Flex - 如何更改打开的DropDownList高度

Question

使用FB4,我想改变一个开放的火花DropDownList的高度.默认情况下,它在滚动前最多显示6个项目.我的下拉列表包含7个项目,因此我想更改打开的下拉列表的高度以适应所有7项而不滚动.作为一种解决方法,我已经改变了项目的字体大小,使它们更小,所有7都适合,但较小的字体看起来不太好.有没有办法改变这个高度？我对Flash很新,所以如果它是一个复杂的解决方案,请详细说明:-).

Answer 1

如果你使用verticalLayout的requestedRowCount属性不是更容易吗？

<s:DropDownList dataProvider="{myDataProvider}">
    <s:layout>
        <s:VerticalLayout requestedRowCount="10"/>
    </s:layout>
</s:DropDownList>

Answer 2

问题是,在Flex 4中,DropDownListSkin已经maxHeight="134"为您可能正在使用的默认皮肤定义了.如果对象超出该高度,则强制滚动条出现.您需要做的就是将DropDownListSkin代码复制/粘贴到自定义皮肤中,然后通过CSS将其应用于DropDownList:

VariableHeightDropDownListSkin

<?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" 
    alpha.disabled=".5"> 

    <!-- host component -->
    <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">

        <!-- removed maxHeight! -->
        <s:Group id="dropDown" minHeight="22">
            <!-- border/fill -->
            <s:Rect left="0" right="0" top="0" bottom="0">
                <s:stroke>
                    <s:SolidColorStroke color="0x5380D0" />
                </s:stroke>
                <s:fill>
                    <s:SolidColor color="0xFFFFFF" />
                </s:fill>
            </s:Rect>

            <s:Scroller left="0" top="0" right="0" bottom="0" focusEnabled="false" minViewportInset="1">
                <s:DataGroup id="dataGroup" itemRenderer="spark.skins.spark.DefaultItemRenderer">
                    <s:layout>
                        <s:VerticalLayout gap="0" horizontalAlign="contentJustify"/>
                    </s:layout>
                </s:DataGroup>
            </s:Scroller>

            <s:filters>
                <s:DropShadowFilter blurX="20" blurY="20" distance="7" angle="90" alpha="0.45" color="0x6087CC" />
            </s:filters>
        </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" lineBreak="explicit"
        mouseEnabled="false" mouseChildren="false"
        left="7" right="30" top="2" bottom="2" width="75" verticalCenter="1" /> 

</s:Skin>

样品申请

<?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:mx="library://ns.adobe.com/flex/mx">

    <fx:Style>
        @namespace mx "library://ns.adobe.com/flex/mx";
        @namespace s "library://ns.adobe.com/flex/spark";

        s|DropDownList
        {
            skinClass: ClassReference("VariableHeightDropDownListSkin");
        }
    </fx:Style>

        <s:DropDownList labelField="name" horizontalCenter="0" verticalCenter="0">
            <s:layout>
                <s:VerticalLayout requestedRowCount="7"/>
            </s:layout>
            <s:dataProvider>
                <mx:ArrayCollection>
                    <fx:Object name="one"/>
                    <fx:Object name="two"/>
                    <fx:Object name="three"/>
                    <fx:Object name="four"/>
                    <fx:Object name="five"/>
                    <fx:Object name="six"/>
                    <fx:Object name="seven"/>
                </mx:ArrayCollection>
            </s:dataProvider>
        </s:DropDownList>

</s:Application>

让我知道,如果这有帮助,兰斯

Answer 3

viatropos答案会起作用,但你应尽量避免覆盖整个皮肤.

在这种情况下,您会注意到在viatropos的VariableHeightDropDownListSkin代码中,除去了maxHeight属性的组,还指定了一个"id".

现在看一下DropDownList的文档,你会在SkinParts部分注意到有一个"dropDown"外观部件.这实际上是DropDownList的一个属性.

因此,不要覆盖皮肤,只需使用actionscript(我在这里使用UIComponent.DEFAULT_MAX_HEIGHT,但您可以使用任何您想要的):

(MyDropDownList.dropDown as UIComponent).maxHeight = UIComponent.DEFAULT_MAX_HEIGHT;