flex中如何用图像给按钮做皮肤

<?xml version="1.0" encoding="utf-8"?>

<s:sparkbuttonskin xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark"
xmlns:fb="http://ns.adobe.com/flashbuilder/2009"
minwidth="42" minheight="30"
alpha.disabled="0.5">

<fx:metadata>
<![cdata[
/**
* @copy spark.skins.spark.applicationskin#hostcomponent
*/
[hostcomponent("spark.components.button")]
]]>
</fx:metadata>
<fx:declarations>

</fx:declarations>

<!-- states -->
<s:states>
<s:state name="up" />
<s:state name="over" />
<s:state name="down" />
<s:state name="disabled" />
</s:states>
<s:rect left="0" right="0" top="0" bottom="0">
<s:fill>
<s:bitmapfill source.up="@embed('images/1_130927114244_1.png')" smooth="true" fillmode="scale"/>
</s:fill>
</s:rect>

</s:sparkbuttonskin>