tree的labelFunction

     可以通过labelFunction来自定义ComboBox、tree等组件的显示内容。有时我们需要统计非叶子节点子节点的个数。利用labelFunction就可以很容易的实现该功能，当然也可以通过itemRenderer实现。

 

   

 private function tree_labelFunc(item:XML):String {
                var children:ICollectionView;
                var suffix:String = "";
                if (tree.dataDescriptor.isBranch(item)) {
                    children = tree.dataDescriptor.getChildren(item);
                    suffix = " (" + children.length + ")";
                }
                return item[tree.labelField] + suffix;
            }

 

 

 

<mx:Tree id="tree"
            dataProvider="{dp}"
            showRoot="false"
            labelField="@label"
            labelFunction="tree_labelFunc"
            width="300"
            rowCount="6"
            itemClick="tree_itemClick(event);" />

 

 

 

 利用itemRenderer实现labelFunction的功能。

 

 

package myComponents
{
    // itemRenderers/tree/myComponents/MyTreeItemRenderer.as
    import mx.controls.treeClasses.*;
    import mx.collections.*;

    public class MyTreeItemRenderer extends TreeItemRenderer
    {

        // Define the constructor.      
        public function MyTreeItemRenderer() {
            super();
        }
        
        // Override the set method for the data property
        // to set the font color and style of each node.        
        override public function set data(value:Object):void {
            super.data = value;
            if(TreeListData(super.listData).hasChildren)
            {
                setStyle("color", 0xff0000);
                setStyle("fontWeight", 'bold');
            }
            else
            {
                setStyle("color", 0x000000);
                setStyle("fontWeight", 'normal');
            }  
        }
     
        // Override the updateDisplayList() method 
        // to set the text for each tree node.      
        override protected function updateDisplayList(unscaledWidth:Number, 
            unscaledHeight:Number):void {
       
            super.updateDisplayList(unscaledWidth, unscaledHeight);
            if(super.data)
            {
                if(TreeListData(super.listData).hasChildren)
                {
                    var tmp:XMLList = 
                        new XMLList(TreeListData(super.listData).item);
                    var myStr:int = tmp[0].children().length();
                    super.label.text =  TreeListData(super.listData).label + 
                        "(" + myStr + ")";
                }
            }
        }
    }
}