PreferredSizeWidget class Null safety
An interface for widgets that can return the size this widget would prefer if it were otherwise unconstrained.
There are a few cases, notably AppBar and TabBar, where it would be undesirable for the widget to constrain its own size but where the widget needs to expose a preferred or "default" size. For example a primary Scaffold sets its app bar height to the app bar's preferred height plus the height of the system status bar.
Widgets that need to know the preferred size of their child can require
that their child implement this interface by using this class rather
than Widget as the type of their child property.
Use PreferredSize to give a preferred size to an arbitrary widget.
- Implemented types
- Implementers
Constructors
Properties
- hashCode → int
-
The hash code for this object.
read-onlyinherited
- key → Key?
-
Controls how one widget replaces another widget in the tree.
finalinherited
- preferredSize → Size
-
The size this widget would prefer if it were otherwise unconstrained.
read-only
- runtimeType → Type
-
A representation of the runtime type of the object.
read-onlyinherited
Methods
-
createElement(
) → Element - Inflates this configuration to a concrete instance.
-
debugDescribeChildren(
) → List< DiagnosticsNode> -
Returns a list of
DiagnosticsNodeobjects describing this node's children.protected">@protectedinherited -
debugFillProperties(
DiagnosticPropertiesBuilder properties) → void -
Add additional properties associated with the node.
inherited
-
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a non-existent 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