Flex4 spark.components.DropDownList 行数设置rowcount

Flex3里的ComboBox可以设置rowcount。但是spark.components.DropDownList里没有该属性。

最后仔细研究，发现奥妙全部都在skin里。

 

新建一个DropDownList的skin，关键属性处我已经设置成了加亮显示，自己一试便知。

<?xml version="1.0" encoding="utf-8"?>
<s:SparkSkin xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark"
    xmlns:fb="http://ns.adobe.com/flashbuilder/2009" alpha.disabled=".5">
    <fx:Metadata>
    <![CDATA[
        /**
         * @copy spark.skins.spark.ApplicationSkin#hostComponent
         */
        [HostComponent("spark.components.DropDownList")]
    ]]>
    </fx:Metadata>
    <s:states>
        <s:State name="normal" />
        <s:State name="open" />
        <s:State name="disabled" />
    </s:states>
    <s:PopUpAnchor id="popUp"  displayPopUp.normal="false" displayPopUp.open="true" includeIn="open"
        left="0" right="0" top="0" bottom="0" itemDestructionPolicy="auto"
        popUpPosition="below" popUpWidthMatchesAnchorWidth="true">
        <s:Group id="dropDown" maxHeight="270" minHeight="22" >
            <s:RectangularDropShadow id="dropShadow" blurX="20" blurY="20" alpha="0.45" distance="7"
                 angle="90" color="#000000" left="0" top="0" right="0" bottom="0"/>
            <s:Rect id="border" left="0" right="0" top="0" bottom="0">
                <s:stroke>
                    <s:SolidColorStroke id="borderStroke" weight="1"/>
                </s:stroke>
            </s:Rect>
            <s:Rect id="background" left="1" right="1" top="1" bottom="1" >
                <s:fill>
                    <s:SolidColor id="bgFill" color="0xFFFFFF" />
                </s:fill>
            </s:Rect>
            <s:Scroller id="scroller" left="0" top="0" right="0" bottom="0" hasFocusableChildren="false" minViewportInset="1">
                <s:DataGroup id="dataGroup" itemRenderer="spark.skins.spark.DefaultItemRenderer">
                    <s:layout>
                        <s:VerticalLayout gap="0" horizontalAlign="contentJustify" requestedRowCount="10"/>
                    </s:layout>
                </s:DataGroup>
            </s:Scroller>
        </s:Group>
    </s:PopUpAnchor>
    <s:Button id="openButton" left="0" right="0" top="0" bottom="0" focusEnabled="false"
        skinClass="spark.skins.spark.DropDownListButtonSkin" /> 
    <s:Label id="labelDisplay" verticalAlign="middle" maxDisplayedLines="1"
        mouseEnabled="false" mouseChildren="false"
        left="7" right="30" top="2" bottom="2" width="75" verticalCenter="1" />
</s:SparkSkin>