ObserverElementMixin mixin

A mixin that overrides build to listen to the observables used by ObserverWidgetMixin.

Superclass constraints
Mixin applications

Properties

buildScope → BuildScope
A BuildScope whose dirty Elements can only be rebuilt by BuildOwner.buildScope calls whose context argument is an Element within this BuildScope.
no setterinherited
debugDoingBuild → bool
Whether the widget is currently updating the widget or render tree.
no setterinherited
debugIsActive → bool
Returns true if the Element is active.
no setterinherited
debugIsDefunct → bool
Returns true if the Element is defunct.
no setterinherited
depth → int
An integer that is guaranteed to be greater than the parent's, if any. The element at the root of the tree must have a depth greater than 0.
no setterinherited
dirty → bool
Returns true if the element has been marked as needing rebuilding.
no setterinherited
hashCode → int
The hash code for this object.
no setterinherited
mounted → bool
Whether the Widget this context is associated with is currently mounted in the widget tree.
no setterinherited
owner → BuildOwner?
The object that manages the lifecycle of this element.
no setterinherited
reaction → ReactionImpl
no setter
renderObject → RenderObject?
The render object at (or below) this location in the tree.
no setterinherited
renderObjectAttachingChild → Element?
Returns the child of this Element that will insert a RenderObject into an ancestor of this Element to construct the render tree.
no setterinherited
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
size → Size?
The size of the RenderBox returned by findRenderObject.
no setterinherited
slot → Object?
Information set by parent to define where this child fits in its parent's child list.
no setterinherited
widget → Widget
The configuration for this element.
no setterinherited

Methods

activate() → void
Transition from the "inactive" to the "active" lifecycle state.
inherited
attachNotificationTree() → void
Called in Element.mount and Element.activate to register this element in the notification tree.
inherited
attachRenderObject(Object? newSlot) → void
Add renderObject to the render tree at the location specified by newSlot.
inherited
build() → Widget
Subclasses should override this function to actually call the appropriate build function (e.g., StatelessWidget.build or State.build) for their widget.
override
deactivate() → void
Transition from the "active" to the "inactive" lifecycle state.
inherited
deactivateChild(Element child) → void
Move the given element to the list of inactive elements and detach its render object from the render tree.
inherited
debugDeactivated() → void
Called, in debug mode, after children have been deactivated (see deactivate).
inherited
debugDescribeChildren() → List<DiagnosticsNode>
Returns a list of DiagnosticsNode objects describing this node's children.
inherited
debugExpectsRenderObjectForSlot(Object? slot) → bool
Whether the child in the provided slot (or one of its descendants) must insert a RenderObject into its ancestor RenderObjectElement by calling RenderObjectElement.insertRenderObjectChild on it.
inherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void
Add additional properties associated with the node.
inherited
debugGetCreatorChain(int limit) → String
Returns a description of what caused this element to be created.
inherited
debugGetDiagnosticChain() → List<Element>
Returns the parent chain from this element back to the root of the tree.
inherited
debugVisitOnstageChildren(ElementVisitor visitor) → void
Calls the argument for each child considered onstage.
inherited
dependOnInheritedElement(InheritedElement ancestor, {Object? aspect}) → InheritedWidget
Registers this build context with ancestor such that when ancestor's widget changes this build context is rebuilt.
inherited
dependOnInheritedWidgetOfExactType<T extends InheritedWidget>({Object? aspect}) → T?
Returns the nearest widget of the given type T and creates a dependency on it, or null if no appropriate widget is found.
inherited
describeElement(String name, {DiagnosticsTreeStyle style = DiagnosticsTreeStyle.errorProperty}) → DiagnosticsNode
Returns a description of the Element associated with the current build context.
inherited
describeMissingAncestor({required Type expectedAncestorType}) → List<DiagnosticsNode>
Adds a description of a specific type of widget missing from the current build context's ancestry tree.
inherited
describeOwnershipChain(String name) → DiagnosticsNode
Adds a description of the ownership chain from a specific Element to the error report.
inherited
describeWidget(String name, {DiagnosticsTreeStyle style = DiagnosticsTreeStyle.errorProperty}) → DiagnosticsNode
Returns a description of the Widget associated with the current build context.
inherited
detachRenderObject() → void
Remove renderObject from the render tree.
inherited
didChangeDependencies() → void
Called when a dependency of this element changes.
inherited
dispatchNotification(Notification notification) → void
Start bubbling this notification at the given build context.
inherited
doesDependOnInheritedElement(InheritedElement ancestor) → bool
Returns true if dependOnInheritedElement was previously called with ancestor.
inherited
findAncestorRenderObjectOfType<T extends RenderObject>() → T?
Returns the RenderObject object of the nearest ancestor RenderObjectWidget widget that is an instance of the given type T.
inherited
findAncestorStateOfType<T extends State<StatefulWidget>>() → T?
Returns the State object of the nearest ancestor StatefulWidget widget that is an instance of the given type T.
inherited
findAncestorWidgetOfExactType<T extends Widget>() → T?
Returns the nearest ancestor widget of the given type T, which must be the type of a concrete Widget subclass.
inherited
findRenderObject() → RenderObject?
The current RenderObject for the widget. If the widget is a RenderObjectWidget, this is the render object that the widget created for itself. Otherwise, it is the render object of the first descendant RenderObjectWidget.
inherited
findRootAncestorStateOfType<T extends State<StatefulWidget>>() → T?
Returns the State object of the furthest ancestor StatefulWidget widget that is an instance of the given type T.
inherited
forgetChild(Element child) → void
Remove the given child from the element's child list, in preparation for the child being reused elsewhere in the element tree.
inherited
getElementForInheritedWidgetOfExactType<T extends InheritedWidget>() → InheritedElement?
Obtains the element corresponding to the nearest widget of the given type T, which must be the type of a concrete InheritedWidget subclass.
inherited
getInheritedWidgetOfExactType<T extends InheritedWidget>() → T?
Returns the nearest widget of the given InheritedWidget subclass T or null if an appropriate ancestor is not found.
inherited
inflateWidget(Widget newWidget, Object? newSlot) → Element
Create an element for the given widget and add it as a child of this element in the given slot.
inherited
invalidate() → void
markNeedsBuild() → void
Marks the element as dirty and adds it to the global list of widgets to rebuild in the next frame.
inherited
mount(Element? parent, dynamic newSlot) → void
Add this element to the tree in the given slot of the given parent.
override
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
performRebuild() → void
Calls the StatelessWidget.build method of the StatelessWidget object (for stateless widgets) or the State.build method of the State object (for stateful widgets) and then updates the widget tree.
inherited
reassemble() → void
Called whenever the application is reassembled during debugging, for example during hot reload.
inherited
rebuild({bool force = false}) → void
Cause the widget to update itself. In debug builds, also verify various invariants.
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 element.
inherited
unmount() → void
Transition from the "inactive" to the "defunct" lifecycle state.
override
update(covariant Widget newWidget) → void
Change the widget used to configure this element.
inherited
updateChild(Element? child, Widget? newWidget, Object? newSlot) → Element?
Update the given child with the given new configuration.
inherited
updateChildren(List<Element> oldChildren, List<Widget> newWidgets, {Set<Element>? forgottenChildren, List<Object?>? slots}) → List<Element>
Updates the children of this element to use new widgets.
inherited
updateSlot(Object? newSlot) → void
Called by updateSlotForChild when the framework needs to change the slot that this Element occupies in its ancestor.
inherited
updateSlotForChild(Element child, Object? newSlot) → void
Change the slot that the given child occupies in its parent.
inherited
visitAncestorElements(ConditionalElementVisitor visitor) → void
Walks the ancestor chain, starting with the parent of this build context's widget, invoking the argument for each ancestor.
inherited
visitChildElements(ElementVisitor visitor) → void
Wrapper around visitChildren for BuildContext.
inherited
visitChildren(ElementVisitor visitor) → void
Calls the argument for each child. Must be overridden by subclasses that support having children.
inherited

Operators

operator ==(Object other) → bool
Compare two widgets for equality.
inherited