CustomShrinkWrappingViewport class

A widget that is bigger on the inside and shrink wraps its children in the main axis.

ShrinkWrappingViewport displays a subset of its children according to its own dimensions and the given offset. As the offset varies, different children are visible through the viewport.

ShrinkWrappingViewport differs from Viewport in that Viewport expands to fill the main axis whereas ShrinkWrappingViewport sizes itself to match its children in the main axis. This shrink wrapping behavior is expensive because the children, and hence the viewport, could potentially change size whenever the offset changes (e.g., because of a collapsing header).

ShrinkWrappingViewport cannot contain box children directly. Instead, use a SliverList, SliverFixedExtentList, SliverGrid, or a SliverToBoxAdapter, for example.

See also:

• ListView, PageView, GridView, and CustomScrollView, which combine Scrollable and ShrinkWrappingViewport into widgets that are easier to use.
• SliverToBoxAdapter, which allows a box widget to be placed inside a sliver context (the opposite of this widget).
• Viewport, a viewport that does not shrink-wrap its contents.

Inheritance

• Object
• DiagnosticableTree
• Widget
• RenderObjectWidget
• MultiChildRenderObjectWidget
• CustomViewport
• CustomShrinkWrappingViewport

Constructors

CustomShrinkWrappingViewport({Key? key, AxisDirection axisDirection = AxisDirection.down, AxisDirection? crossAxisDirection, double anchor = 0.0, required ViewportOffset offset, List<RenderSliver>? children, Key? center, double? cacheExtent, List<Widget> slivers = const <Widget>[]})

Creates a widget that is bigger on the inside and shrink wraps its children in the main axis.

Properties

anchor → double

The relative position of the zero scroll offset.

no setter, override

axisDirection → AxisDirection

The direction in which the offset's ViewportOffset.pixels increases.

final, inherited

cacheExtent → double?

The viewport has an area before and after the visible area to cache items that are about to become visible when the user scrolls.

final, inherited

cacheExtentStyle → CacheExtentStyle

Controls how the cacheExtent is interpreted.

final, inherited

center → Key?

The first child in the GrowthDirection.forward growth direction.

final, inherited

children → List<Widget>

The widgets below this widget in the tree.

final, inherited

clipBehavior → Clip

The content will be clipped (or not) according to this option.

final, inherited

crossAxisDirection → AxisDirection?

The direction in which child should be laid out in the cross axis.

final, inherited

hashCode → int

The hash code for this object.

no setter, inherited

key → Key?

Controls how one widget replaces another widget in the tree.

final, inherited

offset → ViewportOffset

Which part of the content inside the viewport should be visible.

final, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

createElement() → _ViewportElement

RenderObjectWidgets always inflate to a RenderObjectElement subclass.

inherited

createRenderObject(BuildContext context) → CustomRenderShrinkWrappingViewport

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 CustomRenderShrinkWrappingViewport 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