flex checkboxlist

package com.components.checkBoxList
{
    import flash.events.Event;
   
    import mx.collections.ArrayCollection;
    import mx.collections.ICollectionView;
    import mx.collections.IList;
    import mx.collections.ListCollectionView;
    import mx.collections.XMLListCollection;
    import mx.containers.Tile;
    import mx.controls.CheckBox;
    import mx.controls.Alert;
    import mx.core.IUIComponent;
   
    public class CheckBoxList extends Tile
    {               
        protected var collection:ICollectionView;            //显示的数据源
        private var _labelField:String = "label";            //显示的数据字段
        private var _dataField : String = "selected";        //选中的状态
        private var _selectedName : String = "";             //设置选中的值
        private var _splitString : String = "、";            //设置选中值的分割符
        private var _checkBoxNum:Number = 10;                //设置显示的复选框个数
        private var cellWidth:Number;
        private var cellHeight:Number;
       
       
        public function CheckBoxList()
        {
            super();
        }
       
        //数据源
        [Bindable("collectionChanged")]
        public function get dataProvider():Object
        {
            return collection;
        }
        public function set dataProvider(value:Object):void
        {
            if (value is Array)
            {
                collection = new ArrayCollection(value as Array);
            }
            else if (value is ICollectionView)
            {
                collection = ICollectionView(value);
            }
            else if (value is IList)
            {
                collection = new ListCollectionView(IList(value));
            }
            else if (value is XMLList)
            {
                collection = new XMLListCollection(value as XMLList);
            }
            else
            {
                // convert it to an array containing this one item
                var tmp:Array = [value];
                collection = new ArrayCollection(tmp);
            }           
           
            dispatchEvent(new Event("collectionChanged"));
            addOrResetChildren();
        }
       
        //显示字段
        [Bindable("labelFieldChanged")]
        public function get labelField():String
        {
            return _labelField;
        }
        public function set labelField(value:String):void
        {
            _labelField = value;
            dispatchEvent(new Event("labelFieldChanged"));
        }
       
        //设定选中的状态
        [Bindable("dataFieldChanged")]
        public function get dataField() : String
        {
            return _dataField;
        }
        public function set dataField(value : String) : void
        {
            _dataField = value;
            dispatchEvent(new Event("dataFieldChanged"));
        }
       
        //设定选中的值
        [Bindable("selectedNameChanged")]
        public function get selectedName() : String
        {
            var value : String = "";
            var splitStr:String = "";
            for each (var obj : Object in this.getChildren())
            {
                if(obj[dataField] == true)
                {
                    value += splitStr + obj[labelField] ;
                    splitStr = _splitString;
                }
            }
            return value;
        }
        public function set selectedName(value:String) : void
        {
            if(value != null && value != "")
            {
              var selectedNames:Array = value.split(this.splitString);
              for each(var label:String in selectedNames)
              {
               for each(var object:Object in this.getChildren())
               {
                if(object[labelField] == label)
                {
                 object[dataField] = "selected";
                }
               }
              }
            }
            dispatchEvent(new Event("selectedNameChanged"));
        }
       
        //显示的复选框个数
        [Bindable("checkBoxNumChanged")]
        public function get checkBoxNum():Number
        {
        return this._checkBoxNum;
        }
        public function set checkBoxNum(value : Number):void
        {
        this._checkBoxNum = value;
        dispatchEvent(new Event("checkBoxNumChanged"));
        }
       
        //设定分割符
        [Bindable("splitStringChanged")]
        public function get splitString() : String
        {
            return _splitString;   
        }
        public function set splitString(value : String) : void
        {
            _splitString = value;
            dispatchEvent(new Event("splitStringChanged"));
        }
       
        //新增或重置子列表
        public function addOrResetChildren() : void
        {
            this.removeAllChildren();
            if(collection == null) return;
            for (var i : int =0; i < collection.length; i++)
            {
            var cb : CheckBox = new CheckBox();
           
            cb.id = collection[i].id;
                cb.selected= collection[i][dataField]=="true" ? true : false;
                cb.label = collection[i][labelField];  
                cb.setStyle("color","#333333");
                cb.setStyle("textRollOverColor","#333333");
                cb.setStyle("textSelectedColor","#333333");
                cb.setStyle("fontSize","12");
                cb.setStyle("fontFamily","宋体");
               
                addChild(cb);
            }
        }
       
        //拿到当前选中的checkBox的Id
        public function getSelectedIds() : Array
        {
            var arr : Array = new Array();
            for each (var obj : Object in this.getChildren())
            {
                if(obj.selected == true)
                {
                    arr.push(obj.id);
                }
            }
            return arr;
        }
       
        //显示格式
        protected override function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void
        {
            super.updateDisplayList(unscaledWidth,unscaledHeight);
            findCellSize();
           
            if(numChildren<=0) return ;  
            var horizontalGap:Number = getStyle("horizontalGap");
            var verticalGap:Number = getStyle("verticalGap");
            this.width = cellWidth + 20; //只显示一列，如果dataProvider的length大于显示的checkBox数量会出现滚动条，这里预留出滚动条的宽度20象素
            this.height = (cellHeight + verticalGap) * _checkBoxNum;
//            var num : Number = Math.floor(width / (cellWidth + horizontalGap) );
//            height = Math.ceil((cellHeight + verticalGap) * Math.ceil(numChildren/num));           
        }

        private function findCellSize():void
        {
            // If user explicitly supplied both a tileWidth and
            // a tileHeight, then use those values.
            var widthSpecified:Boolean = !isNaN(tileWidth);
            var heightSpecified:Boolean = !isNaN(tileHeight);
            if (widthSpecified && heightSpecified)
            {
                cellWidth = tileWidth;
                cellHeight = tileHeight;
                return;
            }
   
            // Reset the max child width and height
            var maxChildWidth:Number = 0;
            var maxChildHeight:Number = 0;
           
            // Loop over the children to find the max child width and height.
            var n:int = numChildren;
            for (var i:int = 0; i < n; i++)
            {
                var child:IUIComponent = IUIComponent(getChildAt(i));
   
                if (!child.includeInLayout)
                {
                    continue;
                }
               
                var width:Number = child.getExplicitOrMeasuredWidth();
                if (width > maxChildWidth)
                {
                    maxChildWidth = width;
                }
               
                var height:Number = child.getExplicitOrMeasuredHeight();
                if (height > maxChildHeight)
                {
                    maxChildHeight = height;
                }
            }
           
            // If user explicitly specified either width or height, use the
            // user-supplied value instead of the one we computed.
            cellWidth = widthSpecified ? tileWidth : maxChildWidth;
            cellHeight = heightSpecified ? tileHeight : maxChildHeight;
        }
    }
}