PrimaryScrollController class Null safety

Associates a ScrollController with a subtree.

When a ScrollView has ScrollView.primary set to true, the ScrollView uses of to inherit the PrimaryScrollController associated with its subtree.

A ScrollView that doesn't have a controller or the primary flag set will inherit the PrimarySCrollController, if shouldInherit allows it. By default shouldInherit is true for mobile platforms when the ScrollView has a scroll direction of Axis.vertical. This automatic inheritance can be configured with automaticallyInheritForPlatforms and scrollDirection.

Inheriting this ScrollController can provide default behavior for scroll views in a subtree. For example, the Scaffold uses this mechanism to implement the scroll-to-top gesture on iOS.

Another default behavior handled by the PrimaryScrollController is default ScrollActions. If a ScrollAction is not handled by an otherwise focused part of the application, the ScrollAction will be evaluated using the scroll view associated with a PrimaryScrollController, for example, when executing Shortcuts key events like page up and down.

See also:



PrimaryScrollController({Key? key, required ScrollController controller, Set<TargetPlatform> automaticallyInheritForPlatforms = _kMobilePlatforms, Axis? scrollDirection = Axis.vertical, required Widget child})
Creates a widget that associates a ScrollController with a subtree.
PrimaryScrollController.none({Key? key, required Widget child})
Creates a subtree without an associated ScrollController.


automaticallyInheritForPlatforms Set<TargetPlatform>
The TargetPlatforms this controller is configured for ScrollViews to automatically inherit.
child Widget
The widget below this widget in the tree.
final, inherited
controller ScrollController?
The ScrollController associated with the subtree.
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
scrollDirection Axis?
The Axis this controller is configured for ScrollViews to automatically inherit.


createElement() InheritedElement
Inflates this configuration to a concrete instance.
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
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.
updateShouldNotify(covariant PrimaryScrollController oldWidget) bool
Whether the framework should notify widgets that inherit from this widget.


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

Static Methods

of(BuildContext context) ScrollController?
Returns the ScrollController most closely associated with the given context.
shouldInherit(BuildContext context, Axis scrollDirection) bool
Returns true if this PrimaryScrollController is configured to be automatically inherited for the current TargetPlatform and the given Axis.