The following example shows how you can detect when the vertical scroll bar is scrolled on a Spark List control in Flex 4 by listening for the change
event on the List control’s VScrollBar instance.
The following example(s) require Flash Player 10 and the Adobe Flex 4 SDK. To download the Adobe Flash Builder 4 trial, see www.adobe.com/products/flex/. To download the latest nightly build of the Flex 4 SDK, see opensource.adobe.com/wiki/display/flexsdk/Download+Flex+4.
For more information on getting started with Flex 4 and Flash Builder 4, see the official Adobe Flex Team blog.
<?xml version="1.0" encoding="utf-8"?> <!-- http://blog.flexexamples.com/2009/05/31/detecting-when-the-vertical-scroll-bar-is-scrolled-on-a-spark-list-control-in-flex-4/ --> <s:Application name="Spark_List_scroller_verticalScrollBar_change_test" 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:Script> <![CDATA[ import spark.components.VScrollBar; private function init():void { list.scroller.verticalScrollBar.addEventListener(Event.CHANGE, list_verticalScrollBar_change); } private function list_verticalScrollBar_change(evt:Event):void { var vsb:VScrollBar = evt.currentTarget as VScrollBar; var obj:Object = {}; obj.type = evt.type; obj.val = vsb.value; obj.max = vsb.maximum; arrColl.addItem(obj); callLater(dgScroll); } private function dgScroll():void { dataGrid.verticalScrollPosition = dataGrid.maxVerticalScrollPosition; } ]]> </fx:Script> <fx:Declarations> <mx:ArrayCollection id="arrColl" /> </fx:Declarations> <s:HGroup horizontalCenter="0" verticalCenter="0"> <s:List id="list" creationComplete="init();"> <s:layout> <s:VerticalLayout gap="0" horizontalAlign="contentJustify" requestedRowCount="4" /> </s:layout> <s:dataProvider> <s:ArrayList> <fx:String>The</fx:String> <fx:String>Quick</fx:String> <fx:String>Brown</fx:String> <fx:String>Fox</fx:String> <fx:String>Jumps</fx:String> <fx:String>Over</fx:String> <fx:String>The</fx:String> <fx:String>Lazy</fx:String> <fx:String>Dog</fx:String> </s:ArrayList> </s:dataProvider> </s:List> <mx:DataGrid id="dataGrid" dataProvider="{arrColl}" width="200" verticalScrollPolicy="on"> <mx:columns> <mx:DataGridColumn dataField="type" /> <mx:DataGridColumn dataField="val" /> <mx:DataGridColumn dataField="max" /> </mx:columns> </mx:DataGrid> </s:HGroup> </s:Application> |
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View source is enabled in the following example.
This entry is based on a beta version of the Flex 4 SDK and therefore is very likely to change as development of the Flex SDK continues. The API can (and will) change causing examples to possibly not compile in newer versions of the Flex 4 SDK.
Seems to only be the case when you use mouse buttons and not the mouse wheel! very strange
@Tyrone Neill,
Good catch! I filed a bug at http://bugs.adobe.com/jira/browse/SDK-26533 and attached a possible workaround.
Peter