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      1 /*
      2  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
      3  * Copyright (C) 2013 Intel Corporation. All rights reserved.
      4  *
      5  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
      6  *
      7  * Other contributors:
      8  *   Robert O'Callahan <roc+@cs.cmu.edu>
      9  *   David Baron <dbaron (at) fas.harvard.edu>
     10  *   Christian Biesinger <cbiesinger (at) web.de>
     11  *   Randall Jesup <rjesup (at) wgate.com>
     12  *   Roland Mainz <roland.mainz (at) informatik.med.uni-giessen.de>
     13  *   Josh Soref <timeless (at) mac.com>
     14  *   Boris Zbarsky <bzbarsky (at) mit.edu>
     15  *
     16  * This library is free software; you can redistribute it and/or
     17  * modify it under the terms of the GNU Lesser General Public
     18  * License as published by the Free Software Foundation; either
     19  * version 2.1 of the License, or (at your option) any later version.
     20  *
     21  * This library is distributed in the hope that it will be useful,
     22  * but WITHOUT ANY WARRANTY; without even the implied warranty of
     23  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     24  * Lesser General Public License for more details.
     25  *
     26  * You should have received a copy of the GNU Lesser General Public
     27  * License along with this library; if not, write to the Free Software
     28  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
     29  *
     30  * Alternatively, the contents of this file may be used under the terms
     31  * of either the Mozilla Public License Version 1.1, found at
     32  * http://www.mozilla.org/MPL/ (the "MPL") or the GNU General Public
     33  * License Version 2.0, found at http://www.fsf.org/copyleft/gpl.html
     34  * (the "GPL"), in which case the provisions of the MPL or the GPL are
     35  * applicable instead of those above.  If you wish to allow use of your
     36  * version of this file only under the terms of one of those two
     37  * licenses (the MPL or the GPL) and not to allow others to use your
     38  * version of this file under the LGPL, indicate your decision by
     39  * deletingthe provisions above and replace them with the notice and
     40  * other provisions required by the MPL or the GPL, as the case may be.
     41  * If you do not delete the provisions above, a recipient may use your
     42  * version of this file under any of the LGPL, the MPL or the GPL.
     43  */
     44 
     45 #ifndef RenderLayerClipper_h
     46 #define RenderLayerClipper_h
     47 
     48 #include "core/rendering/ClipRect.h"
     49 #include "core/rendering/RenderBox.h" // For OverlayScrollbarSizeRelevancy.
     50 
     51 namespace WebCore {
     52 
     53 class RenderLayer;
     54 class RenderRegion;
     55 
     56 struct ClipRectsContext {
     57     ClipRectsContext(const RenderLayer* inRootLayer, RenderRegion* inRegion, ClipRectsType inClipRectsType, OverlayScrollbarSizeRelevancy inOverlayScrollbarSizeRelevancy = IgnoreOverlayScrollbarSize, ShouldRespectOverflowClip inRespectOverflowClip = RespectOverflowClip)
     58         : rootLayer(inRootLayer)
     59         , region(inRegion)
     60         , clipRectsType(inClipRectsType)
     61         , overlayScrollbarSizeRelevancy(inOverlayScrollbarSizeRelevancy)
     62         , respectOverflowClip(inRespectOverflowClip)
     63     { }
     64     const RenderLayer* rootLayer;
     65     RenderRegion* region;
     66     ClipRectsType clipRectsType;
     67     OverlayScrollbarSizeRelevancy overlayScrollbarSizeRelevancy;
     68     ShouldRespectOverflowClip respectOverflowClip;
     69 };
     70 
     71 class RenderLayerClipper {
     72     WTF_MAKE_NONCOPYABLE(RenderLayerClipper);
     73 public:
     74     RenderLayerClipper(RenderLayerModelObject* renderer)
     75     : m_renderer(renderer)
     76     {
     77     }
     78 
     79     ClipRects* clipRects(const ClipRectsContext& context) const
     80     {
     81         ASSERT(context.clipRectsType < NumCachedClipRectsTypes);
     82         return m_clipRectsCache ? m_clipRectsCache->getClipRects(context.clipRectsType, context.respectOverflowClip).get() : 0;
     83     }
     84 
     85     // Compute and cache clip rects computed with the given layer as the root
     86     void updateClipRects(const ClipRectsContext&);
     87 
     88     void clearClipRectsIncludingDescendants(ClipRectsType typeToClear = AllClipRectTypes);
     89     void clearClipRects(ClipRectsType typeToClear = AllClipRectTypes);
     90 
     91     // Compute and return the clip rects. If useCached is true, will used previously computed clip rects on ancestors
     92     // (rather than computing them all from scratch up the parent chain).
     93     void calculateClipRects(const ClipRectsContext&, ClipRects&) const;
     94 
     95 private:
     96     // FIXME: Could this be a RenderBox?
     97     RenderLayerModelObject* m_renderer;
     98 
     99     OwnPtr<ClipRectsCache> m_clipRectsCache;
    100 };
    101 
    102 } // namespace WebCore
    103 
    104 #endif // RenderLayerClipper_h
    105