Setting the border alpha on a Spark TextInput control in Flex 4

In a previous example, “Hiding the border on a Spark TextInput control in Flex 4”, we saw how you could toggle the border visibility on a Spark TextInput control in Flex 4 by setting the Boolean borderVisible style.

The following example shows how you can set the border alpha on a Spark TextInput control in Flex 4 by setting the borderAlpha 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/2010/02/05/setting-the-border-alpha-on-a-spark-textinput-control-in-flex-4/ -->
<s:Application name="Spark_TextInput_borderAlpha_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:controlBarContent>
        <mx:Form>
            <mx:FormItem label="borderAlpha:">
                <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:TextInput id="txtInput"
            borderAlpha="{sl.value}"
            fontSize="32"
            horizontalCenter="0" verticalCenter="0"
            initialize="txtInput.text = mx_internal::VERSION;" />
 
</s:Application>

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View source is enabled in the following example.

You can also set the borderAlpha 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-border-alpha-on-a-spark-textinput-control-in-flex-4/ -->
<s:Application name="Spark_TextInput_borderAlpha_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|TextInput {
            borderAlpha: 0.0;
        }
    </fx:Style>
 
    <s:TextInput id="txtInput"
                 fontSize="32"
                 horizontalCenter="0" verticalCenter="0"
                 initialize="txtInput.text = mx_internal::VERSION;" />
 
</s:Application>

Or you can set the borderAlpha 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-border-alpha-on-a-spark-textinput-control-in-flex-4/ -->
<s:Application name="Spark_TextInput_borderAlpha_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:controlBarContent>
        <mx:Form>
            <mx:FormItem label="borderAlpha:">
                <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>
 
    <fx:Script>
        <![CDATA[
            protected function sl_changeHandler(evt:Event):void {
                txtInput.setStyle("borderAlpha", sl.value);
            }
        ]]>
    </fx:Script>
 
    <s:TextInput id="txtInput"
            fontSize="32"
            horizontalCenter="0" verticalCenter="0"
            initialize="txtInput.text = mx_internal::VERSION;" />
 
</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.