Angular meets Project Fugu: Produktivitäts-PWAs auf Desktopniveau (Hands-on)

Angular meets Project Fugu
Produktivitäts-PWAs auf Desktopniveau
Christian Liebel
@christianliebel
Consultant

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Hello, it’s me.
Christian Liebel
Twitter:
@christianliebel
Email:
christian.liebel
@thinktecture.com
Angular & PWA
Slides:
thinktecture.com
/christian-liebel

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Timetable
09:00–10:30 Block 1
10:30–11:00 Break
11:00–12:30 Block 2

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Things NOT to expect
- Blueprint for PWA
development
- No AuthN/AuthZ
- No 1:1 support
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

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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
Demo Use Case

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(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
Demo Use Case

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Setup complete?
(Node.js, Google Chrome, Editor, Git)
Setup (1/3)
LAB

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Optional
Download and install Chrome Canary:
https://www.google.com/intl/de/chrome/canary/
Setup (2/3)
LAB

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git clone https://github.com/thinktecture/angular-
days-spring-2021-fugu.git
cd angular-days-spring-2021-fugu
npm i
npm start
Setup (3/3)
LAB

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Paint PWA Capabilities
Progressive
Enhancement
Agenda

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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+
Paint

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Canvas
Add a canvas element to app.component.html (line 5):

Query the canvas element in app.component.ts (line 10):
@ViewChild('canvas') canvas: ElementRef;
context: CanvasRenderingContext2D;
Paint
EX #1

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Canvas 2D Context
fillRect(x, y, width, height)
strokeRect(x, y, width, height)
beginPath()
moveTo(x, y)
lineTo(x, y)
fill()
stroke()
Paint

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Canvas 2D Context
Get the 2D context and prepare the canvas in app.component.ts in the
method ngAfterViewInit():
const canvas = this.canvas.nativeElement;
const ctx = this.context = canvas.getContext('2d');
ctx.fillStyle = 'white';
ctx.fillRect(0, 0, canvas.width, canvas.height);
ctx.fillStyle = 'black';
Paint
EX #2

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Low-latency Rendering
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)

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Low-latency Rendering
Opt-in to low-latency rendering (app.component.ts):
const ctx = this.context = canvas.getContext('2d', {
desynchronized: true
});
Paint
EX #3

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Pointer Events
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

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Pointer Events
Add event listeners (app.component.html and app.component.ts):
(pointerdown)="onPointerDown($event)"
(pointermove)="onPointerMove(canvas, $event)"
(pointerup)="onPointerUp()">
onPointerMove(canvas: HTMLCanvasElement, event: PointerEvent): void {
this.context.fillRect(~~event.offsetX, ~~event.offsetY, 2, 2);
}
Paint
EX #4

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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
Paint

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Bresenham Line Algorithm
Update the method onPointerMove() in app.component.ts:
if (this.previousPoint) {
const currentPoint = {x: Math.floor(event.offsetX), y:
Math.floor(event.offsetY)};
const points = this.paintService.bresenhamLine(this.previousPoint.x,
this.previousPoint.y, currentPoint.x, currentPoint.y);
for (const {x, y} of points) {
this.context.fillRect(x, y, 2, 2);
this.previousPoint = currentPoint;
}
}
Paint
EX #5

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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:

Paint

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Color Selection
1. In app.component.html, add the following input to the node:

2. In app.component.ts, add the following code in the method
colorChange():
this.context.fillStyle = $event.target.value;
Paint
EX #6

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Progressive
Enhancement
Agenda

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Responsive Linkable Discoverable Installable App-like
Connectivity
Independent
Fresh Safe Re-engageable Progressive

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Web App
Manifest
Service
Worker

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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

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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
Names
Icons
Display Mode
Shortcuts
Start URL
Theme color (status bar/window bar)

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Manifest Display Modes
PWA

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Manifest Icon Purposes
(any)
any context (e.g. app icon)
monochrome
different color requirements
(at risk)
maskable
user agent masks icon as required
PWA
Safe Zone
Windows iOS Android

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Web App Manifest
1. In your console, run: npx ng add @angular/pwa
2. Update the new file manifest.webmanifest and set:
a) name and short_name to values of your choice
b) theme_color to #000080 and background_color to #808080
3. In index.html, set theme_color to #000080 as well.
4. Run npm run start
5. Test manifest in DevTools: F12 > Application > Manifest
PWA
EX #7

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Manifest Shortcuts
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

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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": "/index.html",
"icons": [{ "src": "assets/icons/icon-512x512.png", "sizes": "512x512" }]
}],
2. Test in DevTools: F12 > Application > Manifest
PWA
EX #8

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Web App Manifest – Chrome Installability Signals
Web App is not already installed
Meets a user engagement heuristic (previously: user has interacted with
domain for at least 30 seconds)
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
Served over HTTPS
Has a registered service worker with a fetch event handler
PWA

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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

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Service Worker
PWA
Service
Worker
Internet
Website
HTML/JS
Cache
fetch

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NgServiceWorker
Angular CLI supports Service
Worker generation by simply
adding PWA support:
ng add @angular/pwa
One-size-fits-all Service
Worker
Pre-defined functionality,
limited customizability
PWA

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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

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Service Worker
1. Start build with npm run build -- --prod
2. Go to dist folder: cd dist/angular-days-spring-2021-fugu
3. Start with npx lite-server
4. Test in DevTools: F12 > Application > Service Worker
5. Install the app: Address Bar > ⊕ Install
PWA
EX #9

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Push Notifications
Just as native apps, PWAs
can receive push notifications
Combination of two
technologies: Web
Notifications and Push API
(Not supported on Safari for
macOS, iOS and iPadOS!)
PWA

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Service Worker Debugging
More information on installed
service workers can be found on
• chrome://serviceworker-
internals (Google Chrome)
• about:serviceworkers
(Mozilla Firefox)
PWA

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Service Worker Debugging
PWA

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Lighthouse
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

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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
EX #10

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Progressive
Enhancement
Agenda

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Project Fugu
Capabilities
»Let’s bring the web
back – API by API«
Thomas Steiner, Google

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Capabilities
Contacts
Picker
Screen Wake
Lock API
File System
Access API
Shape
Detection API

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Capabilities
https://goo.gle/fugu-api-tracker

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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/)
Capabilities

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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?
Capabilities

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Capabilities
navigator.share({ url: 'http://example.com' });
ShareIntent DataTransferManager
…
NSSharingServicePicker

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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
Shipped with Google Chrome
86
Capabilities

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1. Add the following buttons to the bar in app.component.html (before the color
input):
Open
Save
Copy
Paste
Share
Capabilities
EX #11

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2. Add the following lines at the top of app.component.ts:
private fileOptions = {
types: [{
description: 'PNG files',
accept: {'image/png': ['.png']}
}]
};
Capabilities
EX #11

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3. Add the following lines in the method save of app.component.ts:
const blob = await this.paintService.toBlob(this.canvas.nativeElement);
const handle = await (window as any).showSaveFilePicker(this.fileOptions);
const writable = await handle.createWritable();
await writable.write(blob);
await writable.close();
Capabilities
EX #11

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Add the following code int the method open() of app.component.ts:
const [handle] = await (window as any).showOpenFilePicker(this.fileOptions);
const file = await handle.getFile();
const image = await this.paintService.getImage(file);
this.context.drawImage(image, 0, 0);
Capabilities
EX #12

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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
Capabilities

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Async Clipboard API
Add the following code in the method copy() of app.component.ts:
await navigator.clipboard.write([
new ClipboardItem({[blob.type]: blob})
]);
Capabilities
EX #13

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Async Clipboard API
Add the following code in the method paste() of app.component.ts:
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 this.paintService.getImage(blob);
this.context.drawImage(image, 0, 0);
}
}
}
Capabilities
EX #14

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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)
Files supported in Chrome on
Android, Edge on Windows
Capabilities

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Web Share API
Add the following code in the share() method in the app.component.ts:
const file = new File([blob], 'untitled.png', {type: 'image/png'});
const item = {files: [file], title: 'untitled.png'};
if (await navigator.canShare(item)) {
await navigator.share(item);
}
Capabilities
EX #15

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File System 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
Capabilities

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1. Enable the following flag in Chrome Canary and restart the browser:
chrome://flags/#file-handling-api
2. Add the following property to your manifest (manifest.webmanifest):
"file_handlers": [{
"action": "/index.html",
"accept": {
"image/png": [".png"]
}
}]
Capabilities
EX #16

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3. Add the following code to the bottom of the ngAfterViewInit() method of app.component.ts:
if ('launchQueue' in window) {
(window as any).launchQueue.setConsumer(async params => {
const [handle] = params.files;
if (handle) {
const file = await handle.getFile();
const image = await this.paintService.getImage(file);
ctx.drawImage(image, 0, 0);
}
});
}
4. Re-generate Service Worker: npm run build -- --prod in main folder
5. Go to dist/angular-days-spring-2021-fugu and run npx lite-server
Capabilities
EX #16

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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
Capabilities

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Progressive
Enhancement
Agenda

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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
Progressive Enhancement

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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)
Progressive Enhancement

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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!
Summary

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

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Angular meets Project Fugu: Produktivitäts-PWAs auf Desktopniveau (Hands-on)

Angular meets Project Fugu: Produktivitäts-PWAs auf Desktopniveau (Hands-on)

Christian Liebel
PRO

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Angular meets Project Fugu: Produktivitäts-PWAs auf Desktopniveau (Hands-on)

Angular meets Project Fugu: Produktivitäts-PWAs auf Desktopniveau (Hands-on)

Christian Liebel PRO

More Decks by Christian Liebel

Other Decks in Programming

Featured

Transcript

Christian Liebel
PRO