MACROMEDIA FLEX 2-MIGRATING APPLICATIONS TO FLEX 2 Manual do Utilizador descarregar pdf (Página 172)

172 Additional Migration Issues

Embedding resources

In Flex 1.5, embedded resources were bound to Strings that were used to reference the

individual images by name. Although the preferred method of embedding resources in Flex 2

uses Class variables, you can still use String variables for some level of backward compatibility.

However, the various objects and tags that use your embedded assets expect them to be tied to

Class variables, so you need to use the

getDefinitionByName() method to cast your string

variables. You also still need to use the

[Bindable] metadata tag to declare the string variable

bindable.

For instance, the following application uses string variables and casting to display an

embedded image:

<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml">

<mx:Script>

<![CDATA[

[Embed(source="logo.gif")]

[Bindable]

public var imgStr:String;

]]>

</mx:Script>

<mx:Image source="{getDefinitionByName(imgStr)}"/>

</mx:Application>

Although this method works, Adobe recommends that you use Class variables instead. The

equivalent application, using a Class variable, is simpler:

<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml">

<mx:Script>

<![CDATA[

[Embed(source="logo.gif")]

[Bindable]

public var imgCls:Class;

]]>

</mx:Script>

<mx:Image source="{imgCls}"/>

</mx:Application>

Alternatively, when you use MXML, this becomes a one line application:

<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml">

<mx:Image source="@Embed(source='logo.gif')" />

</mx:Application>

For more information, see Chapter 30, “Embedding Assets,” in the Flex 2 Developer’s Guide.

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MACROMEDIA FLEX 2-MIGRATING APPLICATIONS TO FLEX 2 Manual do Utilizador Página 172