Overlay class

A stack of entries that can be managed independently.

Overlays let independent child widgets "float" visual elements on top of other widgets by inserting them into the overlay's stack. The overlay lets each of these widgets manage their participation in the overlay using OverlayEntry objects.

Although you can create an Overlay directly, it's most common to use the overlay created by the Navigator in a WidgetsApp, CupertinoApp or a MaterialApp. The navigator uses its overlay to manage the visual appearance of its routes.

The Overlay widget uses a custom stack implementation, which is very similar to the Stack widget. The main use case of Overlay is related to navigation and being able to insert widgets on top of the pages in an app. For layout purposes unrelated to navigation, consider using Stack instead.

An Overlay widget requires a Directionality widget to be in scope, so that it can resolve direction-sensitive coordinates of any Positioned.directional children.

For widgets drawn in an OverlayEntry, do not assume that the size of the Overlay is the size returned by MediaQuery.sizeOf. Nested overlays can have different sizes.

This example shows how to use the Overlay to highlight the NavigationBar destination.
link

To create a local project with this code sample, run:
flutter create --sample=widgets.Overlay.1 mysample

See also:

Inheritance

Constructors

Overlay({Key? key, List<OverlayEntry> initialEntries = const <OverlayEntry>[], Clip clipBehavior = Clip.hardEdge})
Creates an overlay.
const

Properties

clipBehavior Clip
The content will be clipped (or not) according to this option.
final
hashCode int
The hash code for this object.
no setterinherited
initialEntries List<OverlayEntry>
The entries to include in the overlay initially.
final
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

Methods

createElement() StatefulElement
Creates a StatefulElement to manage this widget's location in the tree.
inherited
createState() OverlayState
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.
inherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void
Add additional properties associated with the node.
inherited
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}) 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.
inherited

Static Methods

maybeOf(BuildContext context, {bool rootOverlay = false}) OverlayState?
The OverlayState from the closest instance of Overlay that encloses the given context within the closest LookupBoundary, if any.
of(BuildContext context, {bool rootOverlay = false, Widget? debugRequiredFor}) OverlayState
The OverlayState from the closest instance of Overlay that encloses the given context within the closest LookupBoundary, and, in debug mode, will throw if one is not found.
wrap({Key? key, Clip clipBehavior = Clip.hardEdge, required Widget child}) Widget
Wrap the provided child in an Overlay to allow other visual elements (packed in OverlayEntrys) to float on top of the child.