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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 <wtf/FixedArray.h>
     33 #include <wtf/HashMap.h>
     34 #include <wtf/OwnPtr.h>
     35 #include <wtf/unicode/Unicode.h>
     36 
     37 namespace WebCore {
     38 
     39 typedef unsigned short Glyph;
     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     ~GlyphMetricsMap()
     48     {
     49         if (m_pages)
     50             deleteAllValues(*m_pages);
     51     }
     52 
     53     T metricsForGlyph(Glyph glyph)
     54     {
     55         return locatePage(glyph / GlyphMetricsPage::size)->metricsForGlyph(glyph);
     56     }
     57 
     58     void setMetricsForGlyph(Glyph glyph, const T& metrics)
     59     {
     60         locatePage(glyph / GlyphMetricsPage::size)->setMetricsForGlyph(glyph, metrics);
     61     }
     62 
     63 private:
     64     struct GlyphMetricsPage {
     65         static const size_t size = 256; // Usually covers Latin-1 in a single page.
     66         FixedArray<T, size> m_metrics;
     67 
     68         T metricsForGlyph(Glyph glyph) const { return m_metrics[glyph % size]; }
     69         void setMetricsForGlyph(Glyph glyph, const T& metrics)
     70         {
     71             setMetricsForIndex(glyph % size, metrics);
     72         }
     73         void setMetricsForIndex(unsigned index, const T& metrics)
     74         {
     75             m_metrics[index] = metrics;
     76         }
     77     };
     78 
     79     GlyphMetricsPage* locatePage(unsigned pageNumber)
     80     {
     81         if (!pageNumber && m_filledPrimaryPage)
     82             return &m_primaryPage;
     83         return locatePageSlowCase(pageNumber);
     84     }
     85 
     86     GlyphMetricsPage* locatePageSlowCase(unsigned pageNumber);
     87 
     88     static T unknownMetrics();
     89 
     90     bool m_filledPrimaryPage;
     91     GlyphMetricsPage m_primaryPage; // We optimize for the page that contains glyph indices 0-255.
     92     OwnPtr<HashMap<int, GlyphMetricsPage*> > m_pages;
     93 };
     94 
     95 template<> inline float GlyphMetricsMap<float>::unknownMetrics()
     96 {
     97     return cGlyphSizeUnknown;
     98 }
     99 
    100 template<> inline FloatRect GlyphMetricsMap<FloatRect>::unknownMetrics()
    101 {
    102     return FloatRect(0, 0, cGlyphSizeUnknown, cGlyphSizeUnknown);
    103 }
    104 
    105 template<class T> typename GlyphMetricsMap<T>::GlyphMetricsPage* GlyphMetricsMap<T>::locatePageSlowCase(unsigned pageNumber)
    106 {
    107     GlyphMetricsPage* page;
    108     if (!pageNumber) {
    109         ASSERT(!m_filledPrimaryPage);
    110         page = &m_primaryPage;
    111         m_filledPrimaryPage = true;
    112     } else {
    113         if (m_pages) {
    114             if ((page = m_pages->get(pageNumber)))
    115                 return page;
    116         } else
    117             m_pages = adoptPtr(new HashMap<int, GlyphMetricsPage*>);
    118         page = new GlyphMetricsPage;
    119         m_pages->set(pageNumber, page);
    120     }
    121 
    122     // Fill in the whole page with the unknown glyph information.
    123     for (unsigned i = 0; i < GlyphMetricsPage::size; i++)
    124         page->setMetricsForIndex(i, unknownMetrics());
    125 
    126     return page;
    127 }
    128 
    129 } // namespace WebCore
    130 
    131 #endif
    132