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26-12-2019 - |
题
这是我的组件的代码:
<?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"
xmlns:mx="library://ns.adobe.com/flex/mx"
width="950" height="50" creationComplete="this_creationCompleteHandler(event)"
currentState="default" enabled="{currentBox!=null}">
<s:states>
<s:State name="default"/>
<s:State name="boxSelected" stateGroups="admin"/>
<s:State name="textBoxSelected" stateGroups="user"/>
<s:State name="imageBoxSelected" stateGroups="user"/>
</s:states>
<s:layout>
<s:HorizontalLayout gap="10" horizontalAlign="left" paddingBottom="10" paddingLeft="10"
paddingRight="10" paddingTop="10" verticalAlign="middle"/>
</s:layout>
<fx:Script>
<![CDATA[
import mx.events.FlexEvent;
public var model:Model;
private var _currentBox:Box = null;
[Bindable]
public function set currentBox(box:Box):void
{
_currentBox = box;
if(model.userType == Model.USER_TYPE_ADMIN)
currentState = "boxSelected";
else if(box is TextBox)
currentState = "textBoxSelected";
else if(box is ImageBox)
currentState = "imageBoxSelected";
else
currentState = "default";
}
public function get currentBox():Box
{
return _currentBox;
}
protected function this_creationCompleteHandler(event:FlexEvent):void
{
AppEventBus.instance.addListener(AppEvent.BOX_SELECTED, boxSelectedHandler);
AppEventBus.instance.addListener(AppEvent.PAGE_SELECTED, pageSelectedhandler);
}
protected function boxSelectedHandler(event:AppEvent):void
{
currentBox = event.data as Box;
}
protected function pageSelectedhandler(event:AppEvent):void
{
currentBox = null;
}
]]>
</fx:Script>
<fx:Declarations>
<!-- Place non-visual elements (e.g., services, value objects) here -->
</fx:Declarations>
<s:ToggleButton id="secureLockButton" includeIn="admin, user" width="20" height="20"
selected="@{currentBox.secured}"
styleName="secureButtonStyle"/>
<s:DropDownList id="fontsList" includeIn="textBoxSelected" width="150" height="20"
selectedItem="@{(currentBox as TextBox).font}"
dataProvider="{(currentBox as TextBox).fonts}"/>
<s:DropDownList id="fontSizesList" includeIn="textBoxSelected" width="60" height="20"
selectedItem="@{(currentBox as TextBox).fontSize}"
dataProvider="{(currentBox as TextBox).fontSizes}"/>
<s:DropDownList id="boxTypes" includeIn="boxSelected" width="70" height="20"
dataProvider="{Box.BOX_TYPES}" selectedItem="{currentBox.boxType}"/>
<s:TextInput id="boxName" includeIn="boxSelected" width="70" height="20"
text="@{currentBox.name}"/>
</s:BorderContainer>
Box
类有两个继承者: TextBox
和 ImageBox
.所有这些类都是 [Bindable]
.在我选择的其他组件中 Box
对象并通知上面的组件有关此事件 EventBus
.我也用它来传递。 Box
对象。每个 TextBox
对象有 ArrayCollection
可用的字体大小(字体)和一个选定的。我要绑定我的 DropDownList
到这些值的两种方式。所以 DropDownList
始终显示框当前选定的字体大小(字体),如果用户从列表中选择另一个值,则将其设置为当前值 TextBox
对象。
当我第一次选择TextBox对象时,一切正常,但是当我选择另一个对象时,我得到错误:
RangeError:属性fontSize值0超出范围 在flashx.textLayout.property::Property$/defaultErrorHandler()[C:\Vellum\branches\v2\2.0\dev\output\openSource extLayout\src\flashx extLayout\property\Property.as:31] 在flashx.textLayout.property::Property/setHelper()[C:\Vellum\branches\v2\2.0\dev\output\openSource extLayout\src\flashx extLayout\property\Property.as:230] 在flashx.textLayout.formats::TextLayoutFormat/setStyleByProperty()[C:\Vellum\branches\v2\2.0\dev\output\openSource extLayout\src\flashx extLayout\formats extLayoutFormat.as:628] 在flashx。textLayout。格式::TextLayoutFormat/set fontSize()[C:\Vellum\branches\v2\2.0\dev\output\openSource extLayout\src\flashx extLayout\formats extLayoutFormat.as:1044] 在spark.core::CSSTextLayoutFormat()[E:\dev\4.y\frameworks\projects\spark\src\spark\core\CSSTextLayoutFormat.as:75] 在spark.components::RichEditableText/updateStylesIfChanged()[E:\dev\4.y\frameworks\projects\spark\src\spark\components ichEditableText.as:3649] 在spark.components::RichEditableText/commitProperties()[E:\dev\4.y\frameworks\projects\spark\src\spark\components ichEditableText.as:2509] 在mx.core::UIComponent/validateProperties()[E:\dev\4.y\frameworks\projects\framework\src\mx\core\UIComponent.as:8219] 在mx.managers::LayoutManager/validateProperties()[E:\dev\4.y\frameworks\projects\framework\src\mx\managers\LayoutManager.as:597] 在mx.managers::LayoutManager/doPhasedInstantiation()[E:\dev\4.y\frameworks\projects\framework\src\mx\managers\LayoutManager.as:813] 在mx.managers::LayoutManager/doPhasedInstantiationCallback()[E:\dev\4.y\frameworks\projects\framework\src\mx\managers\LayoutManager.as:1180]
不知怎的 selectedValue
的财产 DropDownList
变为0。我做错了什么?
解决方案
不调试这个实际的应用程序,就不容易看到"引擎盖下"发生了什么。您可以自己跟踪所有setter以查看bindibgs发生的顺序。
因为在我看来,这两个绑定(selectedItem和dataProvider)不同步。你永远不知道哪一个会首先发生,更重要的是,当你设置其中一个时,drpdownlist内部会发生什么。结果是,在一个点上,双向绑定设置回selectedItem在那一刻为null,并将0设置为fontSize(因为Number(null)为0)。而0会导致在其他地方发生的错误。
只需尝试在fontSize setter中实际设置的内容(在其中放置一个trace())即可开始。
你知道,由于双向绑定似乎是一个好主意,我总是以处理change事件(在此事件处理程序中设置)结束回到"经典绑定"。在使用双向绑定时,我们总是遇到类似这样的问题.