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To ensure that your application
achieves the highest performance, implement item renderers in ActionScript.
Typically, you create item renderers in ActionScript only for mobile
applications, but you can create them for desktop application as
well.
The item renderer typically implements two interfaces:
Item renderer interface
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Implemented by
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Use
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IDataRenderer
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Item renderer
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Defines the data property
used to pass information to an item renderer.
At a minimum,
an item renderer must implement IDataRenderer to display data.
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IItemRenderer
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Item renderer
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Defines the APIs that a component must implement
to create an item renderer that can communicate with a host component
to support user interaction with the data item. User interactions
include selection, dragging, and the caret indicator. For some components,
such as the Spark List control, user interaction includes item selection.
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Create an ActionScript item renderer in one of the following
ways:
Create an ActionScript subclass from an existing item
renderer class, such as spark.components.LabelItemRenderer, spark.components.IconItemRenderer, or spark.components.supportClasses.ItemRenderer.
The existing item renderer classes already implement all necessary
interfaces.
For the highest performance in a mobile application,
create a subclass of spark.components.LabelItemRenderer. In your
subclass, you can control the background display and the layout
of the data items.
If you want to use the built-in Flex layout
mechanism, and are not as concerned with performance, create a subclass
of spark.components.supportClasses.ItemRenderer.
For more
information, see Create an ActionScript item renderer as a subclass of the LabelItemRenderer class.
For more information on using LabelItemRenderer
and IconItemRenderer, see Using a mobile item renderer with a Spark list-based control.
Create an ActionScript subclass of the mx.core.UIComponent
class.
By implementing an item renderer as a subclass of the
UIComponent class, you can obtain the best performance because you
only have to implement the logic necessary to support your application.
However, basing an item renderer on UIComponent requires the most
effort. To be used as an item renderer, your subclass must implement
the mx.core.IDataRenderer and spark.components.IItemRenderer interfaces.
For example implementations of item renderers written in ActionScript,
view the source code for the spark.components.LabelItemRenderer,
spark.components.IconItemRenderer, and spark.components.supportClasses.ItemRenderer classes.
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