LazyWrap class

A performant scrollable wrap widget for Flutter, combining the layout behavior of Wrap with the lazy rendering of ListView.

Use LazyWrap.fixed for items with known, uniform sizes (best performance). Use LazyWrap.dynamic for items with variable or unknown sizes.

Both modes support vertical and horizontal scrolling via scrollDirection.

Inheritance

Constructors

LazyWrap.dynamic({required int itemCount, required Widget itemBuilder(BuildContext, int), Key? key, double spacing = 8, double runSpacing = 8, EdgeInsetsGeometry padding = EdgeInsets.zero, MainAxisAlignment rowAlignment = MainAxisAlignment.start, Axis scrollDirection = Axis.vertical, double cacheExtent = 300, int? batchSize = 50, Widget loadingBuilder(BuildContext)?, bool fadeInItems = true, Duration? fadeInDuration = const Duration(milliseconds: 200), Curve? fadeInCurve = Curves.easeOut, ScrollController? controller, double? loadThreshold = 300, int? measureBatchSize = 15, LazyWrapEngine? engine = LazyWrapEngine.offstageV1, double itemWidthBuilder(int)?, double itemHeightBuilder(int)?})
Creates a LazyWrap for items with variable sizes.
const
LazyWrap.fixed({required int itemCount, required Widget itemBuilder(BuildContext, int), required double? estimatedItemWidth, required double? estimatedItemHeight, Key? key, double spacing = 8, double runSpacing = 8, EdgeInsetsGeometry padding = EdgeInsets.zero, MainAxisAlignment rowAlignment = MainAxisAlignment.start, Axis scrollDirection = Axis.vertical, double cacheExtent = 300})
Creates a LazyWrap for items with known, uniform sizes.
const

Properties

batchSize → int?
Items to load per batch (dynamic mode only). Default: 50.
final
cacheExtent → double
Pixels to pre-render beyond the viewport for smoother scrolling. Default: 300.
final
controller → ScrollController?
Optional external scroll controller (dynamic mode only).
final
engine → LazyWrapEngine?
Dynamic engine selection (dynamic mode only).
final
estimatedItemHeight → double?
Height of each item (required for fixed mode, ignored in dynamic mode).
final
estimatedItemWidth → double?
Width of each item (required for fixed mode, ignored in dynamic mode).
final
fadeInCurve → Curve?
Curve of fade-in animation (dynamic mode only). Default: Curves.easeOut.
final
fadeInDuration → Duration?
Duration of fade-in animation (dynamic mode only). Default: 200ms.
final
fadeInItems → bool
Whether items fade in when first appearing (dynamic mode only). Default: true.
final
hashCode → int
The hash code for this object.
no setterinherited
isDynamic → bool
Whether using dynamic measurement mode.
final
itemBuilder → Widget Function(BuildContext, int)
Builder function called to create each item widget.
final
itemCount → int
Total number of items to display.
final
itemHeightBuilder → double Function(int)?
Deterministic height builder used by sliverV2 (dynamic mode only).
final
itemWidthBuilder → double Function(int)?
Deterministic width builder used by sliverV2 (dynamic mode only).
final
key → Key?
Controls how one widget replaces another widget in the tree.
finalinherited
loadingBuilder → Widget Function(BuildContext)?
Custom loading indicator (dynamic mode only).
final
loadThreshold → double?
Distance from the end at which to trigger loading (dynamic mode only). Default: 300.
final
measureBatchSize → int?
Max items measured per frame in Offstage (dynamic mode only). Default: 15.
final
padding → EdgeInsetsGeometry
Padding around the entire wrap content. Default: EdgeInsets.zero.
final
rowAlignment → MainAxisAlignment
Alignment of items within each row. Default: MainAxisAlignment.start.
final
runSpacing → double
Vertical spacing between rows. Default: 8.
final
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
scrollDirection → Axis
Scroll direction. Default: Axis.vertical.
final
spacing → double
Horizontal spacing between items within a row. Default: 8.
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, int wrapWidth = 65}) → 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