Adding a hover glow filter to an MX Image control in Flex 4

The following example shows how you can apply a hover glow filter to an MX Image control in Flex 4 by using the rollOver and rollOut events to set the filters property on the Image control to an array with a GlowFilter instance.

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/2010/06/25/adding-a-hover-glow-filter-to-an-mx-image-control-in-flex-4/ -->
<s:Application name="MX_Image_filters_GlowFilter_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"
        xmlns:comps="comps.*">
    <s:layout>
        <s:HorizontalLayout horizontalAlign="center" verticalAlign="middle" />
    </s:layout>
 
    <fx:Script>
        <![CDATA[
            import flash.filters.GlowFilter;
 
            protected function img_rollOverHandler(evt:MouseEvent):void {
                Image(evt.currentTarget).filters = [new GlowFilter(0xFF0000)];
            }
 
            protected function img1_rollOutHandler(evt:MouseEvent):void {
                Image(evt.currentTarget).filters = [];
            }
        ]]>
    </fx:Script>
 
    <mx:Image id="img1"
            source="http://helpexamples.com/flash/images/image1.jpg"
            rollOver="img_rollOverHandler(event);"
            rollOut="img1_rollOutHandler(event);" />
 
</s:Application>

View source is enabled in the following example.

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Or, instead of specifying the rollOver and rollOut event handlers for each Image component instance, you could create a custom component that extends the MX Image control and adds the rollOver/rollOut logic, as seen in the following example:

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2010/06/25/adding-a-hover-glow-filter-to-an-mx-image-control-in-flex-4/ -->
<s:Application name="MX_Image_filters_GlowFilter_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"
        xmlns:comps="comps.*">
    <s:layout>
        <s:HorizontalLayout horizontalAlign="center" verticalAlign="middle" />
    </s:layout>
 
    <comps:GlowImage id="img2"
            source="http://helpexamples.com/flash/images/image2.jpg"
            scaleX="0.5" scaleY="0.5" />
 
    <comps:GlowImage id="img3"
            source="http://helpexamples.com/flash/images/image3.jpg"
            scaleX="0.5" scaleY="0.5" />
 
</s:Application>

And the custom MX Image control, comps/GlowImage.mxml, is as follows:

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2010/06/25/adding-a-hover-glow-filter-to-an-mx-image-control-in-flex-4/ -->
<mx:Image name="GlowImage"
        xmlns:fx="http://ns.adobe.com/mxml/2009"
        xmlns:s="library://ns.adobe.com/flex/spark"
        xmlns:mx="library://ns.adobe.com/flex/mx"
        rollOver="rollOverHandler(event);"
        rollOut="rollOutHandler(event);">
 
    <fx:Script>
        <![CDATA[
            import flash.filters.GlowFilter;
 
            protected function rollOverHandler(evt:MouseEvent):void {
                filters = [new GlowFilter(0xFF0000)];
            }
 
            protected function rollOutHandler(evt:MouseEvent):void {
                filters = [];
            }
        ]]>
    </fx:Script>
 
</mx:Image>

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.

7 thoughts on “Adding a hover glow filter to an MX Image control in Flex 4

  1. I’m curious about the use of the rollOver/rollOut. I normally use mouseOver/mouseOut for this type of thing. I’m wondering if there’s a difference between the two pairs of events. The API docs say exactly the same thing for both. E.g., for rollOver/mouseOver:
    Dispatched when the user moves a pointing device over an InteractiveObject instance.

    1. rollOver and rollOut are both container aware mouseOver and mouseOut are not. If you were to rollover a container’s children, the mouseOut events would occur for that container. so i guess to simplify things, rollOver and rollOut are used to interact with container children. if you’d read the docs, there’s an explanation of this in the 2nd paragraph for mouseOver.

      http://livedocs.adobe.com/flex/3/langref/flash/display/InteractiveObject.html#event:mouseOver

  2. Sorry this is off topic but Ely Greenfield (also an Adobe employee?) doesn’t seem to be accepting comments on his blog anymore.

    We are making the move to Flex 4 but unfortunately it breaks some important Flex 3 code.

    A simple example of this would be Ely’s “Declaration” application.

    http://demo.quietlyscheming.com/landscape/Declaration.html

    I was wondering if anyone has managed to get this working in Flex 4??

  3. i.it does not follow the component life cycle at all….. think it should set some private property, liked rolledOver = true, invalidateProperties() and only in ovderridden commiProperties() actually set the filter…..since it is cpu demmanding. and of course setting filter after events in between frames makes no sense….

  4. @SDaniel — I haven’t looked at that code in a while, but I have a hunch why it’s not working in Flex 4, and what you might want to do to fix it. if you mail me at egreenfi @ (the company I work for which you guessed) I can give you more details.

    Ely.

  5. Hi Ely

    I send an email to you a couple of days ago. Just mentioning it here in case I dropped into the email spam dumpster.

    The email subject line was: “Declaration” App
    S

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