flex 学习笔记 一个可以动态缩放的tree

代码：自定义的ResizeTree.as

package  contr
{
    import flash.events.*;
    import flash.utils.*;

    import mx.controls.Alert;
    import mx.controls.Tree;
    import mx.events.TreeEvent;

    public class ResizeTree extends Tree {

        private var timer:Timer = new Timer(10, 1);
        private var _autoStretch_:Boolean = false;
        [Bindable]
        public function get autoStretch():Boolean{
            return _autoStretch_;
        }

        public function set autoStretch(value:Boolean):void{
            _autoStretch_ = value;
            if (_autoStretch_) {
                this.addEventListener(Event.RESIZE, doStretch);
                this.addEventListener(TreeEvent.ITEM_OPEN, startStretch);
                this.addEventListener(TreeEvent.ITEM_CLOSE, startStretch);
                this.verticalScrollPolicy = "off";
                stretch();
            } else {
                timer.stop();
                this.removeEventListener(Event.RESIZE, doStretch);
                this.removeEventListener(TreeEvent.ITEM_OPEN, startStretch);
                this.removeEventListener(TreeEvent.ITEM_CLOSE, startStretch);
                this.verticalScrollPolicy = "auto";
            }
        }

        protected function stretch(evtObj:Event = null):void{
            var items:Array = this.listItems;
            var borderThickness:Number = this.getStyle("borderThickness");
            if (this.height - borderThickness * 2 < this.rowHeight) {
                thisthis.height = this.rowHeight + borderThickness * 2;
            }
            if (this.maxVerticalScrollPosition > 0) {
                this.height += this.rowHeight - (this.height - borderThickness * 2) % this.rowHeight;
                return;
            } else if (items[items.length - 1] == "") {
                this.height -= this.rowHeight + (this.height - borderThickness * 2) % this.rowHeight;
                return;
            }
        }

        protected function startStretch(evtObj:Event = null):void{
            timer.stop();
            timer.delay = this.getStyle("openDuration") + 50;
            timer.start();
        }

        protected function doStretch(evtObj:Event = null):void{
            timer.stop();
            timer.delay = 10;
            timer.start();
        }

        protected function onTimerComplete(evtObj:Event = null):void{
            stretch();
        }

        public function ResizeTree():void{
            super();
            timer.addEventListener(TimerEvent.TIMER_COMPLETE, onTimerComplete);
        }
    }
}

使用：

xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
               xmlns:s="library://ns.adobe.com/flex/spark"
               xmlns:mx="library://ns.adobe.com/flex/mx"
               minWidth="955" minHeight="600" xmlns:logic="contr.*">
    <fx:Declarations>

        <fx:XMLList id="treeData">
            <node label="选择数据集">
                <node label="hsql">
                    <node label="tabels">
                          <node label="订单" head="p_w_picpaths/install.jpg"/>
                          <node label="订单明细" head="p_w_picpaths/install.jpg"/>
                          <node label="雇员" head="p_w_picpaths/install.jpg"/>
                    node>
                node>
                <node label="mysql">
                    <node label="tabels">
                          <node label="demo_salesday" head="p_w_picpaths/install.jpg"/>
                          <node label="Personal" head="p_w_picpaths/install.jpg"/>
                    node>
                node>
            node>
        fx:XMLList>
    fx:Declarations>
    <mx:VBox backgroundColor="#CCCCCC" width="100%" height="100%" verticalAlign="middle" horizontalAlign="center">
        <logic:ResizeTree dataProvider="{treeData}" height="100" autoStretch="true" labelField="@label"  depthColors="[#CCCCCC,#f60f0f,#1c47e8,#31eb18]"/>
    mx:VBox>
s:Application>

效果：点击节点 打开或关闭时 tree的高度会动态变化