ConstraintLayout class

A super powerful Stack, build flexible layouts with constraints. Similar to ConstraintLayout for Android and AutoLayout for iOS. But the code implementation is much more efficient, it has O(n) layout time complexity and no linear equation solving is required.

It is a layout and a more modern general layout framework.

No matter how complex the layout is and how deep the constraints are it has almost the same performance as a single Flex or Stack. When facing complex layouts, it provides better performance, flexibility and a very flat code hierarchy than Flex and Stack. Say no to 'nested hell'.

Flutter ConstraintLayout has extremely high layout performance. It does not require linear equations to solve. At any time, each child element will only be laid out once. When its own width or height is set to wrapContent, some child elements may calculate the offset twice.

ConstraintLayout itself can be arbitrarily nested without performance issues, each child element in the render tree is only laid out once, and the time complexity is O(n) instead of O(2n) or worse.

Warning: For layout performance considerations, constraints are always one-way, and there should be no two child elements directly or indirectly restrain each other(for example, the right side of A is constrained to the left side of B, and the left side of B is in turn constrained to A right). Each constraint should describe exactly where the child elements are located. Although constraints can only be one-way, you can still better handle things that were previously (Android ConstraintLayout) two-way constraints, such as chains(not yet supported, please use with Flex).

author: hackware home page: https:///github.com/hackware1993 email: hackware1993@gmail.com

Inheritance
Available Extensions

Constructors

ConstraintLayout({Key? key, List<ConstraintDefine>? childConstraints, List<Widget>? children, bool showLayoutPerformanceOverlay = false, bool showHelperWidgets = false, bool showClickArea = false, bool showZIndex = false, bool showChildDepth = false, bool debugPrintConstraints = false, double width = matchParent, double height = matchParent, double? size, ConstraintLayoutController? controller, bool rtl = false})

Properties

childConstraints → List<ConstraintDefine>?
Constraints can be separated from widgets
final
children → List<Widget>
The widgets below this widget in the tree.
finalinherited
controller → ConstraintLayoutController?
Every frame, ConstraintLayout compares the parameters and decides the following things:
final
debugPrintConstraints → bool
final
hashCode → int
The hash code for this object.
no setterinherited
height → double
final
key → Key?
Controls how one widget replaces another widget in the tree.
finalinherited
rtl → bool
final
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
showChildDepth → bool
Will show the constraint depth (layout priority) of each child element
final
showClickArea → bool
Will show the click area of each child element
final
showHelperWidgets → bool
Guideline and Barrier will be displayed
final
showLayoutPerformanceOverlay → bool
It will display the time-consuming of constraint calculation, layout, and drawing
final
showZIndex → bool
Will show the z-index of each child element
final
size → double?
When size is non-null, both width and height are set to size
final
width → double
final

Methods

createElement() → MultiChildRenderObjectElement
RenderObjectWidgets always inflate to a RenderObjectElement subclass.
inherited
createRenderObject(BuildContext context) → RenderObject
Creates an instance of the RenderObject class that this RenderObjectWidget represents, using the configuration described by this RenderObjectWidget.
override
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
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.
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
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.
override

Operators

operator ==(Object other) → bool
The equality operator.
inherited