flex tree 自适应显示横向滚动条_flex 横向滚动条-优快云博客

本文介绍了一种使用 Flex 实现的自适应滚动条组件，该组件能够根据实际内容的宽度自动调整滚动条的最大宽度，确保内容完整显示且不被截断。通过自定义 AS3 类 `AutoSizeTree` 扩展了默认的 Tree 组件，实现了水平滚动条的自动隐藏功能。

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原文见博客：http://blog.youkuaiyun.com/siy020513/article/details/5262550

亲测，可用！

mxml:

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" xmlns:cmp="com.render.*" 
    height="100%" width="100%" paddingTop="0" paddingBottom="0" paddingLeft="0" paddingRight="0">
    <cmp:AutoSizeTree
            id="checkTree"
            itemRenderer="com.render.CheckTreeRenderer"
            change="updataDataGrid()"
            labelField="@label"
             width="100%" height="100%"  
             horizontalScrollPolicy="auto" >
     </cmp:AutoSizeTree>
</mx:Application>

actionscript:

package com.render
{
    import flash.events.Event;
    import mx.controls.Alert;
    import mx.controls.Tree;
    import mx.core.ScrollPolicy;
    import mx.core.mx_internal;
    public class AutoSizeTree extends Tree
    {
        public function AutoSizeTree()
        {
            super();
            horizontalScrollPolicy = ScrollPolicy.AUTO;
        }
     
        override public function get maxHorizontalScrollPosition():Number
        {
             if (isNaN(mx_internal::_maxHorizontalScrollPosition))         
                return 0;                          
            return mx_internal::_maxHorizontalScrollPosition;      
        }           
                       
        override public function set maxHorizontalScrollPosition(value:Number):void
        {
            mx_internal::_maxHorizontalScrollPosition = value;             
            dispatchEvent(new Event("maxHorizontalScrollPositionChanged"));     
            scrollAreaChanged = true;            
            invalidateDisplayList();       
        }

        override protected function updateDisplayList(unscaledWidth:Number, unscaledHeight:Number):void
        {    
                var diffWidth:Number = measureWidthOfItems(0,0) - (unscaledWidth - viewMetrics.left - viewMetrics.right);   
                var indentation:Number = getStyle("indentation");
                if (diffWidth <= 0)                   
                    maxHorizontalScrollPosition = NaN;
                else
                    maxHorizontalScrollPosition = diffWidth + indentation;                                    
                super.updateDisplayList(unscaledWidth, unscaledHeight); 
        }
    }
}