Element class abstract

An instantiation of a Component at a particular location in the tree.

Components describe how to configure a subtree but the same component can be used to configure multiple subtrees simultaneously because components are immutable. An Element represents the use of a component to configure a specific location in the tree. Over time, the component associated with a given element can change, for example, if the parent component rebuilds and creates a new component for this location..

Implemented types

• BuildContext

Available extensions

• AppContext
• ProjectContext
• ScreenContext
• ThemeContext

Constructors

Element(Component component)

Creates an element that uses the given component as its configuration.

Properties

binding → AppBinding

The root component binding that manages the component tree.

no setter, override

component → Component

The configuration for this element.

no setter, override

debugDoingBuild → bool

Whether the component is currently updating the component or render tree.

no setter, inherited

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 setter

dirty → bool

no setter

hashCode → int

The hash code for this object.

no setter, override

owner → BuildOwner

The root build owner that manages the build cycle.

no setter

parent → Element?

no setter

parentRenderObjectElement → RenderObjectElement?

no setter

project → Project

Available on BuildContext, provided by the ProjectContext extension

Returns the Project from the nearest ancestor ProjectProvider.

no setter

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

screen → Screen

Available on BuildContext, provided by the ScreenContext extension

Access responsive rendering helpers.

no setter

slot → ElementSlot

Information set by parent to define where this child fits in its parent's child list.

no setter

theme → Theme

Available on BuildContext, provided by the ThemeContext extension

Returns the Theme from the nearest ancestor ThemeProvider.

no setter

url → String

Available on BuildContext, provided by the AppContext extension

The currently active url.

no setter

Methods

activate() → void

Transition from the "inactive" to the "active" lifecycle state.

attachNotificationTree() → void

Called in Element.mount and Element.activate to register this element in the notification tree.

attachRenderObject() → void

deactivate() → void

Transition from the "active" to the "inactive" lifecycle state.

deactivateChild(Element child) → void

Move the given element to the list of inactive elements and detach its render object from the render tree.

dependOnInheritedComponentOfExactType<T extends InheritedComponent>({Object? aspect}) → T?

Obtains the nearest component of the given type T, which must be the type of a concrete InheritedComponent subclass, and registers this build context with that component such that when that component changes (or a new component of that type is introduced, or the component goes away), this build context is rebuilt so that it can obtain new values from that component.

override

dependOnInheritedElement(InheritedElement ancestor, {Object? aspect}) → InheritedComponent

Registers this build context with ancestor such that when ancestor's component changes this build context is rebuilt.

override

detachRenderObject() → void

didChangeDependencies() → void

Called when a dependency of this element changes.

didMount() → void

didRebuild() → void

didUpdate(covariant Component oldComponent) → void

dispatchNotification(Notification notification) → void

Start bubbling this notification at the given build context.

override

findAncestorStateOfType<T extends State<StatefulComponent>>() → T?

Returns the State object of the nearest ancestor StatefulComponent component that is an instance of the given type T.

override

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.

getElementForInheritedComponentOfExactType<T extends InheritedComponent>() → InheritedElement?

Obtains the element corresponding to the nearest component of the given type T, which must be the type of a concrete InheritedComponent subclass.

override

inflateComponent(Component newComponent, ElementSlot newSlot) → Element

Create an element for the given component and add it as a child of this element.

markNeedsBuild() → void

Marks the element as dirty and schedules a rebuild.

mount(Element? parent, ElementSlot newSlot) → void

Add this element to the tree as a child of the given parent.

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

performRebuild() → void

Cause the component to update itself.

rebuild() → void

Cause the component to update itself.

shouldRebuild(covariant Component newComponent) → bool

Implement this method to determine whether a rebuild can be skipped.

toString() → String

A string representation of this object.

inherited

unmount() → void

Transition from the "inactive" to the "defunct" lifecycle state.

update(covariant Component newComponent) → void

Change the component used to configure this element.

updateChild(Element? child, Component? newComponent, ElementSlot newSlot) → Element?

Update the given child with the given new configuration.

updateChildren(List<Element> oldChildren, List<Component> newComponents, {Set<Element>? forgottenChildren}) → List<Element>

Updates the children of this element to use new components.

updateSlot(ElementSlot newSlot) → void

Called by updateSlotForChild when the framework needs to change the slot that this Element occupies in its ancestor.

updateSlotForChild(Element child, ElementSlot newSlot) → void

Change the slot that the given child occupies in its parent.

visitAncestorElements(bool visitor(Element element)) → void

Walks the ancestor chain, starting with the parent of this build context's component, invoking the argument for each ancestor. The callback is given a reference to the ancestor component's corresponding Element object. The walk stops when it reaches the root component or when the callback returns false. The callback must not return null.

override

visitChildElements(ElementVisitor visitor) → void

Wrapper around visitChildren for BuildContext.

override

visitChildren(ElementVisitor visitor) → void

Calls the argument for each child.

Operators

operator ==(Object other) → bool

Compare two components for equality.

override