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 @@
+# from https://github.com/github/gitignore/blob/main/Node.gitignore
+
+# Logs
+logs
 *.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+lerna-debug.log*
+.pnpm-debug.log*
+
+# Diagnostic reports (https://nodejs.org/api/report.html)
+report.[0-9]*.[0-9]*.[0-9]*.[0-9]*.json
+
+# Runtime data
+pids
+*.pid
+*.seed
+*.pid.lock
+
+# Directory for instrumented libs generated by jscoverage/JSCover
+lib-cov
+
+# Coverage directory used by tools like istanbul
+coverage
+*.lcov
+
+# nyc test coverage
+.nyc_output
+
+# Grunt intermediate storage (https://gruntjs.com/creating-plugins#storing-task-files)
+.grunt
+
+# Bower dependency directory (https://bower.io/)
+bower_components
+
+# node-waf configuration
+.lock-wscript
+
+# Compiled binary addons (https://nodejs.org/api/addons.html)
+build/Release
+
+# Dependency directories
+node_modules/
+jspm_packages/
+
+# Snowpack dependency directory (https://snowpack.dev/)
+web_modules/
+
+# TypeScript cache
+*.tsbuildinfo
+
+# Optional npm cache directory
+.npm
+
+# Optional eslint cache
+.eslintcache
+
+# Optional stylelint cache
+.stylelintcache
+
+# Microbundle cache
+.rpt2_cache/
+.rts2_cache_cjs/
+.rts2_cache_es/
+.rts2_cache_umd/
+
+# Optional REPL history
+.node_repl_history
+
+# Output of 'npm pack'
 *.tgz
+
+# Yarn Integrity file
+.yarn-integrity
+
+# dotenv environment variable files
+.env
+.env.development.local
+.env.test.local
+.env.production.local
+.env.local
+
+# parcel-bundler cache (https://parceljs.org/)
+.cache
+.parcel-cache
+
+# Next.js build output
+.next
+out
+
+# Nuxt.js build / generate output
+.nuxt
 dist
-node_modules
+
+# Gatsby files
+.cache/
+# Comment in the public line in if your project uses Gatsby and not Next.js
+# https://nextjs.org/blog/next-9-1#public-directory-support
+# public
+
+# vuepress build output
+.vuepress/dist
+
+# vuepress v2.x temp and cache directory
+.temp
+.cache
+
+# vitepress build output
+**/.vitepress/dist
+
+# vitepress cache directory
+**/.vitepress/cache
+
+# Docusaurus cache and generated files
+.docusaurus
+
+# Serverless directories
+.serverless/
+
+# FuseBox cache
+.fusebox/
+
+# DynamoDB Local files
+.dynamodb/
+
+# TernJS port file
+.tern-port
+
+# Stores VSCode versions used for testing VSCode extensions
+.vscode-test
+
+# yarn v2
+.yarn/cache
+.yarn/unplugged
+.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 zoom } from './src/modules/zoom.js';
+export { default as pan, programmaticPan } from './src/modules/pan';
+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;
-  max-height: 586.033px;
-  margin: 0 auto;
-  overflow: hidden;
+  margin: 5px;
  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;
-}
-
-.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;
+  min-height: 0;
 }
--- 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"?>
-<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
-  "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
 <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
-      to zoom in and out.
+      Click and drag the image to pan. Use the mouse wheel to zoom in and out.
    </p>

-    <p>
-      <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>
+    <object type="image/svg+xml" data="assets/images/image.svg"></object>
    <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 pan from './modules/pan.js';
+import zoom from './modules/zoom';
+import pan from './modules/pan';

 const optionalZoomFactor = 0.1,
-  container = document.querySelector('.container'),
-  object = document.querySelector('object'),
-  img = document.querySelector('img'),
-  button = document.querySelector('button');
-
-function reset(elements) {
-  elements.forEach(el => el.removeAttribute('style'));
-}
+  object = document.querySelector('object');

 // 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', () => {
-    [button, container].forEach(el => el.classList.toggle('switch'));
-    reset(pannableAndZoomableElements);
-  });
+  svg.addEventListener('wheel', zoom(targetEl, optionalZoomFactor), options);
+  svg.addEventListener('pointerdown', pan(targetEl), options);

-  pannableAndZoomableElements.forEach(el => {
-    el.addEventListener('wheel', e => zoom(el, e, optionalZoomFactor), { passive: false });
-    el.addEventListener('pointerdown', e => pan(el, e), { passive: false });
+  svg.addEventListener('pointermove', e => {
+    const pt = new DOMPoint(e.clientX, e.clientY),
+      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) {
-  point.x = e.clientX;
-  point.y = e.clientY;
-
-  return point;
+function mainButtonPressed(e) {
+  return e.button === 0;
 }

 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) {
-  e.preventDefault();
+function getTransformMatrices(el) {
+  return {
+    computed: getComputedTransformMatrix(el),
+    inverseScreen: el.getScreenCTM().inverse()
+  };
+}

-  const mtx = getComputedTransformMatrix(el),
-    startPt = new DOMPoint(e.clientX, e.clientY),
-    movePt = new DOMPoint();
+function clientToSvgPt(e, inverseScreenMtx, pt = new DOMPoint()) {
+  pt.x = e.clientX;
+  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);
-      setToCurrentPointerCoords(startPt, e);
+      startPt = clientToSvgPt(e, matrices.inverseScreen, startPt);
      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(
-    'pointerup',
-    () => el.removeEventListener('pointermove', pointerMove),
-    { once: true }
-  );
+    isPanning = false;
+    matrices = getTransformMatrices(el);
+    startPt = new DOMPoint(e.clientX, e.clientY);
+    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) {
-  return zoomIn(e.deltaY) ? 1 + factor : 1 - factor;
+function getScale(deltaY, factor) {
+  const outMult = 1 - factor;
+  const inMult = 1 + factor / outMult
+
+  return zoomIn(deltaY) ? inMult : outMult;
 }

-function getFocalPointBeforeTransform(el, e) {
-  const { x, y, width, height } = el.getBoundingClientRect();
+function getTranslateMatrix(el, clientX, clientY) {
+  const inverseScreenCTM = el.getScreenCTM().inverse();
+  const translateMtx = new DOMMatrix();
+  const pointer = new DOMPoint(clientX, clientY)
+  const { x, y } = pointer.matrixTransform(inverseScreenCTM);

-  return {
-    x: e.clientX,
-    y: e.clientY,
-    relativeToImageSize: {
-      x: (e.clientX - x) / width,
-      y: (e.clientY - y) / height
-    }
-  };
+  return translateMtx.translate(x, y);
 }

-function getFocalPointAfterTransform(el, fpBeforeTrans) {
-  const { x, y, width, height } = el.getBoundingClientRect(),
-    relativeFocalPoint = fpBeforeTrans.relativeToImageSize;
+function setTransform(el, computedMtx, translateMtx, scale) {
+  const transformMtx =
+    computedMtx.multiply(translateMtx).scale(scale).multiply(translateMtx.inverse());

-  return {
-    x: x + width * relativeFocalPoint.x,
-    y: y + height * relativeFocalPoint.y
-  };
+  el.style.transform = transformMtx;
 }

-function getTranslateMatrix(el, e, scaleMatrix) {
-  const fpBeforeTrans = getFocalPointBeforeTransform(el, e);
+export default function (el, factor = 0.1) {
+  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),
-    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);
+    setTransform(el, computedMtx, translateMtx, 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