Flex Spark RadioButton Deselected Event? - apache-flex

Question

Is there a way to listen for this? I can easily listen for click which selects a RadioButton, but I can't seem to find a way to listen for when the RadioButton has been deselected.
Any ideas?
Thanks!

Answer 1

Back in the Flex 2 days, the "change" event triggered when a radio button was deselected. However, this little convenience disappeared in Flex 3, for some reason, and I don't believe that we were provided with any sort of replacement event.
Handling your events at the RadioButtonGroup level is all fine and well, except that there are times when you really want to handle the events on the radio button level -- particularly if you were hoping to interact with a data provider entry via an itemRenderer that is drawing the radio button.
Conveniently, I have a little bit of boilerplate code you can use as drop-in replacements for RadioButton and RadioButtonGroup that provide a "unselect" event at the radio button level. Here is the SmartRadioButton, first of all:
<?xml version="1.0" encoding="utf-8"?>
<s:RadioButton 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[
import events.SmartRadioButtonEvent;
public function notifyDeselect():void {
dispatchEvent(new SmartRadioButtonEvent('deselect'));
}
]]>
</fx:Script>
<fx:Metadata>
[Event(name="deselect", type="events.SmartRadioButtonEvent")]
</fx:Metadata>
</s:RadioButton>
And here is the SmartRadioButtonGroup:
<?xml version="1.0" encoding="utf-8"?>
<s:RadioButtonGroup xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark"
xmlns:mx="library://ns.adobe.com/flex/mx"
change="selectionChanged();"
>
<fx:Script>
<![CDATA[
import spark.components.RadioButton;
import components.SmartRadioButton;
protected var oldSelection:SmartRadioButton = null;
// Notify our old selection that it has been deselected, and update
// the reference to the new selection.
public function selectionChanged():void {
var newSelection:SmartRadioButton = this.selection as SmartRadioButton;
if (oldSelection == newSelection) return;
if (oldSelection != null) {
oldSelection.notifyDeselect();
}
oldSelection = newSelection;
}
// Override some properties to make sure that we update oldSelection correctly,
// in the event of a programmatic selection change.
override public function set selectedValue(value:Object):void {
super.selectedValue = value;
oldSelection = super.selection as SmartRadioButton;
}
override public function set selection(value:RadioButton):void {
super.selection = value;
oldSelection = super.selection as SmartRadioButton;
}
]]>
</fx:Script>
</s:RadioButtonGroup>
The two property overrides are in there to make sure that we correctly update the oldSelection, in the event of a programmatic change to the group's selection.
SmartRadioButtonEvent isn't anything fancy or important. It could probably just be a plain Event, since there isn't a special payload.
I have tested the above code, and it all works, but there are surely edge conditions, and other oddities that should be addressed, if it's used in a larger system.