如何訪問不可見的Flex組件？

Question

我是一個新手來flex和建立一個flex 4.5應用程序，它有一個自定義組件擴展SkinnableContainer。這個自定義組件基本上是一種可摺疊面板。當你打開它時，你會看到contentGroup中的所有控件，當你關閉它們時，它們就會消失，你將留下標題。這是通過使contentGroup僅包含在打開狀態中而在皮膚中完成的。

我在應用程序中有一堆這些容器，有些是默認打開的，有些是關閉的。 所以在MXML結構的樣子：

<ui:MyCustomContainer open="false" label="bla"> 
    <s:HGroup> 
    <s:Button /> 
    <ui:AnotherComponent /> 
    <etc /> 
    </s:HGroup> 
</ui:MyCustomContainer> 

我的問題是，我無法訪問（通過動作，例如，在事件處理）從封閉容器中的組分（實際上他們的初始化事件代碼不運行），直到他們已被打開至少一次。

做一些挖掘我發現flex有關延遲創建組件的某種性能增強。因此，認爲這必須回答我的SkinnableContainer的creationPolicy設置爲「all」：

<ui:MyCustomContainer open="false" label="bla" creationPolicy="all" > 

但是，這是行不通的。有任何想法嗎？

UPDATE：下面

完整的示例Revealer.as的換膚的容器（從書的Flex 4中所採取的行動，並剝離下來比特）

package 
{ 
import flash.events.Event; 

import spark.components.SkinnableContainer; 
import spark.components.ToggleButton; 
import spark.components.supportClasses.TextBase; 

[SkinState("open")] 
[SkinState("closed")] 
[SkinState("disabled")] //Not used: just appeasing compiler in the skin when host component is defined. 
[SkinState("normal")] //Not used: just appeasing compiler in the skin when host component is defined. 

public class Revealer extends SkinnableContainer 
{ 
    private var m_open:Boolean = true; 
    private var m_label:String; 

    [SkinPart] 
    public var toggler:ToggleButton; 

    [SkinPart(required="false")] 
    public var labelDisplay:TextBase; 


    public function Revealer() 
    { 
     super(); 
    } 

    public function get open():Boolean { return m_open; } 
    public function set open(value:Boolean):void 
    { 
     if(m_open == value) 
      return; 
     m_open = value; 
     invalidateSkinState(); 
     invalidateProperties(); 
    }  

    public function get label():String { return m_label; } 
    public function set label(value:String):void 
    { 
     if(m_label == value) 
      return; 
     m_label = value; 
     if(labelDisplay != null) 
      labelDisplay.text = value; 
    } 

    override protected function getCurrentSkinState():String { return m_open ? "open" : "closed"; } 

    override protected function partAdded(name:String, instance:Object):void 
    { 
     super.partAdded(name, instance); 
     if(instance == toggler) 
     { 
      toggler.addEventListener(Event.CHANGE, toggleButtonChangeHandler); 
      toggler.selected = m_open; 
     } 
     else if(instance == labelDisplay) 
     { 
      labelDisplay.text = m_label; 
     } 
    } 

    private function toggleButtonChangeHandler(e:Event):void 
    { 
     open = toggler.selected;  
    } 
} 
} 

RevealerSkin.mxml皮膚爲容器

<?xml version="1.0" encoding="utf-8"?> 
<s:Skin xmlns:fx="http://ns.adobe.com/mxml/2009" 
    xmlns:s="library://ns.adobe.com/flex/spark" > 
<fx:Metadata>[HostComponent("Revealer")]</fx:Metadata> 
<s:states> 
    <s:State name="open" /> 
    <s:State name="closed" /> 
    <s:State name="disabled" /> <!--not used: just appeasing compiler in the skin when host component is defined. --> 
    <s:State name="normal" /> <!--not used: just appeasing compiler in the skin when host component is defined. --> 
</s:states> 
<s:Rect radiusX="5" top="0" left="0" right="0" bottom="0" minWidth="200"> 
    <s:stroke><s:SolidColorStroke weight="2" alpha="0.5"/></s:stroke> 
</s:Rect> 
<s:Group left="0" top="0" right="0" bottom="5"> 
    <s:ToggleButton id="toggler" label="toggle" left="5" top="5" /> 
</s:Group> 
<s:Label id="labelDisplay" left="{toggler.width + 10}" top="10" right="0" /> 
<s:Group id="contentGroup" includeIn="open" itemCreationPolicy="immediate" left="5" right="5" top="35" bottom="5" /> 
</s:Skin> 

MyControl.mxml放在容器

<?xml version="1.0" encoding="utf-8"?> 
<s:BorderContainer xmlns:fx="http://ns.adobe.com/mxml/2009" 
      xmlns:s="library://ns.adobe.com/flex/spark" 
        borderWeight="2" borderColor="black" 
       borderAlpha="0.2" cornerRadius="2" 
      height="25"> 
<fx:Script> 
    <![CDATA[ 
     [Bindable] public var minVal:Number; 
     [Bindable] public var maxVal:Number; 
     [Bindable] public var defaultVal:Number;    
     public function get value():Number { return valueSlider.value; } 
    ]]> 
</fx:Script> 
<s:layout> 
    <s:VerticalLayout/> 
</s:layout> 
<s:HGroup width="100%" paddingTop="5" paddingBottom="5" paddingLeft="5" paddingRight="5"> 
    <s:Label text="Value:" /> 
    <s:Spacer width="100%" /> 
    <s:HSlider id="valueSlider" minimum="{minVal}" maximum="{maxVal}" value="{defaultVal}" /> 
</s:HGroup> 
</s:BorderContainer> 

RevealerTest.mxml一個示例應用程序來演示這個問題

<?xml version="1.0" encoding="utf-8"?> 
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
      xmlns:s="library://ns.adobe.com/flex/spark" 
      xmlns:local="*" 
      minWidth="955" minHeight="600" > 
<fx:Script> 
    <![CDATA[ 
     protected function onClick(e:MouseEvent):void { 
      debugArea.text += control1.value + "\n" + control2.value + "\n"; 
     } 
    ]]> 
</fx:Script> 
<s:HGroup> 
    <s:VGroup> 
     <s:Button label="click me" click="onClick(event)" /> 
     <local:Revealer label="Group 1" skinClass="RevealerSkin" creationPolicy="all"> 
      <local:MyControl id="control1" minVal="0" maxVal="10" defaultVal="5"/> 
     </local:Revealer> 
     <local:Revealer label="Group 2" open="false" skinClass="RevealerSkin" creationPolicy="all"> 
      <local:MyControl id="control2" minVal="0" maxVal="100" defaultVal="50"/> 
     </local:Revealer> 
    </s:VGroup> 
    <s:TextArea id="debugArea" /> 
</s:HGroup> 
</s:Application> 

注意內部的自定義控件，如果你打我點擊按鈕開幕前第二個容器中，我們無法從初始摺疊組中的控件獲取值。打開組只允許訪問該值。摺疊組仍然沒問題。這是第一次是這個問題。我已將creationPolicy添加到容器並將itemCreationPolicy添加到皮膚中的內容組，但沒有運氣！

Answer 1

其實，它不是creationPolicy你正在尋找，但itemCreationPolicy。這是您的隱藏元素（contentGroup）的屬性。如果元素事件由於currentState而未顯示，您必須將其設置爲immediate以訪問元素事件。