package{
    import flash.events.Event;
 
    import mx.controls.Tree;
    import mx.core.mx_internal;
    import mx.core.ScrollPolicy;
    import mx.events.TreeEvent;
 
    public class AutoSizeTree extends Tree
    {
         public function AutoSizeTree(){
              super();
              horizontalScrollPolicy = ScrollPolicy.AUTO;
         }
 
         // we need to override maxHorizontalScrollPosition because setting
         // Tree's maxHorizontalScrollPosition adds an indent value to it,
         // which we don't need as measureWidthOfItems seems to return exactly
         // what we need.  Not only that, but getIndent() seems to be broken
         // anyways (SDK-12578).
 
         // I hate using mx_internal stuff, but we can't do
         // super.super.maxHorizontalScrollPosition in AS 3, so we have to
         // emulate it.
         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
         {
              // we call measureWidthOfItems to get the max width of the item renderers.
              // then we see how much space we need to scroll, setting maxHorizontalScrollPosition appropriately
              var diffWidth:Number = measureWidthOfItems(0,0) - (unscaledWidth - viewMetrics.left - viewMetrics.right);
 
              if (diffWidth <= 0)
                  maxHorizontalScrollPosition = NaN;
              else
                  maxHorizontalScrollPosition = diffWidth;
 
              super.updateDisplayList(unscaledWidth, unscaledHeight);
         }
    }
}

package{ import flash.events.Event; import mx.controls.Tree; import mx.core.mx_internal; import mx.core.ScrollPolicy; import mx.events.TreeEvent; public class AutoSizeTree extends Tree { public function AutoSizeTree(){ super(); horizontalScrollPolicy = ScrollPolicy.AUTO; } // we need to override maxHorizontalScrollPosition because setting // Tree's maxHorizontalScrollPosition adds an indent value to it, // which we don't need as measureWidthOfItems seems to return exactly // what we need. Not only that, but getIndent() seems to be broken // anyways (SDK-12578). // I hate using mx_internal stuff, but we can't do // super.super.maxHorizontalScrollPosition in AS 3, so we have to // emulate it. 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 { // we call measureWidthOfItems to get the max width of the item renderers. // then we see how much space we need to scroll, setting maxHorizontalScrollPosition appropriately var diffWidth:Number = measureWidthOfItems(0,0) - (unscaledWidth - viewMetrics.left - viewMetrics.right); if (diffWidth <= 0) maxHorizontalScrollPosition = NaN; else maxHorizontalScrollPosition = diffWidth; super.updateDisplayList(unscaledWidth, unscaledHeight); } } }