Make app bar in home pages translucent when scrolled

app/lib/widget/home_app_bar.dart

@@ -12,6 +12,7 @@ import 'package:nc_photos/widget/account_picker_dialog.dart';
 import 'package:nc_photos/widget/app_bar_circular_progress_indicator.dart';
 import 'package:nc_photos/widget/app_bar_title_container.dart';
 import 'package:nc_photos/widget/settings.dart';
+import 'package:nc_photos/widget/translucent_sliver_app_bar.dart';
 
 /// AppBar for home screens
 class HomeSliverAppBar extends StatelessWidget {
@@ -27,7 +28,7 @@ class HomeSliverAppBar extends StatelessWidget {
   @override
   build(BuildContext context) {
     final accountLabel = AccountPref.of(account).getAccountLabel();
-    return SliverAppBar(
+    return TranslucentSliverAppBar(
       title: InkWell(
         onTap: () {
           showDialog(
@@ -53,6 +54,8 @@ class HomeSliverAppBar extends StatelessWidget {
                     )),
         ),
       ),
+      scrolledUnderBackgroundColor:
+          Theme.of(context).homeNavigationBarBackgroundColor,
       floating: true,
       automaticallyImplyLeading: false,
       actions: (actions ?? []) +

app/lib/widget/translucent_sliver_app_bar.dart

@@ -0,0 +1,708 @@
+// ignore_for_file: deprecated_member_use, unnecessary_null_comparison, curly_braces_in_flow_control_structures, deprecated_member_use_from_same_package
+
+import 'dart:math' as math;
+import 'dart:ui';
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
+import 'package:flutter/services.dart';
+
+/// A translucent sliver app bar used in home pages
+///
+/// This calss is adopted from Flutter's SliverAppBar
+class TranslucentSliverAppBar extends StatefulWidget {
+  /// Creates a material design app bar that can be placed in a [CustomScrollView].
+  ///
+  /// The arguments [forceElevated], [primary], [floating], [pinned], [snap]
+  /// and [automaticallyImplyLeading] must not be null.
+  const TranslucentSliverAppBar({
+    Key? key,
+    this.leading,
+    this.automaticallyImplyLeading = true,
+    this.title,
+    this.actions,
+    this.flexibleSpace,
+    this.bottom,
+    this.elevation,
+    this.shadowColor,
+    this.surfaceTintColor,
+    this.forceElevated = false,
+    this.backgroundColor,
+    this.scrolledUnderBackgroundColor,
+    this.foregroundColor,
+    @Deprecated(
+      'This property is no longer used, please use systemOverlayStyle instead. '
+      'This feature was deprecated after v2.4.0-0.0.pre.',
+    )
+        this.brightness,
+    this.iconTheme,
+    this.actionsIconTheme,
+    @Deprecated(
+      'This property is no longer used, please use toolbarTextStyle and titleTextStyle instead. '
+      'This feature was deprecated after v2.4.0-0.0.pre.',
+    )
+        this.textTheme,
+    this.primary = true,
+    this.centerTitle,
+    this.excludeHeaderSemantics = false,
+    this.titleSpacing,
+    this.collapsedHeight,
+    this.expandedHeight,
+    this.floating = false,
+    this.pinned = false,
+    this.snap = false,
+    this.stretch = false,
+    this.stretchTriggerOffset = 100.0,
+    this.onStretchTrigger,
+    this.shape,
+    this.toolbarHeight = kToolbarHeight,
+    this.leadingWidth,
+    @Deprecated(
+      'This property is obsolete and is false by default. '
+      'This feature was deprecated after v2.4.0-0.0.pre.',
+    )
+        this.backwardsCompatibility,
+    this.toolbarTextStyle,
+    this.titleTextStyle,
+    this.systemOverlayStyle,
+  })  : assert(automaticallyImplyLeading != null),
+        assert(forceElevated != null),
+        assert(primary != null),
+        assert(floating != null),
+        assert(pinned != null),
+        assert(snap != null),
+        assert(stretch != null),
+        assert(toolbarHeight != null),
+        assert(floating || !snap,
+            'The "snap" argument only makes sense for floating app bars.'),
+        assert(stretchTriggerOffset > 0.0),
+        assert(collapsedHeight == null || collapsedHeight >= toolbarHeight,
+            'The "collapsedHeight" argument has to be larger than or equal to [toolbarHeight].'),
+        super(key: key);
+
+  /// {@macro flutter.material.appbar.leading}
+  ///
+  /// This property is used to configure an [AppBar].
+  final Widget? leading;
+
+  /// {@macro flutter.material.appbar.automaticallyImplyLeading}
+  ///
+  /// This property is used to configure an [AppBar].
+  final bool automaticallyImplyLeading;
+
+  /// {@macro flutter.material.appbar.title}
+  ///
+  /// This property is used to configure an [AppBar].
+  final Widget? title;
+
+  /// {@macro flutter.material.appbar.actions}
+  ///
+  /// This property is used to configure an [AppBar].
+  final List<Widget>? actions;
+
+  /// {@macro flutter.material.appbar.flexibleSpace}
+  ///
+  /// This property is used to configure an [AppBar].
+  final Widget? flexibleSpace;
+
+  /// {@macro flutter.material.appbar.bottom}
+  ///
+  /// This property is used to configure an [AppBar].
+  final PreferredSizeWidget? bottom;
+
+  /// {@macro flutter.material.appbar.elevation}
+  ///
+  /// This property is used to configure an [AppBar].
+  final double? elevation;
+
+  /// {@macro flutter.material.appbar.shadowColor}
+  ///
+  /// This property is used to configure an [AppBar].
+  final Color? shadowColor;
+
+  /// {@macro flutter.material.appbar.surfaceTintColor}
+  ///
+  /// This property is used to configure an [AppBar].
+  final Color? surfaceTintColor;
+
+  /// Whether to show the shadow appropriate for the [elevation] even if the
+  /// content is not scrolled under the [AppBar].
+  ///
+  /// Defaults to false, meaning that the [elevation] is only applied when the
+  /// [AppBar] is being displayed over content that is scrolled under it.
+  ///
+  /// When set to true, the [elevation] is applied regardless.
+  ///
+  /// Ignored when [elevation] is zero.
+  final bool forceElevated;
+
+  /// {@macro flutter.material.appbar.backgroundColor}
+  ///
+  /// This property is used to configure an [AppBar].
+  final Color? backgroundColor;
+
+  final Color? scrolledUnderBackgroundColor;
+
+  /// {@macro flutter.material.appbar.foregroundColor}
+  ///
+  /// This property is used to configure an [AppBar].
+  final Color? foregroundColor;
+
+  /// {@macro flutter.material.appbar.brightness}
+  ///
+  /// This property is used to configure an [AppBar].
+  @Deprecated(
+    'This property is no longer used, please use systemOverlayStyle instead. '
+    'This feature was deprecated after v2.4.0-0.0.pre.',
+  )
+  final Brightness? brightness;
+
+  /// {@macro flutter.material.appbar.iconTheme}
+  ///
+  /// This property is used to configure an [AppBar].
+  final IconThemeData? iconTheme;
+
+  /// {@macro flutter.material.appbar.actionsIconTheme}
+  ///
+  /// This property is used to configure an [AppBar].
+  final IconThemeData? actionsIconTheme;
+
+  /// {@macro flutter.material.appbar.textTheme}
+  ///
+  /// This property is used to configure an [AppBar].
+  @Deprecated(
+    'This property is no longer used, please use toolbarTextStyle and titleTextStyle instead. '
+    'This feature was deprecated after v2.4.0-0.0.pre.',
+  )
+  final TextTheme? textTheme;
+
+  /// {@macro flutter.material.appbar.primary}
+  ///
+  /// This property is used to configure an [AppBar].
+  final bool primary;
+
+  /// {@macro flutter.material.appbar.centerTitle}
+  ///
+  /// This property is used to configure an [AppBar].
+  final bool? centerTitle;
+
+  /// {@macro flutter.material.appbar.excludeHeaderSemantics}
+  ///
+  /// This property is used to configure an [AppBar].
+  final bool excludeHeaderSemantics;
+
+  /// {@macro flutter.material.appbar.titleSpacing}
+  ///
+  /// This property is used to configure an [AppBar].
+  final double? titleSpacing;
+
+  /// Defines the height of the app bar when it is collapsed.
+  ///
+  /// By default, the collapsed height is [toolbarHeight]. If [bottom] widget is
+  /// specified, then its height from [PreferredSizeWidget.preferredSize] is
+  /// added to the height. If [primary] is true, then the [MediaQuery] top
+  /// padding, [EdgeInsets.top] of [MediaQueryData.padding], is added as well.
+  ///
+  /// If [pinned] and [floating] are true, with [bottom] set, the default
+  /// collapsed height is only the height of [PreferredSizeWidget.preferredSize]
+  /// with the [MediaQuery] top padding.
+  final double? collapsedHeight;
+
+  /// The size of the app bar when it is fully expanded.
+  ///
+  /// By default, the total height of the toolbar and the bottom widget (if
+  /// any). If a [flexibleSpace] widget is specified this height should be big
+  /// enough to accommodate whatever that widget contains.
+  ///
+  /// This does not include the status bar height (which will be automatically
+  /// included if [primary] is true).
+  final double? expandedHeight;
+
+  /// Whether the app bar should become visible as soon as the user scrolls
+  /// towards the app bar.
+  ///
+  /// Otherwise, the user will need to scroll near the top of the scroll view to
+  /// reveal the app bar.
+  ///
+  /// If [snap] is true then a scroll that exposes the app bar will trigger an
+  /// animation that slides the entire app bar into view. Similarly if a scroll
+  /// dismisses the app bar, the animation will slide it completely out of view.
+  ///
+  /// ## Animated Examples
+  ///
+  /// The following animations show how the app bar changes its scrolling
+  /// behavior based on the value of this property.
+  ///
+  /// * App bar with [floating] set to false:
+  ///   {@animation 476 400 https://flutter.github.io/assets-for-api-docs/assets/material/app_bar.mp4}
+  /// * App bar with [floating] set to true:
+  ///   {@animation 476 400 https://flutter.github.io/assets-for-api-docs/assets/material/app_bar_floating.mp4}
+  ///
+  /// See also:
+  ///
+  ///  * [SliverAppBar] for more animated examples of how this property changes the
+  ///    behavior of the app bar in combination with [pinned] and [snap].
+  final bool floating;
+
+  /// Whether the app bar should remain visible at the start of the scroll view.
+  ///
+  /// The app bar can still expand and contract as the user scrolls, but it will
+  /// remain visible rather than being scrolled out of view.
+  ///
+  /// ## Animated Examples
+  ///
+  /// The following animations show how the app bar changes its scrolling
+  /// behavior based on the value of this property.
+  ///
+  /// * App bar with [pinned] set to false:
+  ///   {@animation 476 400 https://flutter.github.io/assets-for-api-docs/assets/material/app_bar.mp4}
+  /// * App bar with [pinned] set to true:
+  ///   {@animation 476 400 https://flutter.github.io/assets-for-api-docs/assets/material/app_bar_pinned.mp4}
+  ///
+  /// See also:
+  ///
+  ///  * [SliverAppBar] for more animated examples of how this property changes the
+  ///    behavior of the app bar in combination with [floating].
+  final bool pinned;
+
+  /// {@macro flutter.material.appbar.shape}
+  ///
+  /// This property is used to configure an [AppBar].
+  final ShapeBorder? shape;
+
+  /// If [snap] and [floating] are true then the floating app bar will "snap"
+  /// into view.
+  ///
+  /// If [snap] is true then a scroll that exposes the floating app bar will
+  /// trigger an animation that slides the entire app bar into view. Similarly
+  /// if a scroll dismisses the app bar, the animation will slide the app bar
+  /// completely out of view. Additionally, setting [snap] to true will fully
+  /// expand the floating app bar when the framework tries to reveal the
+  /// contents of the app bar by calling [RenderObject.showOnScreen]. For
+  /// example, when a [TextField] in the floating app bar gains focus, if [snap]
+  /// is true, the framework will always fully expand the floating app bar, in
+  /// order to reveal the focused [TextField].
+  ///
+  /// Snapping only applies when the app bar is floating, not when the app bar
+  /// appears at the top of its scroll view.
+  ///
+  /// ## Animated Examples
+  ///
+  /// The following animations show how the app bar changes its scrolling
+  /// behavior based on the value of this property.
+  ///
+  /// * App bar with [snap] set to false:
+  ///   {@animation 476 400 https://flutter.github.io/assets-for-api-docs/assets/material/app_bar_floating.mp4}
+  /// * App bar with [snap] set to true:
+  ///   {@animation 476 400 https://flutter.github.io/assets-for-api-docs/assets/material/app_bar_floating_snap.mp4}
+  ///
+  /// See also:
+  ///
+  ///  * [SliverAppBar] for more animated examples of how this property changes the
+  ///    behavior of the app bar in combination with [pinned] and [floating].
+  final bool snap;
+
+  /// Whether the app bar should stretch to fill the over-scroll area.
+  ///
+  /// The app bar can still expand and contract as the user scrolls, but it will
+  /// also stretch when the user over-scrolls.
+  final bool stretch;
+
+  /// The offset of overscroll required to activate [onStretchTrigger].
+  ///
+  /// This defaults to 100.0.
+  final double stretchTriggerOffset;
+
+  /// The callback function to be executed when a user over-scrolls to the
+  /// offset specified by [stretchTriggerOffset].
+  final AsyncCallback? onStretchTrigger;
+
+  /// {@macro flutter.material.appbar.toolbarHeight}
+  ///
+  /// This property is used to configure an [AppBar].
+  final double toolbarHeight;
+
+  /// {@macro flutter.material.appbar.leadingWidth}
+  ///
+  /// This property is used to configure an [AppBar].
+  final double? leadingWidth;
+
+  /// {@macro flutter.material.appbar.backwardsCompatibility}
+  ///
+  /// This property is used to configure an [AppBar].
+  @Deprecated(
+    'This property is obsolete and is false by default. '
+    'This feature was deprecated after v2.4.0-0.0.pre.',
+  )
+  final bool? backwardsCompatibility;
+
+  /// {@macro flutter.material.appbar.toolbarTextStyle}
+  ///
+  /// This property is used to configure an [AppBar].
+  final TextStyle? toolbarTextStyle;
+
+  /// {@macro flutter.material.appbar.titleTextStyle}
+  ///
+  /// This property is used to configure an [AppBar].
+  final TextStyle? titleTextStyle;
+
+  /// {@macro flutter.material.appbar.systemOverlayStyle}
+  ///
+  /// This property is used to configure an [AppBar].
+  final SystemUiOverlayStyle? systemOverlayStyle;
+
+  @override
+  State<TranslucentSliverAppBar> createState() => _SliverAppBarState();
+}
+
+class _SliverAppBarState extends State<TranslucentSliverAppBar>
+    with TickerProviderStateMixin {
+  FloatingHeaderSnapConfiguration? _snapConfiguration;
+  OverScrollHeaderStretchConfiguration? _stretchConfiguration;
+  PersistentHeaderShowOnScreenConfiguration? _showOnScreenConfiguration;
+
+  void _updateSnapConfiguration() {
+    if (widget.snap && widget.floating) {
+      _snapConfiguration = FloatingHeaderSnapConfiguration(
+        curve: Curves.easeOut,
+        duration: const Duration(milliseconds: 200),
+      );
+    } else {
+      _snapConfiguration = null;
+    }
+
+    _showOnScreenConfiguration = widget.floating & widget.snap
+        ? const PersistentHeaderShowOnScreenConfiguration(
+            minShowOnScreenExtent: double.infinity)
+        : null;
+  }
+
+  void _updateStretchConfiguration() {
+    if (widget.stretch) {
+      _stretchConfiguration = OverScrollHeaderStretchConfiguration(
+        stretchTriggerOffset: widget.stretchTriggerOffset,
+        onStretchTrigger: widget.onStretchTrigger,
+      );
+    } else {
+      _stretchConfiguration = null;
+    }
+  }
+
+  @override
+  void initState() {
+    super.initState();
+    _updateSnapConfiguration();
+    _updateStretchConfiguration();
+  }
+
+  @override
+  void didUpdateWidget(TranslucentSliverAppBar oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    if (widget.snap != oldWidget.snap || widget.floating != oldWidget.floating)
+      _updateSnapConfiguration();
+    if (widget.stretch != oldWidget.stretch) _updateStretchConfiguration();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    assert(!widget.primary || debugCheckHasMediaQuery(context));
+    final double bottomHeight = widget.bottom?.preferredSize.height ?? 0.0;
+    final double topPadding =
+        widget.primary ? MediaQuery.of(context).padding.top : 0.0;
+    final double collapsedHeight =
+        (widget.pinned && widget.floating && widget.bottom != null)
+            ? (widget.collapsedHeight ?? 0.0) + bottomHeight + topPadding
+            : (widget.collapsedHeight ?? widget.toolbarHeight) +
+                bottomHeight +
+                topPadding;
+
+    return MediaQuery.removePadding(
+      context: context,
+      removeBottom: true,
+      child: SliverPersistentHeader(
+        floating: widget.floating,
+        pinned: widget.pinned,
+        delegate: _SliverAppBarDelegate(
+          vsync: this,
+          leading: widget.leading,
+          automaticallyImplyLeading: widget.automaticallyImplyLeading,
+          title: widget.title,
+          actions: widget.actions,
+          flexibleSpace: widget.flexibleSpace,
+          bottom: widget.bottom,
+          elevation: widget.elevation,
+          shadowColor: widget.shadowColor,
+          surfaceTintColor: widget.surfaceTintColor,
+          forceElevated: widget.forceElevated,
+          backgroundColor: widget.backgroundColor,
+          scrolledUnderBackgroundColor: widget.scrolledUnderBackgroundColor,
+          foregroundColor: widget.foregroundColor,
+          brightness: widget.brightness,
+          iconTheme: widget.iconTheme,
+          actionsIconTheme: widget.actionsIconTheme,
+          textTheme: widget.textTheme,
+          primary: widget.primary,
+          centerTitle: widget.centerTitle,
+          excludeHeaderSemantics: widget.excludeHeaderSemantics,
+          titleSpacing: widget.titleSpacing,
+          expandedHeight: widget.expandedHeight,
+          collapsedHeight: collapsedHeight,
+          topPadding: topPadding,
+          floating: widget.floating,
+          pinned: widget.pinned,
+          shape: widget.shape,
+          snapConfiguration: _snapConfiguration,
+          stretchConfiguration: _stretchConfiguration,
+          showOnScreenConfiguration: _showOnScreenConfiguration,
+          toolbarHeight: widget.toolbarHeight,
+          leadingWidth: widget.leadingWidth,
+          backwardsCompatibility: widget.backwardsCompatibility,
+          toolbarTextStyle: widget.toolbarTextStyle,
+          titleTextStyle: widget.titleTextStyle,
+          systemOverlayStyle: widget.systemOverlayStyle,
+        ),
+      ),
+    );
+  }
+}
+
+class _SliverAppBarDelegate extends SliverPersistentHeaderDelegate {
+  _SliverAppBarDelegate({
+    required this.leading,
+    required this.automaticallyImplyLeading,
+    required this.title,
+    required this.actions,
+    required this.flexibleSpace,
+    required this.bottom,
+    required this.elevation,
+    required this.shadowColor,
+    required this.surfaceTintColor,
+    required this.forceElevated,
+    required this.backgroundColor,
+    required this.scrolledUnderBackgroundColor,
+    required this.foregroundColor,
+    required this.brightness,
+    required this.iconTheme,
+    required this.actionsIconTheme,
+    required this.textTheme,
+    required this.primary,
+    required this.centerTitle,
+    required this.excludeHeaderSemantics,
+    required this.titleSpacing,
+    required this.expandedHeight,
+    required this.collapsedHeight,
+    required this.topPadding,
+    required this.floating,
+    required this.pinned,
+    required this.vsync,
+    required this.snapConfiguration,
+    required this.stretchConfiguration,
+    required this.showOnScreenConfiguration,
+    required this.shape,
+    required this.toolbarHeight,
+    required this.leadingWidth,
+    required this.backwardsCompatibility,
+    required this.toolbarTextStyle,
+    required this.titleTextStyle,
+    required this.systemOverlayStyle,
+  })  : assert(primary || topPadding == 0.0),
+        assert(
+          !floating ||
+              (snapConfiguration == null &&
+                  showOnScreenConfiguration == null) ||
+              vsync != null,
+          'vsync cannot be null when snapConfiguration or showOnScreenConfiguration is not null, and floating is true',
+        ),
+        _bottomHeight = bottom?.preferredSize.height ?? 0.0;
+
+  final Widget? leading;
+  final bool automaticallyImplyLeading;
+  final Widget? title;
+  final List<Widget>? actions;
+  final Widget? flexibleSpace;
+  final PreferredSizeWidget? bottom;
+  final double? elevation;
+  final Color? shadowColor;
+  final Color? surfaceTintColor;
+  final bool forceElevated;
+  final Color? backgroundColor;
+  final Color? scrolledUnderBackgroundColor;
+  final Color? foregroundColor;
+  final Brightness? brightness;
+  final IconThemeData? iconTheme;
+  final IconThemeData? actionsIconTheme;
+  final TextTheme? textTheme;
+  final bool primary;
+  final bool? centerTitle;
+  final bool excludeHeaderSemantics;
+  final double? titleSpacing;
+  final double? expandedHeight;
+  final double collapsedHeight;
+  final double topPadding;
+  final bool floating;
+  final bool pinned;
+  final ShapeBorder? shape;
+  final double? toolbarHeight;
+  final double? leadingWidth;
+  final bool? backwardsCompatibility;
+  final TextStyle? toolbarTextStyle;
+  final TextStyle? titleTextStyle;
+  final SystemUiOverlayStyle? systemOverlayStyle;
+  final double _bottomHeight;
+
+  @override
+  double get minExtent => collapsedHeight;
+
+  @override
+  double get maxExtent => math.max(
+      topPadding +
+          (expandedHeight ?? (toolbarHeight ?? kToolbarHeight) + _bottomHeight),
+      minExtent);
+
+  @override
+  final TickerProvider vsync;
+
+  @override
+  final FloatingHeaderSnapConfiguration? snapConfiguration;
+
+  @override
+  final OverScrollHeaderStretchConfiguration? stretchConfiguration;
+
+  @override
+  final PersistentHeaderShowOnScreenConfiguration? showOnScreenConfiguration;
+
+  @override
+  Widget build(
+      BuildContext context, double shrinkOffset, bool overlapsContent) {
+    final double visibleMainHeight = maxExtent - shrinkOffset - topPadding;
+    final double extraToolbarHeight = math.max(
+        minExtent -
+            _bottomHeight -
+            topPadding -
+            (toolbarHeight ?? kToolbarHeight),
+        0.0);
+    final double visibleToolbarHeight =
+        visibleMainHeight - _bottomHeight - extraToolbarHeight;
+
+    final bool isScrolledUnder =
+        overlapsContent || (pinned && shrinkOffset > maxExtent - minExtent);
+    final bool isPinnedWithOpacityFade =
+        pinned && floating && bottom != null && extraToolbarHeight == 0.0;
+    final double toolbarOpacity = !pinned || isPinnedWithOpacityFade
+        ? (visibleToolbarHeight / (toolbarHeight ?? kToolbarHeight))
+            .clamp(0.0, 1.0)
+        : 1.0;
+
+    final Widget appBar = FlexibleSpaceBar.createSettings(
+      minExtent: minExtent,
+      maxExtent: maxExtent,
+      currentExtent: math.max(minExtent, maxExtent - shrinkOffset),
+      toolbarOpacity: toolbarOpacity,
+      isScrolledUnder: isScrolledUnder,
+      child: Stack(
+        children: [
+          SizedBox(
+            width: double.infinity,
+            height: math.max(minExtent, maxExtent - shrinkOffset),
+            child: ClipRect(
+              child: BackdropFilter(
+                filter: ImageFilter.blur(sigmaX: 4, sigmaY: 4),
+                child: const ColoredBox(
+                  color: Colors.transparent,
+                ),
+              ),
+            ),
+          ),
+          AppBar(
+            leading: leading,
+            automaticallyImplyLeading: automaticallyImplyLeading,
+            title: title,
+            actions: actions,
+            flexibleSpace: (title == null &&
+                    flexibleSpace != null &&
+                    !excludeHeaderSemantics)
+                ? Semantics(
+                    header: true,
+                    child: flexibleSpace,
+                  )
+                : flexibleSpace,
+            bottom: bottom,
+            elevation: forceElevated || isScrolledUnder ? elevation : 0.0,
+            scrolledUnderElevation: 0,
+            shadowColor: shadowColor,
+            surfaceTintColor: surfaceTintColor,
+            backgroundColor: isScrolledUnder
+                ? scrolledUnderBackgroundColor
+                : backgroundColor,
+            foregroundColor: foregroundColor,
+            brightness: brightness,
+            iconTheme: iconTheme,
+            actionsIconTheme: actionsIconTheme,
+            textTheme: textTheme,
+            primary: primary,
+            centerTitle: centerTitle,
+            excludeHeaderSemantics: excludeHeaderSemantics,
+            titleSpacing: titleSpacing,
+            shape: shape,
+            toolbarOpacity: toolbarOpacity,
+            bottomOpacity: pinned
+                ? 1.0
+                : ((visibleMainHeight / _bottomHeight).clamp(0.0, 1.0)),
+            toolbarHeight: toolbarHeight,
+            leadingWidth: leadingWidth,
+            backwardsCompatibility: backwardsCompatibility,
+            toolbarTextStyle: toolbarTextStyle,
+            titleTextStyle: titleTextStyle,
+            systemOverlayStyle: systemOverlayStyle,
+          ),
+        ],
+      ),
+    );
+    return appBar;
+  }
+
+  @override
+  bool shouldRebuild(covariant _SliverAppBarDelegate oldDelegate) {
+    return leading != oldDelegate.leading ||
+        automaticallyImplyLeading != oldDelegate.automaticallyImplyLeading ||
+        title != oldDelegate.title ||
+        actions != oldDelegate.actions ||
+        flexibleSpace != oldDelegate.flexibleSpace ||
+        bottom != oldDelegate.bottom ||
+        _bottomHeight != oldDelegate._bottomHeight ||
+        elevation != oldDelegate.elevation ||
+        shadowColor != oldDelegate.shadowColor ||
+        backgroundColor != oldDelegate.backgroundColor ||
+        scrolledUnderBackgroundColor !=
+            oldDelegate.scrolledUnderBackgroundColor ||
+        foregroundColor != oldDelegate.foregroundColor ||
+        brightness != oldDelegate.brightness ||
+        iconTheme != oldDelegate.iconTheme ||
+        actionsIconTheme != oldDelegate.actionsIconTheme ||
+        textTheme != oldDelegate.textTheme ||
+        primary != oldDelegate.primary ||
+        centerTitle != oldDelegate.centerTitle ||
+        titleSpacing != oldDelegate.titleSpacing ||
+        expandedHeight != oldDelegate.expandedHeight ||
+        topPadding != oldDelegate.topPadding ||
+        pinned != oldDelegate.pinned ||
+        floating != oldDelegate.floating ||
+        vsync != oldDelegate.vsync ||
+        snapConfiguration != oldDelegate.snapConfiguration ||
+        stretchConfiguration != oldDelegate.stretchConfiguration ||
+        showOnScreenConfiguration != oldDelegate.showOnScreenConfiguration ||
+        forceElevated != oldDelegate.forceElevated ||
+        toolbarHeight != oldDelegate.toolbarHeight ||
+        leadingWidth != oldDelegate.leadingWidth ||
+        backwardsCompatibility != oldDelegate.backwardsCompatibility ||
+        toolbarTextStyle != oldDelegate.toolbarTextStyle ||
+        titleTextStyle != oldDelegate.titleTextStyle ||
+        systemOverlayStyle != oldDelegate.systemOverlayStyle;
+  }
+
+  @override
+  String toString() {
+    return '${describeIdentity(this)}(topPadding: ${topPadding.toStringAsFixed(1)}, bottomHeight: ${_bottomHeight.toStringAsFixed(1)}, ...)';
+  }
+}