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.