Scrollable class Null safety

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:

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.
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.

Constructors

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, ScrollBehavior? scrollBehavior, Clip clipBehavior = Clip.hardEdge}): Creates a widget that scrolls.
const

Properties

axis → Axis: The axis along which the scroll view scrolls.
read-only
axisDirection → AxisDirection: The direction in which this widget scrolls.
final
clipBehavior → Clip: The content will be clipped (or not) according to this option.
final
controller → ScrollController?: An object that can be used to control the position to which this widget is scrolled.
final
dragStartBehavior → DragStartBehavior: Determines the way that drag start behavior is handled.
final
excludeFromSemantics → bool: Whether the scroll actions introduced by this Scrollable are exposed in the semantics tree.
final
hashCode → int: The hash code for this object.
nonVirtual">@nonVirtualread-onlyinherited
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.
final
key → Key?: Controls how one widget replaces another widget in the tree.
finalinherited
physics → ScrollPhysics?: How the widgets should respond to user input.
final
restorationId → String?: Restoration ID to save and restore the scroll offset of the scrollable.
final
runtimeType → Type: A representation of the runtime type of the object.
read-onlyinherited
scrollBehavior → ScrollBehavior?: A ScrollBehavior that will be applied to this widget individually.
final
semanticChildCount → int?: The number of children that will contribute semantic information.
final
viewportBuilder → ViewportBuilder: Builds the viewport through which the scrollable content is displayed.
final

Methods

createElement() → StatefulElement: Creates a StatefulElement to manage this widget's location in the tree.
inherited
createState() → ScrollableState: 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.
protected">@protectedinherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void: Add additional properties associated with the node.
override
noSuchMethod(Invocation invocation) → dynamic: Invoked when a non-existent 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}) → 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.
nonVirtual">@nonVirtualinherited

Static Methods

ensureVisible(BuildContext context, {double alignment = 0.0, Duration duration = Duration.zero, 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.

Flutter
widgets
Scrollable class