Add test commit

Conjugate scaling operation by translating to the origin
https://stackoverflow.com/questions/38446666/scaling-around-a-specific-point-in-2d-coordinate-system
2025-06-04 11:49:38 -07:00 · 2025-03-17 09:58:10 -07:00 · 2025-03-06 21:47:00 -08:00 · 2025-03-06 10:59:01 -08:00 · 2025-03-06 10:58:40 -08:00 · 2025-03-05 17:55:03 -08:00
20 changed files with 4242 additions and 164 deletions
--- a/.gitignore
+++ b/.gitignore
@ -1,4 +1,138 @@
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 .cache
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 # Next.js build output
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 out
 # Nuxt.js build / generate output
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 dist
-node_modules
+
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 # yarn v2
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 .yarn/build-state.yml
 .yarn/install-state.gz
 .pnp.*
--- a/README.md
+++ b/README.md
@ -1,15 +1,113 @@
 # Pan-Zoom
-Pan/zoom library for web browsers. Hold and drag an element to pan. Use the mouse wheel to zoom. See `src/app.js` for a usage example.
+Pan/zoom library for SVG elements. Hold and drag to pan. Use the mouse wheel to
 zoom. See `src/app.js` for a usage example.
-## To view the demo using Docker
+## Usage
 ### Requirements
 All the content to be panned/zoomed must be in one root element.
 `image.svg`
 ``` xml
 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
 <svg viewBox="..." version="1.1" xmlns="http://www.w3.org/2000/svg">
    <g id="main">
        <!-- SVG elements to be panned/zoomed... -->
    </g>
 </svg>
 ```
 `index.html`
 ``` html
 <!DOCTYPE html>
 <html>
  <head>
    <meta charset="utf-8"/>
    <meta name="viewport" content="width=device-width, initial-scale=1.0"/>
  </head>
  <body>
    <object type="image/svg+xml" data="image.svg"></object>
    <script src="index.js"></script>
  </body>
 </html>
 ```
 ### Standard
 `index.js`
 ``` js
 import { pan, zoom } from 'pan-zoom';
 const optionalZoomFactor = 0.1,
  object = document.querySelector('object');
 window.addEventListener('load', function () {
  const svg = object.contentDocument.querySelector('svg'),
    targetEl = svg.querySelector('#main');
  svg.addEventListener('wheel', zoom(targetEl, optionalZoomFactor), { passive: false });
  svg.addEventListener('pointerdown', pan(targetEl), { passive: false });
 });
 ```
 ### With restore
 The same as standard except the pan/zoom returns to what it was after a page
 refresh.
 `index.js`
 ``` js
 import { withRestore as panzoom } from 'pan-zoom';
 const object = document.querySelector('object');
 window.addEventListener('load', function () {
  const svg = object.contentDocument.querySelector('svg');
  panzoom.start(svg, '#main');
 });
 ```
 ## Start the demo
 ### Docker
 1. Install the development server packages.
-       docker run --rm -w /app -v $PWD:/app -u $(id -u):$(id -u) node npm install
+        $ docker run --rm -w /app -v $PWD:/app -u $(id -u):$(id -u) node npm install
 2. Start the server.
-       docker run --rm --init -it -w /app -v $PWD:/app -p 8080:8080 node node dev-server.js
+        $ docker run --rm --init -it -w /app -v $PWD:/app -p 8080:8080 node npm run start
 3. Visit `localhost:8080` to view.
 ### Debian
 1. Install the development server packages.
        $ npm install
 2. Start the server.
        $ npm run start
 3. Visit `localhost:8080` to view.
 ## Tests
 Requires Chrome/ChromeDriver or Chromium/ChromiumDriver.
 ### Docker
    $ docker run --rm --init -it -w /app -v $PWD:/app node bash -c "apt-get \
        update && apt-get install -y chromium-driver chromium && npm run test"
 ### Debian
    $ apt-get update && apt-get install chromium-driver chromium
    $ npm run test
--- a/tests/integration/page.spec.js
+++ b/tests/integration/page.spec.js
@ -0,0 +1,21 @@
 const { Builder } = require('selenium-webdriver');
 const chrome = require('selenium-webdriver/chrome');
 const chromeOptions = new chrome.Options();
 let driver;
 chromeOptions.addArguments('--headless', '--disable-gpu', '--no-sandbox');
 beforeEach(async () => {
  const builder = new Builder().forBrowser('chrome').setChromeOptions(chromeOptions);
  driver = builder.build();
 });
 it('loads the page', async () => {
  await driver.get('http://localhost:8080');
  expect(await driver.getTitle()).toEqual('SVG Element Pan & Zoom Demo');
 });
 afterEach(async () => {
  await driver.quit();
 });
--- a/tests/integration/setup.js
+++ b/tests/integration/setup.js
@ -0,0 +1,21 @@
 const { spawn } = require('child_process');
 module.exports = async function (globalConfig, projectConfig) {
  console.info('\nSpawning server process...');
  const child = spawn('node', ['server.js']);
  child.stdout.on('data', data => {
    console.log(`${data}`);
  });
  globalThis.__INTEG_TEST_SERVER_PID__ = child.pid;
  child.stderr.on('data', data => {
    const str = data.toString();
    console.log('[server]', str);
    if (str.includes(projectConfig.globals.testServerUrl)) {
      setTimeout(resolve, 200);
    }
  });
 };
--- a/tests/integration/teardown.js
+++ b/tests/integration/teardown.js
@ -0,0 +1,4 @@
 module.exports = async function (globalConfig, projectConfig) {
  console.info('Stopping server.');
  process.kill(globalThis.__INTEG_TEST_SERVER_PID__);
 };
--- a/dev-server.js
+++ b/dev-server.js
@ -1,11 +0,0 @@
 require('esbuild-server')
  .createServer(
    {
      bundle: true,
      entryPoints: ['src/app.js'],
    },
    {
      static: 'public',
    }
  )
  .start();
--- a/index.js
+++ b/index.js
@ -1,2 +1,3 @@
-export { default as pan } from './src/modules/pan.js';
+export { default as pan, programmaticPan } from './src/modules/pan';
-export { default as zoom } from './src/modules/zoom.js';
+export { default as zoom } from './src/modules/zoom';
 export * as withRestore from './src/modules/with-restore';
--- a/jest.config.js
+++ b/jest.config.js
@ -0,0 +1,219 @@
 /**
 * For a detailed explanation regarding each configuration property, visit:
 * https://jestjs.io/docs/configuration
 */
 /** @type {import('jest').Config} */
 const config = {
  // All imported modules in your tests should be mocked automatically
  // automock: false,
  // Stop running tests after `n` failures
  // bail: 0,
  // The directory where Jest should store its cached dependency information
  // cacheDirectory: "/tmp/jest_rs",
  // Automatically clear mock calls, instances, contexts and results before every test
  clearMocks: true,
  // Indicates whether the coverage information should be collected while executing the test
  // collectCoverage: false,
  // An array of glob patterns indicating a set of files for which coverage information should be collected
  // collectCoverageFrom: undefined,
  // The directory where Jest should output its coverage files
  // coverageDirectory: undefined,
  // An array of regexp pattern strings used to skip coverage collection
  // coveragePathIgnorePatterns: [
  //   "/node_modules/"
  // ],
  // Indicates which provider should be used to instrument code for coverage
  coverageProvider: "v8",
  // A list of reporter names that Jest uses when writing coverage reports
  // coverageReporters: [
  //   "json",
  //   "text",
  //   "lcov",
  //   "clover"
  // ],
  // An object that configures minimum threshold enforcement for coverage results
  // coverageThreshold: undefined,
  // A path to a custom dependency extractor
  // dependencyExtractor: undefined,
  // Make calling deprecated APIs throw helpful error messages
  // errorOnDeprecated: false,
  // The default configuration for fake timers
  // fakeTimers: {
  //   "enableGlobally": false
  // },
  // Force coverage collection from ignored files using an array of glob patterns
  // forceCoverageMatch: [],
  // A path to a module which exports an async function that is triggered once before all test suites
  // globalSetup: undefined,
  globalSetup: './__tests__/integration/setup.js',
  // A path to a module which exports an async function that is triggered once after all test suites
  // globalTeardown: undefined,
  globalTeardown: './__tests__/integration/teardown.js',
  // A set of global variables that need to be available in all test environments
  // globals: {},
  // The maximum amount of workers used to run your tests. Can be specified as
  // % or a number. E.g. maxWorkers: 10% will use 10% of your CPU amount + 1 as
  // the maximum worker number. maxWorkers: 2 will use a maximum of 2 workers.
  // maxWorkers: "50%",
  // An array of directory names to be searched recursively up from the requiring module's location
  // moduleDirectories: [
  //   "node_modules"
  // ],
  // An array of file extensions your modules use
  // moduleFileExtensions: [
  //   "js",
  //   "mjs",
  //   "cjs",
  //   "jsx",
  //   "ts",
  //   "tsx",
  //   "json",
  //   "node"
  // ],
  // A map from regular expressions to module names or to arrays of module
  // names that allow to stub out resources with a single module
  // moduleNameMapper: {},
  // An array of regexp pattern strings, matched against all module paths
  // before considered 'visible' to the module loader
  // modulePathIgnorePatterns: [],
  // Activates notifications for test results
  // notify: false,
  // An enum that specifies notification mode. Requires { notify: true }
  // notifyMode: "failure-change",
  // A preset that is used as a base for Jest's configuration
  // preset: undefined,
  // Run tests from one or more projects
  // projects: undefined,
  // Use this configuration option to add custom reporters to Jest
  // reporters: undefined,
  // Automatically reset mock state before every test
  // resetMocks: false,
  // Reset the module registry before running each individual test
  // resetModules: false,
  // A path to a custom resolver
  // resolver: undefined,
  // Automatically restore mock state and implementation before every test
  // restoreMocks: false,
  // The root directory that Jest should scan for tests and modules within
  // rootDir: undefined,
  // A list of paths to directories that Jest should use to search for files in
  // roots: [
  //   "<rootDir>"
  // ],
  // Allows you to use a custom runner instead of Jest's default test runner
  // runner: "jest-runner",
  // The paths to modules that run some code to configure or set up the testing environment before each test
  // setupFiles: [],
  // A list of paths to modules that run some code to configure or set up the testing framework before each test
  // setupFilesAfterEnv: [],
  // The number of seconds after which a test is considered as slow and reported as such in the results.
  // slowTestThreshold: 5,
  // A list of paths to snapshot serializer modules Jest should use for snapshot testing
  // snapshotSerializers: [],
  // The test environment that will be used for testing
  //testEnvironment: "jsdom",
  testEnvironment: "node",
  // Options that will be passed to the testEnvironment
  // testEnvironmentOptions: {},
  // Adds a location field to test results
  // testLocationInResults: false,
  // The glob patterns Jest uses to detect test files
  // testMatch: [
  //   "**/__tests__/**/*.[jt]s?(x)",
  //   "**/?(*.)+(spec|test).[tj]s?(x)"
  // ],
  // An array of regexp pattern strings that are matched against all test paths, matched tests are skipped
  // testPathIgnorePatterns: [
  //   "/node_modules/"
  // ],
  testPathIgnorePatterns: [
    "/node_modules/",
    "setup.js",
    "teardown.js",
  ],
  // The regexp pattern or array of patterns that Jest uses to detect test files
  // testRegex: [],
  // This option allows the use of a custom results processor
  // testResultsProcessor: undefined,
  // This option allows use of a custom test runner
  // testRunner: "jest-circus/runner",
  // A map from regular expressions to paths to transformers
  // transform: undefined,
  // An array of regexp pattern strings that are matched against all source
  // file paths, matched files will skip transformation
  // transformIgnorePatterns: [
  //   "/node_modules/",
  //   "\\.pnp\\.[^\\/]+$"
  // ],
  // An array of regexp pattern strings that are matched against all modules
  // before the module loader will automatically return a mock for them
  // unmockedModulePathPatterns: undefined,
  // Indicates whether each individual test should be reported during the run
  // verbose: undefined,
  verbose: true,
  // An array of regexp patterns that are matched against all source file paths
  // before re-running tests in watch mode
  // watchPathIgnorePatterns: [],
  // Whether to use watchman for file crawling
  // watchman: true,
  // Shuffle the order of the tests within a file
  randomize: true,
 };
 console.info('Jest config file read.');
 module.exports = config;
--- a/package-lock.json
+++ b/package-lock.json
--- a/package.json
+++ b/package.json
@ -1,12 +1,29 @@
 {
  "name": "pan-zoom",
-  "version": "0.1.0",
+  "version": "0.3.1",
  "description": "Pan/zoom SVG images in the browser",
  "browser": "index.js",
  "devDependencies": {
    "esbuild": "^0.20.2",
    "esbuild-server": "^0.3.0"
  },
  "files": [
    "./src/modules"
-  ]
+  ],
  "scripts": {
    "test": "jest"
  },
  "repository": {
    "type": "git",
    "url": "git://git.webdevcat.me/pan-zoom.git"
  },
  "keywords": [
    "SVG",
    "pan",
    "zoom"
  ],
  "author": "Catalin Mititiuc <webdevcat@proton.me> (https://webdevcat.me)",
  "license": "ISC",
  "devDependencies": {
    "esbuild": "^0.20.2",
    "esbuild-server": "^0.3.0",
    "jest": "^29.7.0",
    "selenium-webdriver": "^4.29.0"
  }
 }
--- a/public/assets/css/style.css
+++ b/public/assets/css/style.css
@ -1,40 +1,17 @@
 body {
  text-align: center;
-  max-width: 100vw;
+  max-height: 100vh;
  display: flex;
  flex-direction: column;
  margin: 0;
 }
-.container {
+object {
  padding: 0;
-  max-width: 586.033px;
+  margin: 5px;
  max-height: 586.033px;
  margin: 0 auto;
  overflow: hidden;
  border: 1px solid steelblue;
  background-color: gray;
 }
 img, object {
  touch-action: none;
 }
 img {
  max-width: 100%;
  border: 1px solid silver;
  transform: scale(0.9);
 }
 .container object, .container.switch img {
  display: block;
-}
+  min-height: 0;
 .container img, .container.switch object {
  display: none;
 }
 button .button-text.raster, button.switch .button-text.svg {
  display: none;
 }
 button.switch .button-text.raster {
  display: inline;
 }
--- a/public/assets/images/41156165560-4438592e93-o.webp
+++ b/public/assets/images/41156165560-4438592e93-o.webp
--- a/public/assets/images/image.svg
+++ b/public/assets/images/image.svg
@ -1,22 +1,20 @@
-<?xml version="1.0" standalone="no"?>
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
  "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
 <svg viewBox="-200 -150 400 300" version="1.1" xmlns="http://www.w3.org/2000/svg">
  <style>
    svg {
      overflow: hidden;
      border: 1px solid silver;
      transform: scale(0.9);
    }
    circle, rect {
      fill-opacity: 0.9;
      filter: drop-shadow(5px 5px 2px rgba(0, 0, 0, .5));
    }
  </style>
  <g>
    <circle id="pointer" cx="0" cy="0" r="5" fill="red" stroke="maroon"/>
  </g>
  <script type="text/javascript">//<![CDATA[
    const svgns = 'http://www.w3.org/2000/svg',
      svg = document.querySelector('svg'),
      group = svg.querySelector('g'),
      pointerEl = svg.querySelector('#pointer'),
      { x: vbX, y: vbY, width: vbWidth, height: vbHeight } = svg.viewBox.baseVal,
      shapeCount = 100,
@ -103,6 +101,6 @@
    [...Array(shapeCount)]
      .map(() => getRandomFillAndStrokeVals())
-      .forEach(fillAndStrokeVal => svg.appendChild(getRandomShape(fillAndStrokeVal)));
+      .forEach(fillAndStrokeVal => pointerEl.before(getRandomShape(fillAndStrokeVal)));
  //]]></script>
 </svg>
--- a/public/index.html
+++ b/public/index.html
@ -3,28 +3,17 @@
  <head>
    <meta charset="utf-8"/>
    <meta name="viewport" content="width=device-width, initial-scale=1.0"/>
-    <title>JavaScript/CSS Pan & Zoom Demo</title>
+    <title>SVG Element Pan & Zoom Demo</title>
    <link rel="stylesheet" href="assets/css/style.css">
  </head>
  <body>
-    <h1>Pan & Zoom an Element with CSS/JavaScript</h1>
+    <h1>Pan & Zoom SVG Element with CSS/JavaScript</h1>
    <p>
-      Click and drag on the image to pan. Use the mouse wheel
+      Click and drag the image to pan. Use the mouse wheel to zoom in and out.
      to zoom in and out.
    </p>
-    <p>
+    <object type="image/svg+xml" data="assets/images/image.svg"></object>
      <button>
        <span class="button-text svg">Raster image</span>
        <span class="button-text raster">SVG image</span>
      </button>
    </p>
    <div class="container">
      <object type="image/svg+xml" data="assets/images/image.svg"></object>
      <img src="assets/images/41156165560-4438592e93-o.webp"/>
    </div>
    <script src="app.js"></script>
  </body>
 </html>
--- a/server.js
+++ b/server.js
@ -0,0 +1,27 @@
 const { createServer } = require('esbuild-server');
 //https://esbuild.github.io/api/#build
 const buildOptions = {
  bundle: true,
  entryPoints: ['src/app.js'],
 };
 //https://github.com/oblador/esbuild-server?tab=readme-ov-file#serveroptions
 const serverOptions = {
  static: 'public',
 };
 const env = process.env.NODE_ENV === 'test' ? 'Test' : 'Development';
 const server = createServer(buildOptions, serverOptions);
 const buildStart = Date.now();
 server
  .start()
  .then(() => {
    console.log(`Build completed in ${Date.now() - buildStart}ms`);
  })
  .catch(() => {
    console.error('Build failed');
  });
 console.log(`${env} server running at ${server.url}`);
--- a/src/app.js
+++ b/src/app.js
@ -1,15 +1,8 @@
-import zoom from './modules/zoom.js';
+import zoom from './modules/zoom';
-import pan from './modules/pan.js';
+import pan from './modules/pan';
 const optionalZoomFactor = 0.1,
-  container = document.querySelector('.container'),
+  object = document.querySelector('object');
  object = document.querySelector('object'),
  img = document.querySelector('img'),
  button = document.querySelector('button');
 function reset(elements) {
  elements.forEach(el => el.removeAttribute('style'));
 }
 // If embedding an SVG using an <object> tag, it's necessary to wait until the
 // page has loaded before querying its `contentDocument`, otherwise it will be
@ -17,15 +10,18 @@ function reset(elements) {
 window.addEventListener('load', function () {
  const svg = object.contentDocument.querySelector('svg'),
-    pannableAndZoomableElements = [img, svg];
+    targetEl = svg.querySelector('g'),
    pointer = svg.querySelector('#pointer'),
    options = { passive: false };
-  button.addEventListener('click', () => {
+  svg.addEventListener('wheel', zoom(targetEl, optionalZoomFactor), options);
-    [button, container].forEach(el => el.classList.toggle('switch'));
+  svg.addEventListener('pointerdown', pan(targetEl), options);
    reset(pannableAndZoomableElements);
  });
-  pannableAndZoomableElements.forEach(el => {
+  svg.addEventListener('pointermove', e => {
-    el.addEventListener('wheel', e => zoom(el, e, optionalZoomFactor), { passive: false });
+    const pt = new DOMPoint(e.clientX, e.clientY),
-    el.addEventListener('pointerdown', e => pan(el, e), { passive: false });
+      svgP = pt.matrixTransform(targetEl.getScreenCTM().inverse());
    pointer.setAttributeNS(null, 'cx', svgP.x);
    pointer.setAttributeNS(null, 'cy', svgP.y);
  });
 });
--- a/src/modules/pan.js
+++ b/src/modules/pan.js
@ -1,19 +1,16 @@
-import getComputedTransformMatrix from './utils.js';
+import { default as getComputedTransformMatrix } from './utils';
 const minDistanceThreshold = 5;
-function setToCurrentPointerCoords(point, e) {
+function mainButtonPressed(e) {
-  point.x = e.clientX;
+  return e.button === 0;
  point.y = e.clientY;
  return point;
 }
 function distanceBetween({ x: x1, y: y1 }, { x: x2, y: y2 }) {
  return Math.sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2);
 }
-function minDistanceThresholdIsMet(startPt, endPt) {
+function exceedsMinDistanceThreshhold(startPt, endPt) {
  return distanceBetween(startPt, endPt) >= minDistanceThreshold;
 }
@ -27,35 +24,71 @@ function getTranslateMatrix(startPt, movePt) {
  return translateMatrix.translate(movePt.x - startPt.x, movePt.y - startPt.y);
 }
-export default function (el, e) {
+function getTransformMatrices(el) {
-  e.preventDefault();
+  return {
    computed: getComputedTransformMatrix(el),
    inverseScreen: el.getScreenCTM().inverse()
  };
 }
-  const mtx = getComputedTransformMatrix(el),
+function clientToSvgPt(e, inverseScreenMtx, pt = new DOMPoint()) {
-    startPt = new DOMPoint(e.clientX, e.clientY),
+  pt.x = e.clientX;
-    movePt = new DOMPoint();
+  pt.y = e.clientY;
  return pt.matrixTransform(inverseScreenMtx);
 }
-  let isPanning = false;
+function setTransform(el, computedMtx, startPt, endPt) {
  const translateMtx = getTranslateMatrix(startPt, endPt);
  const transformMtx = computedMtx.multiply(translateMtx);
  el.style.transform = transformMtx;
 }
 export function programmaticPan(el, from, to) {
  const matrices = getTransformMatrices(el);
  const startPt = clientToSvgPt(from, matrices.inverseScreen);
  const endPt = clientToSvgPt(to, matrices.inverseScreen);
  el.style.transition = 'transform 0.5s';
  setTransform(el, matrices.computed, startPt, endPt);
  el.addEventListener('transitionend', () => el.style.transition = '', { once: true });
 }
 export default function (el) {
  let matrices, startPt, movePt, isPanning;
  function pointerMove(e) {
-    setToCurrentPointerCoords(movePt, e);
+    movePt.x = e.clientX;
    movePt.y = e.clientY;
-    if (!isPanning && minDistanceThresholdIsMet(startPt, movePt)) {
+    if (!isPanning && exceedsMinDistanceThreshhold(startPt, movePt)) {
      isPanning = true;
-      e.target.setPointerCapture(e.pointerId);
+      startPt = clientToSvgPt(e, matrices.inverseScreen, startPt);
      setToCurrentPointerCoords(startPt, e);
      stopEventPropagationToChildren(el, 'click');
    }
    if (isPanning) {
-      el.style.transform = getTranslateMatrix(startPt, movePt).multiply(mtx);
+      movePt = clientToSvgPt(e, matrices.inverseScreen, movePt);
      setTransform(el, matrices.computed, startPt, movePt);
    }
  }
-  el.addEventListener('pointermove', pointerMove);
+  return function(e) {
    if (!mainButtonPressed(e)) return;
    e.preventDefault();
    e.target.setPointerCapture(e.pointerId);
-  el.addEventListener(
+    isPanning = false;
-    'pointerup',
+    matrices = getTransformMatrices(el);
-    () => el.removeEventListener('pointermove', pointerMove),
+    startPt = new DOMPoint(e.clientX, e.clientY);
-    { once: true }
+    movePt = new DOMPoint();
-  );
+
    this.addEventListener('pointermove', pointerMove);
    this.addEventListener(
      'pointerup',
      () => this.removeEventListener('pointermove', pointerMove),
      { once: true }
    );
  }
 }
--- a/src/modules/with-restore.js
+++ b/src/modules/with-restore.js
@ -0,0 +1,36 @@
 import zoom from './zoom';
 import pan from './pan';
 const storageKey = "pan-zoom";
 const zoomFactor = 0.25;
 function restorePanZoomVal(el) {
  const storedPanZoomVal = localStorage.getItem(storageKey);
  if (storedPanZoomVal) el.style.transform = storedPanZoomVal;
 }
 function addEventListeners(svg, el) {
  svg.addEventListener("wheel", zoom(el, zoomFactor), { passive: false });
  svg.addEventListener("pointerdown", pan(el), { passive: false });
 }
 function storePanZoomVal(transformMatrix) {
  localStorage.setItem(storageKey, transformMatrix);
 }
 function observePanZoomChanges(el) {
  const observer = new MutationObserver(() =>
    storePanZoomVal(el.style.transform),
  );
  observer.observe(el, { attributeFilter: ["style"] });
 }
 export function start(svg, selector) {
  const targetEl = svg.querySelector(selector);
  restorePanZoomVal(targetEl);
  addEventListeners(svg, targetEl);
  observePanZoomChanges(targetEl);
 }
--- a/src/modules/zoom.js
+++ b/src/modules/zoom.js
@ -1,56 +1,40 @@
-import getComputedTransformMatrix from './utils.js';
+import { default as getComputedTransformMatrix } from './utils';
 function zoomIn(deltaY) {
  return deltaY < 0;
 }
-function getScale(e, factor) {
+function getScale(deltaY, factor) {
-  return zoomIn(e.deltaY) ? 1 + factor : 1 - factor;
+  const outMult = 1 - factor;
  const inMult = 1 + factor / outMult
  return zoomIn(deltaY) ? inMult : outMult;
 }
-function getFocalPointBeforeTransform(el, e) {
+function getTranslateMatrix(el, clientX, clientY) {
-  const { x, y, width, height } = el.getBoundingClientRect();
+  const inverseScreenCTM = el.getScreenCTM().inverse();
  const translateMtx = new DOMMatrix();
  const pointer = new DOMPoint(clientX, clientY)
  const { x, y } = pointer.matrixTransform(inverseScreenCTM);
-  return {
+  return translateMtx.translate(x, y);
    x: e.clientX,
    y: e.clientY,
    relativeToImageSize: {
      x: (e.clientX - x) / width,
      y: (e.clientY - y) / height
    }
  };
 }
-function getFocalPointAfterTransform(el, fpBeforeTrans) {
+function setTransform(el, computedMtx, translateMtx, scale) {
-  const { x, y, width, height } = el.getBoundingClientRect(),
+  const transformMtx =
-    relativeFocalPoint = fpBeforeTrans.relativeToImageSize;
+    computedMtx.multiply(translateMtx).scale(scale).multiply(translateMtx.inverse());
-  return {
+  el.style.transform = transformMtx;
    x: x + width * relativeFocalPoint.x,
    y: y + height * relativeFocalPoint.y
  };
 }
-function getTranslateMatrix(el, e, scaleMatrix) {
+export default function (el, factor = 0.1) {
-  const fpBeforeTrans = getFocalPointBeforeTransform(el, e);
+  return e => {
    e.preventDefault();
-  el.style.transform = scaleMatrix;
+    const computedMtx = getComputedTransformMatrix(el);
    const scale = getScale(e.deltaY, factor);
    const translateMtx = getTranslateMatrix(el, e.clientX, e.clientY);
-  const fpAfterTrans = getFocalPointAfterTransform(el, fpBeforeTrans),
+    setTransform(el, computedMtx, translateMtx, scale);
-    translateMatrix = new DOMMatrix();
+  }
  return translateMatrix.translate(
    fpBeforeTrans.x - fpAfterTrans.x,
    fpBeforeTrans.y - fpAfterTrans.y
  );
 }
 export default function (el, e, factor = 0.1) {
  e.preventDefault();
  const mtx = getComputedTransformMatrix(el),
    scale = getScale(e, factor),
    transMtx = getTranslateMatrix(el, e, mtx.scale(scale));
  el.style.transform = transMtx.multiply(mtx).scale(scale);
 }
--- a/test.md
+++ b/test.md
@ -0,0 +1 @@
 ## hello
Author	SHA1	Message	Date
Catalin Mititiuc	27e43c34e2	Add test commit	2025-06-04 11:49:38 -07:00
Catalin Mititiuc	99d137cc09	Conjugate scaling operation by translating to the origin https://stackoverflow.com/questions/38446666/scaling-around-a-specific-point-in-2d-coordinate-system	2025-03-17 09:58:10 -07:00
Catalin Mititiuc	f0b5c1a511	Add Jest testing framework	2025-03-06 21:47:00 -08:00
Catalin Mititiuc	c0b2d77d14	Update .gitignore file	2025-03-06 10:59:01 -08:00
Catalin Mititiuc	33a9b2256e	Update package.json	2025-03-06 10:58:40 -08:00
Catalin Mititiuc	dbfe9c6fe7	Update README	2025-03-05 17:55:03 -08:00
Catalin Mititiuc	79964ead91	Add module to save and restore pan/zoom values on page reload	2025-03-05 14:18:31 -08:00
Catalin Mititiuc	ffdf173cda	Add function for panning programmatically	2025-03-05 12:17:28 -08:00
Catalin Mititiuc	ad69b0011a	Fix formatting in README.md	2024-11-08 12:48:07 -08:00
Catalin Mititiuc	9c34e15c47	Update implementation to account for WebKit bug getScreenCTM() on WebKit does not reflect transformations applied to an ancestor (see bug https://bugs.webkit.org/show_bug.cgi?id=209220), so instead of transforming the root <svg> element, we can only transform a child element	2024-06-11 15:09:41 -07:00