在 itemrenderer 中操作数据对象 - Adob​​e Flex 4

Question

我有一个简单的 Itemrenderer，包含以下代码：

<?xml version="1.0" encoding="utf-8"?>
<s:ItemRenderer xmlns:fx="http://ns.adobe.com/mxml/2009" 
xmlns:s="library://ns.adobe.com/flex/spark" 
xmlns:mx="library://ns.adobe.com/flex/mx" 
autoDrawBackground="true" width="90" height="90">
<s:VGroup horizontalAlign="center">
 <mx:Image source="{data.photo}" toolTip="{data.name}" />
</s:VGroup>
</s:ItemRenderer>

我想在将数据对象绑定到图像属性（源和工具提示）之前对其进行操作。为此，我以这种方式修改了代码：

<?xml version="1.0" encoding="utf-8"?>
<s:ItemRenderer xmlns:fx="http://ns.adobe.com/mxml/2009" 
xmlns:s="library://ns.adobe.com/flex/spark" 
xmlns:mx="library://ns.adobe.com/flex/mx" 
autoDrawBackground="true" width="90" height="90"
initialize="itemrenderer1_initializeHandler(event)">
 <fx:Script>
 <![CDATA[
 import mx.events.FlexEvent;


 protected function itemrenderer1_initializeHandler(event:FlexEvent):void
  {
    var obj:Object = this.data;
    //here the manipulation
  }

 ]]>
 </fx:Script>
 <s:VGroup horizontalAlign="center">
 <mx:Image source="{data.photo}" toolTip="{data.name}" />
 </s:VGroup>
</s:ItemRenderer>

当我尝试访问 this.data 对象时，它始终是空的！有没有办法在绑定之前操作数据对象？也许我不必使用 this.data，但我找不到任何其他对象来编辑

Answer 1

另一个解决方案是重写设置数据函数，如下所示：

<?xml version="1.0" encoding="utf-8"?>
<s:ItemRenderer xmlns:fx="http://ns.adobe.com/mxml/2009" 
            xmlns:s="library://ns.adobe.com/flex/spark" 
            xmlns:mx="library://ns.adobe.com/flex/mx" 
            autoDrawBackground="true" width="90" height="90"
           creationComplete="itemrenderer1_creationCompleteHandler(event)"
            >
<fx:Script>
    <![CDATA[
        import mx.events.FlexEvent;
        import valueObjects.Product;
        [Bindable]
        private var prd:Product;

        override public function set data(value:Object):void
        {
           super.data = value;
           //here i can access to the this.data object!
           this.prd = this.data as Product;
        }

    ]]>
</fx:Script>
<s:VGroup horizontalAlign="center">
    <mx:Image source="{prd.photo}" toolTip="{prd.name}" width="70" />
    <mx:Label text="{prd.name}"/>
</s:VGroup>

Answer 2

我找到了！只有当ItemRenderer创建完成后我才能访问this.data对象！为此，我必须在创建完成事件之后操作该对象！
这里是代码：

<?xml version="1.0" encoding="utf-8"?>
<s:ItemRenderer xmlns:fx="http://ns.adobe.com/mxml/2009" 
                xmlns:s="library://ns.adobe.com/flex/spark" 
                xmlns:mx="library://ns.adobe.com/flex/mx" 
                autoDrawBackground="true" width="90" height="90"
               creationComplete="itemrenderer1_creationCompleteHandler(event)"
                >
    <fx:Script>
        <![CDATA[
            import mx.events.FlexEvent;
            import valueObjects.Product;
            [Bindable]
            private var prd:Product;

protected function itemrenderer1_creationCompleteHandler(event:FlexEvent):void
            {
                            //here i can access to the this.data object!
                            this.prd = this.data as Product;
            }

        ]]>
    </fx:Script>
    <s:VGroup horizontalAlign="center">
        <mx:Image source="{prd.photo}" toolTip="{prd.name}" width="70" />
        <mx:Label text="{prd.name}"/>
    </s:VGroup>
</s:ItemRenderer>

Answer 3

虽然不是新线程，但不要使用 CreationComplete。该事件仅被调用一次。每当托管组件决定应重新使用 itemRenderer 时，就会设置数据。例如，对于列表，useVirtualLayout=true。