PrimaryScrollController class
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:
- ScrollAction, an Action that scrolls the Scrollable that encloses the current primaryFocus or is attached to the PrimaryScrollController.
- Shortcuts, a widget that establishes a ShortcutManager to be used by its descendants when invoking an Action via a keyboard key combination that maps to an Intent.
- Inheritance
-
- Object
- DiagnosticableTree
- Widget
- ProxyWidget
- InheritedWidget
- PrimaryScrollController
Constructors
- 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. const
- PrimaryScrollController.none({Key? key, required Widget child})
- Creates a subtree without an associated ScrollController. const
Properties
- automaticallyInheritForPlatforms → Set<
TargetPlatform> - The TargetPlatforms this controller is configured for ScrollViews to automatically inherit. final
- child → Widget
- The widget below this widget in the tree. finalinherited
- controller → ScrollController?
- The ScrollController associated with the subtree. final
- hashCode → int
- The hash code for this object. no setterinherited
- key → Key?
- Controls how one widget replaces another widget in the tree. finalinherited
- runtimeType → Type
- A representation of the runtime type of the object. no setterinherited
- scrollDirection → Axis?
- The Axis this controller is configured for ScrollViews to automatically inherit. final
Methods
- createElement(
) → InheritedElement - Inflates this configuration to a concrete instance. inherited
- 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. override
- 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
- updateShouldNotify(
covariant PrimaryScrollController oldWidget) → bool - Whether the framework should notify widgets that inherit from this widget. override
Operators
- operator ==(
Object other) → bool - The equality operator. inherited
Static Methods
- maybeOf(
BuildContext context) → ScrollController? - Returns the ScrollController most closely associated with the given context.
- 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.