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 "FontBaseline.h"
24#include <wtf/MathExtras.h>
25
26namespace WebCore {
27
28const unsigned gDefaultUnitsPerEm = 1000;
29
30class FontMetrics {
31public:
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
125private:
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
150static 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