diff -r 000000000000 -r 4f2f89ce4247 WebCore/page/SpatialNavigation.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/WebCore/page/SpatialNavigation.h	Fri Sep 17 09:02:29 2010 +0300
@@ -0,0 +1,140 @@
+/*
+ * Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies)
+ * Copyright (C) 2009 Antonio Gomes <tonikitoo@webkit.org>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public License
+ * along with this library; see the file COPYING.LIB.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef SpatialNavigation_h
+#define SpatialNavigation_h
+
+#include "FocusDirection.h"
+#include "Node.h"
+
+#include <limits>
+
+namespace WebCore {
+
+class Element;
+class Frame;
+class IntRect;
+class RenderObject;
+
+using namespace std;
+
+inline long long maxDistance()
+{
+    return numeric_limits<long long>::max();
+}
+
+inline int fudgeFactor()
+{
+    return 2;
+}
+
+// Spatially speaking, two given elements in a web page can be:
+// 1) Fully aligned: There is a full intersection between the rects, either
+//    vertically or horizontally.
+//
+// * Horizontally       * Vertically
+//    _
+//   |_|                   _ _ _ _ _ _
+//   |_|...... _          |_|_|_|_|_|_|
+//   |_|      |_|         .       .
+//   |_|......|_|   OR    .       .
+//   |_|      |_|         .       .
+//   |_|......|_|          _ _ _ _
+//   |_|                  |_|_|_|_|
+//
+//
+// 2) Partially aligned: There is a partial intersection between the rects, either
+//    vertically or horizontally.
+//
+// * Horizontally       * Vertically
+//    _                   _ _ _ _ _
+//   |_|                 |_|_|_|_|_|
+//   |_|.... _      OR           . .
+//   |_|    |_|                  . .
+//   |_|....|_|                  ._._ _
+//          |_|                  |_|_|_|
+//          |_|
+//
+// 3) Or, otherwise, not aligned at all.
+//
+// * Horizontally       * Vertically
+//         _              _ _ _ _
+//        |_|            |_|_|_|_|
+//        |_|                    .
+//        |_|                     .
+//       .          OR             .
+//    _ .                           ._ _ _ _ _
+//   |_|                            |_|_|_|_|_|
+//   |_|
+//   |_|
+//
+// "Totally Aligned" elements are preferable candidates to move
+// focus to over "Partially Aligned" ones, that on its turns are
+// more preferable than "Not Aligned".
+enum RectsAlignment {
+    None = 0,
+    Partial,
+    Full
+};
+
+struct FocusCandidate {
+    FocusCandidate()
+        : node(0)
+        , enclosingScrollableBox(0)
+        , distance(maxDistance())
+        , parentDistance(maxDistance())
+        , alignment(None)
+        , parentAlignment(None)
+    {
+    }
+
+    FocusCandidate(Node* n)
+        : node(n)
+        , enclosingScrollableBox(0)
+        , distance(maxDistance())
+        , parentDistance(maxDistance())
+        , alignment(None)
+        , parentAlignment(None)
+    {
+    }
+
+    bool isNull() const { return !node; }
+    bool inScrollableContainer() const { return node && enclosingScrollableBox; }
+    Document* document() const { return node ? node->document() : 0; }
+
+    Node* node;
+    Node* enclosingScrollableBox;
+    long long distance;
+    long long parentDistance;
+    RectsAlignment alignment;
+    RectsAlignment parentAlignment;
+};
+
+void distanceDataForNode(FocusDirection direction, Node* start, FocusCandidate& candidate);
+bool scrollInDirection(Frame*, FocusDirection, const FocusCandidate& candidate = FocusCandidate());
+void scrollIntoView(Element*);
+bool hasOffscreenRect(Node*);
+bool isInRootDocument(Node*);
+bool isScrollableContainerNode(Node*);
+bool isNodeDeepDescendantOfDocument(Node*, Document*);
+
+} // namspace WebCore
+
+#endif // SpatialNavigation_h