Designing for Different Devices (Viewport Size, Touch/Hover, etc.)

Documentazione Guide per sviluppatori
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This document outlines the APIs used to adapt Discourse’s user interface for different devices.

Viewport Size

The most important characteristic to consider is the viewport size. We design “mobile first” and then add customizations for larger devices as needed. The breakpoints we use are:

Breakpoint Size Pixels (at 16px body font size)
sm 40rem 640px
md 48rem 768px
lg 64rem 1024px
xl 80rem 1280px
2xl 96rem 1536px

To use these in an SCSS file, add @use "lib/viewport"; at the top of the file, then use one of the available mixins:

@use "lib/viewport";

@include viewport.from(lg) {
  // SCSS rules here will be applied to
  // devices larger than the lg breakpoint
}

@include viewport.until(sm) {
  // SCSS rules here will be applied to
  // devices smaller than the sm breakpoint
}

@include viewport.between(sm, md) {
  // SCSS rules here will be applied to
  // devices with a size between the sm
  // and md breakpoints
}

In general, SCSS is the recommended way to handle layout differences based on viewport size. For advanced cases, the same breakpoints can be accessed in Ember components via the capabilities service. For example:

import Component from "@glimmer/component";
import { service } from "@ember/service";

class MyComponent extends Component {
  @service capabilities;

  <template>
    {{#if this.capabilities.viewport.lg}}
      This text will be displayed for devices larger than the lg breakpoint
    {{/if}}

    {{#unless this.capabilities.viewport.sm}}
      This text will be displayed for devices smaller than the sm breakpoint
    {{/unless}}
  </template>
}

These properties are reactive, and Ember will automatically re-render the relevant parts of the template as the browser is resized.

Touch & Hover

Some devices only have touchscreens, some only have a traditional mouse pointer, and some have both. Importantly, touchscreen users cannot “hover” over elements. Therefore, interfaces should be designed to work entirely without hover states, with hover-specific enhancements added for devices that support them.

There are several ways to detect touch/hover capability via CSS and JavaScript. For consistency, we recommend using Discourse’s helpers instead of those CSS/JS APIs directly.

For CSS, you can target the .discourse-touch and .discourse-no-touch classes, which are added to the <html> element. These are determined based on the (any-pointer: coarse) media query.

For example:

html.discourse-touch {
  // SCSS rules here will apply to devices with a touch screen,
  // including mobiles/tablets and laptops/desktops with touch screens.
}

html.discourse-no-touch {
  // SCSS rules here will apply to devices with no touch screen.
}

This information is also available in Ember components via the capabilities service:

import Component from "@glimmer/component";
import { service } from "@ember/service";

class MyComponent extends Component {
  @service capabilities;

  <template>
    {{#if this.capabilities.touch}}
      This text will be displayed for devices with a touch screen
    {{/if}}

    {{#unless this.capabilities.touch}}
      This text will be displayed for devices with no touch screen
    {{/unless}}
  </template>
}

Legacy Mobile / Desktop Modes

Historically, Discourse shipped two completely different layouts and stylesheets for “mobile” and “desktop” views, based on the browser’s user-agent. Developers would target these modes by putting CSS in specific mobile/desktop directories, by using the .mobile-view/.desktop-view HTML classes, and the site.mobileView boolean in JavaScript.

These techniques are now considered deprecated and should be replaced with the viewport and capability-based strategies discussed above. We will be removing the dedicated modes in the near future, making “mobile mode” an alias for “viewport width less than sm” for backwards compatibility.

This document is version controlled - suggest changes on github.

9 Mi Piace
2

Quindi qualcosa del genere sarebbe deprecato?

@service site;
...
const mobileView = this.site.mobileView;
3

Se lo fai in un contesto statico, allora sì, non sarà compatibile con la prossima “modalità mobile basata sulla viewport” (attualmente disabilitata).

Se fai il controllo in un contesto di autotracking come questo:

@service site;
...

<template>
  {{#if this.site.mobileView}}
    ...
  {{/if}}
</template>

Allora Ember ri-renderizzerà automaticamente le cose quando il booleano mobileView cambia (cioè quando il browser viene ridimensionato). Quindi va bene.

4

Quindi, per essere sicuri, metterlo in un getter è deprecato, ma non metterlo in <template>?

5

Metterlo in un getter va bene anche, dato che sarà tracciato automaticamente da Ember.

@service site;

get shouldRender(){
  return this.site.mobileView;
}


<template>
  {{#if this.shouldRender}}
    ...
  {{/if}}
</template>

^^ questo va bene

Un esempio sbagliato sarebbe

export default apiInitializer((api) => {
  if(api.container.lookup("service:site").mobileView){
    api.renderInOutlet("some-outlet", <template>My content</template>)
  }
});

Perché in questa situazione, mobileView viene controllato solo all’avvio dell’applicazione. Ridimensionare il browser non rieseguirà l’initializer.

Quindi si rifarebbe a qualcosa come

export default apiInitializer((api) => {
  const site = api.container.lookup("service:site");
  api.renderInOutlet("some-outlet", <template>
    {{#if site.mobileView}}My content{{/if}}
  </template>);
});

In modo che le modifiche a mobileView abbiano effetto quando il browser viene ridimensionato.

3 Mi Piace
6

Capito ora. Grazie per la spiegazione!

1 Mi Piace
7

(post eliminato dall’autore)

1 Mi Piace
8

La raccomandazione generale è: non farlo. Perché quel tipo di esperienze dovrebbe differire in base alle dimensioni dello schermo?

Un utile esperimento mentale è: come ti aspetti che si comporti su telefoni pieghevoli o tablet, che non rientrano esplicitamente nei contenitori mobile/desktop.

Se desideri davvero che questo tipo di cambiamento di comportamento si basi sullo user-agent del browser (come funzionavano le vecchie modalità mobile/desktop), allora abbiamo capabilities.isMobileDevice, che letteralmente controlla la parola “mobile” nella stringa user-agent:

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9

beh nel mio caso è che fornisco l’opzione per il desktop di passare la homepage al percorso delle intersezioni dei tag - la cui interfaccia non esiste sul cellulare … (anche se il percorso funziona effettivamente - i controlli aggiuntivi sono nascosti)

… ma il punto è chiaro, probabilmente ci ripenserò!

1 Mi Piace
10

Interessante! Mi chiedo se sia intenzionale… Penso che dovrebbe funzionare su qualsiasi dispositivo :thinking:

2 Mi Piace