = 4; // RGBA
-
-  for (let pixelIndex = 0; pixelIndex < imgA.data.length; pixelIndex += numColorParams) {
-    // Get pixel's color for each image.
-    const [aR, aG, aB] = imgA.data.subarray(pixelIndex, pixelIndex + numColorParams);
-    const [bR, bG, bB] = imgB.data.subarray(pixelIndex, pixelIndex + numColorParams);
-
-    // Get average pixel's color for each image (make them greyscale).
-    const aAvgColor = Math.floor((aR + aG + aB) / 3);
-    const bAvgColor = Math.floor((bR + bG + bB) / 3);
-
-    // Compare pixel colors.
-    if (Math.abs(aAvgColor - bAvgColor) > threshold) {
-      differentPixels += 1;
-    }
-  }
-
-  return differentPixels;
-}
-
-describe('resizeImageWidth', () => {
-  it('should perform content-aware image width reduction', () => {
-    // @see: https://jestjs.io/docs/asynchronous
-    return Promise.all([
-      loadImage(testImageBeforePath),
-      loadImage(testImageAfterPath),
-    ]).then(([imgBefore, imgAfter]) => {
-      // Original image.
-      const canvasBefore = createCanvas(imgBefore.width, imgBefore.height);
-      const ctxBefore = canvasBefore.getContext('2d');
-      ctxBefore.drawImage(imgBefore, 0, 0, imgBefore.width, imgBefore.height);
-      const imgDataBefore = ctxBefore.getImageData(0, 0, imgBefore.width, imgBefore.height);
-
-      // Resized image saved.
-      const canvasAfter = createCanvas(imgAfter.width, imgAfter.height);
-      const ctxAfter = canvasAfter.getContext('2d');
-      ctxAfter.drawImage(imgAfter, 0, 0, imgAfter.width, imgAfter.height);
-      const imgDataAfter = ctxAfter.getImageData(0, 0, imgAfter.width, imgAfter.height);
-
-      const toWidth = Math.floor(imgBefore.width / 2);
-
-      const {
-        img: resizedImg,
-        size: resizedSize,
-      } = resizeImageWidth({ img: imgDataBefore, toWidth });
-
-      expect(resizedImg).toBeDefined();
-      expect(resizedSize).toBeDefined();
-
-      // Resized image generated.
-      const canvasTest = createCanvas(resizedSize.w, resizedSize.h);
-      const ctxTest = canvasTest.getContext('2d');
-      ctxTest.putImageData(resizedImg, 0, 0, 0, 0, resizedSize.w, resizedSize.h);
-      const imgDataTest = ctxTest.getImageData(0, 0, resizedSize.w, resizedSize.h);
-
-      expect(resizedSize).toEqual({ w: toWidth, h: imgBefore.height });
-      expect(imgDataTest.width).toBe(toWidth);
-      expect(imgDataTest.height).toBe(imgBefore.height);
-      expect(imgDataTest.width).toBe(imgAfter.width);
-      expect(imgDataTest.height).toBe(imgAfter.height);
-
-      const colorThreshold = 50;
-      const differentPixels = pixelsDiff(imgDataTest, imgDataAfter, colorThreshold);
-
-      // Allow 10% of pixels to be different
-      const pixelsThreshold = Math.floor((imgAfter.width * imgAfter.height) / 10);
-
-      expect(differentPixels).toBeLessThanOrEqual(pixelsThreshold);
-    });
-  });
-});