Flex Gumbo中如何通过selectionChanging事件和preventDefault()函数阻止用户选定DropDownList特定项目的例子

By Minidxer | August 11, 2009

接下来的Flex Gumbo中如何通过监听selectionChanging事件和调用preventDefault()函数，阻止用户选定DropDownList特定项目。

下面是main.mxml：

<?xml version="1.0" encoding="utf-8"?>
<s:Application name="DropDownList_selectionChanging_test"
xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark"
xmlns="library://ns.adobe.com/flex/halo">
<fx:Script>
<![CDATA[
import mx.controls.Alert;
import mx.events.IndexChangedEvent;
private function dropDownList_selectionChanging(evt:IndexChangedEvent):void {
var ddl:DropDownList = evt.currentTarget as DropDownList;
if (ddl.selectedItem != null && ddl.selectedItem.hasOwnProperty("selectable") && !ddl.selectedItem.selectable) {
evt.stopImmediatePropagation();
evt.preventDefault();
}
}
private function dropDownList_selectionChanged(evt:IndexChangedEvent):void {
Alert.show("Spark DropDownList selection was changed.");
}
]]>
</fx:Script>
<s:DropDownList id="dropDownList"
labelField="label"
prompt="Please select a string..."
selectionChanging="dropDownList_selectionChanging(event);"
selectionChanged="dropDownList_selectionChanged(event);"
width="200"
horizontalCenter="0"
top="10">
<s:dataProvider>
<s:ArrayList>
<fx:Object label="The" selectable="false" />
<fx:Object label=" Quick" />
<fx:Object label=" Brown" />
<fx:Object label=" Fox" />
<fx:Object label=" Jumps" />
<fx:Object label=" Over" />
<fx:Object label="The" selectable="false" />
<fx:Object label=" Lazy" />
<fx:Object label=" Dog" />
</s:ArrayList>
</s:dataProvider>
</s:DropDownList>
</s:Application>

代码：Peter deHaan 翻译/整理/编译：中文Flex例子

Topics: DropDownList, Gumbo | No Comments » | Tags: Gumbo, preventDefault, selectionChanged, selectionChanging

中文Flex例子