SizedBoxModifier class

A box with a specified size.

If given a child, this widget forces it to have a specific width and/or height. These values will be ignored if this widget's parent does not permit them. For example, this happens if the parent is the screen (forces the child to be the same size as the parent), or another SizedBox (forces its child to have a specific width and/or height). This can be remedied by wrapping the child SizedBox in a widget that does permit it to be any size up to the size of the parent, such as Center or Align.

If either the width or height is null, this widget will try to size itself to match the child's size in that dimension. If the child's size depends on the size of its parent, the height and width must be provided.

If not given a child, SizedBox will try to size itself as close to the specified height and width as possible given the parent's constraints. If height or width is null or unspecified, it will be treated as zero.

The SizedBox.expand constructor can be used to make a SizedBox that sizes itself to fit the parent. It is equivalent to setting width and height to double.infinity.

{@tool snippet}

This snippet makes the child widget (a Card with some Text) have the exact size 200x300, parental constraints permitting:

const SizedBox(
  width: 200.0,
  height: 300.0,
  child: Card(child: Text('Hello World!')),
)

{@end-tool}

See also:

Inheritance
Available extensions

Constructors

SizedBoxModifier({Key? key, Widget? child, Key? modifierKey, double? width, double? height})
Creates a fixed size box. The width and height parameters can be null to indicate that the size of the box should not be constrained in the corresponding dimension.
const
SizedBoxModifier.expand({Key? key, Widget? child, Key? modifierKey})
Creates a box that will become as large as its parent allows.
const
SizedBoxModifier.fromSize({Key? key, Widget? child, Key? modifierKey, Size? size})
Creates a box with the specified size.
SizedBoxModifier.shrink({Key? key, Widget? child, Key? modifierKey})
Creates a box that will become as small as its parent allows.
const
SizedBoxModifier.square({Key? key, Widget? child, Key? modifierKey, double? dimension})
Creates a box whose width and height are equal.
const

Properties

hashCode int
The hash code for this object.
no setterinherited
height double?
If non-null, requires the child to have exactly this height.
final
key Key?
Controls how one widget replaces another widget in the tree.
finalinherited
modifierKey Key?
The actual key of the widget, which Modifier wrapped
finalinherited
runtimeType Type
A representation of the runtime type of the object.
no setterinherited
width double?
If non-null, requires the child to have exactly this width.
final

Methods

build(BuildContext context) Widget
Describes the part of the user interface represented by this widget.
inherited
buildWithChild(BuildContext context, Widget? child) Widget
A build method that receives an extra child parameter.
override
createElement() SingleChildStatelessElement
Create a SingleChildStatelessElement
inherited
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
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}) 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