Creating a custom Halo Accordion header skin in Flex 4

The following example shows how you can style the Halo Accordion header (with default Spark skin) in Flex 4 by creating a new skin based on the default Spark skin and modifying the various skin parts.

The default Halo Accordion header Spark skin can be found at \frameworks\projects\sparkskins\src\mx\skins\spark\AccordionHeaderSkin.mxml.

Full code after the jump.

To use the following code, you must have Flash Player 10 and a Flex 4 SDK installed in your Flex Builder 3. For more information on downloading and installing the Flex 4 SDK into Flex Builder 3, see “Using the beta Gumbo SDK in Flex Builder 3″. To download the latest build of the Flex 4 SDK, see http://opensource.adobe.com/wiki/display/flexsdk/Download+Flex+4.

View MXML

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2009/06/21/creating-a-custom-halo-accordion-header-skin-in-flex-4/ -->
<s:Application name="Accordion_SparkSkin_headerStyleName_skin_test"
   xmlns:fx="http://ns.adobe.com/mxml/2009"
   xmlns:mx="library://ns.adobe.com/flex/halo"
   xmlns:s="library://ns.adobe.com/flex/spark">

<fx:Style>
   .customAccordionHeadStyles {
       skin: ClassReference("skins.CustomAccordionHeaderSkin");
   }
</fx:Style>

<mx:Accordion id="accordion"
       headerStyleName="customAccordionHeadStyles"
       left="20" right="20" top="20" bottom="20">
   <mx:VBox label="Red" width="100%" height="100%">
       <mx:Text text="Panel 1" />

   </mx:VBox>
   <mx:VBox label="Orange" width="100%" height="100%">
       <mx:Text text="Panel 2" />
   </mx:VBox>
   <mx:VBox label="Yellow" width="100%" height="100%">
       <mx:Text text="Panel 3" />

   </mx:VBox>
   <mx:VBox label="Green" width="100%" height="100%">
       <mx:Text text="Panel 4" />
   </mx:VBox>
   <mx:VBox label="Blue" width="100%" height="100%">
       <mx:Text text="Panel 5" />

   </mx:VBox>
</mx:Accordion>

</s:Application>

And the custom Accordion header skin, CustomAccordionHeaderSkin.mxml, is as follows:

View skins/CustomAccordionHeaderSkin.mxml

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

<!-- http://blog.flexexamples.com/2009/06/21/creating-a-custom-halo-accordion-header-skin-in-flex-4/ -->
<s:SparkSkin name="CustomAccordionHeaderSkin"
    xmlns:fx="http://ns.adobe.com/mxml/2009"
    xmlns:s="library://ns.adobe.com/flex/spark"
    minWidth="21" minHeight="21"
    alpha.disabled="0.5">
<!-- states -->
<s:states>
    <s:State name="up" />
    <s:State name="over" />
    <s:State name="down" />

    <s:State name="disabled" />
    <s:State name="selectedUp" />
    <s:State name="selectedOver" />
    <s:State name="selectedDown" />
    <s:State name="selectedDisabled" />
</s:states>

<!-- layer 3: fill -->
<s:Rect left="1" right="1" top="1" bottom="1">
    <s:fill>
        <s:SolidColor color="white"
                color.up="red"
                color.over="haloOrange"
                color.down="yellow"
                color.selectedUp="haloGreen"
                color.selectedOver="haloBlue"
                color.selectedDown="purple" />
    </s:fill>
</s:Rect>

<!-- layer 4: fill lowlight -->
<s:Rect left="1" right="1" bottom="1" height="9">
    <s:fill>
        <s:LinearGradient rotation="90">
            <s:GradientEntry color="0x000000" alpha="0.0099" />
            <s:GradientEntry color="0x000000" alpha="0.0627" />

        </s:LinearGradient>
    </s:fill>
</s:Rect>

<!-- layer 5: fill highlight -->
<s:Rect left="1" right="1" top="1" height="9">
    <s:fill>

        <s:SolidColor color="0xFFFFFF"
                    alpha="0.33"
                    alpha.over="0.22"
                    alpha.down="0.12" />
    </s:fill>
</s:Rect>

<!-- layer 6: highlight stroke (all states except down) -->
<s:Rect left="1" right="1" top="1" bottom="1" excludeFrom="down">
    <s:stroke>

        <s:LinearGradientStroke rotation="90">
            <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) -->
<s:Rect left="1" top="1" bottom="1" width="1" includeIn="down">
    <s:fill>
        <s:SolidColor color="0x000000" alpha="0.07" />
    </s:fill>
</s:Rect>

<s:Rect right="1" top="1" bottom="1" width="1" includeIn="down">
    <s:fill>
        <s:SolidColor color="0x000000" alpha="0.07" />
    </s:fill>
</s:Rect>
<s:Rect left="1" top="1" right="1" height="1" includeIn="down">

    <s:fill>
        <s:SolidColor color="0x000000" alpha="0.25" />
    </s:fill>
</s:Rect>
<s:Rect left="1" top="2" right="1" height="1" includeIn="down">
    <s:fill>

        <s:SolidColor color="0x000000" alpha="0.09" />
    </s:fill>
</s:Rect>

<!-- layer 2: border -->
<s:Rect left="0" right="0" top="0" bottom="0" width="69" height="20">
    <s:stroke>

        <s:SolidColorStroke color="0x696969"
                    alpha="1"
                    alpha.over="1"
                    alpha.down="1" />
    </s:stroke>
</s:Rect>

</s:SparkSkin>

This entry is based on a beta version of the Flex 4 SDK and therefore is very likely to change as development of the Flex SDK continues. The API can (and will) change causing examples to possibly not compile in newer versions of the Flex 4 SDK.