Positioned class

A widget that controls where a child of a Stack is positioned.

A Positioned widget must be a descendant of a Stack, and the path from the Positioned widget to its enclosing Stack must contain only StatelessWidgets or StatefulWidgets (not other kinds of widgets, like RenderObjectWidgets).

If a widget is wrapped in a Positioned, then it is a positioned widget in its Stack. If the top property is non-null, the top edge of this child will be positioned top layout units from the top of the stack widget. The right, bottom, and left properties work analogously.

If both the top and bottom properties are non-null, then the child will be forced to have exactly the height required to satisfy both constraints. Similarly, setting the right and left properties to non-null values will force the child to have a particular width. Alternatively the width and height properties can be used to give the dimensions, with one corresponding position property (e.g. top and height).

If all three values on a particular axis are null, then the Stack.alignment property is used to position the child.

If all six values are null, the child is a non-positioned child. The Stack uses only the non-positioned children to size itself.

See also:

Inheritance

Constructors

Positioned({Key? key, double? left, double? top, double? right, double? bottom, double? width, double? height, required Widget child})
Creates a widget that controls where a child of a Stack is positioned.
const
Positioned.directional({Key? key, required TextDirection textDirection, double? start, double? top, double? end, double? bottom, double? width, double? height, required Widget child})
Creates a widget that controls where a child of a Stack is positioned.
factory
Positioned.fill({Key? key, double? left = 0.0, double? top = 0.0, double? right = 0.0, double? bottom = 0.0, required Widget child})
Creates a Positioned object with left, top, right, and bottom set to 0.0 unless a value for them is passed.
const
Positioned.fromRect({Key? key, required Rect rect, required Widget child})
Creates a Positioned object with the values from the given Rect.
Positioned.fromRelativeRect({Key? key, required RelativeRect rect, required Widget child})
Creates a Positioned object with the values from the given RelativeRect.

Properties

bottom → double?
The distance that the child's bottom edge is inset from the bottom of the stack.
final
child → Widget
This widget can only have one child. To lay out multiple children, let this widget's child be a widget such as Row, Column, or Stack, which have a children property, and then provide the children to that widget.
final
hashCode → int
The hash code for this object.
no setterinherited
height → double?
The child's height.
final
key → Key?
Controls how one widget replaces another widget in the tree.
finalinherited
left → double?
The distance that the child's left edge is inset from the left of the stack.
final
The distance that the child's right edge is inset from the right of the stack.
final
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
top → double?
The distance that the child's top edge is inset from the top of the stack.
final
width → double?
The child's width.
final

Methods

build(BuildContext context) → Widget
Describes the part of the user interface represented by this widget.
override
createElement() → StatelessElement
Creates a StatelessElement to manage this widget's location in the tree.
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