Setting the background alpha on a Spark FormHeading control in Flex Hero

By Peter deHaan On September 1, 2010 · Leave a Comment

The following example shows how you can set the background alpha on a Spark FormHeading control in Flex Hero by setting the backgroundAlpha style.

The following example(s) require Flash Player 10 and the beta Adobe Flex Hero 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 Hero SDK, see http://opensource.adobe.com/wiki/display/flexsdk/Download+Flex+Hero.

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2010/09/01/setting-the-background-alpha-on-a-spark-formheading-control-in-flex-hero/ -->
<s:Application name="Spark_FormHeading_backgroundAlpha_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:layout>
        <s:VerticalLayout horizontalAlign="center" verticalAlign="middle" />
    </s:layout>
    <s:controlBarContent>
        <s:Form>
            <s:FormItem label="backgroundAlpha:">
                <s:HSlider id="sl"
                        minimum="0.0" maximum="1.0"
                        value="1.0"
                        snapInterval="0.1" stepSize="0.1" />
            </s:FormItem>
        </s:Form>
    </s:controlBarContent>
 
    <s:Form id="frm" defaultButton="{submitBtn}" backgroundColor="#EEEEEE">
        <s:FormHeading label="Spark Form Heading"
                backgroundColor="haloSilver"
                backgroundAlpha="{sl.value}" />
        <s:FormItem sequenceLabel="1." label="Username:" required="true">
            <s:helpContent>
                <s:Label text="user@domain.com" />
            </s:helpContent>
            <s:TextInput id="username" />
        </s:FormItem>
        <s:FormItem sequenceLabel="2." label="Password:" required="true">
            <s:helpContent>
                <s:Label text="weak" color="red" />
            </s:helpContent>
            <s:TextInput id="password1" displayAsPassword="true" />
        </s:FormItem>
        <s:FormItem sequenceLabel="3." label="Confirm password:">
            <s:helpContent>
                <s:HGroup>
                    <s:Label text="One" color="red" />
                    <s:Label text="Two" color="blue" />
                </s:HGroup>
            </s:helpContent>
            <s:TextInput id="password2" displayAsPassword="true" />
        </s:FormItem>
        <s:FormItem>
            <s:layout>
                <s:HorizontalLayout />
            </s:layout>
            <s:Button id="resetBtn" label="Reset" />
            <s:Button id="submitBtn" label="Submit" />
        </s:FormItem>
    </s:Form>
 
</s:Application>

You can also set the backgroundAlpha 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/2010/09/01/setting-the-background-alpha-on-a-spark-formheading-control-in-flex-hero/ -->
<s:Application name="Spark_FormHeading_backgroundAlpha_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:layout>
        <s:VerticalLayout horizontalAlign="center" verticalAlign="middle" />
    </s:layout>
 
    <fx:Style>
        @namespace s "library://ns.adobe.com/flex/spark";
        @namespace mx "library://ns.adobe.com/flex/mx";
 
        s|FormHeading {
            backgroundAlpha: 0.2;
            backgroundColor: haloSilver;
        }
    </fx:Style>
 
    <s:Form id="frm" defaultButton="{submitBtn}" backgroundColor="#EEEEEE">
        <s:FormHeading id="fh1"
                label="Spark Form Heading" />
        <s:FormItem sequenceLabel="1." label="Username:" required="true">
            <s:helpContent>
                <s:Label text="user@domain.com" />
            </s:helpContent>
            <s:TextInput id="username" />
        </s:FormItem>
        <s:FormItem sequenceLabel="2." label="Password:" required="true">
            <s:helpContent>
                <s:Label text="weak" color="red" />
            </s:helpContent>
            <s:TextInput id="password1" displayAsPassword="true" />
        </s:FormItem>
        <s:FormItem sequenceLabel="3." label="Confirm password:">
            <s:helpContent>
                <s:HGroup>
                    <s:Label text="One" color="red" />
                    <s:Label text="Two" color="blue" />
                </s:HGroup>
            </s:helpContent>
            <s:TextInput id="password2" displayAsPassword="true" />
        </s:FormItem>
        <s:FormItem>
            <s:layout>
                <s:HorizontalLayout />
            </s:layout>
            <s:Button id="resetBtn" label="Reset" />
            <s:Button id="submitBtn" label="Submit" />
        </s:FormItem>
    </s:Form>
 
</s:Application>

Or you can set the backgroundAlpha style using ActionScript, as seen in the following example:

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2010/09/01/setting-the-background-alpha-on-a-spark-formheading-control-in-flex-hero/ -->
<s:Application name="Spark_FormHeading_backgroundAlpha_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:layout>
        <s:VerticalLayout horizontalAlign="center" verticalAlign="middle" />
    </s:layout>
    <s:controlBarContent>
        <s:Form>
            <s:FormItem label="backgroundAlpha:">
                <s:HSlider id="sl"
                        minimum="0.0" maximum="1.0"
                        value="1.0"
                        snapInterval="0.1" stepSize="0.1"
                        change="sl_changeHandler(event);" />
            </s:FormItem>
        </s:Form>
    </s:controlBarContent>
 
    <fx:Script>
        <![CDATA[
            protected function sl_changeHandler(evt:Event):void {
                fh1.setStyle("backgroundAlpha", sl.value);
            }
        ]]>
    </fx:Script>
 
    <s:Form id="frm" defaultButton="{submitBtn}" backgroundColor="#EEEEEE">
        <s:FormHeading id="fh1"
                label="Spark Form Heading"
                backgroundColor="haloSilver" />
        <s:FormItem sequenceLabel="1." label="Username:" required="true">
            <s:helpContent>
                <s:Label text="user@domain.com" />
            </s:helpContent>
            <s:TextInput id="username" />
        </s:FormItem>
        <s:FormItem sequenceLabel="2." label="Password:" required="true">
            <s:helpContent>
                <s:Label text="weak" color="red" />
            </s:helpContent>
            <s:TextInput id="password1" displayAsPassword="true" />
        </s:FormItem>
        <s:FormItem sequenceLabel="3." label="Confirm password:">
            <s:helpContent>
                <s:HGroup>
                    <s:Label text="One" color="red" />
                    <s:Label text="Two" color="blue" />
                </s:HGroup>
            </s:helpContent>
            <s:TextInput id="password2" displayAsPassword="true" />
        </s:FormItem>
        <s:FormItem>
            <s:layout>
                <s:HorizontalLayout />
            </s:layout>
            <s:Button id="resetBtn" label="Reset" />
            <s:Button id="submitBtn" label="Submit" />
        </s:FormItem>
    </s:Form>
 
</s:Application>

This entry is based on a beta version of the Flex Hero 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 Hero SDK.

Tagged with: backgroundAlpha • Hero

About The Author

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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