A widget that implements the flow layout algorithm.
Flow layouts are optimized for repositioning children using transformation matrices.
The flow container is sized independently from the children by the FlowDelegate.getSize function of the delegate. The children are then sized independently given the constraints from the FlowDelegate.getConstraintsForChild function.
Rather than positioning the children during layout, the children are positioned using transformation matrices during the paint phase using the matrices from the FlowDelegate.paintChildren function. The children can be repositioned efficiently by simply repainting the flow.
The most efficient way to trigger a repaint of the flow is to supply a repaint argument to the constructor of the FlowDelegate. The flow will listen to this animation and repaint whenever the animation ticks, avoiding both the build and layout phases of the pipeline.
See also:
- FlowDelegate, which controls the visual presentation of the children.
- Stack, which arranges children relative to the edges of the container.
- CustomSingleChildLayout, which uses a delegate to control the layout of a single child.
- CustomMultiChildLayout, which uses a delegate to position multiple children.
- Inheritance
Constructors
-
Flow({Key key, @required FlowDelegate delegate, List<Widget> children: const
[] }) -
Creates a flow layout.
-
Flow.unwrapped({Key key, FlowDelegate delegate, List<Widget> children: const
[] }) -
Creates a flow layout.
Properties
- delegate → FlowDelegate
-
The delegate that controls the transformation matrices of the children.
read-only - children → List<Widget>
-
The widgets below this widget in the tree.
read-only, inherited - hashCode → int
-
Get a hash code for this object.
read-only, inherited - key → Key
-
Controls how one widget replaces another widget in the tree.
read-only, inherited - runtimeType → Type
-
A representation of the runtime type of the object.
read-only, inherited
Operators
-
operator ==(
other) → bool -
The equality operator.
inherited
Methods
-
createRenderObject(
BuildContext context) → RenderFlow -
Creates an instance of the
RenderObjectclass that thisRenderObjectWidgetrepresents, using the configuration described by thisRenderObjectWidget. -
updateRenderObject(
BuildContext context, RenderFlow renderObject) → void -
Copies the configuration described by this
RenderObjectWidgetto the givenRenderObject, which will be of the same type as returned by this object'screateRenderObject. -
createElement(
) → MultiChildRenderObjectElement -
RenderObjectWidgets always inflate to a
RenderObjectElementsubclass.inherited -
debugFillDescription(
List<String> description) → void -
Add additional information to the given description for use by toString.
inherited -
didUnmountRenderObject(
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 non-existent method or property is accessed.
inherited -
toString(
) → String -
Returns a string representation of this object.
inherited -
toStringShort(
) → String -
A short, textual description of this widget.
inherited