ConstrainedLayoutBuilder<ConstraintType extends Constraints> class Null safety

An abstract superclass for widgets that defer their building until layout.

Similar to the Builder widget except that the framework calls the builder function at layout time and provides the constraints that this widget should adhere to. This is useful when the parent constrains the child's size and layout, and doesn't depend on the child's intrinsic size.

The builder function is called in the following situations:

  • The first time the widget is laid out.
  • When the parent widget passes different layout constraints.
  • When the parent widget updates this widget.
  • When the dependencies that the builder function subscribes to change.

The builder function is not called during layout if the parent passes the same constraints repeatedly.

Subclasses must return a RenderObject that mixes in RenderConstrainedLayoutBuilder.



ConstrainedLayoutBuilder({Key? key, required Widget builder(BuildContext, ConstraintType)})
Creates a widget that defers its building until layout.


builder Widget Function(BuildContext, ConstraintType)
Called at layout time to construct the widget tree.
hashCode int
The hash code for this object.
@nonVirtual, read-only, inherited
key Key?
Controls how one widget replaces another widget in the tree.
final, inherited
runtimeType Type
A representation of the runtime type of the object.
read-only, inherited


createElement() RenderObjectElement
RenderObjectWidgets always inflate to a RenderObjectElement subclass.
createRenderObject(BuildContext context) RenderObject
Creates an instance of the RenderObject class that this RenderObjectWidget represents, using the configuration described by this RenderObjectWidget.
@factory, @protected, inherited
debugDescribeChildren() List<DiagnosticsNode>
Returns a list of DiagnosticsNode objects describing this node's children.
@protected, inherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void
Add additional properties associated with the node.
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.
@protected, inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed.
toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) DiagnosticsNode
Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.
toString({DiagnosticLevel minLevel =}) String
A string representation of this object.
toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug}) String
Returns a string representation of this node and its descendants.
toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) String
Returns a one-line detailed description of the object.
toStringShort() String
A short, textual description of this widget.
updateRenderObject(BuildContext context, covariant RenderObject 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.
@protected, inherited


operator ==(Object other) bool
The equality operator.
@nonVirtual, inherited