Creating a linear gradient background fill on a Spark List control in Flex 4

The following example shows how you can set a linear gradient background fill on a Spark List control in Flex 4 by setting the skinClass style and setting the background fill to a LinearGradient object.

Full code after the jump.

The following example(s) require Flash Player 10 and the Adobe Flex 4 SDK. To download the Adobe Flash Builder 4 trial, see www.adobe.com/products/flex/. To download the latest nightly build of the Flex 4 SDK, see opensource.adobe.com/wiki/display/flexsdk/Download+Flex+4.

For more information on getting started with Flex 4 and Flash Builder 4, see the official Adobe Flex Team blog.

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2009/04/25/creating-a-linear-gradient-background-fill-on-a-spark-list-control-in-flex-gumbo/ -->
<s:Application name="Spark_List_background_LinearGradient_test"
        xmlns:fx="http://ns.adobe.com/mxml/2009"
        xmlns:s="library://ns.adobe.com/flex/spark"
        xmlns:mx="library://ns.adobe.com/flex/halo">
 
    <s:List id="list"
            skinClass="skins.CustomListSkin"
            horizontalCenter="0"
            verticalCenter="0">
        <s:dataProvider>
            <s:ArrayList>
                <fx:String>The</fx:String>
                <fx:String>Quick</fx:String>
                <fx:String>Brown</fx:String>
                <fx:String>Fox</fx:String>
                <fx:String>Jumps</fx:String>
                <fx:String>Over</fx:String>
                <fx:String>The</fx:String>
                <fx:String>Lazy</fx:String>
                <fx:String>Dog</fx:String>
            </s:ArrayList>
        </s:dataProvider>
    </s:List>
 
</s:Application>

The custom skin file, skins/CustomListSkin.mxml, is as follows:

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2009/04/25/creating-a-linear-gradient-background-fill-on-a-spark-list-control-in-flex-gumbo/ -->
<s:SparkSkin name="CustomListSkin"
        xmlns:fx="http://ns.adobe.com/mxml/2009"
        xmlns:s="library://ns.adobe.com/flex/spark"
        minWidth="112" minHeight="112"
        alpha.disabled="0.5"
        blendMode="normal"> 
    <!-- states -->
    <s:states>
        <s:State name="normal" />
        <s:State name="disabled" />
    </s:states>
 
    <fx:Metadata>
    <![CDATA[
        [HostComponent("spark.components.List")]
    ]]>
    </fx:Metadata>
 
    <fx:Script>
        /* Define the skin elements that should not be colorized.
           For list, the skin itself is colorized but the individual parts are not. */
        static private const exclusions:Array = ["scroller", "background"];
 
        override public function get colorizeExclusions():Array {return exclusions;}
 
        /* Define the content fill items that should be colored by the "contentBackgroundColor" style. */
        static private const contentFill:Array = [];
 
        override public function get contentItems():Array {return contentFill};
    </fx:Script>
 
    <!-- border -->
    <s:Rect left="0" right="0" top="0" bottom="0">
        <s:stroke>
            <s:SolidColorStroke color="0x686868" weight="1"/>
        </s:stroke>
    </s:Rect>
 
    <!-- fill -->
    <!--- Defines the background appearance of the list-based component. -->
    <s:Rect id="background" left="1" right="1" top="1" bottom="1" >
        <s:fill>
            <s:LinearGradient id="bgFill" rotation="90">
                <s:GradientEntry color="red" />
                <s:GradientEntry color="white" />
            </s:LinearGradient>
        </s:fill>
    </s:Rect>
 
    <!--- The Scroller component to add scroll bars to the list. -->
    <s:Scroller id="scroller"
            left="0" top="0" right="0" bottom="0"
            minViewportInset="1"
            focusEnabled="false">
        <!--- The container for the data items. -->
        <s:DataGroup id="dataGroup" itemRenderer="skins.CustomDefaultItemRenderer">
            <s:layout>
                <s:VerticalLayout gap="0" horizontalAlign="contentJustify" requestedRowCount="5" />
            </s:layout>
        </s:DataGroup>
    </s:Scroller>
 
</s:SparkSkin>

And the custom item renderer file, skins/CustomDefaultItemRenderer.mxml, is as follows:

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2009/04/25/creating-a-linear-gradient-background-fill-on-a-spark-list-control-in-flex-gumbo/ -->
<s:ItemRenderer name="CustomDefaultItemRenderer"
        xmlns:fx="http://ns.adobe.com/mxml/2009"
        xmlns:s="library://ns.adobe.com/flex/spark"
        focusEnabled="false">
    <!-- states -->
    <s:states>
        <s:State name="normal" />
        <s:State name="hovered" />
        <s:State name="selected" />
        <s:State name="normalAndShowsCaret"/>
        <s:State name="hoveredAndShowsCaret"/>
        <s:State name="selectedAndShowsCaret"/>
    </s:states>
 
    <fx:Script>
        <![CDATA[
            override public function set label(value:String):void {
                super.label = value;
                labelDisplay.text = label; 
            }
        ]]>
    </fx:Script>
 
    <s:Rect left="0" right="0" top="0" bottom="0">
        <s:stroke.normalAndShowsCaret>
            <s:SolidColorStroke color="{selectionColor}"
                    weight="1"/>
        </s:stroke.normalAndShowsCaret>
        <s:stroke.hoveredAndShowsCaret>
            <s:SolidColorStroke color="{selectionColor}"
                    weight="1"/>
        </s:stroke.hoveredAndShowsCaret>
        <s:stroke.selectedAndShowsCaret>
            <s:SolidColorStroke color="{selectionColor}"
                    weight="1"/>
        </s:stroke.selectedAndShowsCaret>
        <s:fill>
            <s:SolidColor color.normal="{contentBackgroundColor}" alpha.normal="0"
                    color.normalAndShowsCaret="{contentBackgroundColor}"
                    color.hovered="{rollOverColor}"
                    color.hoveredAndShowsCaret="{rollOverColor}"
                    color.selected="{selectionColor}"
                    color.selectedAndShowsCaret="{selectionColor}" />
        </s:fill>
    </s:Rect>
 
    <s:SimpleText id="labelDisplay"
            verticalCenter="0"
            left="3" right="3" top="6" bottom="4"/>
 
</s:ItemRenderer>

View source is enabled in the following example.

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.