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:
- AnimatedPositioned, which automatically transitions the child's position over a given duration whenever the given position changes.
- PositionedTransition, which takes a provided Animation to transition changes in the child's position over a given duration.
- PositionedDirectional, which adapts to the ambient Directionality.
- 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
-
The widget below this widget in the tree.
finalinherited
- debugTypicalAncestorWidgetClass → Type
-
Describes the RenderObjectWidget that is typically used to set up the
ParentData that applyParentData will write to.
no setteroverride
- debugTypicalAncestorWidgetDescription → String
-
Describes the RenderObjectWidget that is typically used to set up the
ParentData that applyParentData will write to.
no setterinherited
- 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
- right → double?
-
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
-
applyParentData(
RenderObject renderObject) → void -
Write the data from this widget into the given render object's parent data.
override
-
createElement(
) → ParentDataElement< StackParentData> -
Inflates this configuration to a concrete instance.
inherited
-
debugCanApplyOutOfTurn(
) → bool -
Whether the ParentDataElement.applyWidgetOutOfTurn method is allowed
with this widget.
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.
override
-
debugIsValidRenderObject(
RenderObject renderObject) → bool -
Checks if this widget can apply its parent data to the provided
renderObject.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