Why i can't set an veriable into animation attributes?

Question

Hello,
I have an simple question, why i can't put variables into animations ?
<?xml version="1.0" encoding="utf-8"?>
<s:Application width="100%" height="100%"
               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:Declarations>
        <s:Parallel id="MoveRect_1ToRight">
            <s:Move xTo="{MoveXto}" target="{Rect_1}" duration="8000" />
        </s:Parallel>
    </fx:Declarations>
    <fx:Script>
        <![CDATA[
            public var MoveXto:Number = -(Rect_1.width - stage.width);
        ]]>
    </fx:Script>
    <s:Group id="Rect_1" width="3000" height="800" verticalCenter="0">
        <s:Rect width="100%" height="100%">
            <s:fill>
                <s:LinearGradient>
                    <s:GradientEntry color="#e8db03"/>
                    <s:GradientEntry color="#153eec"/>
                </s:LinearGradient>
            </s:fill>
        </s:Rect>
    </s:Group>
    <s:Group id="Rect_2" width="80" top="0" bottom="0" right="0"
             rollOver="MoveRect_1ToRight.play();" rollOut="MoveRect_1ToRight.pause();">
        <s:Rect width="100%" height="100%">
            <s:fill><s:SolidColor color="#000000" alpha="0.2"/></s:fill>
        </s:Rect>
    </s:Group>
</s:Application>
Greetings
zombiecook

Answer 1

You need to calculate the value of MoveXto after the application is
created, here I use the creationComplete handler as an example (and I
changed stage to this), but you might also consider using the
applicationComplete handler if you do want a non null stage value.
<?xml version="1.0" encoding="utf-8"?>
 <s:Application
width="100%" height="100%" 
xmlns:fx="http://ns.adobe.com/mxml/2009"               
xmlns:s="library://ns.adobe.com/flex/spark"               
xmlns:mx="library://ns.adobe.com/flex/mx"               
creationComplete="init()">          <fx:Declarations>       
<s:Parallel id="MoveRect_1ToRight">             <s:Move
xTo="{MoveXto}" target="{Rect_1}" duration="8000" />        
</s:Parallel>     </fx:Declarations>         
<fx:Script>         <![CDATA[             [Bindable]
public var MoveXto:Number; 
            private function
init():void {
                MoveXto = -1 * (Rect_1.width -
this.width);
            }         ]]>
</fx:Script>
    <s:Group id="Rect_1" width="3000"
height="800" verticalCenter="0">
        <s:Rect width="100%"
height="100%">
            <s:fill>
<s:LinearGradient>
                    <s:GradientEntry
color="#e8db03"/>
                    <s:GradientEntry
color="#153eec"/>
                </s:LinearGradient>
</s:fill>
        </s:Rect>
    </s:Group>
    <s:Group id="Rect_2" width="80" top="0" bottom="0" right="0"
rollOver="MoveRect_1ToRight.play();"
rollOut="MoveRect_1ToRight.pause();">
        <s:Rect
width="100%" height="100%">
<s:fill><s:SolidColor color="#000000"
alpha="0.2"/></s:fill>
        </s:Rect>
</s:Group>
</s:Application>
Thank you very much !