chore: initial release
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cogwheel0
396
lib/core/services/enhanced_accessibility_service.dart
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396
lib/core/services/enhanced_accessibility_service.dart
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import 'dart:math' as math;
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import 'package:flutter/material.dart';
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import 'package:flutter/services.dart';
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import 'package:flutter/semantics.dart';
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import '../../shared/theme/app_theme.dart';
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import '../../shared/theme/theme_extensions.dart';
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/// Enhanced accessibility service for WCAG 2.2 AA compliance
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class EnhancedAccessibilityService {
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/// Announce text to screen readers
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static void announce(
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String message, {
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TextDirection textDirection = TextDirection.ltr,
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}) {
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SemanticsService.announce(message, textDirection);
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}
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/// Announce loading state
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static void announceLoading(String loadingMessage) {
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announce('Loading: $loadingMessage');
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}
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/// Announce error with helpful context
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static void announceError(String error, {String? suggestion}) {
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final message = suggestion != null
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? 'Error: $error. $suggestion'
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: 'Error: $error';
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announce(message);
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}
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/// Announce success with context
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static void announceSuccess(String successMessage) {
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announce('Success: $successMessage');
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}
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/// Check if reduce motion is enabled
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static bool shouldReduceMotion(BuildContext context) {
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return MediaQuery.of(context).disableAnimations;
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}
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/// Get appropriate animation duration based on motion settings
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static Duration getAnimationDuration(
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BuildContext context,
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Duration defaultDuration,
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) {
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return shouldReduceMotion(context) ? Duration.zero : defaultDuration;
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}
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/// Get text scale factor with bounds for accessibility
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static double getBoundedTextScaleFactor(BuildContext context) {
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final textScaler = MediaQuery.of(context).textScaler;
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final textScaleFactor = textScaler.scale(1.0);
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// Ensure text doesn't get too small or too large
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return textScaleFactor.clamp(0.8, 3.0);
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}
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/// Create accessible button with proper semantics
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static Widget createAccessibleButton({
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required Widget child,
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required VoidCallback? onPressed,
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required String semanticLabel,
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String? semanticHint,
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bool isDestructive = false,
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}) {
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return Builder(
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builder: (context) => Semantics(
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label: semanticLabel,
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hint: semanticHint,
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button: true,
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enabled: onPressed != null,
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child: ElevatedButton(
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onPressed: onPressed,
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style: ElevatedButton.styleFrom(
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minimumSize: const Size(44, 44), // WCAG minimum touch target
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backgroundColor: isDestructive ? context.conduitTheme.error : null,
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),
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child: child,
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),
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),
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);
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}
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/// Create accessible icon button with proper semantics
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static Widget createAccessibleIconButton({
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required IconData icon,
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required VoidCallback? onPressed,
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required String semanticLabel,
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String? semanticHint,
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Color? iconColor,
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double iconSize = 24,
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}) {
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return Semantics(
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label: semanticLabel,
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hint: semanticHint,
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button: true,
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enabled: onPressed != null,
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child: SizedBox(
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width: 44, // Minimum touch target
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height: 44,
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child: IconButton(
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onPressed: onPressed,
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icon: Icon(icon, size: iconSize, color: iconColor),
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padding: EdgeInsets.zero,
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),
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),
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);
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}
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/// Create accessible text field with proper labels
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static Widget createAccessibleTextField({
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required String label,
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TextEditingController? controller,
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String? hintText,
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String? errorText,
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bool isRequired = false,
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TextInputType? keyboardType,
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bool obscureText = false,
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ValueChanged<String>? onChanged,
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}) {
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final effectiveLabel = isRequired ? '$label *' : label;
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return Semantics(
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label: effectiveLabel,
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hint: hintText,
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textField: true,
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child: TextFormField(
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controller: controller,
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keyboardType: keyboardType,
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obscureText: obscureText,
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onChanged: onChanged,
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decoration: InputDecoration(
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labelText: effectiveLabel,
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hintText: hintText,
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errorText: errorText,
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helperText: isRequired ? '* Required field' : null,
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prefixIcon: errorText != null
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? Builder(
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builder: (context) => Icon(
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Icons.error_outline,
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color: context.conduitTheme.error,
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),
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)
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: null,
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),
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),
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);
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}
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/// Create accessible card with proper semantics
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static Widget createAccessibleCard({
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required Widget child,
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VoidCallback? onTap,
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String? semanticLabel,
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String? semanticHint,
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bool isSelected = false,
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}) {
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return Semantics(
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label: semanticLabel,
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hint: semanticHint,
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button: onTap != null,
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selected: isSelected,
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child: Card(
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child: InkWell(
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onTap: onTap,
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child: Padding(
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padding: const EdgeInsets.all(Spacing.md),
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child: child,
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),
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),
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),
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);
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}
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/// Create accessible loading indicator
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static Widget createAccessibleLoadingIndicator({
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String? loadingMessage,
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double size = 24,
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}) {
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return Semantics(
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label: loadingMessage ?? 'Loading',
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liveRegion: true,
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child: SizedBox(
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width: size,
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height: size,
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child: const CircularProgressIndicator(),
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),
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);
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}
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/// Create accessible image with alt text
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static Widget createAccessibleImage({
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required ImageProvider image,
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required String altText,
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bool isDecorative = false,
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double? width,
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double? height,
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BoxFit fit = BoxFit.cover,
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}) {
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if (isDecorative) {
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return Semantics(
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excludeSemantics: true,
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child: Image(image: image, width: width, height: height, fit: fit),
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);
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}
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return Semantics(
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label: altText,
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image: true,
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child: Image(image: image, width: width, height: height, fit: fit),
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);
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}
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/// Create accessible toggle switch
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static Widget createAccessibleSwitch({
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required bool value,
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required ValueChanged<bool>? onChanged,
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required String label,
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String? description,
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}) {
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return Builder(
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builder: (context) => Semantics(
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label: label,
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value: value ? 'On' : 'Off',
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hint: description,
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toggled: value,
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onTap: onChanged != null ? () => onChanged(!value) : null,
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child: SwitchListTile(
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title: Text(
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label,
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style: TextStyle(color: context.conduitTheme.textPrimary),
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),
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subtitle: description != null
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? Text(
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description,
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style: TextStyle(color: context.conduitTheme.textSecondary),
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)
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: null,
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value: value,
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onChanged: onChanged,
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),
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),
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);
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}
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/// Create accessible slider
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static Widget createAccessibleSlider({
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required double value,
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required ValueChanged<double>? onChanged,
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required String label,
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double min = 0.0,
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double max = 1.0,
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int? divisions,
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String Function(double)? valueFormatter,
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}) {
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final formattedValue =
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valueFormatter?.call(value) ?? value.toStringAsFixed(1);
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return Semantics(
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label: label,
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value: formattedValue,
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increasedValue:
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valueFormatter?.call((value + 0.1).clamp(min, max)) ??
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(value + 0.1).clamp(min, max).toStringAsFixed(1),
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decreasedValue:
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valueFormatter?.call((value - 0.1).clamp(min, max)) ??
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(value - 0.1).clamp(min, max).toStringAsFixed(1),
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onIncrease: onChanged != null
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? () => onChanged((value + 0.1).clamp(min, max))
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: null,
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onDecrease: onChanged != null
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? () => onChanged((value - 0.1).clamp(min, max))
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: null,
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child: Slider(
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value: value,
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min: min,
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max: max,
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divisions: divisions,
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onChanged: onChanged,
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label: formattedValue,
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),
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);
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}
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/// Create accessible modal with focus management
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static Future<T?> showAccessibleModal<T>({
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required BuildContext context,
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required Widget child,
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required String title,
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bool barrierDismissible = true,
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}) {
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return showDialog<T>(
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context: context,
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barrierDismissible: barrierDismissible,
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builder: (context) => Semantics(
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scopesRoute: true,
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explicitChildNodes: true,
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label: 'Dialog: $title',
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child: AlertDialog(
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title: Semantics(header: true, child: Text(title)),
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content: child,
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),
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),
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);
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}
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/// Check color contrast ratio (simplified implementation)
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static bool hasGoodContrast(Color foreground, Color background) {
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// Simplified contrast calculation
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final fgLuminance = _getLuminance(foreground);
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final bgLuminance = _getLuminance(background);
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final lighter = fgLuminance > bgLuminance ? fgLuminance : bgLuminance;
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final darker = fgLuminance > bgLuminance ? bgLuminance : fgLuminance;
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final contrast = (lighter + 0.05) / (darker + 0.05);
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// WCAG AA requires 4.5:1 for normal text, 3:1 for large text
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return contrast >= 4.5;
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}
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/// Calculate relative luminance of a color
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static double _getLuminance(Color color) {
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final r = _gammaCorrect((color.r * 255.0).round() / 255.0);
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final g = _gammaCorrect((color.g * 255.0).round() / 255.0);
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final b = _gammaCorrect((color.b * 255.0).round() / 255.0);
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return 0.2126 * r + 0.7152 * g + 0.0722 * b;
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}
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/// Apply gamma correction
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static double _gammaCorrect(double value) {
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return value <= 0.03928
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? value / 12.92
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: math.pow((value + 0.055) / 1.055, 2.4).toDouble();
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}
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/// Provide haptic feedback if available
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static void hapticFeedback() {
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HapticFeedback.lightImpact();
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}
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/// Create accessible focus border
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static BoxDecoration createFocusBorder({
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required bool hasFocus,
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Color? focusColor,
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double borderWidth = 2.0,
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BorderRadius? borderRadius,
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}) {
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return BoxDecoration(
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border: hasFocus
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? Border.all(
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color:
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focusColor ??
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AppTheme.brandPrimary, // Brand primary as fallback
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width: borderWidth,
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)
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: null,
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borderRadius: borderRadius,
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);
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}
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/// Create accessible text with proper scaling
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static Widget createAccessibleText(
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String text, {
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TextStyle? style,
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TextAlign? textAlign,
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bool isHeader = false,
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int? maxLines,
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}) {
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return Builder(
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builder: (context) {
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final textScaleFactor = getBoundedTextScaleFactor(context);
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Widget textWidget = Text(
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text,
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style:
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style?.copyWith(
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fontSize: style.fontSize != null
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? style.fontSize! * textScaleFactor
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: null,
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) ??
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TextStyle(fontSize: AppTypography.bodyLarge * textScaleFactor),
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textAlign: textAlign,
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maxLines: maxLines,
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overflow: maxLines != null ? TextOverflow.ellipsis : null,
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);
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if (isHeader) {
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textWidget = Semantics(header: true, child: textWidget);
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}
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return textWidget;
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},
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);
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}
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}
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