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      1 /*
      2  * Copyright (C) 2006, 2009 Apple Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  *
      8  * 1.  Redistributions of source code must retain the above copyright
      9  *     notice, this list of conditions and the following disclaimer.
     10  * 2.  Redistributions in binary form must reproduce the above copyright
     11  *     notice, this list of conditions and the following disclaimer in the
     12  *     documentation and/or other materials provided with the distribution.
     13  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
     14  *     its contributors may be used to endorse or promote products derived
     15  *     from this software without specific prior written permission.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
     18  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     19  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     20  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
     21  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     22  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     23  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
     24  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 #ifndef GlyphMetricsMap_h
     30 #define GlyphMetricsMap_h
     31 
     32 #include "core/platform/graphics/Glyph.h"
     33 #include "wtf/Assertions.h"
     34 #include "wtf/HashMap.h"
     35 #include "wtf/OwnPtr.h"
     36 #include "wtf/PassOwnPtr.h"
     37 #include "wtf/unicode/Unicode.h"
     38 
     39 namespace WebCore {
     40 
     41 const float cGlyphSizeUnknown = -1;
     42 
     43 template<class T> class GlyphMetricsMap {
     44     WTF_MAKE_NONCOPYABLE(GlyphMetricsMap);
     45 public:
     46     GlyphMetricsMap() : m_filledPrimaryPage(false) { }
     47     T metricsForGlyph(Glyph glyph)
     48     {
     49         return locatePage(glyph / GlyphMetricsPage::size)->metricsForGlyph(glyph);
     50     }
     51 
     52     void setMetricsForGlyph(Glyph glyph, const T& metrics)
     53     {
     54         locatePage(glyph / GlyphMetricsPage::size)->setMetricsForGlyph(glyph, metrics);
     55     }
     56 
     57 private:
     58     class GlyphMetricsPage {
     59     public:
     60         static const size_t size = 256; // Usually covers Latin-1 in a single page.
     61 
     62         T metricsForGlyph(Glyph glyph) const { return m_metrics[glyph % size]; }
     63         void setMetricsForGlyph(Glyph glyph, const T& metrics)
     64         {
     65             setMetricsForIndex(glyph % size, metrics);
     66         }
     67         void setMetricsForIndex(unsigned index, const T& metrics)
     68         {
     69             ASSERT_WITH_SECURITY_IMPLICATION(index < size);
     70             m_metrics[index] = metrics;
     71         }
     72 
     73     private:
     74         T m_metrics[size];
     75     };
     76 
     77     GlyphMetricsPage* locatePage(unsigned pageNumber)
     78     {
     79         if (!pageNumber && m_filledPrimaryPage)
     80             return &m_primaryPage;
     81         return locatePageSlowCase(pageNumber);
     82     }
     83 
     84     GlyphMetricsPage* locatePageSlowCase(unsigned pageNumber);
     85 
     86     static T unknownMetrics();
     87 
     88     bool m_filledPrimaryPage;
     89     GlyphMetricsPage m_primaryPage; // We optimize for the page that contains glyph indices 0-255.
     90     OwnPtr<HashMap<int, OwnPtr<GlyphMetricsPage> > > m_pages;
     91 };
     92 
     93 template<> inline float GlyphMetricsMap<float>::unknownMetrics()
     94 {
     95     return cGlyphSizeUnknown;
     96 }
     97 
     98 template<> inline FloatRect GlyphMetricsMap<FloatRect>::unknownMetrics()
     99 {
    100     return FloatRect(0, 0, cGlyphSizeUnknown, cGlyphSizeUnknown);
    101 }
    102 
    103 template<class T> typename GlyphMetricsMap<T>::GlyphMetricsPage* GlyphMetricsMap<T>::locatePageSlowCase(unsigned pageNumber)
    104 {
    105     GlyphMetricsPage* page;
    106     if (!pageNumber) {
    107         ASSERT(!m_filledPrimaryPage);
    108         page = &m_primaryPage;
    109         m_filledPrimaryPage = true;
    110     } else {
    111         if (m_pages) {
    112             if ((page = m_pages->get(pageNumber)))
    113                 return page;
    114         } else
    115             m_pages = adoptPtr(new HashMap<int, OwnPtr<GlyphMetricsPage> >);
    116         page = new GlyphMetricsPage;
    117         m_pages->set(pageNumber, adoptPtr(page));
    118     }
    119 
    120     // Fill in the whole page with the unknown glyph information.
    121     for (unsigned i = 0; i < GlyphMetricsPage::size; i++)
    122         page->setMetricsForIndex(i, unknownMetrics());
    123 
    124     return page;
    125 }
    126 
    127 } // namespace WebCore
    128 
    129 #endif
    130