Scrollable class

A widget that scrolls.

Scrollable implements the interaction model for a scrollable widget, including gesture recognition, but does not have an opinion about how the viewport, which actually displays the children, is constructed.

It's rare to construct a Scrollable directly. Instead, consider ListView or GridView, which combine scrolling, viewporting, and a layout model. To combine layout models (or to use a custom layout mode), consider using CustomScrollView.

The static Scrollable.of and Scrollable.ensureVisible functions are often used to interact with the Scrollable widget inside a ListView or a GridView.

To further customize scrolling behavior with a Scrollable:

  1. You can provide a viewportBuilder to customize the child model. For example, SingleChildScrollView uses a viewport that displays a single box child whereas CustomScrollView uses a Viewport or a ShrinkWrappingViewport, both of which display a list of slivers.

  2. You can provide a custom ScrollController that creates a custom ScrollPosition subclass. For example, PageView uses a PageController, which creates a page-oriented scroll position subclass that keeps the same page visible when the Scrollable resizes.

See also:



Scrollable({Key key, AxisDirection axisDirection: AxisDirection.down, ScrollController controller, ScrollPhysics physics, @required ViewportBuilder viewportBuilder, ScrollIncrementCalculator incrementCalculator, bool excludeFromSemantics: false, int semanticChildCount, DragStartBehavior dragStartBehavior: DragStartBehavior.start, String restorationId})
Creates a widget that scrolls. [...]


axis Axis
The axis along which the scroll view scrolls. [...]
axisDirection AxisDirection
The direction in which this widget scrolls. [...]
controller ScrollController
An object that can be used to control the position to which this widget is scrolled. [...]
dragStartBehavior DragStartBehavior
Determines the way that drag start behavior is handled. [...]
excludeFromSemantics bool
Whether the scroll actions introduced by this Scrollable are exposed in the semantics tree. [...]
hashCode int
The hash code for this object. [...]
@nonVirtual, read-only, inherited
incrementCalculator ScrollIncrementCalculator
An optional function that will be called to calculate the distance to scroll when the scrollable is asked to scroll via the keyboard using a ScrollAction. [...]
key Key
Controls how one widget replaces another widget in the tree. [...]
final, inherited
physics ScrollPhysics
How the widgets should respond to user input. [...]
restorationId String
Restoration ID to save and restore the scroll offset of the scrollable. [...]
runtimeType Type
A representation of the runtime type of the object.
read-only, inherited
semanticChildCount int
The number of children that will contribute semantic information. [...]
viewportBuilder ViewportBuilder
Builds the viewport through which the scrollable content is displayed. [...]


createElement() StatefulElement
Creates a StatefulElement to manage this widget's location in the tree. [...]
createState() ScrollableState
Creates the mutable state for this widget at a given 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

Static Methods

ensureVisible(BuildContext context, {double alignment: 0.0, Duration duration:, Curve curve: Curves.ease, ScrollPositionAlignmentPolicy alignmentPolicy: ScrollPositionAlignmentPolicy.explicit}) Future<void>
Scrolls the scrollables that enclose the given context so as to make the given context visible.
of(BuildContext context) ScrollableState
The state from the closest instance of this class that encloses the given context. [...]
recommendDeferredLoadingForContext(BuildContext context) bool
Provides a heuristic to determine if expensive frame-bound tasks should be deferred for the context at a specific point in time. [...]