设置ComboBox控件中可见项的个数.

ComboBox控件的rowCount属性学习。
示例：

代码：

<? xml version="1.0" encoding="utf-8" ?>
<!--  http://blog.flexexamples.com/2008/06/11/setting-the-number-of-visible-items-in-a-combobox-controls-dropdown-menu-in-flex/  -->
< mx:Application  xmlns:mx ="http://www.adobe.com/2006/mxml"
        layout ="vertical"
        verticalAlign ="top"
        backgroundColor ="white" >

     < mx:Script >
         <![CDATA[
            import mx.events.NumericStepperEvent;

            private function numericStepper_change(evt:NumericStepperEvent):void {
                callLater(comboBoxOpen);
            }

            private function comboBoxOpen():void {
                comboBox.open();
            }
         ]]>
     </ mx:Script >

     < mx:Array  id ="arr" >
         < mx:Object  label ="One"   />
         < mx:Object  label ="Two"   />
         < mx:Object  label ="Three"   />
         < mx:Object  label ="Four"   />
         < mx:Object  label ="Five"   />
         < mx:Object  label ="Six"   />
         < mx:Object  label ="Seven"   />
         < mx:Object  label ="Eight"   />
         < mx:Object  label ="Nine"   />
     </ mx:Array >

     < mx:ApplicationControlBar  dock ="true" >
         < mx:NumericStepper  id ="numericStepper"
                minimum ="0"
                maximum ="10"
                change ="numericStepper_change(event);"   />
     </ mx:ApplicationControlBar >

     < mx:ComboBox  id ="comboBox"
            dataProvider =" {arr} "
            rowCount =" {numericStepper.value} "
            openDuration ="0"
            closeDuration ="0"
            width ="100"   />

</ mx:Application >

通过AS的方法来实现：

<? xml version="1.0" encoding="utf-8" ?>
<!--  http://blog.flexexamples.com/2008/06/11/setting-the-number-of-visible-items-in-a-combobox-controls-dropdown-menu-in-flex/  -->
< mx:Application  xmlns:mx ="http://www.adobe.com/2006/mxml"
        layout ="vertical"
        verticalAlign ="top"
        backgroundColor ="white"
        initialize ="init();" >

     < mx:Script >
         <![CDATA[
            import mx.controls.ComboBox;
            import mx.controls.NumericStepper;
            import mx.containers.ApplicationControlBar;
            import mx.events.NumericStepperEvent;

            private var arr:Array;
            private var appControlBar:ApplicationControlBar;
            private var numericStepper:NumericStepper;
            private var comboBox:ComboBox;

            private function init():void {
                arr = [];
                arr.push({label:"One"});
                arr.push({label:"Two"});
                arr.push({label:"Three"});
                arr.push({label:"Four"});
                arr.push({label:"Five"});
                arr.push({label:"Six"});
                arr.push({label:"Seven"});
                arr.push({label:"Eight"});
                arr.push({label:"Nine"});

                numericStepper = new NumericStepper();
                numericStepper.minimum = 0;
                numericStepper.maximum = 10;
                numericStepper.addEventListener(NumericStepperEvent.CHANGE, numericStepper_change);

                appControlBar = new ApplicationControlBar();
                appControlBar.dock = true;
                appControlBar.addChild(numericStepper);
                Application.application.addChildAt(appControlBar, 0);

                comboBox = new ComboBox();
                comboBox.dataProvider = arr;
                comboBox.rowCount = 5;
                comboBox.width = 100;
                comboBox.setStyle("openDuration", 0);
                comboBox.setStyle("closeDuration", 0);
                addChild(comboBox);
            }

            private function numericStepper_change(evt:NumericStepperEvent):void {
                comboBox.rowCount = evt.value;
                callLater(comboBoxOpen);
            }

            private function comboBoxOpen():void {
                comboBox.open();
            }
         ]]>
     </ mx:Script >

</ mx:Application >

来自： http://blog.flexexamples.com/2008/06/11/setting-the-number-of-visible-items-in-a-combobox-controls-dropdown-menu-in-flex/