A Material Design app bar that integrates with a CustomScrollView.

An app bar consists of a toolbar and potentially other widgets, such as a TabBar and a FlexibleSpaceBar. App bars typically expose one or more common actions with IconButtons which are optionally followed by a PopupMenuButton for less common operations.

Sliver app bars are typically used as the first child of a CustomScrollView, which lets the app bar integrate with the scroll view so that it can vary in height according to the scroll offset or float above the other content in the scroll view. For a fixed-height app bar at the top of the screen see AppBar, which is used in the Scaffold.appBar slot.

The AppBar displays the toolbar widgets, leading, title, and actions, above the bottom (if any). If a flexibleSpace widget is specified then it is stacked behind the toolbar and the bottom widget.

SliverAppBar(
  expandedHeight: 150.0,
  flexibleSpace: const FlexibleSpaceBar(
    title: Text('Available seats'),
  ),
  actions: <Widget>[
    IconButton(
      icon: const Icon(Icons.add_circle),
      tooltip: 'Add new entry',
      onPressed: () { /* ... */ },
    ),
  ]
)

Animated Examples

The following animations show how app bars with different configurations behave when a user scrolls up and then down again.

• App bar with floating: false, pinned: false, snap: false:

• App bar with floating: true, pinned: false, snap: false:

• App bar with floating: true, pinned: false, snap: true:

• App bar with floating: true, pinned: true, snap: false:

• App bar with floating: true, pinned: true, snap: true:

• App bar with floating: false, pinned: true, snap: false:

The property snap can only be set to true if floating is also true.

See also:

• CustomScrollView, which integrates the SliverAppBar into its scrolling.
• AppBar, which is a fixed-height app bar for use in Scaffold.appBar.
• TabBar, which is typically placed in the bottom slot of the AppBar if the screen has multiple pages arranged in tabs.
• IconButton, which is used with actions to show buttons on the app bar.
• PopupMenuButton, to show a popup menu on the app bar, via actions.
• FlexibleSpaceBar, which is used with flexibleSpace when the app bar can expand and collapse.
• material.io/design/components/app-bars-top.html

Inheritance

• Object
• DiagnosticableTree
• Widget
• StatefulWidget
• SliverAppBar

Constructors

SliverAppBar({Key? key, Widget? leading, bool automaticallyImplyLeading = true, Widget? title, List<Widget>? actions, bool automaticallyImplyActions = true, Widget? flexibleSpace, PreferredSizeWidget? bottom, double? elevation, double? scrolledUnderElevation, Color? shadowColor, Color? surfaceTintColor, bool forceElevated = false, Color? backgroundColor, Color? foregroundColor, IconThemeData? iconTheme, IconThemeData? actionsIconTheme, bool primary = true, bool? centerTitle, double? titleSpacing, double? collapsedHeight, double? expandedHeight, bool floating = false, bool pinned = false, bool snap = false, bool stretch = false, double stretchTriggerOffset = 100.0, AsyncCallback? onStretchTrigger, ShapeBorder? shape, double toolbarHeight = kToolbarHeight, double? leadingWidth, TextStyle? toolbarTextStyle, TextStyle? titleTextStyle, SystemUiOverlayStyle? systemOverlayStyle, bool forceMaterialTransparency = false, bool useDefaultSemanticsOrder = true, Clip? clipBehavior, EdgeInsetsGeometry? actionsPadding})

Creates a Material Design app bar that can be placed in a CustomScrollView.

const

SliverAppBar.large({Key? key, Widget? leading, bool automaticallyImplyLeading = true, Widget? title, List<Widget>? actions, bool automaticallyImplyActions = true, Widget? flexibleSpace, PreferredSizeWidget? bottom, double? elevation, double? scrolledUnderElevation, Color? shadowColor, Color? surfaceTintColor, bool forceElevated = false, Color? backgroundColor, Color? foregroundColor, IconThemeData? iconTheme, IconThemeData? actionsIconTheme, bool primary = true, bool? centerTitle, double? titleSpacing, double? collapsedHeight, double? expandedHeight, bool floating = false, bool pinned = true, bool snap = false, bool stretch = false, double stretchTriggerOffset = 100.0, AsyncCallback? onStretchTrigger, ShapeBorder? shape, double toolbarHeight = _LargeScrollUnderFlexibleConfig.collapsedHeight, double? leadingWidth, TextStyle? toolbarTextStyle, TextStyle? titleTextStyle, SystemUiOverlayStyle? systemOverlayStyle, bool forceMaterialTransparency = false, bool useDefaultSemanticsOrder = true, Clip? clipBehavior, EdgeInsetsGeometry? actionsPadding})

Creates a Material Design large top app bar that can be placed in a CustomScrollView.

const

SliverAppBar.medium({Key? key, Widget? leading, bool automaticallyImplyLeading = true, Widget? title, List<Widget>? actions, bool automaticallyImplyActions = true, Widget? flexibleSpace, PreferredSizeWidget? bottom, double? elevation, double? scrolledUnderElevation, Color? shadowColor, Color? surfaceTintColor, bool forceElevated = false, Color? backgroundColor, Color? foregroundColor, IconThemeData? iconTheme, IconThemeData? actionsIconTheme, bool primary = true, bool? centerTitle, double? titleSpacing, double? collapsedHeight, double? expandedHeight, bool floating = false, bool pinned = true, bool snap = false, bool stretch = false, double stretchTriggerOffset = 100.0, AsyncCallback? onStretchTrigger, ShapeBorder? shape, double toolbarHeight = _MediumScrollUnderFlexibleConfig.collapsedHeight, double? leadingWidth, TextStyle? toolbarTextStyle, TextStyle? titleTextStyle, SystemUiOverlayStyle? systemOverlayStyle, bool forceMaterialTransparency = false, bool useDefaultSemanticsOrder = true, Clip? clipBehavior, EdgeInsetsGeometry? actionsPadding})

Creates a Material Design medium top app bar that can be placed in a CustomScrollView.

const

Properties

actions → List<Widget>?

A list of Widgets to display in a row after the title widget.

final

actionsIconTheme → IconThemeData?

The color, opacity, and size to use for the icons that appear in the app bar's actions.

final

actionsPadding → EdgeInsetsGeometry?

The padding between the actions and the end of the AppBar.

final

automaticallyImplyActions → bool

Controls whether we should try to imply the actions widget if null.

final

automaticallyImplyLeading → bool

Controls whether we should try to imply the leading widget if null.

final

backgroundColor → Color?

The fill color to use for an app bar's Material.

final

bottom → PreferredSizeWidget?

This widget appears across the bottom of the app bar.

final

centerTitle → bool?

Whether the title should be centered.

final

clipBehavior → Clip?

The content will be clipped (or not) according to this option.

final

collapsedHeight → double?

Defines the height of the app bar when it is collapsed.

final

elevation → double?

The z-coordinate at which to place this app bar relative to its parent.

final

Whether the title should be wrapped with header Semantics.

final

expandedHeight → double?

The size of the app bar when it is fully expanded.

final

flexibleSpace → Widget?

This widget is stacked behind the toolbar and the tab bar. Its height will be the same as the app bar's overall height.

final

floating → bool

Whether the app bar should become visible as soon as the user scrolls towards the app bar.

final

forceElevated → bool

Whether to show the shadow appropriate for the elevation even if the content is not scrolled under the AppBar.

final

forceMaterialTransparency → bool

Forces the AppBar's Material widget type to be MaterialType.transparency (instead of Material's default type).

final

foregroundColor → Color?

The default color for Text and Icons within the app bar.

final

hashCode → int

The hash code for this object.

no setterinherited

iconTheme → IconThemeData?

The color, opacity, and size to use for toolbar icons.

final

key → Key?

Controls how one widget replaces another widget in the tree.

finalinherited

leading → Widget?

A widget to display before the toolbar's title.

final

leadingWidth → double?

Defines the width of AppBar.leading widget.

final

onStretchTrigger → AsyncCallback?

The callback function to be executed when a user over-scrolls to the offset specified by stretchTriggerOffset.

final

pinned → bool

Whether the app bar should remain visible at the start of the scroll view.

final

primary → bool

Whether this app bar is being displayed at the top of the screen.

final

runtimeType → Type

A representation of the runtime type of the object.

no setterinherited

scrolledUnderElevation → double?

The elevation that will be used if this app bar has something scrolled underneath it.

final

shadowColor → Color?

The color of the shadow below the app bar.

final

shape → ShapeBorder?

The shape of the app bar's Material as well as its shadow.

final

snap → bool

If snap and floating are true then the floating app bar will "snap" into view.

final

stretch → bool

Whether the app bar should stretch to fill the over-scroll area.

final

stretchTriggerOffset → double

The offset of overscroll required to activate onStretchTrigger.

final

surfaceTintColor → Color?

The color of the surface tint overlay applied to the app bar's background color to indicate elevation.

final

systemOverlayStyle → SystemUiOverlayStyle?

Specifies the style to use for the system overlays (e.g. the status bar on Android or iOS, the system navigation bar on Android).

final

title → Widget?

The primary widget displayed in the app bar.

final

titleSpacing → double?

The spacing around title content on the horizontal axis. This spacing is applied even if there is no leading content or actions. If you want title to take all the space available, set this value to 0.0.

final

titleTextStyle → TextStyle?

The default text style for the AppBar's title widget.

final

toolbarHeight → double

Defines the height of the toolbar component of an AppBar.

final

toolbarTextStyle → TextStyle?

The default text style for the AppBar's leading, and actions widgets, but not its title.

final

useDefaultSemanticsOrder → bool

Whether to use the default semantic ordering for the app bar's children for accessibility traversal order.

final

Methods

createElement() → StatefulElement

Creates a StatefulElement to manage this widget's location in the tree.

inherited

createState() → State<SliverAppBar>

Creates the mutable state for this widget at a given location in the tree.

override

debugDescribeChildren() → List<DiagnosticsNode>

Returns a list of DiagnosticsNode objects describing this node's children.

inherited

debugFillProperties(DiagnosticPropertiesBuilder properties) → void

Add additional properties associated with the node.

inherited

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) → DiagnosticsNode

Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.

inherited

toString({DiagnosticLevel minLevel = DiagnosticLevel.info}) → String

A string representation of this object.

inherited

toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug, int wrapWidth = 65}) → String

Returns a string representation of this node and its descendants.

inherited

toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String

Returns a one-line detailed description of the object.

inherited

toStringShort() → String

A short, textual description of this widget.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited