自定义Button的图片 （位图显示Button）

comp/MyIconButton.mxml

<?xml version="1.0" encoding="utf-8"?>
<s:Button xmlns:fx="http://ns.adobe.com/mxml/2009"
          xmlns:s="library://ns.adobe.com/flex/spark"
          xmlns:mx="library://ns.adobe.com/flex/mx" skinClass="skins.MyIconSkin">
    <fx:Script>
        <![CDATA[
            [Bindable]
            public var icon:Object;
        ]]>
    </fx:Script>
</s:Button>

 skins/MyIconSkin

<?xml version="1.0" encoding="utf-8"?>
<s:SparkSkin 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="21" minHeight="21" alpha.disabled="0.5" xmlns:mx="library://ns.adobe.com/flex/mx">
 
    <!-- host component -->
    <fx:Metadata>
        <![CDATA[
        /**
         * @copy spark.skins.spark.ApplicationSkin#hostComponent
         */
        [HostComponent("comp.MyIconButton")]
        ]]>
    </fx:Metadata>
 
    <!-- states -->
    <s:states>
        <s:State name="up" />
        <s:State name="over" />
        <s:State name="down" />
        <s:State name="disabled" />
    </s:states>
 
    <!-- layer 1: shadow -->
    <!--- @private -->
    <s:Rect id="shadow" left="-1" right="-1" top="-1" bottom="-1" radiusX="2">
        <s:fill>
            <s:LinearGradient rotation="90">
                <s:GradientEntry color="0x000000"
                                 color.down="0xFFFFFF"
                                 alpha="0.01"
                                 alpha.down="0" />
                <s:GradientEntry color="0x000000"
                                 color.down="0xFFFFFF"
                                 alpha="0.07"
                                 alpha.down="0.5" />
            </s:LinearGradient>
        </s:fill>
    </s:Rect>
 
    <!-- layer 2: fill -->
    <!--- @private -->
    <s:Rect id="fill" left="1" right="1" top="1" bottom="1" radiusX="2">
        <s:fill>
            <s:LinearGradient rotation="90">
                <s:GradientEntry color="0xFFFFFF"
                                 color.over="0xBBBDBD"
                                 color.down="0xAAAAAA"
                                 alpha="0.85" />
                <s:GradientEntry color="0xD8D8D8"
                                 color.over="0x9FA0A1"
                                 color.down="0x929496"
                                 alpha="0.85" />
            </s:LinearGradient>
        </s:fill>
    </s:Rect>
 
    <!-- layer 3: fill lowlight -->
    <!--- @private -->
    <s:Rect id="lowlight" left="1" right="1" top="1" bottom="1" radiusX="2">
        <s:fill>
            <s:LinearGradient rotation="270">
                <s:GradientEntry color="0x000000" ratio="0.0" alpha="0.0627" />
                <s:GradientEntry color="0x000000" ratio="0.48" alpha="0.0099" />
                <s:GradientEntry color="0x000000" ratio="0.48001" alpha="0" />
            </s:LinearGradient>
        </s:fill>
    </s:Rect>
 
    <!-- layer 4: fill highlight -->
    <!--- @private -->
    <s:Rect id="highlight" left="1" right="1" top="1" bottom="1" radiusX="2">
        <s:fill>
            <s:LinearGradient rotation="90">
                <s:GradientEntry color="0xFFFFFF"
                                 ratio="0.0"
                                 alpha="0.33"
                                 alpha.over="0.22"
                                 alpha.down="0.12"/>
                <s:GradientEntry color="0xFFFFFF"
                                 ratio="0.48"
                                 alpha="0.33"
                                 alpha.over="0.22"
                                 alpha.down="0.12" />
                <s:GradientEntry color="0xFFFFFF"
                                 ratio="0.48001"
                                 alpha="0" />
            </s:LinearGradient>
        </s:fill>
    </s:Rect>
 
    <!-- layer 5: highlight stroke (all states except down) -->
    <!--- @private -->
    <s:Rect id="highlightStroke" left="1" right="1" top="1" bottom="1" radiusX="2" excludeFrom="down">
        <s:stroke>
            <s:LinearGradientStroke rotation="90" weight="1">
                <s:GradientEntry color="0xFFFFFF" alpha.over="0.22" />
                <s:GradientEntry color="0xD8D8D8" alpha.over="0.22" />
            </s:LinearGradientStroke>
        </s:stroke>
    </s:Rect>
 
    <!-- layer 6: highlight stroke (down state only) -->
    <!--- @private -->
    <s:Rect id="hldownstroke1" left="1" right="1" top="1" bottom="1" radiusX="2" includeIn="down">
        <s:stroke>
            <s:LinearGradientStroke rotation="90" weight="1">
                <s:GradientEntry color="0x000000" alpha="0.25" ratio="0.0" />
                <s:GradientEntry color="0x000000" alpha="0.25" ratio="0.001" />
                <s:GradientEntry color="0x000000" alpha="0.07" ratio="0.0011" />
                <s:GradientEntry color="0x000000" alpha="0.07" ratio="0.965" />
                <s:GradientEntry color="0x000000" alpha="0.00" ratio="0.9651" />
            </s:LinearGradientStroke>
        </s:stroke>
    </s:Rect>
    <!--- @private -->
    <s:Rect id="hldownstroke2" left="2" right="2" top="2" bottom="2" radiusX="2" includeIn="down">
        <s:stroke>
            <s:LinearGradientStroke rotation="90" weight="1">
                <s:GradientEntry color="0x000000" alpha="0.09" ratio="0.0" />
                <s:GradientEntry color="0x000000" alpha="0.00" ratio="0.0001" />
            </s:LinearGradientStroke>
        </s:stroke>
    </s:Rect>
 
    <!-- layer 7: border - put on top of the fill so it doesn't disappear when scale is less than 1 -->
    <!--- @private -->
    <s:Rect id="border" left="0" right="0" top="0" bottom="0" width="69" height="20" radiusX="2">
        <s:stroke>
            <s:LinearGradientStroke rotation="90" weight="1">
                <s:GradientEntry color="0x000000"
                                 alpha="0.5625"
                                 alpha.down="0.6375" />
                <s:GradientEntry color="0x000000"
                                 alpha="0.75"
                                 alpha.down="0.85" />
            </s:LinearGradientStroke>
        </s:stroke>
    </s:Rect>
 
    <!-- layer 8: text -->
    <!--- @copy spark.components.supportClasses.ButtonBase#labelDisplay -->
    <s:Label id="labelDisplay"
             textAlign="center"
             verticalAlign="middle"
             maxDisplayedLines="1"
             horizontalCenter="0" verticalCenter="1"
              right="10" top="2" bottom="2" paddingLeft="10">
    </s:Label>
    <mx:Image source="{hostComponent.icon}" left="5" verticalCenter="0" />
</s:SparkSkin>

 ButtonWithIcon.mxml

<?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" xmlns:comp="comp.*" viewSourceURL="srcview/index.html">
    <s:layout>
        <s:HorizontalLayout horizontalAlign="center" verticalAlign="middle"/>
    </s:layout>
    <comp:MyIconButton icon="@Embed('assets/add.png')" label="BTN 1" />
    <comp:MyIconButton icon="@Embed('assets/alert.png')" label="BTN 2" />
    <comp:MyIconButton icon="@Embed('assets/back.png')" label="BTN 3" />
</s:Application>