Revert revision 16240

samples/swarm/swarm_ui_lib/touch/FxUtil.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of touch;
 
 /**
  * Common effects related helpers.
  */
 class FxUtil {
@@ skipping 49 matching lines @@
   }
 
   /**
    * Determine the position of an [element] relative to a [target] element.
    * Moving the [element] to be a child of [target] and setting the
    * [element]'s top and left values to the returned coordinate should result
    * in the [element]'s position remaining unchanged while its parent is
    * changed.
    */
   static Coordinate computeRelativePosition(Element element, Element target) {
-    final elementPoint = computePagePosition(element);
-    final targetPoint = computePagePosition(target);
-    return new Coordinate(elementPoint.x - targetPoint.x,
-        elementPoint.y - targetPoint.y);
-  }
-
-  /** Computes the position of an element on the page. */
-  static Coordinate computePagePosition(Element element) {
-    num left = 0;
-    num top = 0;
-    do {
-      left += element.offsetLeft;
-      top += element.offsetTop;
-      element = element.offsetParent;
-    } while (element != null);
-    return new Coordinate(left, top);
+    final testPoint = new Point(0, 0);
+    final pagePoint =
+        window.webkitConvertPointFromNodeToPage(element, testPoint);
+    final pointRelativeToTarget =
+        window.webkitConvertPointFromPageToNode(target, pagePoint);
+    return new Coordinate(pointRelativeToTarget.x, pointRelativeToTarget.y);
   }
 
   /** Clear a -webkit-transform from an element. */
   static void clearWebkitTransform(Element el) {
     el.style.transform = '';
   }
 
   /**
    * Checks whether an element has a translate3d webkit transform applied.
    */
@@ skipping 10 matching lines @@
     style.left = '${x}px';
     style.top = '${y}px';
   }
 }
 
 class TransitionTimingFunction {
   static const EASE_IN = 'ease-in';
   static const EASE_OUT = 'ease-out';
   static const EASE_IN_OUT = 'ease-in-out';
 }