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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 GlyphWidthMap_h
     30 #define GlyphWidthMap_h
     31 
     32 #include <wtf/HashMap.h>
     33 #include <wtf/OwnPtr.h>
     34 #include <wtf/unicode/Unicode.h>
     35 
     36 namespace WebCore {
     37 
     38 typedef unsigned short Glyph;
     39 
     40 const float cGlyphWidthUnknown = -1;
     41 
     42 class GlyphWidthMap : public Noncopyable {
     43 public:
     44     GlyphWidthMap() : m_filledPrimaryPage(false) { }
     45     ~GlyphWidthMap() { if (m_pages) { deleteAllValues(*m_pages); } }
     46 
     47     float widthForGlyph(Glyph glyph)
     48     {
     49         return locatePage(glyph / GlyphWidthPage::size)->widthForGlyph(glyph);
     50     }
     51 
     52     void setWidthForGlyph(Glyph glyph, float width)
     53     {
     54         locatePage(glyph / GlyphWidthPage::size)->setWidthForGlyph(glyph, width);
     55     }
     56 
     57 private:
     58     struct GlyphWidthPage {
     59         static const size_t size = 256; // Usually covers Latin-1 in a single page.
     60         float m_widths[size];
     61 
     62         float widthForGlyph(Glyph glyph) const { return m_widths[glyph % size]; }
     63         void setWidthForGlyph(Glyph glyph, float width)
     64         {
     65             setWidthForIndex(glyph % size, width);
     66         }
     67         void setWidthForIndex(unsigned index, float width)
     68         {
     69             m_widths[index] = width;
     70         }
     71     };
     72 
     73     GlyphWidthPage* locatePage(unsigned pageNumber)
     74     {
     75         if (!pageNumber && m_filledPrimaryPage)
     76             return &m_primaryPage;
     77         return locatePageSlowCase(pageNumber);
     78     }
     79 
     80     GlyphWidthPage* locatePageSlowCase(unsigned pageNumber);
     81 
     82     bool m_filledPrimaryPage;
     83     GlyphWidthPage m_primaryPage; // We optimize for the page that contains glyph indices 0-255.
     84     OwnPtr<HashMap<int, GlyphWidthPage*> > m_pages;
     85 };
     86 
     87 }
     88 
     89 #endif
     90