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      1 /*
      2  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
      3  *
      4  * This library is free software; you can redistribute it and/or
      5  * modify it under the terms of the GNU Library General Public
      6  * License as published by the Free Software Foundation; either
      7  * version 2 of the License, or (at your option) any later version.
      8  *
      9  * This library is distributed in the hope that it will be useful,
     10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
     11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     12  * Library General Public License for more details.
     13  *
     14  * You should have received a copy of the GNU Library General Public License
     15  * along with this library; see the file COPYING.LIB.  If not, write to
     16  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     17  * Boston, MA 02110-1301, USA.
     18  *
     19  */
     20 
     21 #ifndef RenderOverflow_h
     22 #define RenderOverflow_h
     23 
     24 #include "platform/geometry/LayoutRect.h"
     25 
     26 namespace WebCore
     27 {
     28 // RenderOverflow is a class for tracking content that spills out of a box.  This class is used by RenderBox and
     29 // InlineFlowBox.
     30 //
     31 // There are two types of overflow: layout overflow (which is expected to be reachable via scrolling mechanisms) and
     32 // visual overflow (which is not expected to be reachable via scrolling mechanisms).
     33 //
     34 // Layout overflow examples include other boxes that spill out of our box,  For example, in the inline case a tall image
     35 // could spill out of a line box.
     36 
     37 // Examples of visual overflow are shadows, text stroke (and eventually outline and border-image).
     38 
     39 // This object is allocated only when some of these fields have non-default values in the owning box.
     40 class RenderOverflow {
     41     WTF_MAKE_NONCOPYABLE(RenderOverflow); WTF_MAKE_FAST_ALLOCATED;
     42 public:
     43     RenderOverflow(const LayoutRect& layoutRect, const LayoutRect& visualRect)
     44         : m_layoutOverflow(layoutRect)
     45         , m_visualOverflow(visualRect)
     46     {
     47     }
     48 
     49     const LayoutRect layoutOverflowRect() const { return m_layoutOverflow; }
     50     const LayoutRect visualOverflowRect() const { return m_visualOverflow; }
     51     LayoutRect contentsVisualOverflowRect() const { return m_contentsVisualOverflow; }
     52 
     53     void move(LayoutUnit dx, LayoutUnit dy);
     54 
     55     void addLayoutOverflow(const LayoutRect&);
     56     void addVisualOverflow(const LayoutRect&);
     57     void addContentsVisualOverflow(const LayoutRect& rect) { m_contentsVisualOverflow.unite(rect); }
     58 
     59     void setLayoutOverflow(const LayoutRect&);
     60     void setVisualOverflow(const LayoutRect&);
     61 
     62     LayoutUnit layoutClientAfterEdge() const { return m_layoutClientAfterEdge; }
     63     void setLayoutClientAfterEdge(LayoutUnit clientAfterEdge) { m_layoutClientAfterEdge = clientAfterEdge; }
     64 
     65 private:
     66     LayoutRect m_layoutOverflow;
     67     LayoutRect m_visualOverflow;
     68     LayoutRect m_contentsVisualOverflow;
     69 
     70     LayoutUnit m_layoutClientAfterEdge;
     71 };
     72 
     73 inline void RenderOverflow::move(LayoutUnit dx, LayoutUnit dy)
     74 {
     75     m_layoutOverflow.move(dx, dy);
     76     m_visualOverflow.move(dx, dy);
     77     m_contentsVisualOverflow.move(dx, dy);
     78 }
     79 
     80 inline void RenderOverflow::addLayoutOverflow(const LayoutRect& rect)
     81 {
     82     LayoutUnit maxX = std::max(rect.maxX(), m_layoutOverflow.maxX());
     83     LayoutUnit maxY = std::max(rect.maxY(), m_layoutOverflow.maxY());
     84     LayoutUnit minX = std::min(rect.x(), m_layoutOverflow.x());
     85     LayoutUnit minY = std::min(rect.y(), m_layoutOverflow.y());
     86     // In case the width/height is larger than LayoutUnit can represent, fix the right/bottom edge and shift the top/left ones
     87     m_layoutOverflow.setWidth(maxX - minX);
     88     m_layoutOverflow.setHeight(maxY - minY);
     89     m_layoutOverflow.setX(maxX - m_layoutOverflow.width());
     90     m_layoutOverflow.setY(maxY - m_layoutOverflow.height());
     91 }
     92 
     93 inline void RenderOverflow::addVisualOverflow(const LayoutRect& rect)
     94 {
     95     LayoutUnit maxX = std::max(rect.maxX(), m_visualOverflow.maxX());
     96     LayoutUnit maxY = std::max(rect.maxY(), m_visualOverflow.maxY());
     97     m_visualOverflow.setX(std::min(rect.x(), m_visualOverflow.x()));
     98     m_visualOverflow.setY(std::min(rect.y(), m_visualOverflow.y()));
     99     m_visualOverflow.setWidth(maxX - m_visualOverflow.x());
    100     m_visualOverflow.setHeight(maxY - m_visualOverflow.y());
    101 }
    102 
    103 inline void RenderOverflow::setLayoutOverflow(const LayoutRect& rect)
    104 {
    105     m_layoutOverflow = rect;
    106 }
    107 
    108 inline void RenderOverflow::setVisualOverflow(const LayoutRect& rect)
    109 {
    110     m_visualOverflow = rect;
    111 }
    112 
    113 } // namespace WebCore
    114 
    115 #endif // RenderOverflow_h
    116