pixijs-accessibility（pixijs 辅助功能）

Enable screen reader and keyboard navigation via PixiJS's AccessibilitySystem. The system creates an invisible shadow DOM overlay positioned over accessible containers so assistive technology can discover and activate them.

Quick Start

const button = new Sprite(await Assets.load("button.png"));
button.accessible = true;
button.accessibleTitle = "Play game";
button.accessibleHint = "Starts a new game session";
button.eventMode = "static";
button.tabIndex = 0;
app.stage.addChild(button);

app.renderer.accessibility.setAccessibilityEnabled(true);

button.on("pointertap", () => startGame());

Related skills: pixijs-events (pointer/tap handlers), pixijs-scene-dom-container (HTML elements on canvas), pixijs-application (init options).

Key points:

• By default the system activates only after the user presses Tab. Set enabledByDefault: true in Application init for immediate activation.
• On mobile, the system creates a hidden touch hook; screen-reader focus activates accessibility for the whole session.
• The AccessibilitySystem requires the main thread; it is not available in a Web Worker.

Core Patterns

Container accessible properties

import { Container, Sprite } from "pixi.js";

const container = new Container();
container.accessible = true;
container.accessibleTitle = "Navigation menu";
container.accessibleHint = "Contains links to other pages";
container.eventMode = "static"; // required for custom tabIndex to apply
container.tabIndex = 0;
container.accessibleType = "div"; // defaults to 'button'

const sprite = new Sprite();
sprite.accessible = true;
sprite.accessibleTitle = "Close dialog";
sprite.accessibleText = "X"; // text content of the shadow div
sprite.eventMode = "static";
sprite.tabIndex = 1;

Available properties on any Container:

• accessible (boolean) - enables the accessible overlay div
• accessibleTitle (string) - sets the title attribute on the shadow div
• accessibleHint (string) - sets the aria-label attribute
• accessibleText (string) - sets inner text content of the shadow div
• accessibleType (string) - HTML tag for the shadow element, defaults to 'button'
• tabIndex (number) - tab order for keyboard navigation (only applied when interactive is true / eventMode is 'static' or 'dynamic')
• accessibleChildren (boolean, default true) - when false, prevents child containers from being accessible
• accessiblePointerEvents (string) - CSS pointer-events value on the shadow div

Custom tab order

Give each accessible container a tabIndex to control the order assistive tech walks through them. Higher numbers come later; equal numbers fall back to scene-graph order.

menuButton.accessible = true;
menuButton.eventMode = "static";
menuButton.tabIndex = 1;

playButton.accessible = true;
playButton.eventMode = "static";
playButton.tabIndex = 2;

settingsButton.accessible = true;
settingsButton.eventMode = "static";
settingsButton.tabIndex = 3;

tabIndex is only forwarded to the shadow div when the container is interactive (eventMode is 'static' or 'dynamic'). Without that, the system clamps the div's tabIndex back to 0, and the order you set is ignored.

Programmatic control

import { Application } from "pixi.js";

const app = new Application();
await app.init({ width: 800, height: 600 });

// Enable accessibility at runtime
app.renderer.accessibility.setAccessibilityEnabled(true);

// Check current state
console.log(app.renderer.accessibility.isActive);
console.log(app.renderer.accessibility.isMobileAccessibility);

// Full init options:
await app.init({
  accessibilityOptions: {
    enabledByDefault: true, // activate immediately (default: false)
    debug: true, // makes overlay divs visible (default: false)
    activateOnTab: true, // Tab key activates system (default: true)
    deactivateOnMouseMove: false, // stay active when mouse moves (default: true)
  },
});

The system can also be configured via static defaults before creating the Application:

import { AccessibilitySystem, Application } from "pixi.js";

AccessibilitySystem.defaultOptions.enabledByDefault = true;
AccessibilitySystem.defaultOptions.deactivateOnMouseMove = false;

const app = new Application();
await app.init();

Handling accessible interactions

import { Sprite } from "pixi.js";

const button = new Sprite();
button.eventMode = "static";
button.accessible = true;
button.accessibleTitle = "Submit form";
button.tabIndex = 0;

// Screen readers trigger click/tap events through the shadow DOM element
button.on("pointertap", () => {
  submitForm();
});

When accessibility is active and a user activates a shadow div (via Enter/Space key or screen reader action), the system dispatches click, pointertap, and tap FederatedEvents to the corresponding container. Focus on the shadow div dispatches mouseover, and focus-out dispatches mouseout. Both eventMode and accessible should be set for full keyboard + pointer support.

Common Mistakes

[MEDIUM] Expecting accessibility to be active without Tab key press

The AccessibilitySystem does not create its DOM overlay until the user presses Tab (or, on mobile, focuses the touch hook). If your application needs accessibility immediately:

const app = new Application();
await app.init({
  accessibilityOptions: {
    enabledByDefault: true,
  },
});

Or at runtime:

app.renderer.accessibility.setAccessibilityEnabled(true);

Without one of these, automated accessibility testing tools will not find the overlay elements.

[MEDIUM] Setting accessible without accessibleTitle

Wrong:

const sprite = new Sprite();
sprite.accessible = true;
// no title or hint set

Correct:

const sprite = new Sprite();
sprite.accessible = true;
sprite.accessibleTitle = "Play button";
sprite.accessibleHint = "Click to start the game";

A container with accessible = true but no accessibleTitle or accessibleHint gets a fallback title of "container {tabIndex}". Screen readers will announce this generic label with no useful context. Always provide at least accessibleTitle.

[MEDIUM] Accessibility deactivates when moving mouse

By default, deactivateOnMouseMove is true. Any mouse movement after Tab-activation will deactivate the overlay. This is by design (assumes keyboard-only users don't use a mouse), but it makes testing with a mouse frustrating.

await app.init({
  accessibilityOptions: {
    deactivateOnMouseMove: false,
  },
});

[MEDIUM] Not importing accessibility extension in custom builds

When using skipExtensionImports: true for a custom build, the accessibility extension is not automatically registered. You must import it explicitly:

import "pixi.js/accessibility";
import { Application } from "pixi.js";

const app = new Application();
await app.init({ skipExtensionImports: true });

Without this import, app.renderer.accessibility will be undefined and no shadow DOM layer will be created.

API Reference

• AccessibilitySystem
• AccessibilitySystemOptions
• AccessibilityOptions
• AccessibleOptions
• PointerEvents