Stop List From Scrolling - apache-flex

Question

I have a datagrid that's using a custom itemrender with a button in it. I have a problem whereby when I click on a button the datagrid list scrolls its self. How can I prevent this behaviour?
Extended datagrid
<mx:DataGrid xmlns:mx="http://www.adobe.com/2006/mxml"
doubleClickEnabled="false"
alternatingItemColors="[#ffffff, #f1f1f1]"
mouseDown="mdhandler(event)"
sortableColumns="true"
xmlns:datagrids="components.content.contents.datagrids.*"
creationComplete="_creationcomplete(event)">
<mx:Script>
<![CDATA[
import mx.binding.utils.BindingUtils;
import components.preview.PreviewPlayEvent;
import mx.controls.Button;
import components.preview.PreviewPlay;
import components.content.contents.FixedHelp.FixedHelp;
import mx.events.FlexEvent;
import mx.core.Application;
import mx.events.ToolTipEvent;
import flash.utils.describeType;
import mx.utils.ObjectUtil;
import components.remix.PadDisplay.PadContent;
import components.remix.PadDisplay.PalletteCode;
import mx.core.IUIComponent;
import mx.controls.Image;
import mx.managers.DragManager;
import mx.core.DragSource;
import mx.events.DragEvent;
// Embed icon image.
[Embed(source='assets/proxy.png')]
public var dragImg:Class;
private var _scrollEnabled:Boolean=true;
private var _currentpath:String="";
public static const TYPE_ARRAY:Array=["loop", "one-shot sample", "stem", "track"]
private function _creationcomplete(e:FlexEvent=null):void
{
addEventListener(Event.ENTER_FRAME, enterframe, false, 0, true);
addEventListener(PreviewPlayEvent.PLAY, previewplayrequest, false, 0, true);
addEventListener(PreviewPlayEvent.STOP,previewstoprequest,false,0,true)
}
private function previewplayrequest(e:PreviewPlayEvent):void
{
_currentpath=e._path;
//Application.application.previewplay(e._path)
invalidateList();
}
private function previewstoprequest(e:PreviewPlayEvent):void
{
_currentpath="";
//Application.application.previewplay(e._path)
invalidateList();
}
public function get critera():String
{
return _currentpath;
}
public function set criteria(value:String):void
{
_currentpath=value;
}
private function enterframe(e:Event):void
{
if (Application.application.hashelp == false)
{
}
else
{
removeEventListener(Event.ENTER_FRAME, enterframe);
var xml:XML=Application.application.helpxml;
var fh:FixedHelp=Application.application.fixedhelp;
var helptext:String=Application.application.helpxml.studio.loops.text;
fh.addItem(helptext, this);
}
}
private function mdhandler(e:MouseEvent):void
{
describeType(e.currentTarget)
e.currentTarget.toString()
if (e.currentTarget.selectedItem != null && getQualifiedClassName(e.target) != "mx.controls::Button")
{
_scrollEnabled=false
var dragdata:XML=XML(e.currentTarget.selectedItem) as XML
var ds:DragSource=new DragSource()
var dragdataasObject:Object=ObjectUtil.copy(e.currentTarget.selectedItem)
ds.addData(dragdataasObject, PadContent.LOOP_FORMAT);
//trace(ds.dataForFormat(PadContent.LOOP_FORMAT)) // I expect xml data to trace out here but it does not
var imageproxy:Image=new Image();
imageproxy.source=dragImg;
imageproxy.height=40;
imageproxy.width=40;
DragManager.doDrag(this, ds, e, imageproxy, (this.x - e.stageX) + 40, (this.y - e.stageY) + 130)
this.selectedItem=null;
}
else
{
e.stopImmediatePropagation();
}
}
private function userLabelFunction(item:Object, column:DataGridColumn):String
{
var newstr:String=new String(item.t + "\n" + TYPE_ARRAY[item.ty])
return newstr;
}
private function catFunction(item:Object, column:DataGridColumn):String
{
var newstr:String=TYPE_ARRAY[item.ty];
return newstr;
}
private function bpmFunction(item:Object, column:DataGridColumn):int
{
var newstr:Number=new Number(item.bp);
return newstr;
}
private function beatCountFunction(item:Object, column:DataGridColumn):int
{
var newstr:int=new int(item.bc);
return newstr;
}
private function sortbpm(obj1:Object, obj2:Object):int
{
var valueA:Number=obj1.bp;
var valueB:Number=obj2.bp;
return ObjectUtil.numericCompare(valueA, valueB);
}
private function sortbeatcount(obj1:Object, obj2:Object):int
{
var valueA:Number=obj1.bc;
var valueB:Number=obj2.bc;
return ObjectUtil.numericCompare(valueA, valueB);
}
public function get scrollEnabled():Boolean
{
return _scrollEnabled;
}
public function set scrollEnabled(value:Boolean):void
{
_scrollEnabled=value;
}
override protected function dragScroll():void
{
if (_scrollEnabled)
{
super.dragScroll();
}
}
]]>
</mx:Script>
<mx:columns>
<mx:DataGridColumn dataField="r"
headerText=""
itemRenderer="components.content.contents.datagrids.ImageRendererLoops"/>
<mx:DataGridColumn dataField="t"
headerText="Title"
labelFunction="userLabelFunction"/>
<mx:DataGridColumn dataField="bc"
headerText="Beats"
labelFunction="beatCountFunction"
sortCompareFunction="sortbeatcount"/>
<mx:DataGridColumn dataField="BPM"
headerText="BPM"
labelFunction="bpmFunction"
sortCompareFunction="sortbpm"/>
<mx:DataGridColumn itemRenderer="components.preview.PreviewPlay"/>
</mx:columns>
</mx:DataGrid>
Item Renderer
<?xml version="1.0" encoding="utf-8"?>
<mx:HBox xmlns:mx="http://www.adobe.com/2006/mxml"
implements="mx.controls.listClasses.IDropInListItemRenderer">
<mx:Script>
<![CDATA[
import mx.controls.DataGrid;
import components.content.contents.datagrids.LoopMastersDataGrid;
import components.remix.PadDisplay.PadContent;
import mx.controls.listClasses.BaseListData;
[Embed(source='assets/play_20.png')]
[Bindable]
public var play20Img:Class;
public static const PLAYING:String="playing";
public static const LOADING:String="loading";
public static const IDLE:String="idle";
private var _listData:BaseListData;
private var _bpm:int;
private var _path:String;
private var _state:String="idle";
public function get listData():BaseListData
{
return _listData;
}
public function set listData(value:BaseListData):void
{
_listData=value;
var criteria:String = (_listData.owner as LoopMastersDataGrid).critera;
if(this._path==criteria)
{
// this track is playing
previewbutton.styleName="stopPreviewButtonStyle";
}else
{
// this track is not playing
previewbutton.styleName="playPreviewButtonStyle";
}
//trace("list data crit=="+criteria);
}
override public function set data(value:Object):void
{
super.data=value;
this._path=new String(PadContent.LOOP_ROOT + value.r + "/" + value.u + ".rocudo");
this._bpm=value.bp;
//trace(this._path);
}
private function sendPreviewRequest(event:Event):void
{
switch(this._state)
{
case(PreviewPlay.IDLE):
(listData.owner as LoopMastersDataGrid).dispatchEvent(new PreviewPlayEvent(PreviewPlayEvent.PLAY,this._bpm,this._path));
break;
case(PreviewPlay.LOADING):
// preview play probably shouldnt care about loading
break;
case(PreviewPlay.PLAYING):
(listData.owner as LoopMastersDataGrid).dispatchEvent(new PreviewPlayEvent(PreviewPlayEvent.STOP,this._bpm,this._path));
break;
}
//dispatchEvent(new PreviewPlayEvent(PreviewPlayEvent.PLAY,this._bpm,this._path));
}
/** override protected function commitProperties():void
{
super.commitProperties();
this._state=PreviewPlay.IDLE;
}**/
]]>
</mx:Script>
<mx:Button id="previewbutton"
width="20"
height="20" click="sendPreviewRequest(event)" styleName="playPreviewButtonStyle">
</mx:Button>
</mx:HBox>
Update
I removed my mouse down handler from the datagrid and removed the cusom component. Clicking on a item in the datagrid makes the datagrid scroll so that the item selected appears first in the list. This is the behaviour I need to stop.