Comments on: Random notes on DataGroup and Spark Containers in Flex 4 (Gumbo)

By: Robert Cesaric

Robert Cesaric — Sun, 10 Jul 2011 20:18:21 +0000

Great post!

If I may add; I’ve noticed with Lists, useVirtualLayout is ignored if you set it in the List’s Layout. It needs to be set directly on the List’s useVirtualLayout property.

By: paopadda

paopadda — Thu, 27 Jan 2011 12:02:10 +0000

Thanks.. It helped a lot..

By: Steven Shongrunden

Steven Shongrunden — Fri, 10 Jul 2009 21:25:42 +0000

In case you’re interested I just posted a sample Flex application that visually demonstrates the difference between using the itemRenderer and itemRendererFunction properties:

http://flexponential.com/2009/07/10/performance-implications-of-the-list-itemrenderer-vs-itemrendererfunction-properties/

By: Andy Hulstkamp

Andy Hulstkamp — Thu, 25 Jun 2009 06:25:55 +0000

Steven,

thanks for your remarks. You are right, this wasn’t very clear, I actually stated the facts in this post but missed to be more precise here.

will update

thanks

By: Steven Shongrunden

Steven Shongrunden — Wed, 24 Jun 2009 00:54:09 +0000

One very subtle correction to your well said notes above:

“Virtualization cannot be used when using the ItemRendererFunction. Well, the function can be set, but no virtualization will be used.”

Actually virtualization will be used even when an item renderer function is defined, but in that case item renderer recycling will not happen. Instead renderers will be created and destroyed roughly as they come in and out of view. (Compare this to the non-virtual case where every renderer is instantiated at startup). ItemRenderer recycling can be more performant than creation and destruction (depending on the renderers) so if you want to get the best performance it’s typically better to define an itemRenderer rather than an itemRendererFunction.