feat: import Chinese-localized Buzz source snapshot

Signed-off-by: cls_宁波本机 <908705107@qq.com>

mobile/lib/shared/widgets/frosted_app_bar.dart

@@ -0,0 +1,298 @@
+import 'dart:ui';
+
+import 'package:flutter/material.dart';
+import 'package:lucide_icons_flutter/lucide_icons.dart';
+
+import '../l10n/l10n.dart';
+import '../theme/theme.dart';
+import 'directional_transition_scope.dart';
+
+/// Minimum height of the frosted app bar content area below the safe area.
+const _kBarContentMinHeight = Grid.xxs + 32 + Grid.xxs; // 48
+const _kBottomBorderWidth = 1.0;
+
+TextStyle _effectiveTitleStyle(BuildContext context, TextStyle? titleStyle) {
+  final baseStyle =
+      context.textTheme.titleMedium ??
+      const TextStyle(fontSize: 20, height: 1.3);
+  return baseStyle.copyWith(fontWeight: FontWeight.w600).merge(titleStyle);
+}
+
+double _barContentHeight(
+  BuildContext context,
+  TextStyle? titleStyle,
+  double titleContentHeight,
+) {
+  final style = _effectiveTitleStyle(context, titleStyle);
+  final scaledFontSize = MediaQuery.textScalerOf(
+    context,
+  ).scale(style.fontSize ?? 20);
+  final scaledTitleHeight = scaledFontSize * (style.height ?? 1);
+  final effectiveTitleHeight = titleContentHeight > scaledTitleHeight
+      ? titleContentHeight
+      : scaledTitleHeight;
+  final accessibleHeight = Grid.xxs + effectiveTitleHeight + Grid.xxs;
+  return accessibleHeight > _kBarContentMinHeight
+      ? accessibleHeight
+      : _kBarContentMinHeight;
+}
+
+/// Height for a compact title rail below the app bar's action row.
+///
+/// The rail normally stays at 40dp, but grows with an accessible title rather
+/// than clipping text at larger system text sizes.
+double frostedAppBarLowerTitleHeight(
+  BuildContext context, {
+  TextStyle? titleStyle,
+}) {
+  final style = _effectiveTitleStyle(context, titleStyle);
+  final scaledFontSize = MediaQuery.textScalerOf(
+    context,
+  ).scale(style.fontSize ?? 20);
+  final titleHeight = scaledFontSize * (style.height ?? 1);
+  return titleHeight > 40 ? titleHeight : 40;
+}
+
+/// Returns the total height of the [FrostedAppBar] including safe area padding.
+///
+/// Use this to add top spacing to body content so it starts below the bar.
+/// Pass the same [titleStyle] and [titleContentHeight] to the bar and this
+/// helper when customizing them.
+double frostedAppBarHeight(
+  BuildContext context, {
+  double bottomHeight = 0,
+  TextStyle? titleStyle,
+  double titleContentHeight = 0,
+}) {
+  return MediaQuery.paddingOf(context).top +
+      _barContentHeight(context, titleStyle, titleContentHeight) +
+      bottomHeight +
+      _kBottomBorderWidth;
+}
+
+/// A frosted-glass floating app bar designed to sit inside a [Stack].
+///
+/// Renders as a [Positioned] widget pinned to the top of its parent Stack.
+/// Content scrolls underneath with a translucent backdrop blur effect.
+class FrostedAppBar extends StatelessWidget {
+  /// Widget displayed on the leading (left) side. If null and the navigator
+  /// can pop, a back button is shown automatically.
+  final Widget? leading;
+
+  /// Whether to infer a back button from the current navigator.
+  final bool automaticallyImplyLeading;
+
+  /// Widget displayed in the center/title area.
+  final Widget? title;
+
+  /// Optional style merged over the default title style.
+  final TextStyle? titleStyle;
+
+  /// Scaled height needed by a custom title with multiple text lines.
+  ///
+  /// Pass the same value to [frostedAppBarHeight] when spacing body content.
+  final double titleContentHeight;
+
+  /// Optional content displayed below the title row in the same surface.
+  final Widget? bottom;
+
+  /// Height reserved for [bottom].
+  final double bottomHeight;
+
+  /// Extends [bottom] upward into the title row without moving the app bar's
+  /// outer bounds. This keeps overlapping controls inside the app bar's hit
+  /// test region as well as its paint region.
+  final double bottomOverlap;
+
+  /// Widgets displayed on the trailing (right) side.
+  final List<Widget> actions;
+
+  /// Horizontal inset for the app bar's leading, title, and actions.
+  final double horizontalInset;
+
+  /// Color applied to icons in the app bar.
+  final Color? iconColor;
+
+  /// Paints over the frosted fill instead of the default translucent surface.
+  /// Used by the Buzz themes to carry their branded gradient across the app's
+  /// top section — see [buzzTopSectionGradient].
+  final Gradient? gradient;
+
+  /// Whether to apply the translucent blur treatment behind the app bar.
+  ///
+  /// A page can leave its painted backdrop exposed at rest, then turn this on
+  /// when scrolling moves content beneath the controls.
+  final bool frosted;
+
+  /// Opacity of the frosted surface above the blurred backdrop.
+  final double frostedSurfaceOpacity;
+
+  /// Blur strength of the frosted backdrop.
+  final double frostedBlurSigma;
+
+  /// Whether to draw a divider below the app bar.
+  final bool showBottomDivider;
+
+  /// Opacity of the divider below the app bar.
+  final double bottomDividerOpacity;
+
+  const FrostedAppBar({
+    super.key,
+    this.leading,
+    this.automaticallyImplyLeading = true,
+    this.title,
+    this.titleStyle,
+    this.titleContentHeight = 0,
+    this.bottom,
+    this.bottomHeight = 0,
+    this.bottomOverlap = 0,
+    this.actions = const [],
+    this.horizontalInset = Grid.quarter,
+    this.iconColor,
+    this.gradient,
+    this.frosted = true,
+    this.frostedSurfaceOpacity = 0.5,
+    this.frostedBlurSigma = 20,
+    this.showBottomDivider = true,
+    this.bottomDividerOpacity = 0.15,
+  }) : assert(bottom == null || bottomHeight > 0),
+       assert(bottomOverlap >= 0),
+       assert(bottom != null || bottomOverlap == 0),
+       assert(frostedBlurSigma >= 0),
+       assert(bottomDividerOpacity >= 0 && bottomDividerOpacity <= 1);
+
+  @override
+  Widget build(BuildContext context) {
+    final topPadding = MediaQuery.paddingOf(context).top;
+    final canPop = Navigator.canPop(context);
+    final effectiveTitleStyle = _effectiveTitleStyle(context, titleStyle);
+    final barContentHeight = _barContentHeight(
+      context,
+      titleStyle,
+      titleContentHeight,
+    );
+
+    final effectiveLeading =
+        leading ??
+        (automaticallyImplyLeading && canPop
+            ? SizedBox(
+                width: 48,
+                height: 48,
+                child: IconButton(
+                  onPressed: () => Navigator.of(context).pop(),
+                  color: iconColor,
+                  icon: const Icon(LucideIcons.chevronLeft),
+                  tooltip: context.l10n.back,
+                ),
+              )
+            : null);
+
+    final titleRow = SizedBox(
+      height: barContentHeight,
+      child: Padding(
+        padding: EdgeInsets.symmetric(horizontal: horizontalInset),
+        child: IconTheme.merge(
+          data: IconThemeData(color: iconColor),
+          child: Row(
+            children: [
+              ?effectiveLeading,
+              if (title != null)
+                Expanded(
+                  child: Padding(
+                    padding: EdgeInsets.only(
+                      left: effectiveLeading != null
+                          ? 0
+                          : horizontalInset < Grid.gutter
+                          ? Grid.gutter - horizontalInset
+                          : 0,
+                      right: actions.isEmpty
+                          ? horizontalInset < Grid.gutter
+                                ? Grid.gutter - horizontalInset
+                                : 0
+                          : 0,
+                    ),
+                    child: DefaultTextStyle.merge(
+                      style: effectiveTitleStyle,
+                      overflow: TextOverflow.ellipsis,
+                      maxLines: 1,
+                      child: title!,
+                    ),
+                  ),
+                )
+              else
+                const Spacer(),
+              ...actions,
+            ],
+          ),
+        ),
+      ),
+    );
+    final contentBody = bottom != null && bottomOverlap > 0
+        ? SizedBox(
+            height: barContentHeight + bottomHeight,
+            child: Stack(
+              children: [
+                Positioned(top: 0, left: 0, right: 0, child: titleRow),
+                Positioned(
+                  top: barContentHeight - bottomOverlap,
+                  left: 0,
+                  right: 0,
+                  height: bottomHeight + bottomOverlap,
+                  child: bottom!,
+                ),
+              ],
+            ),
+          )
+        : Column(
+            mainAxisSize: MainAxisSize.min,
+            children: [
+              titleRow,
+              if (bottom != null) SizedBox(height: bottomHeight, child: bottom),
+            ],
+          );
+
+    final content = DirectionalTransitionMotion(
+      transformKey: const ValueKey(
+        'frosted-app-bar-content-transition-transform',
+      ),
+      opacityKey: const ValueKey('frosted-app-bar-content-transition-opacity'),
+      child: contentBody,
+    );
+
+    final background = Container(
+      key: const ValueKey('frosted-app-bar-background'),
+      padding: EdgeInsets.only(top: topPadding),
+      decoration: BoxDecoration(
+        color: !frosted
+            ? Colors.transparent
+            : gradient == null
+            ? context.colors.surface.withValues(alpha: frostedSurfaceOpacity)
+            : null,
+        gradient: gradient,
+        border: showBottomDivider
+            ? Border(
+                bottom: BorderSide(
+                  color: navigationDivider(context, bottomDividerOpacity),
+                  width: _kBottomBorderWidth,
+                ),
+              )
+            : null,
+      ),
+      child: content,
+    );
+
+    final child = ClipRect(
+      child: frosted
+          ? BackdropFilter(
+              filter: ImageFilter.blur(
+                sigmaX: frostedBlurSigma,
+                sigmaY: frostedBlurSigma,
+              ),
+              child: background,
+            )
+          : background,
+    );
+
+    return Positioned(top: 0, left: 0, right: 0, child: child);
+  }
+}