capacitor-accessibility

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Original

English
🇨🇳

Translation

Chinese

Accessibility in Capacitor Apps

Capacitor应用中的无障碍设计

Build inclusive apps that work for everyone.
打造面向所有用户的包容性应用。

When to Use This Skill

何时使用本技能

  • User needs accessibility
  • User wants screen reader support
  • User asks about WCAG
  • User needs focus management
  • 用户需要提升应用无障碍性
  • 用户希望支持屏幕阅读器
  • 用户咨询WCAG相关问题
  • 用户需要焦点管理方案

Quick Checklist

快速检查清单

  • Semantic HTML
  • Alt text for images
  • Touch targets 44x44pt
  • Color contrast 4.5:1
  • Focus indicators
  • Screen reader labels
  • Keyboard navigation
  • 语义化HTML
  • 图片替代文本
  • 触控目标尺寸44x44pt
  • 色彩对比度4.5:1
  • 焦点指示器
  • 屏幕阅读器标签
  • 键盘导航

Screen Reader Support

屏幕阅读器支持

Labels and Hints

标签与提示

tsx
// Accessible button
<button
  aria-label="Delete item"
  aria-describedby="delete-hint"
>
  <TrashIcon />
</button>
<span id="delete-hint" className="sr-only">
  Permanently removes this item
</span>

// Accessible input
<label htmlFor="email">Email</label>
<input
  id="email"
  type="email"
  aria-required="true"
  aria-invalid={hasError}
  aria-describedby={hasError ? "email-error" : undefined}
/>
{hasError && <span id="email-error">Invalid email</span>}
tsx
// Accessible button
<button
  aria-label="Delete item"
  aria-describedby="delete-hint"
>
  <TrashIcon />
</button>
<span id="delete-hint" className="sr-only">
  Permanently removes this item
</span>

// Accessible input
<label htmlFor="email">Email</label>
<input
  id="email"
  type="email"
  aria-required="true"
  aria-invalid={hasError}
  aria-describedby={hasError ? "email-error" : undefined}
/>
{hasError && <span id="email-error">Invalid email</span>}

Live Regions

实时区域

tsx
// Announce dynamic content
<div aria-live="polite" aria-atomic="true">
  {message}
</div>

// Urgent announcements
<div aria-live="assertive" role="alert">
  {error}
</div>
tsx
// Announce dynamic content
<div aria-live="polite" aria-atomic="true">
  {message}
</div>

// Urgent announcements
<div aria-live="assertive" role="alert">
  {error}
</div>

Touch Targets

触控目标

css
/* Minimum 44x44pt */
button, a, input {
  min-height: 44px;
  min-width: 44px;
}

/* Icon buttons need padding */
.icon-button {
  padding: 12px;
}
css
/* Minimum 44x44pt */
button, a, input {
  min-height: 44px;
  min-width: 44px;
}

/* Icon buttons need padding */
.icon-button {
  padding: 12px;
}

Color Contrast

色彩对比度

css
/* Good contrast (4.5:1 for text) */
.text {
  color: #333333;
  background: #ffffff;
}

/* Don't rely on color alone */
.error {
  color: #d32f2f;
  border-left: 4px solid #d32f2f; /* Visual indicator */
}
.error::before {
  content: "⚠ "; /* Icon indicator */
}
css
/* Good contrast (4.5:1 for text) */
.text {
  color: #333333;
  background: #ffffff;
}

/* Don't rely on color alone */
.error {
  color: #d32f2f;
  border-left: 4px solid #d32f2f; /* Visual indicator */
}
.error::before {
  content: "⚠ "; /* Icon indicator */
}

Focus Management

焦点管理

typescript
// Move focus after navigation
useEffect(() => {
  const heading = document.querySelector('h1');
  heading?.focus();
}, [page]);

// Trap focus in modals
function trapFocus(element: HTMLElement) {
  const focusable = element.querySelectorAll(
    'button, [href], input, select, textarea, [tabindex]:not([tabindex="-1"])'
  );
  const first = focusable[0] as HTMLElement;
  const last = focusable[focusable.length - 1] as HTMLElement;

  element.addEventListener('keydown', (e) => {
    if (e.key === 'Tab') {
      if (e.shiftKey && document.activeElement === first) {
        e.preventDefault();
        last.focus();
      } else if (!e.shiftKey && document.activeElement === last) {
        e.preventDefault();
        first.focus();
      }
    }
  });
}
typescript
// Move focus after navigation
useEffect(() => {
  const heading = document.querySelector('h1');
  heading?.focus();
}, [page]);

// Trap focus in modals
function trapFocus(element: HTMLElement) {
  const focusable = element.querySelectorAll(
    'button, [href], input, select, textarea, [tabindex]:not([tabindex="-1"])'
  );
  const first = focusable[0] as HTMLElement;
  const last = focusable[focusable.length - 1] as HTMLElement;

  element.addEventListener('keydown', (e) => {
    if (e.key === 'Tab') {
      if (e.shiftKey && document.activeElement === first) {
        e.preventDefault();
        last.focus();
      } else if (!e.shiftKey && document.activeElement === last) {
        e.preventDefault();
        first.focus();
      }
    }
  });
}

Native Accessibility

原生无障碍支持

iOS VoiceOver

iOS VoiceOver

swift
// Custom accessibility in native code
element.isAccessibilityElement = true
element.accessibilityLabel = "Play video"
element.accessibilityHint = "Double tap to play"
element.accessibilityTraits = .button
swift
// Custom accessibility in native code
element.isAccessibilityElement = true
element.accessibilityLabel = "Play video"
element.accessibilityHint = "Double tap to play"
element.accessibilityTraits = .button

Android TalkBack

Android TalkBack

kotlin
// Custom accessibility
ViewCompat.setAccessibilityDelegate(view, object : AccessibilityDelegateCompat() {
    override fun onInitializeAccessibilityNodeInfo(
        host: View,
        info: AccessibilityNodeInfoCompat
    ) {
        super.onInitializeAccessibilityNodeInfo(host, info)
        info.contentDescription = "Play video"
    }
})
kotlin
// Custom accessibility
ViewCompat.setAccessibilityDelegate(view, object : AccessibilityDelegateCompat() {
    override fun onInitializeAccessibilityNodeInfo(
        host: View,
        info: AccessibilityNodeInfoCompat
    ) {
        super.onInitializeAccessibilityNodeInfo(host, info)
        info.contentDescription = "Play video"
    }
})

Testing

测试

bash
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bash
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iOS: Enable VoiceOver in Simulator

iOS: 在模拟器中启用VoiceOver

Settings > Accessibility > VoiceOver

设置 > 辅助功能 > VoiceOver

Android: Enable TalkBack

Android: 启用TalkBack

Settings > Accessibility > TalkBack

设置 > 辅助功能 > TalkBack

Web: Use axe-core

Web: 使用axe-core

bunx @axe-core/cli https://localhost:3000
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bunx @axe-core/cli https://localhost:3000
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Resources

相关资源