[flexcoders] Whay are too many itemrenderers being created?

[Chris Velevitch]

I'm using Flex 4.11 with Air 4.0 to create a mobile app.

I have a spark list with a custom mxml itemRenderer. Only 4 instances will
be visible in the list. The dataprovider is initially empty.

When I assign the array collection with an array of 147 items, I get 147
traces on dataChange event and on the render event. I traced out the value
of 'this' and I get 147 unique objects.

I was under the impression that only 4 instances of the itemRenderer will
be created and get reused as I scroll through the list.

What have I overlooked?

The list is defined as:-

<s:List id="lImages" dataProvider="{imageList}" width="100%" height="100%"
allowMultipleSelection="true"
           change="lImagesChange(event)" itemRenderer="PhotoThumbNail"
doubleClickEnabled="true" doubleClick="showImage(event)">
<s:layout>
<s:TileLayout/>
</s:layout>
</s:List>

and the itemRenderer is defined as:-

<?xml version="1.0"?>
<s:ItemRenderer
        xmlns:fx="http://ns.adobe.com/mxml/2009";
        xmlns:s="library://ns.adobe.com/flex/spark"
        dataChange="onDataChange(event)"
        render="onRender(event)"
        width="150" height="175"
        >

    <s:layout>
        <s:VerticalLayout/>
    </s:layout>

    <fx:Script><![CDATA[
        import DateUtils;

        import mx.events.FlexEvent;

        private function onDataChange(event:FlexEvent):void {
            trace(DateUtils.currentTime() + "PhotoThumbNail.onDataChange:
dataChange event, index=" + itemIndex + ", this="+this);
        }

        private function onRender(event:Event):void {
            trace(DateUtils.currentTime() + "PhotoThumbNail.onRender;
render event, index=" + itemIndex + ", this="+this);
        }
        ]]></fx:Script>
    <s:BitmapImage source="{data.image}" width="150" height="150"/>
    <s:Label text="{data.timestamp}" width="150"/>

</s:ItemRenderer>

-- 


Chris
--
Chris Velevitch
Manager - Adobe Platform Users Group, Sydney
m: 0415 469 095
www.apugs.org.au

Adobe Platform Users Group, Sydney
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