Spark includes the following containers:
For more information on the Application container, see Application containers.
Interchangeable layouts
Most Spark containers support interchangeable layouts. That means
you can set the layout of a container to any of the supported layout
types, such as basic, horizontal, vertical, or tiled layout. You
can also define a custom layout.
Note: Some Spark containers, such as HGroup, VGroup, and TileGroup,
have a predefined layout that you cannot change.
Skinning
To improve performance and minimize application size, some Spark
containers do not support skinning. Use the Group and DataGroup
containers to manage child layout. Use SkinnableContainer and SkinnableDataContainer
to manage child layout and to support custom skins.
Visual child components
The Group and SkinnableContainer classes can take any visual
components as children. Visual components implement the IVisualElement
interface, and include subclasses of the UIComponent class and the
GraphicElement class.
The UIComponent class
is the base class of all Flex components. Therefore, you can use
any Flex component as a child of the Group and SkinnableContainer class.
The GraphicElement class
is the base class for the Flex drawing classes, such as the Ellipse, Line, and Rect classes.
Therefore, you can use subclass of the GraphicElement class as a
child of the Group and SkinnableContainer class.
The DataGroup and SkinnableDataContainer classes take as children
visual components that implement the IVisualElement interface
and are subclasses of DisplayObject.
This includes subclasses of the UIComponent class.
Data items
However, the DataGroup and SkinnableDataContainer containers
are optimized to hold data items. Data items can be simple data
items such as String and Number objects, and more complicated data
items such as Object and XMLNode objects. Therefore, while these
containers can hold visual children, use Group and SkinnableContainer
for children that are visual components.
Main characteristics of Spark containers
The following table lists the main characteristics of the Spark
containers:
Container
|
Children
|
Skinnable
|
Scrollable
|
Creation policy
|
Primary use
|
|---|
Group (including HGroup, VGroup,
and TileGroup)
|
IVisualElement
|
No
|
As a child of Scroller
|
All
|
Lay out visual children.
|
DataGroup
|
Data Item IVisualElement and
DisplayObject
|
No
|
As a child of Scroller
|
All
|
Render and lay out data items.
|
SkinnableContainer
|
IVisualElement
|
Yes
|
By skinning
|
Selectable
|
Lay out visual children in a skinnable container.
|
SkinnablePopUpContainer
|
IVisualElement
|
Yes
|
By skinning
|
Selectable
|
Lay out visual children in a skinnable container
opened as a pop up window.
|
SkinnableDataContainer
|
Data item IVisualElement and
DisplayObject
|
Yes
|
By skinning
|
Selectable
|
Render and lay out data items in a skinnable
container.
|
BorderContainer
|
IVisualElement
|
Yes
|
No
|
Selectable
|
Lay out visual children in a basic container
that includes a border.
|
Form
|
IVisualElement
|
Yes
|
Yes
|
Selectable
|
Lay out FormItem and FormHeading children
similar to an HTML form.
|
NavigatorContent
|
IVisualElement
|
Yes
|
By skinning
|
Inherited from parent container
|
Subclass of SkinnableContainer that can
be used as the child of an MX navigator container.
|
Panel
|
IVisualElement
|
Yes
|
By skinning
|
Selectable
|
Subclass of SkinnableContainer that adds
a title bar and other visual elements to the container.
|
TitleWindow
|
IVisualElement
|
Yes
|
By skinning
|
Selectable
|
Subclass of Panel that is optimized for
use as a pop-up window.
|
For information on skinning, see Spark Skinning.
Adobe Evangelist Renaun Erickson explores the Flex
4 container classes in Migrating to Flex 4: Containers.
Creation policy
Container creation policy determines how and when children of
containers are created. For information on creation policy, see About the creation policy.
