It depends on how you coded the renderer. Our list classes have very general and somewhat inefficient update strategies because we want to make sure most collection updates renderer correctly. I haven't looked at how Spark List thinks, but mx:List will refresh all renderers even if only one item changes because it doesn't know if another renderer might have "look-ahead" and also care about the item even though its data item is some other item in the collection.
You might be better off suppressing the setItemAt if it is the same. Alex Harui Flex SDK Developer Adobe Systems Inc.<http://www.adobe.com/> Blog: http://blogs.adobe.com/aharui From: flexcoders@yahoogroups.com [mailto:flexcod...@yahoogroups.com] On Behalf Of Baz Sent: Monday, October 05, 2009 3:18 PM To: flexcoders@yahoogroups.com Subject: Re: [flexcoders] custom itemrender flicker Hey Alex, thanks a lot for your reply. So it is *proper* behaviour that if you setItemAt in a custom itemrenderer that the whole control is rebuilt visually? Incidentally I am using Flex 4, so this might be of even more interest. I have a SkinnableDataContainer with an ArrayCollection dataprovider that holds custom objects ('reports' in this case). If my current collection has: 1. Report #1 = Name: 1stReportName, Path: 1stReportPath 2. Report #2 = Name: 2ndReportName, Path: 2ndReportPath And then I do a myArrayCollection.setItemAt(Report1, 0), which basically sets the first item to the same report it currently has. The itemrenderer empties of all items, then re-displays them, causing a flicker or flash that is noticeable on a slow computer. Wouldn't it make more sense for the itemrender NOT to re-build itself from scratch on every change? What if you had 100 items and u onl;y set one item? Thanks a lot! Baz On Mon, Oct 5, 2009 at 3:05 PM, Alex Harui <aha...@adobe.com<mailto:aha...@adobe.com>> wrote: It depends on how you wrote the renderer. You can try overriding the "function set data()" to check for changes to the object referenced by the renderer, but then if some sub-property changes, the renderer will not update. Might be better to understand why it flickers when updating. Alex Harui Flex SDK Developer Adobe Systems Inc.<http://www.adobe.com/> Blog: http://blogs.adobe.com/aharui From: flexcoders@yahoogroups.com<mailto:flexcoders@yahoogroups.com> [mailto:flexcoders@yahoogroups.com<mailto:flexcoders@yahoogroups.com>] On Behalf Of Baz Sent: Monday, October 05, 2009 12:32 PM To: flexcoders@yahoogroups.com<mailto:flexcoders@yahoogroups.com> Subject: [flexcoders] custom itemrender flicker If I have a custom item render based on an ArrayCollection with 10 times, and just for fun, I loop through those 10 items and setItemAt the exact same values that are already there - on screen the list of items reloads in a sense, re-building itself to the exact same values. I would like that in such a case, the on-screen controls know that they are the same as before and not to rebuild themselves. Is this possible? Can I intercept some event to double check whether they are the same or different? The goal of course, is to have this behaviour even if one some items changed. For example if I change only the 10th item, I would expect only the 10th item to refresh, no the whole collection. Thanks for any ideas! P.S. I am not useing refresh() on the ArrayCollection is it set to auto-update. Also, all my setItemAt calls are done in commitProperties()
