Flex s：DataGrid全部ItemRenderer被触发 [英] Flex s:DataGrid all ItemRenderer are fired

问题描述

我不明白为什么当我们更改 dataprovider 上的数据时，受影响的列的所有 itemRenderers 叫？以下是我的问题的一个例子：

I don't understand why when we change data on dataprovider, all the itemRenderers of the impacted column are called ? Here is a little example of my problem :

应用程序：

    <?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
               xmlns:s="library://ns.adobe.com/flex/spark" 
               xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="955" minHeight="600" creationComplete="application1_creationCompleteHandler(event)">

<fx:Script>
    <![CDATA[
        import mx.collections.ArrayCollection;
        import mx.events.FlexEvent;

        private var _ac:ArrayCollection = new ArrayCollection();

        protected function application1_creationCompleteHandler(event:FlexEvent):void
        {
            var i:int = 10;

            while(i >= 0)
            {
                _ac.addItem({fieldA:Math.random() * 100, fieldB:Math.random() * 100});
                i--;
            }

            dg.dataProvider = _ac;
            dg.requestedRowCount = _ac.length;
        }

        protected function button1_clickHandler(event:MouseEvent):void
        {
            _ac.getItemAt(0)["fieldA"] = Math.random() * 100;
            _ac.getItemAt(0)["fieldB"] = Math.random() * 100;
            _ac.refresh();
        }

    ]]>
</fx:Script>

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

<s:Button label="change data" click="button1_clickHandler(event)" />

<s:DataGrid id="dg">
    <s:columns>
        <s:ArrayList>
            <s:GridColumn dataField="fieldA" itemRenderer="MyItemRenderer" />
            <s:GridColumn dataField="fieldB" />


    </s:ArrayList>
        </s:columns>
    </s:DataGrid>

</s:Application>

myItemRenderer：

myItemRenderer :

 <?xml version="1.0" encoding="utf-8"?>
<s:GridItemRenderer xmlns:fx="http://ns.adobe.com/mxml/2009" 
                    xmlns:s="library://ns.adobe.com/flex/spark" 
                    xmlns:mx="library://ns.adobe.com/flex/mx" clipAndEnableScrolling="true">

    <fx:Declarations>
        <s:Sequence id="myAnimation" duration="2000" target="{col}" >
            <s:Fade alphaFrom="0.0" alphaTo="1.0"/>
            <s:Fade alphaFrom="1.0" alphaTo="0.0"/>
        </s:Sequence>                   
    </fx:Declarations>

    <fx:Script>
        <![CDATA[

            private var _data:Object;

            override public function set data(value:Object):void
            {
                super.data = value;

                _data = value;

                if(null != _data)
                {
                    display();
                }
            }

            private function display():void
            {
                lblData.text = _data[column.dataField];
                myAnimation.play();
            }

        ]]>
    </fx:Script>

    <s:Rect top="-2" left="0" right="0" bottom="-2">
        <s:fill>
            <s:SolidColor id="col" color="0xFF0000" />
        </s:fill>
    </s:Rect>

    <s:Label id="lblData" top="9" left="7"/>

</s:GridItemRenderer>

我只想在受影响的单元格上播放动画，但每次都会触发每个单元格上的动画。如何编码？

I just want to play animation on the impacted cell but each time, animation on each cell is fired. How can I code that please ?

推荐答案

所有回收的原因是这样的：你打电话给刷新方法，因此您明确要求所有的回收。它将使应用于您的集合的所有排序和过滤器无效，因此datagrid中所有项目的位置都将无效，并且每个项目都被回收。

The reason for all that recycling is this: you're calling the refresh method, hence you're explicitly asking for all this recycling. It will invalidate all the sorts and filters applied to your collection, hence all the positions of the items in the datagrid are invalidated and every item is recycled.

所以你应该删除这个电话。之后，应该这样做，然后做你想要的：

So you should remove this call. After that something like this should then do what you expect:

    private var colValue:String;

    override public function prepare(hasBeenRecycled:Boolean):void {
        if (data && colValue != data[column.dataField]) {
            colValue = data[column.dataField];
            lblData.text = colValue;
            myAnimation.play();
        }
    }

准备方法仍然会每次调用，但您的动画只有在实际更改值时才会播放。

The prepare method will still be called every time, but your animation will only be played when the value has actually changed.

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