PopScope class
Manages back navigation gestures.
The canPop parameter disables back gestures when set to false.
The onPopInvoked parameter reports when pop navigation was attempted, and
didPop indicates whether or not the navigation was successful.
Android has a system back gesture that is a swipe inward from near the edge of the screen. It is recognized by Android before being passed to Flutter. iOS has a similar gesture that is recognized in Flutter by CupertinoRouteTransitionMixin, not by iOS, and is therefore not a system back gesture.
If canPop is false, then a system back gesture will not pop the route off
of the enclosing Navigator. onPopInvoked will still be called, and
didPop will be false. On iOS when using CupertinoRouteTransitionMixin
with canPop set to false, no gesture will be detected at all, so
onPopInvoked will not be called. Programmatically attempting pop
navigation will also result in a call to onPopInvoked, with didPop
indicating success or failure.
If canPop is true, then a system back gesture will cause the enclosing
Navigator to receive a pop as usual. onPopInvoked will be called with
didPop as true, unless the pop failed for reasons unrelated to
PopScope, in which case it will be false.
To create a local project with this code sample, run:
flutter create --sample=widgets.PopScope.1 mysample
See also:
- NavigatorPopHandler, which is a less verbose way to handle system back gestures in simple cases of nested Navigators.
- Form.canPop and Form.onPopInvoked, which can be used to handle system back gestures in the case of a form with unsaved data.
- ModalRoute.registerPopEntry and ModalRoute.unregisterPopEntry, which this widget uses to integrate with Flutter's navigation system.
- Inheritance
-
- Object
- DiagnosticableTree
- Widget
- StatefulWidget
- PopScope
Constructors
- PopScope({Key? key, required Widget child, bool canPop = true, PopInvokedCallback? onPopInvoked})
-
Creates a widget that registers a callback to veto attempts by the user to
dismiss the enclosing ModalRoute.
const
Properties
- canPop → bool
-
When false, blocks the current route from being popped.
final
- child → Widget
-
The widget below this widget in the tree.
final
- hashCode → int
-
The hash code for this object.
no setterinherited
- key → Key?
-
Controls how one widget replaces another widget in the tree.
finalinherited
- onPopInvoked → PopInvokedCallback?
-
Called after a route pop was handled.
final
- 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(
) → State< PopScope> -
Creates the mutable state for this widget at a given location in the tree.
override
-
debugDescribeChildren(
) → List< DiagnosticsNode> -
Returns a list of
DiagnosticsNodeobjects 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