Flex4中的皮肤（4）：使用SkinPart约束Skin

在SkinnableComponent中，可以声明SkinPart元标签对Skin进行约束，同时在组件中提供对Skin元素的引用：

 

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1. [SkinPart(required="false")]           
2. public var labelElement:SimpleText;  

[SkinPart(required="false")] public var labelElement:SimpleText;

 

如果声明了SkinPart并且required="true"，则Skin中必须包含该类型灯元素并且具有相同的id：

<s:SimpleText id="labelElement" .../>

SkinnableComponent中还提供了partAdded和partRemoved方法：

 

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1. //--------------------------------------------------------------------------   
2.     //   
3.     //  Methods - Parts   
4.     //   
5.     //--------------------------------------------------------------------------   
6.        
7.     /**  
8.      *  Called when a skin part is added.   
9.      *  You do not call this method directly.   
10.      *  For static parts, Flex calls it automatically when it calls the <code>attachSkin()</code> method.   
11.      *  For dynamic parts, Flex calls it automatically when it calls   
12.      *  the <code>createDynamicPartInstance()</code> method.   
13.      *  
14.      *  <p>Override this function to attach behavior to the part.   
15.      *  If you want to override behavior on a skin part that is inherited from a base class,   
16.      *  make sure that you do not call the <code>super.partAdded()</code> method.   
17.      *  Otherwise, you should always call the <code>super.partAdded()</code> method.</p>  
18.      *  
19.      *  @param partname The name of the part.  
20.      *  
21.      *  @param instance The part.  
22.      *    
23.      *  @langversion 3.0  
24.      *  @playerversion Flash 10  
25.      *  @playerversion AIR 1.5  
26.      *  @productversion Flex 4  
27.      */  
28.     protected function partAdded(partName:String, instance:Object):void  
29.     {      
30.     }   
31.     /**  
32.      *  Called when an instance of a skin part is being removed.   
33.      *  You do not call this method directly.   
34.      *  For static parts, Flex calls it automatically when it calls the <code>detachSkin()</code> method.   
35.      *  For dynamic parts, Flex calls it automatically when it calls   
36.      *  the <code>removeDynamicPartInstance()</code> method.   
37.      *  
38.      *  <p>Override this function to remove behavior from the part.</p>  
39.      *  
40.      *  @param partname The name of the part.  
41.      *  
42.      *  @param instance The part.  
43.      *    
44.      *  @langversion 3.0  
45.      *  @playerversion Flash 10  
46.      *  @playerversion AIR 1.5  
47.      *  @productversion Flex 4  
48.      */  
49.     protected function partRemoved(partName:String, instance:Object):void  
50.     {          
51.     }   
52.       

//-------------------------------------------------------------------------- // // Methods - Parts // //-------------------------------------------------------------------------- /** * Called when a skin part is added. * You do not call this method directly. * For static parts, Flex calls it automatically when it calls the <code>attachSkin()</code> method. * For dynamic parts, Flex calls it automatically when it calls * the <code>createDynamicPartInstance()</code> method. * * <p>Override this function to attach behavior to the part. * If you want to override behavior on a skin part that is inherited from a base class, * make sure that you do not call the <code>super.partAdded()</code> method. * Otherwise, you should always call the <code>super.partAdded()</code> method.</p> * * @param partname The name of the part. * * @param instance The part. * * @langversion 3.0 * @playerversion Flash 10 * @playerversion AIR 1.5 * @productversion Flex 4 */ protected function partAdded(partName:String, instance:Object):void { } /** * Called when an instance of a skin part is being removed. * You do not call this method directly. * For static parts, Flex calls it automatically when it calls the <code>detachSkin()</code> method. * For dynamic parts, Flex calls it automatically when it calls * the <code>removeDynamicPartInstance()</code> method. * * <p>Override this function to remove behavior from the part.</p> * * @param partname The name of the part. * * @param instance The part. * * @langversion 3.0 * @playerversion Flash 10 * @playerversion AIR 1.5 * @productversion Flex 4 */ protected function partRemoved(partName:String, instance:Object):void { }

 

在增加或删除SkinPart时会调用这些方法。

通过重写这些方法可以对SkinPart进行额外的操作，比如增加SkinPart时为其添加事件监听：

 

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1. override protected function partAdded(partName:String, instance:Object) : void  
2. {   
3.        super.partAdded(partName, instance);   
4.        if (instance == labelElement)   
5.            labelElement.addEventListener(...);   
6. }  

转载于:https://www.cnblogs.com/gisera/archive/2010/12/28/1919117.html