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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 "platform/fonts/Glyph.h"
     33 #include "platform/geometry/FloatRect.h"
     34 #include "wtf/Assertions.h"
     35 #include "wtf/HashMap.h"
     36 #include "wtf/OwnPtr.h"
     37 #include "wtf/PassOwnPtr.h"
     38 #include "wtf/unicode/Unicode.h"
     39 
     40 namespace blink {
     41 
     42 const float cGlyphSizeUnknown = -1;
     43 
     44 template<class T> class GlyphMetricsMap {
     45     WTF_MAKE_NONCOPYABLE(GlyphMetricsMap);
     46 public:
     47     GlyphMetricsMap() : m_filledPrimaryPage(false) { }
     48     T metricsForGlyph(Glyph glyph)
     49     {
     50         return locatePage(glyph / GlyphMetricsPage::size)->metricsForGlyph(glyph);
     51     }
     52 
     53     void setMetricsForGlyph(Glyph glyph, const T& metrics)
     54     {
     55         locatePage(glyph / GlyphMetricsPage::size)->setMetricsForGlyph(glyph, metrics);
     56     }
     57 
     58 private:
     59     class GlyphMetricsPage {
     60     public:
     61         static const size_t size = 256; // Usually covers Latin-1 in a single page.
     62 
     63         T metricsForGlyph(Glyph glyph) const { return m_metrics[glyph % size]; }
     64         void setMetricsForGlyph(Glyph glyph, const T& metrics)
     65         {
     66             setMetricsForIndex(glyph % size, metrics);
     67         }
     68         void setMetricsForIndex(unsigned index, const T& metrics)
     69         {
     70             ASSERT_WITH_SECURITY_IMPLICATION(index < size);
     71             m_metrics[index] = metrics;
     72         }
     73 
     74     private:
     75         T m_metrics[size];
     76     };
     77 
     78     GlyphMetricsPage* locatePage(unsigned pageNumber)
     79     {
     80         if (!pageNumber && m_filledPrimaryPage)
     81             return &m_primaryPage;
     82         return locatePageSlowCase(pageNumber);
     83     }
     84 
     85     GlyphMetricsPage* locatePageSlowCase(unsigned pageNumber);
     86 
     87     static T unknownMetrics();
     88 
     89     bool m_filledPrimaryPage;
     90     GlyphMetricsPage m_primaryPage; // We optimize for the page that contains glyph indices 0-255.
     91     OwnPtr<HashMap<int, OwnPtr<GlyphMetricsPage> > > m_pages;
     92 };
     93 
     94 template<> inline float GlyphMetricsMap<float>::unknownMetrics()
     95 {
     96     return cGlyphSizeUnknown;
     97 }
     98 
     99 template<> inline FloatRect GlyphMetricsMap<FloatRect>::unknownMetrics()
    100 {
    101     return FloatRect(0, 0, cGlyphSizeUnknown, cGlyphSizeUnknown);
    102 }
    103 
    104 template<class T> typename GlyphMetricsMap<T>::GlyphMetricsPage* GlyphMetricsMap<T>::locatePageSlowCase(unsigned pageNumber)
    105 {
    106     GlyphMetricsPage* page;
    107     if (!pageNumber) {
    108         ASSERT(!m_filledPrimaryPage);
    109         page = &m_primaryPage;
    110         m_filledPrimaryPage = true;
    111     } else {
    112         if (m_pages) {
    113             page = m_pages->get(pageNumber);
    114             if (page)
    115                 return page;
    116         } else
    117             m_pages = adoptPtr(new HashMap<int, OwnPtr<GlyphMetricsPage> >);
    118         page = new GlyphMetricsPage;
    119         m_pages->set(pageNumber, adoptPtr(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 blink
    130 
    131 #endif
    132