Slide 1

Slide 1 text

PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Christian Liebel @christianliebel Consultant

Slide 2

Slide 2 text

Hello, it’s me. PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Christian Liebel Twitter: @christianliebel Email: christian.liebel @thinktecture.com Angular & PWA Slides: thinktecture.com /christian-liebel

Slide 3

Slide 3 text

PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Timetable 09:00–10:30 Block 1 10:30–11:00 Break 11:00–12:30 Block 2 12:30–13:30 Lunch Break 13:30–15:00 Block 3 15:00–15:30 Break 15:30–17:00 Block 4

Slide 4

Slide 4 text

Things NOT to expect - Blueprint for PWA development - No AuthN/AuthZ Things To Expect - Extensive/up-to-date insights into PWA and Project Fugu - A productivity app use case that works on your desktop & smartphone - Lots of fun - Hands-on exercises From 0 to MS Paint with Project Fugu (Hands-on) PWA Workshop

Slide 5

Slide 5 text

https://paint.js.org – Productivity app – Draw images – Lots of actions & tools – Installable – Read/save files – Copy/paste images from/to clipboard – Share files to other apps – Register for file extensions PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Demo Use Case

Slide 6

Slide 6 text

(Workshop Edition) – Productivity app – Draw images – Lots of actions & tools – Installable – Read/save files – Copy/paste images from/to clipboard – Share files to other apps – Register for file extensions PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Demo Use Case

Slide 7

Slide 7 text

Setup complete? (Node.js, Google Chrome, Editor, Git) PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Setup (1/3) LAB #0

Slide 8

Slide 8 text

Optional Download and install Chrome Canary: https://www.google.com/intl/de/chrome/canary/ PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Setup (2/3) LAB #0

Slide 9

Slide 9 text

git clone https://github.com/thinktecture/ ijs-muc-2022-pwa.git cd ijs-muc-2022-pwa npm i npm start PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Setup (3/3) LAB #0

Slide 10

Slide 10 text

Paint PWA Capabilities Progressive Enhancement PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Agenda

Slide 11

Slide 11 text

Paint PWA Capabilities Progressive Enhancement PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Agenda

Slide 12

Slide 12 text

Canvas – Plain bitmap for the web – Cross-platform, hardware- accelerated graphics operations – Supports different contexts (2D, 3D: WebGL, WebGL 2.0) – Supported on all evergreen browsers and on IE 9+ PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Paint

Slide 13

Slide 13 text

Canvas Add a canvas element to index.html: Query the canvas element in app.js: const canvas = document.querySelector('#canvas'); PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Paint LAB #1

Slide 14

Slide 14 text

Canvas 2D Context fillRect(x, y, width, height) strokeRect(x, y, width, height) beginPath() moveTo(x, y) lineTo(x, y) fill() stroke() PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Paint

Slide 15

Slide 15 text

Canvas 2D Context Get the 2D context and prepare the canvas in app.js: const canvas = document.querySelector('#canvas'); const ctx = canvas.getContext('2d'); ctx.fillStyle = 'white'; ctx.fillRect(0, 0, canvas.width, canvas.height); ctx.fillStyle = 'black'; PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Paint LAB #2

Slide 16

Slide 16 text

Low-latency Rendering PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Paint Web pages need to synchronize with the DOM on graphics updates causing latencies that can make drawing difficult Low-latency rendering skips syncing with the DOM with can lead to a more natural experience Supported on Chrome (Chrome OS and Windows only)

Slide 17

Slide 17 text

Low-latency Rendering Opt-in to low-latency rendering (app.js): const ctx = canvas.getContext('2d', { desynchronized: true }); PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Paint LAB #3

Slide 18

Slide 18 text

Pointer Events PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Paint Users nowadays use different input methods, cross-platform apps should cover all of them Pointer Events offer an abstract interface to catch all input methods (pointerdown, pointermove, pointerup) event.offsetX/event.offsetY contain the pointer’s position relative to the listener

Slide 19

Slide 19 text

Pointer Events Add event listeners (bottom of app.js): canvas.addEventListener('pointerdown', event => {}); canvas.addEventListener('pointermove', event => { ctx.fillRect(event.offsetX, event.offsetY, 2, 2); }); canvas.addEventListener('pointerup', () => {}); PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Paint LAB #4

Slide 20

Slide 20 text

Bresenham Line Algorithm The user may move faster than the input can be processed For this case, we need to remember the previous point and interpolate the points in between The Bresenham line algorithm calculates the missing pixels between two given points PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Paint

Slide 21

Slide 21 text

Bresenham Line Algorithm 1. Add the following import to the top of app.js (“.js” is required, otherwise the request will 404): import {bresenhamLine} from "./helpers.js"; 2. Then, adjust the event listeners: a) In the pointerdown event handler, store event.offsetX/event.offsetY in a variable called previousPoint b) In pointermove i. only draw if the pointer is down ii. retrieve the current point (event.offsetX|Y) iii. In a for…of loop, call bresenhamLine() with previousPoint.x|y & currentPoint.x|y and draw a 2x2 rectangle for each returned point. iv. store current point in previousPoint c) In pointerup, set previousPoint to null again. PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Paint LAB #5

Slide 22

Slide 22 text

Bresenham Line Algorithm let previousPoint = null; canvas.addEventListener('pointerdown', event => previousPoint = {x: event.offsetX, y: event.offsetY}); canvas.addEventListener('pointermove', event => { if (previousPoint) { const currentPoint = {x: event.offsetX, y: event.offsetY}; for(let {x, y} of bresenhamLine(previousPoint.x, previousPoint.y, currentPoint.x, currentPoint.y)) { ctx.fillRect(x, y, 2, 2); } previousPoint = currentPoint; } }); canvas.addEventListener('pointerup', () => previousPoint = null); PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Paint

Slide 23

Slide 23 text

Color Selection For this demo, we will only implement the brush tool. However, we want to bring in some color. A simple method to implement a color selection is to use the HTML color-type input element that shows the native color picker: PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Paint

Slide 24

Slide 24 text

Color Selection 1. In index.html, add the following input to the node: 2. In app.js, add the following code at the bottom: const txtColor = document.querySelector('#color'); txtColor.addEventListener('change', () => { ctx.fillStyle = txtColor.value; }); PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Paint LAB #6

Slide 25

Slide 25 text

Paint PWA Capabilities Progressive Enhancement PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Agenda

Slide 26

Slide 26 text

From 0 to MS Paint with Project Fugu (Hands-on) PWA Workshop Responsive Linkable Discoverable Installable App-like Connectivity Independent Fresh Safe Re-engageable Progressive

Slide 27

Slide 27 text

PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Web App Manifest Service Worker

Slide 28

Slide 28 text

Web App Manifest Distinguishes Web Apps from Websites JSON-based file containing metadata for apps only Apps can be identified by search engines, app store providers, etc. PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) PWA

Slide 29

Slide 29 text

manifest.webmanifest { "short_name": "Paint", "name": "Paint Workshop", "theme_color": "white", "icons": [{ "src": "icon.png", "sizes": "512x512" }], "start_url": "/index.html", "display": "standalone", "shortcuts": [/* … */] } PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) PWA Names Icons Display Mode Shortcuts Start URL Theme color (status bar/window bar)

Slide 30

Slide 30 text

Manifest Display Modes PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) PWA browser minimal-ui standalone fullscreen

Slide 31

Slide 31 text

Manifest Icon Purposes (any) any context (e.g. app icon) monochrome different color requirements (at risk) maskable user agent masks icon as required PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) PWA Safe Zone Windows iOS Android

Slide 32

Slide 32 text

Web App Manifest 1. In index.html, add the following tag to the document’s node (e.g., after the stylesheet): 2. Create the new file manifest.webmanifest and set: a) name and short_name to values of your choice b) display to standalone c) theme_color to #000080 and background_color to #808080 d) start_url to /index.html and scope to / e) icons to [{ "src": "icon.png", "sizes": "512x512" }] 3. Test manifest in DevTools: F12 > Application > Manifest PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) PWA LAB #7

Slide 33

Slide 33 text

Manifest Shortcuts PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) PWA Secondary entrypoints for your application (e.g., home screen quick actions, jump lists, …) Static definition in Web App Manifest Dynamic API may follow in the future Supported by Google Chrome for Android, macOS and Windows

Slide 34

Slide 34 text

Web App Manifest 1. In manifest.webmanifest, add (at least) the following shortcut: "shortcuts": [{ "name": "About Paint", "short_name": "About", "description": "Show information about Paint", "url": "/about.html", "icons": [{ "src": "icon.png", "sizes": "512x512" }] }], 2. Test in DevTools: F12 > Application > Manifest PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) PWA LAB #8

Slide 35

Slide 35 text

Web App Manifest – Chrome Install Criteria 1. Web App is not already installed 2. Meets a user engagement heuristic (user has interacted and clicked with origin for at least 30 seconds) 3. Includes a Web App Manifest that has short_name or name, at least a 192px and 512px icon, a start_url and a display mode of fullscreen, standalone or minimal-ui 4. Served over HTTPS 5. Has a registered service worker with a fetch event handler (subject to change) PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) PWA https://web.dev/install-criteria/

Slide 36

Slide 36 text

Service Worker JavaScript snippet executed in an own thread, registered by the website Acts as a controller, proxy, or interceptor Has a cache to store responses (for offline availability and performance) Can wake up even when the website is closed and perform background tasks (e.g., push notifications or sync) PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) PWA

Slide 37

Slide 37 text

Service Worker PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) PWA Service Worker Internet Website HTML/JS Cache fetch

Slide 38

Slide 38 text

Workbox Toolchain by Google Includes a CLI Generates a service worker implementation from directory contents (e.g., build output, or our development directory) Allows you to modify the service worker behavior (maximum flexibility) PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) PWA

Slide 39

Slide 39 text

Service Worker 1. In your console, run: a) npm run workbox wizard (use “src” as project root and defaults for the rest) b) npm run workbox generateSW 2. In index.html, add the following script to the bottom of the node: if (navigator.serviceWorker) { navigator.serviceWorker.register('sw.js'); } 3. Test in DevTools: F12 > Application > Service Worker 4. Install the app: Address Bar > Install PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) PWA LAB #9

Slide 40

Slide 40 text

Service Worker Debugging More information on installed service workers can be found on • about://serviceworker- internals (Chromium-based browsers) • about:serviceworkers (Mozilla Firefox) PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) PWA

Slide 41

Slide 41 text

Service Worker Debugging PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) PWA

Slide 42

Slide 42 text

Lighthouse PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) PWA Auditing tool by Google, integrated in Chrome DevTools Automatically checks performance metrics, PWA support, accessibility, SEO and other best practices and gives tips on how to improve Can simulate mobile devices

Slide 43

Slide 43 text

Lighthouse 1. Make sure only one tab/window of your PWA is open 2. Open DevTools: F12 > Lighthouse 3. Make sure to select at least the “Progressive Web App” category 4. Click “Generate report” PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) PWA LAB #10

Slide 44

Slide 44 text

Paint PWA Capabilities Progressive Enhancement PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Agenda

Slide 45

Slide 45 text

PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on)

Slide 46

Slide 46 text

Project Fugu PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Capabilities »Let’s bring the web back – API by API« Thomas Steiner, Google

Slide 47

Slide 47 text

PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Capabilities Contacts Picker Screen Wake Lock API File System Access API Shape Detection API

Slide 48

Slide 48 text

PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Capabilities https://goo.gle/fugu-api-tracker

Slide 49

Slide 49 text

Fugu Process – Write an Explainer (https://github.com/WICG/native-file- system/blob/master/EXPLAINER.md) – Discuss capability with developers, browser vendors, standard orgs – Iterate – Compile a design document – W3C TAG Review (https://github.com/w3ctag/design- reviews/issues/390) – Formal spec within Web Incubator Community Group (WICG, https://wicg.github.io/native-file-system/) PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Capabilities

Slide 50

Slide 50 text

Fugu Process – Implementation in Chromium – Launches behind a flag (chrome://flags/#enable-experimental-web- platform-features) – Origin Trial (https://developers.chrome.com/origintrials/) – Transfer to W3C Working Group + Recommendation? PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Capabilities

Slide 51

Slide 51 text

Browser PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Capabilities navigator.share({ url: 'http://example.com' }); ShareIntent DataTransferManager … NSSharingServicePicker

Slide 52

Slide 52 text

File System Access API Some applications heavily rely on working with files (e.g. Visual Studio Code, Adobe Photoshop, …) File System Access API allows you to open, save and override files and directories Supported by Chrome, Edge PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Capabilities

Slide 53

Slide 53 text

File System Access API 1. Add the following buttons to the bar in index.html (before the color input): Open Save Copy Paste Share PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Capabilities LAB #11

Slide 54

Slide 54 text

File System Access API 2. At the top of app.js, change the import as follows: import {bresenhamLine, getImage, toBlob} from "./helpers.js"; 3. Add the following lines at the bottom of app.js: const fileOptions = { types: [{ description: 'PNG files', accept: {'image/png': ['.png']} }] }; PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Capabilities LAB #11

Slide 55

Slide 55 text

File System Access API 4. Add the following lines at the bottom of app.js: const btnSave = document.querySelector('#save'); btnSave.addEventListener('click', async () => { const blob = await toBlob(canvas); const handle = await window.showSaveFilePicker(fileOptions); const writable = await handle.createWritable(); await writable.write(blob); await writable.close(); }); PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Capabilities LAB #11

Slide 56

Slide 56 text

File System Access API Add the following code at the end of app.js: const btnOpen = document.querySelector('#open'); btnOpen.addEventListener('click', async () => { const [handle] = await window.showOpenFilePicker(fileOptions); const file = await handle.getFile(); const image = await getImage(file); ctx.drawImage(image, 0, 0); }); PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Capabilities LAB #12

Slide 57

Slide 57 text

Async Clipboard API Allows reading from/writing to the clipboard in an asynchronous manner (UI won’t freeze during long-running operations) Reading from the clipboard requires user consent first (privacy!) Supported by Chrome, Edge and Safari and Firefox (plain- text only) PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Capabilities

Slide 58

Slide 58 text

Async Clipboard API Add the following code at the end of app.js: const btnCopy = document.querySelector('#copy'); btnCopy.addEventListener('click', async () => { await navigator.clipboard.write([ new ClipboardItem({'image/png': toBlob(canvas)}) ]); }); PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Capabilities LAB #13

Slide 59

Slide 59 text

Async Clipboard API const btnPaste = document.querySelector('#paste'); btnPaste.addEventListener('click', async () => { const clipboardItems = await navigator.clipboard.read(); for (const clipboardItem of clipboardItems) { for (const type of clipboardItem.types) { if (type === 'image/png') { const blob = await clipboardItem.getType(type); const image = await getImage(blob); ctx.drawImage(image, 0, 0); } } } }); PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Capabilities LAB #14

Slide 60

Slide 60 text

Web Share API Allows sharing a title, URL, text, or files API can only be invoked as a result of a user action (i.e. a click or keypress) Supported by Chrome, Edge, Safari and Firefox (Android only) PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Capabilities

Slide 61

Slide 61 text

Web Share API const btnShare = document.querySelector('#share'); btnShare.addEventListener('click', async () => { const blob = await toBlob(canvas); const file = new File([blob], 'untitled.png', {type: 'image/png'}); const item = {files: [file], title: 'untitled.png'}; if (navigator.canShare(item)) { await navigator.share(item); } }); PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Capabilities LAB #15

Slide 62

Slide 62 text

File Handling API Register your PWA as a handler for file extensions Requires installing the application first Declare supported extensions in Web App Manifest and add imperative code to your application logic PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Capabilities

Slide 63

Slide 63 text

File Handling API 1. Add the following property to your manifest (manifest.webmanifest): "file_handlers": [{ "action": "/index.html", "accept": { "image/png": [".png"] } }] PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Capabilities LAB #16

Slide 64

Slide 64 text

File Handling API 2. Add the following code to the bottom of app.js: if ('launchQueue' in window) { launchQueue.setConsumer(async params => { const [handle] = params.files; if (handle) { const file = await handle.getFile(); const image = await getImage(file); ctx.drawImage(image, 0, 0); } }); } 3. Re-generate Service Worker: npm run workbox generateSW PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Capabilities LAB #16

Slide 65

Slide 65 text

Summary - Project Fugu helps the web to become more and more capable - Project Fugu APIs could bring many more app experiences to the web (IDEs, productivity apps, etc.) - But: Web is threatened by alternative approaches and platforms, support for modern Web API varies from platform to platform - You can make a difference! - File bugs in browser engine bugtrackers - File Fugu requests: https://goo.gle/new-fugu-request PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Capabilities

Slide 66

Slide 66 text

Paint PWA Capabilities Progressive Enhancement PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Agenda

Slide 67

Slide 67 text

Overview Use available interfaces and functions of a system (opposite of Graceful Degradation) Users with modern, feature-rich browsers get a better experience Apps are available on older browsers, but with limited functionality Concept: Browser feature support should grow over time—thereby more users can enjoy an increasing number of features PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Progressive Enhancement

Slide 68

Slide 68 text

Overview if ('serviceWorker' in navigator) { navigator.serviceWorker.register(…) .then(() => /* … */); } In JavaScript: check whether an API/feature is available. If yes—use it! Otherwise: 1. Disable the functionality 2. Fall back to an alternative API (if available) PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Progressive Enhancement

Slide 69

Slide 69 text

Disabling unsupported features In app.js, disable the buttons in case the respective API does not exist, e.g.: btnSave.disabled = !('showSaveFilePicker' in window); 1. Save: !('showSaveFilePicker' in window) 2. Open: !('showOpenFilePicker' in window) 3. Copy: !('clipboard' in navigator && 'write' in navigator.clipboard) 4. Paste: !('clipboard' in navigator && 'read' in navigator.clipboard) 5. Share: !('canShare' in navigator) PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Progressive Enhancement LAB #17

Slide 70

Slide 70 text

Providing an alternative implementation 1. In app.js, test for the existence of the showSaveFilePicker() method on the window object. 2. If the method does not exist, fall back to the following code for save: const anchor = document.createElement('a'); const url = URL.createObjectURL(blob); anchor.href = url; anchor.download = ''; anchor.click(); URL.revokeObjectURL(url); 3. Remove the code that disabled the button. PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Progressive Enhancement LAB #18

Slide 71

Slide 71 text

Deployment PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Electron/Capacitor JS HTML CSS .ipa .exe .app ELF .apk .appx Single-Page Application Capacitor Electron

Slide 72

Slide 72 text

(Simplified) PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Store Deployments https://example.com .appx .apk Server Microsoft Store Play Store Source Files

Slide 73

Slide 73 text

Run app on your device npm run workbox generateSW https://ngrok.com/download ngrok http 3000 PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) LAB #19

Slide 74

Slide 74 text

Crunch Time PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) LAB #20

Slide 75

Slide 75 text

Q&A PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on)

Slide 76

Slide 76 text

New powerful APIs regularly ship with new releases of Chromium-based browsers Some only add minor finishing touches, others enable whole application categories as productivity apps to finally make the shift to the web Some APIs already made their way into other browsers (e.g., Web Share) Fugu process makes sure that capabilities are implemented in a secure, privacy-preserving manner Let’s make the web a more capable platform! PWA Workshop From 0 to MS Paint with Project Fugu (Hands-on) Summary

Slide 77

Slide 77 text

Thank you for your kind attention! Christian Liebel @christianliebel [email protected]