CustomMultiChildLayout class

A widget that uses a delegate to size and position multiple children.

The delegate can determine the layout constraints for each child and can decide where to position each child. The delegate can also determine the size of the parent, but the size of the parent cannot depend on the sizes of the children.

CustomMultiChildLayout is appropriate when there are complex relationships between the size and positioning of multiple widgets. To control the layout of a single child, CustomSingleChildLayout is more appropriate. For simple cases, such as aligning a widget to one or another edge, the Stack widget is more appropriate.

Each child must be wrapped in a LayoutId widget to identify the widget for the delegate.

This example shows a CustomMultiChildLayout widget being used to lay out colored blocks from start to finish in a cascade that has some overlap.

It responds to changes in Directionality by re-laying out its children.

link

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

See also:

Inheritance

Constructors

CustomMultiChildLayout({Key? key, required MultiChildLayoutDelegate delegate, List<Widget> children = const <Widget>[]})
Creates a custom multi-child layout.
const

Properties

children → List<Widget>
The widgets below this widget in the tree.
finalinherited
delegate → MultiChildLayoutDelegate
The delegate that controls the layout of the children.
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

Methods

createElement() → MultiChildRenderObjectElement
RenderObjectWidgets always inflate to a RenderObjectElement subclass.
inherited
createRenderObject(BuildContext context) → RenderCustomMultiChildLayoutBox
Creates an instance of the RenderObject class that this RenderObjectWidget represents, using the configuration described by this RenderObjectWidget.
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
didUnmountRenderObject(covariant RenderObject renderObject) → void
A render object previously associated with this widget has been removed from the tree. The given RenderObject will be of the same type as returned by this object's createRenderObject.
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, 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
updateRenderObject(BuildContext context, covariant RenderCustomMultiChildLayoutBox renderObject) → void
Copies the configuration described by this RenderObjectWidget to the given RenderObject, which will be of the same type as returned by this object's createRenderObject.
override

Operators

operator ==(Object other) → bool
The equality operator.
inherited