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      1 /*
      2  * Copyright (C) Research In Motion Limited 2010-2011. 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 #ifndef FontMetrics_h
     21 #define FontMetrics_h
     22 
     23 #include "platform/fonts/FontBaseline.h"
     24 #include "wtf/MathExtras.h"
     25 
     26 namespace WebCore {
     27 
     28 const unsigned gDefaultUnitsPerEm = 1000;
     29 
     30 class FontMetrics {
     31 public:
     32     FontMetrics()
     33         : m_unitsPerEm(gDefaultUnitsPerEm)
     34         , m_ascent(0)
     35         , m_descent(0)
     36         , m_lineGap(0)
     37         , m_lineSpacing(0)
     38         , m_xHeight(0)
     39         , m_zeroWidth(0)
     40         , m_hasXHeight(false)
     41         , m_hasZeroWidth(false)
     42     {
     43     }
     44 
     45     unsigned unitsPerEm() const { return m_unitsPerEm; }
     46     void setUnitsPerEm(unsigned unitsPerEm) { m_unitsPerEm = unitsPerEm; }
     47 
     48     float floatAscent(FontBaseline baselineType = AlphabeticBaseline) const
     49     {
     50         if (baselineType == AlphabeticBaseline)
     51             return m_ascent;
     52         return floatHeight() / 2;
     53     }
     54 
     55     void setAscent(float ascent) { m_ascent = ascent; }
     56 
     57     float floatDescent(FontBaseline baselineType = AlphabeticBaseline) const
     58     {
     59         if (baselineType == AlphabeticBaseline)
     60             return m_descent;
     61         return floatHeight() / 2;
     62     }
     63 
     64     void setDescent(float descent) { m_descent = descent; }
     65 
     66     float floatHeight(FontBaseline baselineType = AlphabeticBaseline) const
     67     {
     68         return floatAscent(baselineType) + floatDescent(baselineType);
     69     }
     70 
     71     float floatLineGap() const { return m_lineGap; }
     72     void setLineGap(float lineGap) { m_lineGap = lineGap; }
     73 
     74     float floatLineSpacing() const { return m_lineSpacing; }
     75     void setLineSpacing(float lineSpacing) { m_lineSpacing = lineSpacing; }
     76 
     77     float xHeight() const { return m_xHeight; }
     78     void setXHeight(float xHeight)
     79     {
     80         m_xHeight = xHeight;
     81         m_hasXHeight = true;
     82     }
     83 
     84     bool hasXHeight() const { return m_hasXHeight && m_xHeight > 0; }
     85     void setHasXHeight(bool hasXHeight) { m_hasXHeight = hasXHeight; }
     86 
     87     // Integer variants of certain metrics, used for HTML rendering.
     88     int ascent(FontBaseline baselineType = AlphabeticBaseline) const
     89     {
     90         if (baselineType == AlphabeticBaseline)
     91             return lroundf(m_ascent);
     92         return height() - height() / 2;
     93     }
     94 
     95     int descent(FontBaseline baselineType = AlphabeticBaseline) const
     96     {
     97         if (baselineType == AlphabeticBaseline)
     98             return lroundf(m_descent);
     99         return height() / 2;
    100     }
    101 
    102     int height(FontBaseline baselineType = AlphabeticBaseline) const
    103     {
    104         return ascent(baselineType) + descent(baselineType);
    105     }
    106 
    107     int lineGap() const { return lroundf(m_lineGap); }
    108     int lineSpacing() const { return lroundf(m_lineSpacing); }
    109 
    110     bool hasIdenticalAscentDescentAndLineGap(const FontMetrics& other) const
    111     {
    112         return ascent() == other.ascent() && descent() == other.descent() && lineGap() == other.lineGap();
    113     }
    114 
    115     float zeroWidth() const { return m_zeroWidth; }
    116     void setZeroWidth(float zeroWidth)
    117     {
    118         m_zeroWidth = zeroWidth;
    119         m_hasZeroWidth = true;
    120     }
    121 
    122     bool hasZeroWidth() const { return m_hasZeroWidth; }
    123     void setHasZeroWidth(bool hasZeroWidth) { m_hasZeroWidth = hasZeroWidth; }
    124 
    125 private:
    126     friend class SimpleFontData;
    127 
    128     void reset()
    129     {
    130         m_unitsPerEm = gDefaultUnitsPerEm;
    131         m_ascent = 0;
    132         m_descent = 0;
    133         m_lineGap = 0;
    134         m_lineSpacing = 0;
    135         m_xHeight = 0;
    136         m_hasXHeight = false;
    137     }
    138 
    139     unsigned m_unitsPerEm;
    140     float m_ascent;
    141     float m_descent;
    142     float m_lineGap;
    143     float m_lineSpacing;
    144     float m_xHeight;
    145     float m_zeroWidth;
    146     bool m_hasXHeight;
    147     bool m_hasZeroWidth;
    148 };
    149 
    150 inline float scaleEmToUnits(float x, unsigned unitsPerEm)
    151 {
    152     return unitsPerEm ? x / unitsPerEm : x;
    153 }
    154 
    155 } // namespace WebCore
    156 
    157 #endif // FontMetrics_h
    158