Yes. A gigantic 15 items. ;) I wouldn't have thought going through a list
of 15 items would be quite so processor intensive.
Though even if it's just 5 items and I use Array instead of ArrayCollection,
it's still choppy.
The problem isn't so much that it's scanning through the entire collection,
as if you change "item.highlighted = list.isItemHighlighted(item)" to "
trace('here');", the choppiness disappears.
So, the problem is that it's setting this bound variable highlighted 15
times (or even just 5) for each item as it rolls over them. And the strange
thing is that the data all gets set behind the scenes. What happens that
the grid cells don't get repainted properly. If you actually play with the
program a little, dragging your mouse around a bit, you'll see what I'm
talking about. Here's a video that might be helpful:
http://www.youtube.com/watch?v=7LQFlQtiHsc
So it seems odd to me that the data is getting updated but the grid is
losing track of the ability to highlight.
You know what's really interesting? Change the style function this:
private function getColStyle(data:Object,
column:AdvancedDataGridColumn):Object
{
return { fontWeight:(data.highlighted ? "bold" : "normal") }
}
Now you'll see that the bolding tracks perfectly! The reason it failed
before was the same reason the blue mouseover highlight was failing.
Internally, the grid is losing the ability to highlight.
On Thu, Jun 4, 2009 at 11:28 PM, Alex Harui <aha...@adobe.com> wrote:
>
>
> The rollover handler is scanning the entire arraycollection.
>
>
>
> 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 *Pan Troglodytes
> *Sent:* Thursday, June 04, 2009 12:00 PM
> *To:* flexcoders
> *Subject:* [flexcoders] how to fix poor performance in this example
> (AdvancedDataGrid and Binding)
>
>
>
>
>
>
> I have the following example that is a very simplified form of what I
> need to do in my much larger program. The goal is to have a mouseover on a
> grid item set a variable in the data object. In the real program, this
> fires off some other code which makes that item visible and the others
> hidden, etc. But here, I'm just trying the first part.
>
> *TestObject.as:*
> package
> {
> public class TestObject
> {
> [Bindable] public var label:String;
> [Bindable] public var highlighted:Boolean;
> }
> }
>
> *GenericTest.mxml:
> *<?xml version="1.0" encoding="utf-8"?>
> <Application
> xmlns="http://www.adobe.com/2006/mxml";
> creationComplete="cc()"
> layout="horizontal"
> >
> <Script>
> <![CDATA[
> import mx.events.ListEvent;
> import mx.collections.ArrayCollection;
> [Bindable] public var d:ArrayCollection = new ArrayCollection([]);
>
> private const ITEM_COUNT:int = 15;
>
> private function cc():void
> {
> for (var i:int = 0; i < ITEM_COUNT; i++)
> {
> var item:TestObject = new TestObject;
> item.label = "Item " + i;
> d.addItem(item);
> }
> }
>
> private function listRollover(e:ListEvent):void
> {
> for each (var item:TestObject in d)
> item.highlighted = list.isItemHighlighted(item);
> }
>
> private function getColStyle(data:Object,
> column:AdvancedDataGridColumn):Object
> {
> return { fontWeight:(list.isItemHighlighted(data) ? "bold" :
> "normal") }
> }
>
> private function getColStyle2(data:Object,
> column:AdvancedDataGridColumn):Object
> {
> return { fontWeight:(list2.isItemHighlighted(data) ? "bold" :
> "normal") }
> }
>
> ]]>
> </Script>
> <AdvancedDataGrid id="list" dataProvider="{d}" height="100%"
> itemRollOver="listRollover(event)">
> <columns>
> <AdvancedDataGridColumn styleFunction="getColStyle"
> dataField="label"/>
> </columns>
> </AdvancedDataGrid>
> <AdvancedDataGrid id="list2" dataProvider="{d}" height="100%">
> <columns>
> <AdvancedDataGridColumn styleFunction="getColStyle2"
> dataField="label"/>
> </columns>
> </AdvancedDataGrid>
> </Application>
>
> To see the problem, run your mouse up and down the list on the left and the
> list on the right. If you get the same results I do with SDK 3.0.2 and
> player 10,0,12,36 (FF 3.0.6 or IE 7), you'll see that the list on the right
> tracks very smoothly but the one on the left is choppy. The only difference
> between the two is that the one on the left has a rollOver handler that sets
> a Bindable variable in the data object.
>
> If you comment out the [Bindable] on TestObject's highlighted variable, the
> choppiness goes away. So it's something to do with all the binding glue
> being fired behind the scenes. Is there some good way to work around this
> while still being able to use binding in this way?
>
> --
> Jason
>
>
>
--
Jason
