Creating a custom scroll bar track skin on an MX TextArea control in Flex 4

The following example shows how you can create a custom scroll bar track skin on an MX TextArea control in Flex 4 by setting the trackSkin, verticalScrollBarStyleName, and horizontalScrollBarStyleName and styles.

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/2010/04/16/creating-a-custom-scroll-bar-track-skin-on-an-mx-textarea-control-in-flex-4/ -->
<s:Application name="MX_TextArea_ScrollBar_trackSkin_test"
        xmlns:fx="http://ns.adobe.com/mxml/2009"
        xmlns:s="library://ns.adobe.com/flex/spark"
        xmlns:mx="library://ns.adobe.com/flex/mx">
 
    <fx:Style>
        @namespace s "library://ns.adobe.com/flex/spark";
        @namespace mx "library://ns.adobe.com/flex/mx";
 
        mx|TextArea {
            verticalScrollBarStyleName: sbTrackStyles;
            horizontalScrollBarStyleName: sbTrackStyles;
        }
 
        .sbTrackStyles {
            trackSkin: ClassReference("skins.CustomMXScrollBarTrackSkin");
        }
    </fx:Style>
 
    <mx:TextArea id="txtArea"
            horizontalScrollPolicy="on"
            verticalScrollPolicy="on"
            wordWrap="false"
            horizontalCenter="0" verticalCenter="0"
            width="400" height="100">
        <mx:text><fx:String source="lorem.txt" /></mx:text>
    </mx:TextArea>
 
</s:Application>

[HaloSparkSkins]

And the custom MX ScrollBar track skin, skins/CustomMXScrollBarTrackSkin.mxml, is as follows:

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2010/04/16/creating-a-custom-scroll-bar-track-skin-on-an-mx-textarea-control-in-flex-4/ -->
<s:SparkSkin xmlns:fx="http://ns.adobe.com/mxml/2009"
             xmlns:s="library://ns.adobe.com/flex/spark" 
             alpha.disabled="0.5">
    <!-- states -->
    <s:states>
        <s:State name="up" />
        <s:State name="down" />
        <s:State name="over" />
        <s:State name="disabled" />
    </s:states>
 
    <fx:Script>
        <![CDATA[
            override protected function initializationComplete():void {
                useChromeColor = true;
                super.initializationComplete();
            }
        ]]>
    </fx:Script>
 
    <!-- border/fill -->
    <s:Rect top="0" bottom="0" left="0" right="0"
            minWidth="14" minHeight="14">
        <s:stroke>
            <s:SolidColorStroke color="0x686868" weight="1"/>
        </s:stroke>
        <s:fill>
            <s:BitmapFill source="@Embed('skins/pattern_143.gif')" fillMode="repeat" />
        </s:fill>
    </s:Rect>
 
    <!-- shadow -->
    <s:Rect left="1" top="1" bottom="1" width="1">
        <s:fill>
            <s:SolidColor color="0x000000" alpha="0.24" />
        </s:fill>
    </s:Rect>
    <s:Rect left="2" top="1" bottom="1" width="1">
        <s:fill>
            <s:SolidColor color="0x000000" alpha="0.12" />
        </s:fill>
    </s:Rect>
    <s:Rect left="2" right="1" top="1" height="2">
        <s:fill>
            <s:SolidColor color="0x000000" alpha="0.12" />
        </s:fill>
    </s:Rect>
    <s:Rect left="2" right="1" bottom="1" height="3">
        <s:fill>
            <s:SolidColor color="0x000000" alpha="0.12" />
        </s:fill>
    </s:Rect>
 
</s:SparkSkin>

[GoogleAdsWide]

View source is enabled in the following example.

[Squidfingers]

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.

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