Flex Examples
In a previous example, “Hiding the border on a Spark List control in Flex 4″, we saw how you could toggle the border visibility on a Spark List control in Flex 4 by setting the Boolean borderVisible style.
The following example shows how you can set the content background alpha on a Spark List control in Flex 4 by setting the contentBackgroundAlpha style to a number between 0.0 and 1.0.
The following example(s) require Flash Player 10 and the Adobe Flex 4 SDK. To download the Adobe Flash Builder 4 trial, see http://www.adobe.com/products/flex/. To download the latest nightly build of the Flex 4 SDK, see http://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/2010/02/05/setting-the-content-background-alpha-a-spark-list-control-in-flex-4/ --> <s:Application name="Spark_List_contentBackgroundAlpha_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"> <s:Panel title="Spark List test" horizontalCenter="0" verticalCenter="0"> <s:controlBarContent> <mx:Form> <mx:FormItem label="contentBackgroundAlpha:"> <s:HSlider id="sl" minimum="0.0" maximum="1.0" value="1.0" snapInterval="0.1" stepSize="0.1" /> </mx:FormItem> </mx:Form> </s:controlBarContent> <s:Rect width="100%" height="100%"> <s:fill> <s:LinearGradient rotation="45"> <s:GradientEntry color="red" /> <s:GradientEntry color="yellow" /> <s:GradientEntry color="haloBlue" /> </s:LinearGradient> </s:fill> </s:Rect> <s:List id="lst" contentBackgroundAlpha="{sl.value}" left="20" right="20" top="20" bottom="20"> <s:layout> <s:VerticalLayout requestedRowCount="4" gap="0" horizontalAlign="contentJustify" /> </s:layout> <s:dataProvider> <s:ArrayList id="arr" source="[red,orange,yellow,green,blue]" /> </s:dataProvider> </s:List> </s:Panel> </s:Application>
View source is enabled in the following example.
You can also 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/2010/02/05/setting-the-content-background-alpha-a-spark-list-control-in-flex-4/ --> <s:Application name="Spark_List_contentBackgroundAlpha_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"; s|List { contentBackgroundAlpha: 0.6; /* 60% */ } </fx:Style> <s:Panel title="Spark List test" horizontalCenter="0" verticalCenter="0"> <s:Rect width="100%" height="100%"> <s:fill> <s:LinearGradient rotation="45"> <s:GradientEntry color="red" /> <s:GradientEntry color="yellow" /> <s:GradientEntry color="haloBlue" /> </s:LinearGradient> </s:fill> </s:Rect> <s:List id="lst" left="20" right="20" top="20" bottom="20"> <s:layout> <s:VerticalLayout requestedRowCount="4" gap="0" horizontalAlign="contentJustify" /> </s:layout> <s:dataProvider> <s:ArrayList id="arr" source="[red,orange,yellow,green,blue]" /> </s:dataProvider> </s:List> </s:Panel> </s:Application>
Or you can set the contentBackgroundAlpha style using ActionScript, as seen in the following example:
<?xml version="1.0" encoding="utf-8"?> <!-- http://blog.flexexamples.com/2010/02/05/setting-the-content-background-alpha-a-spark-list-control-in-flex-4/ --> <s:Application name="Spark_List_contentBackgroundAlpha_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:Script> <![CDATA[ protected function sl_changeHandler(evt:Event):void { lst.setStyle("contentBackgroundAlpha", sl.value); } ]]> </fx:Script> <s:Panel title="Spark List test" horizontalCenter="0" verticalCenter="0"> <s:controlBarContent> <mx:Form> <mx:FormItem label="contentBackgroundAlpha:"> <s:HSlider id="sl" minimum="0.0" maximum="1.0" value="1.0" snapInterval="0.1" stepSize="0.1" change="sl_changeHandler(event);"/> </mx:FormItem> </mx:Form> </s:controlBarContent> <s:Rect width="100%" height="100%"> <s:fill> <s:LinearGradient rotation="45"> <s:GradientEntry color="red" /> <s:GradientEntry color="yellow" /> <s:GradientEntry color="haloBlue" /> </s:LinearGradient> </s:fill> </s:Rect> <s:List id="lst" left="20" right="20" top="20" bottom="20"> <s:layout> <s:VerticalLayout requestedRowCount="4" gap="0" horizontalAlign="contentJustify" /> </s:layout> <s:dataProvider> <s:ArrayList id="arr" source="[red,orange,yellow,green,blue]" /> </s:dataProvider> </s:List> </s:Panel> </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.
Peter deHaan
Peter deHaan currently works for Adobe on the Flex SDK QA team. While not working on Flex, Flash, and ColdFusion applications, Peter enjoys making up bios and writing in 3rd person. Peter's rarely updated blog can be found at blogs.adobe.com/pdehaan/, actionscriptexamples.com, airexamples.com, and coldfusionexamples.com.
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Whee! SWFs!!!
I know it’s more work, but i LOVE IT when you include the swf example!!!!!