Implementing desktop-class productivity apps with Angular and Project Fugu 🅰️💘🐡

Christian Liebel
@christianliebel
Consultant
Implementing desktop-class productivity
apps with Angular and Project Fugu 🅰💘🐡

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Hello, it’s me.
Implementing desktop-class productivity apps
with Angular and Project Fugu 🅰💘🐡
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
12:30–14:00 Lunch Break
14:00–15:30 Block 3
15:30–16:00 Break
16:00–17:30 Block 4

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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

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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 #0

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git clone https://github.com/thinktecture/ng-de-
2022-fugu.git
cd ng-de-2022-pwa
npm i
git pull
npm start -- --open
Setup (3/3)
LAB #0

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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:

Query the canvas element in app.component.ts:
@ViewChild('canvas') canvas?: ElementRef;
Paint
LAB #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
1. Introduce a new ﬁeld at the top of
app.component.ts:
context?: CanvasRenderingContext2D;
2. Get the 2D context in ngAfterViewInit():
const canvas =
this.canvas!.nativeElement;
const ctx = canvas.getContext('2d')!;
this.context = ctx;
3. Prepare the canvas:
ctx.fillStyle = 'white';
ctx.fillRect(0, 0,
canvas.width,
canvas.height);
ctx.fillStyle = 'black';
Paint LAB #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.js):
const ctx = canvas.getContext('2d', {
desynchronized: true
})!;
Paint
LAB #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
1. In app.component.html, add event bindings for the pointer events:
(pointerdown)="onPointerDown($event)"
(pointermove)="onPointerMove($event)"
(pointerup)="onPointerUp()"
>
2. In app.component.ts (onPointerMove()), draw the user input:
this.context!.fillRect(event.offsetX, event.offsetY, 2, 2);
Paint LAB #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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1. At the top of app.component.ts, a ﬁeld called previousPoint to store
the previous point:
previousPoint?: { x: number, y: number };
2. In onPointerDown(), set the current point as the previous point:
this.previousPoint = { x: event.offsetX, y: event.offsetY };
3. In onPointerUp(), set this.previousPoint to undefined.
Paint LAB #5

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4. In onPointerMove(), call the Bresenham line algorithm with the points:
if (this.previousPoint) {
const currentPoint = { x: event.offsetX, y: event.offsetY };
for (const point of
this.paintService.bresenhamLine(this.previousPoint,
currentPoint)) {
this.context!.fillRect(point.x, point.y, 2, 2);
}
this.previousPoint = currentPoint;
}
Paint LAB #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, replace the content of the node with:

2. In app.component.ts (onColorChange()), update the context’s ﬁll style
accordingly:
this.context!.fillStyle = color.value;
Paint
LAB #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
browser minimal-ui standalone fullscreen

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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. Run the following command to add PWA support to the current
project: ng add @angular/pwa
2. In manifest.webmanifest,
a) set name and short_name to values of your choice
b) change the theme_color to #000080
c) change the background_color to #808080
3. In index.html, change the theme-color to #000080.
4. Test manifest in DevTools: F12 > Application > Manifest
PWA LAB #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, macOS and
Windows

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

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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
PWA
https://web.dev/install-criteria/

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Service Worker
JavaScript 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. In your console, run: npm run pwa
2. Test in DevTools: F12 > Application > Service Worker
3. Install the app: Address Bar > Install
PWA
LAB #9

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Service Worker Debugging
More information on installed
service workers can be found on
• about://serviceworker-
internals (Chromium-based
browsers)
• 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 “Analyze page load”
PWA
LAB #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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Browser
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
Supported by Chrome, Edge
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
LAB #11

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

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3. Add the following lines to the save() function:
const blob = await
this.paintService.toBlob(this.canvas!.nativeElement);
const handle = await
window.showSaveFilePicker(this.fileOptions);
const writable = await handle.createWritable();
await writable.write(blob);
await writable.close();
Capabilities
LAB #11

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Add the following code to the open() function:
const [handle] = await
window.showOpenFilePicker(this.fileOptions);
const file = await handle.getFile();
const image = await this.paintService.getImage(file);
this.context!.drawImage(image, 0, 0);
Capabilities
LAB #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 and Firefox (plain-
text only)
Capabilities

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Async Clipboard API
Add the following code to the copy() function:
await navigator.clipboard.write([
new ClipboardItem({ "image/png":
this.paintService.toBlob(this.canvas!.nativeElement) }),
]);
Capabilities
LAB #13

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Async Clipboard API
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
LAB #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)
Supported by Chrome, Edge,
Safari and Firefox (Android only)
Capabilities

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Web Share API
const blob = await
this.paintService.toBlob(this.canvas!.nativeElement);
const file = new File([blob], 'untitled.png', {type:
'image/png'});
const item = { files: [file], text: 'Awesome drawing' };
if (navigator.canShare(item)) {
await navigator.share(item);
}
Capabilities
LAB #15

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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
Capabilities

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File Handling API
1. Add the following property to your manifest (manifest.webmanifest):
"file_handlers": [{
"action": "/index.html",
"accept": {
"image/png": [".png"]
}
}]
Capabilities
LAB #16

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File Handling API
2. Add the following code to ngAfterViewInit() in app.component.ts:
if ('launchQueue' in window) {
window.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);
}
});
}
Capabilities
LAB #16

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File Handling API
3. Rebuild PWA: npm run pwa
Note: Wait for a few seconds and reload the application after opening, as
the PWA needs to fetch the new ﬁles ﬁrst.
Capabilities
LAB #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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Disabling unsupported features
In app.component.ts, introduce the following check object:
readonly supported = {
open: 'showOpenFilePicker' in window,
} as const;
In app.component.html, disable the open button if the API is unsupported:

Open
Progressive Enhancement LAB #17

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Disabling unsupported features
Introduce checks for the remaining APIs:
1. Save: 'showSaveFilePicker' in window
2. Copy: navigator.clipboard && 'write' in navigator.clipboard
3. Paste: navigator.clipboard && 'read' in navigator.clipboard
4. Share: 'canShare' in navigator

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Providing an alternative implementation
1. In the save() method of app.component.ts, 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 compatibility check to always enable the button.

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Deployment
Electron/Capacitor
JS
HTML
CSS
.ipa
.exe .app ELF
.apk .appx
Single-Page
Application
Capacitor
Electron

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(Simpliﬁed)
Store Deployments
https://example.com
.appx
.apk
Server
Microsoft
Store
Play
Store
Source
Files

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Run app on your device
npm run pwa
https://ngrok.com/download
ngrok http 3000
LAB #19

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Crunch Time
LAB #20

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Q&A

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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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Implementing desktop-class productivity apps with Angular and Project Fugu 🅰️💘🐡

Implementing desktop-class productivity apps with Angular and Project Fugu 🅰️💘🐡

Christian Liebel
PRO

More Decks by Christian Liebel

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Implementing desktop-class productivity apps with Angular and Project Fugu 🅰️💘🐡

Implementing desktop-class productivity apps with Angular and Project Fugu 🅰️💘🐡

Christian Liebel PRO

More Decks by Christian Liebel

Other Decks in Programming

Featured

Transcript

Christian Liebel
PRO