SliverAppBar class

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.

This is an example that could be included in a CustomScrollView's CustomScrollView.slivers list:
  expandedHeight: 150.0,
  flexibleSpace: const FlexibleSpaceBar(
    title: Text('Available seats'),
  actions: <Widget>[
      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.

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

See also:



SliverAppBar({Key key, Widget leading, bool automaticallyImplyLeading: true, Widget title, List<Widget> actions, Widget flexibleSpace, PreferredSizeWidget bottom, double elevation, bool forceElevated: false, Color backgroundColor, Brightness brightness, IconThemeData iconTheme, IconThemeData actionsIconTheme, TextTheme textTheme, bool primary: true, bool centerTitle, bool excludeHeaderSemantics: false, double titleSpacing: NavigationToolbar.kMiddleSpacing, double expandedHeight, bool floating: false, bool pinned: false, bool snap: false, bool stretch: false, double stretchTriggerOffset: 100.0, AsyncCallback onStretchTrigger, ShapeBorder shape})
Creates a material design app bar that can be placed in a CustomScrollView. [...]


actions List<Widget>
Widgets to display after the title widget. [...]
actionsIconTheme IconThemeData
The color, opacity, and size to use for trailing app bar icons. This should only be used when the trailing icons should be themed differently than the leading icons. [...]
automaticallyImplyLeading bool
Controls whether we should try to imply the leading widget if null. [...]
backgroundColor Color
The color to use for the app bar's material. Typically this should be set along with brightness, iconTheme, textTheme. [...]
bottom PreferredSizeWidget
This widget appears across the bottom of the app bar. [...]
brightness Brightness
The brightness of the app bar's material. Typically this is set along with backgroundColor, iconTheme, textTheme. [...]
centerTitle bool
Whether the title should be centered. [...]
elevation double
The z-coordinate at which to place this app bar when it is above other content. This controls the size of the shadow below the app bar. [...]
excludeHeaderSemantics bool
Whether the title should be wrapped with header Semantics. [...]
expandedHeight double
The size of the app bar when it is fully expanded. [...]
flexibleSpace Widget
This widget is stacked behind the toolbar and the tab bar. It's height will be the same as the app bar's overall height. [...]
floating bool
Whether the app bar should become visible as soon as the user scrolls towards the app bar. [...]
forceElevated bool
Whether to show the shadow appropriate for the elevation even if the content is not scrolled under the AppBar. [...]
iconTheme IconThemeData
The color, opacity, and size to use for app bar icons. Typically this is set along with backgroundColor, brightness, textTheme. [...]
leading Widget
A widget to display before the title. [...]
onStretchTrigger AsyncCallback
The callback function to be executed when a user over-scrolls to the offset specified by stretchTriggerOffset.
pinned bool
Whether the app bar should remain visible at the start of the scroll view. [...]
primary bool
Whether this app bar is being displayed at the top of the screen. [...]
shape ShapeBorder
The material's shape as well as its shadow. [...]
snap bool
If snap and floating are true then the floating app bar will "snap" into view. [...]
stretch bool
Whether the app bar should stretch to fill the over-scroll area. [...]
stretchTriggerOffset double
The offset of overscroll required to activate onStretchTrigger. [...]
textTheme TextTheme
The typographic styles to use for text in the app bar. Typically this is set along with brightness backgroundColor, iconTheme. [...]
title Widget
The primary widget displayed in the app bar. [...]
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. [...]
hashCode int
The hash code for this object.
@nonVirtual, read-only, inherited
key Key
Controls how one widget replaces another widget in the tree.
final, inherited
runtimeType Type
A representation of the runtime type of the object.
read-only, inherited


createState() → _SliverAppBarState
Creates the mutable state for this widget at a given location in the tree. [...]
createElement() StatefulElement
Creates a StatefulElement to manage this widget's location in the tree.
debugDescribeChildren() List<DiagnosticsNode>
Returns a list of DiagnosticsNode objects describing this node's children.
@protected, inherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void
Add additional properties associated with the node.
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed. [...]
toDiagnosticsNode({String name, DiagnosticsTreeStyle style}) DiagnosticsNode
Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.
toString({DiagnosticLevel minLevel:}) String
Returns a string representation of this object.
toStringDeep({String prefixLineOne: '', String prefixOtherLines, DiagnosticLevel minLevel: DiagnosticLevel.debug}) String
Returns a string representation of this node and its descendants.
toStringShallow({String joiner: ', ', DiagnosticLevel minLevel: DiagnosticLevel.debug}) String
Returns a one-line detailed description of the object.
toStringShort() String
A short, textual description of this widget.


operator ==(Object other) bool
The equality operator.
@nonVirtual, inherited