Setting the background alpha on the MX LinkBar control in Flex 4

The following example shows how you can set the background alpha on an MX LinkBar control in Flex 4 by setting the contentBackgroundAlpha style.

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/2010/05/06/setting-the-background-alpha-on-the-mx-linkbar-control-in-flex-4/ -->
<s:Application name="MX_LinkBar_contentBackgroundAlpha_test"
        xmlns:fx="http://ns.adobe.com/mxml/2009"
        xmlns:mx="library://ns.adobe.com/flex/mx"
        xmlns:s="library://ns.adobe.com/flex/spark">
    <s:controlBarContent>
        <mx:Form>
            <mx:FormItem label="contentBackgroundAlpha:">
                <s:HSlider id="sldr"
                        minimum="0.0" maximum="1.0"
                        snapInterval="0.1"
                        stepSize="0.1"
                        change="sldr_changeHandler(event);" />
            </mx:FormItem>
            <mx:FormItem label="contentBackgroundColor:">
                <mx:ColorPicker id="clrPckr"
                        change="clrPckr_changeHandler(event);" />
            </mx:FormItem>
        </mx:Form>
    </s:controlBarContent>
 
    <fx:Script>
        <![CDATA[
            import mx.events.ColorPickerEvent;
            import mx.events.FlexEvent;
 
            protected function sldr_changeHandler(evt:Event):void {
                lBar.setStyle("contentBackgroundAlpha", sldr.value);
            }
 
            protected function clrPckr_changeHandler(evt:ColorPickerEvent):void {
                lBar.setStyle("contentBackgroundColor", clrPckr.selectedColor);
            }
 
            protected function lBar_creationCompleteHandler(evt:FlexEvent):void {
                sldr.value = lBar.getStyle("contentBackgroundAlpha");
                clrPckr.selectedColor = lBar.getStyle("contentBackgroundColor");
            }
        ]]>
    </fx:Script>
 
    <s:TitleWindow id="tWin"
            title="Spark TitleWindow title"
            left="40" right="40" top="40" bottom="40">
        <s:controlBarContent>
            <mx:LinkBar id="lBar"
                    dataProvider="[One,Two,Three,Four,Five,Six,Seven]"
                    creationComplete="lBar_creationCompleteHandler(event);" />
        </s:controlBarContent>
    </s:TitleWindow>
 
</s:Application>

View source is enabled in the following example.

You can also set the contentBackgroundAlpha style using MXML, as seen in the following example:

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2010/05/06/setting-the-background-alpha-on-the-mx-linkbar-control-in-flex-4/ -->
<s:Application name="MX_LinkBar_contentBackgroundAlpha_test"
        xmlns:fx="http://ns.adobe.com/mxml/2009"
        xmlns:mx="library://ns.adobe.com/flex/mx"
        xmlns:s="library://ns.adobe.com/flex/spark">
 
    <s:TitleWindow id="tWin"
            title="Spark TitleWindow title"
            left="40" right="40" top="40" bottom="40">
        <s:controlBarContent>
            <mx:LinkBar id="lBar"
                    dataProvider="[One,Two,Three,Four,Five,Six,Seven]"
                    contentBackgroundAlpha="0.0" />
        </s:controlBarContent>
    </s:TitleWindow>
 
</s:Application>

Or you can set the contentBackgroundAlpha style in an external .CSS file or <Style> block, as seen in the following example:

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2010/05/06/setting-the-background-alpha-on-the-mx-linkbar-control-in-flex-4/ -->
<s:Application name="MX_LinkBar_contentBackgroundAlpha_test"
        xmlns:fx="http://ns.adobe.com/mxml/2009"
        xmlns:mx="library://ns.adobe.com/flex/mx"
        xmlns:s="library://ns.adobe.com/flex/spark">
 
    <fx:Style>
        @namespace mx "library://ns.adobe.com/flex/mx";
        @namespace s "library://ns.adobe.com/flex/spark";
 
        mx|LinkBar {
            contentBackgroundAlpha: 0.0;
        }
    </fx:Style>
 
    <s:TitleWindow id="tWin"
            title="Spark TitleWindow title"
            left="40" right="40" top="40" bottom="40">
        <s:controlBarContent>
            <mx:LinkBar id="lBar"
                    dataProvider="[One,Two,Three,Four,Five,Six,Seven]" />
        </s:controlBarContent>
    </s:TitleWindow>
 
</s:Application>

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.