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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/ClipRectsCache.h"
     49 #include "core/rendering/RenderBox.h"
     50 
     51 namespace blink {
     52 
     53 class RenderLayer;
     54 
     55 enum ShouldRespectOverflowClip {
     56     IgnoreOverflowClip,
     57     RespectOverflowClip
     58 };
     59 
     60 class ClipRectsContext {
     61 public:
     62     ClipRectsContext(const RenderLayer* root, ClipRectsCacheSlot slot, OverlayScrollbarSizeRelevancy relevancy = IgnoreOverlayScrollbarSize, const LayoutSize& accumulation = LayoutSize())
     63         : rootLayer(root)
     64         , scrollbarRelevancy(relevancy)
     65         , cacheSlot(slot)
     66         , subPixelAccumulation(accumulation)
     67         , respectOverflowClip(slot == PaintingClipRectsIgnoringOverflowClip ? IgnoreOverflowClip : RespectOverflowClip)
     68     {
     69     }
     70 
     71     void setIgnoreOverflowClip()
     72     {
     73         ASSERT(!usesCache() || cacheSlot == PaintingClipRects);
     74         ASSERT(respectOverflowClip == RespectOverflowClip);
     75         if (usesCache())
     76             cacheSlot = PaintingClipRectsIgnoringOverflowClip;
     77         respectOverflowClip = IgnoreOverflowClip;
     78     }
     79 
     80     bool usesCache() const
     81     {
     82         return cacheSlot != UncachedClipRects;
     83     }
     84 
     85     const RenderLayer* const rootLayer;
     86     const OverlayScrollbarSizeRelevancy scrollbarRelevancy;
     87 
     88 private:
     89     friend class RenderLayerClipper;
     90 
     91     ClipRectsCacheSlot cacheSlot;
     92     LayoutSize subPixelAccumulation;
     93     ShouldRespectOverflowClip respectOverflowClip;
     94 };
     95 
     96 class RenderLayerClipper {
     97     WTF_MAKE_NONCOPYABLE(RenderLayerClipper);
     98 public:
     99     explicit RenderLayerClipper(RenderLayerModelObject&);
    100 
    101     void clearClipRectsIncludingDescendants();
    102     void clearClipRectsIncludingDescendants(ClipRectsCacheSlot);
    103 
    104     LayoutRect childrenClipRect() const; // Returns the foreground clip rect of the layer in the document's coordinate space.
    105     LayoutRect localClipRect() const; // Returns the background clip rect of the layer in the local coordinate space.
    106 
    107     ClipRects* getClipRects(const ClipRectsContext&) const;
    108 
    109     ClipRect backgroundClipRect(const ClipRectsContext&) const;
    110 
    111     // This method figures out our layerBounds in coordinates relative to
    112     // |rootLayer|. It also computes our background and foreground clip rects
    113     // for painting/event handling.
    114     // Pass offsetFromRoot if known.
    115     void calculateRects(const ClipRectsContext&, const LayoutRect& paintDirtyRect, LayoutRect& layerBounds,
    116         ClipRect& backgroundRect, ClipRect& foregroundRect, ClipRect& outlineRect, const LayoutPoint* offsetFromRoot = 0) const;
    117 
    118 private:
    119     void calculateClipRects(const ClipRectsContext&, ClipRects&) const;
    120 
    121     ClipRects* clipRectsIfCached(const ClipRectsContext&) const;
    122     ClipRects* storeClipRectsInCache(const ClipRectsContext&, ClipRects* parentClipRects, const ClipRects&) const;
    123 
    124     // cachedClipRects looks buggy: It doesn't check whether context.rootLayer and entry.root match.
    125     // FIXME: Move callers to clipRectsIfCached, which does the proper checks.
    126     ClipRects* cachedClipRects(const ClipRectsContext& context) const
    127     {
    128         return m_cache ? m_cache->get(context.cacheSlot).clipRects.get() : 0;
    129     }
    130 
    131     void getOrCalculateClipRects(const ClipRectsContext&, ClipRects&) const;
    132 
    133     RenderLayer* clippingRootForPainting() const;
    134 
    135     ClipRectsCache& cache() const
    136     {
    137         if (!m_cache)
    138             m_cache = adoptPtr(new ClipRectsCache);
    139         return *m_cache;
    140     }
    141 
    142     // FIXME: Could this be a RenderBox?
    143     RenderLayerModelObject& m_renderer;
    144     mutable OwnPtr<ClipRectsCache> m_cache;
    145 };
    146 
    147 } // namespace blink
    148 
    149 #endif // RenderLayerClipper_h
    150