third_party/WebKit/Source/platform/fonts/FontMetrics.h

/*
 * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#ifndef FontMetrics_h
#define FontMetrics_h

#include "platform/fonts/FontBaseline.h"
#include "wtf/Allocator.h"
#include "wtf/MathExtras.h"

namespace blink {

const unsigned gDefaultUnitsPerEm = 1000;

class FontMetrics {
  DISALLOW_NEW();

 public:
  FontMetrics()
      : m_unitsPerEm(gDefaultUnitsPerEm),
        m_ascent(0),
        m_descent(0),
        m_lineGap(0),
        m_lineSpacing(0),
        m_xHeight(0),
        m_zeroWidth(0),
        m_underlinethickness(0),
        m_underlinePosition(0),
        m_ascentInt(0),
        m_descentInt(0),
        m_hasXHeight(false),
        m_hasZeroWidth(false) {}

  unsigned unitsPerEm() const { return m_unitsPerEm; }
  void setUnitsPerEm(unsigned unitsPerEm) { m_unitsPerEm = unitsPerEm; }

  float floatAscent(FontBaseline baselineType = AlphabeticBaseline) const {
    if (baselineType == AlphabeticBaseline)
      return m_ascent;
    return floatHeight() / 2;
  }

  void setAscent(float ascent) {
    m_ascent = ascent;
    m_ascentInt = lroundf(ascent);
  }

  float floatDescent(FontBaseline baselineType = AlphabeticBaseline) const {
    if (baselineType == AlphabeticBaseline)
      return m_descent;
    return floatHeight() / 2;
  }

  void setDescent(float descent) {
    m_descent = descent;
    m_descentInt = lroundf(descent);
  }

  float floatHeight(FontBaseline baselineType = AlphabeticBaseline) const {
    return floatAscent() + floatDescent();
  }

  float floatLineGap() const { return m_lineGap; }
  void setLineGap(float lineGap) { m_lineGap = lineGap; }

  float floatLineSpacing() const { return m_lineSpacing; }
  void setLineSpacing(float lineSpacing) { m_lineSpacing = lineSpacing; }

  float xHeight() const { return m_xHeight; }
  void setXHeight(float xHeight) {
    m_xHeight = xHeight;
    m_hasXHeight = true;
  }

  bool hasXHeight() const { return m_hasXHeight && m_xHeight > 0; }
  void setHasXHeight(bool hasXHeight) { m_hasXHeight = hasXHeight; }

  // Integer variants of certain metrics, used for HTML rendering.
  int ascent(FontBaseline baselineType = AlphabeticBaseline) const {
    if (baselineType == AlphabeticBaseline)
      return m_ascentInt;
    return height() - height() / 2;
  }

  int descent(FontBaseline baselineType = AlphabeticBaseline) const {
    if (baselineType == AlphabeticBaseline)
      return m_descentInt;
    return height() / 2;
  }

  int height(FontBaseline baselineType = AlphabeticBaseline) const {
    return ascent() + descent();
  }

  int lineGap() const { return lroundf(m_lineGap); }
  int lineSpacing() const { return lroundf(m_lineSpacing); }

  bool hasIdenticalAscentDescentAndLineGap(const FontMetrics& other) const {
    return ascent() == other.ascent() && descent() == other.descent() &&
           lineGap() == other.lineGap();
  }

  float zeroWidth() const { return m_zeroWidth; }
  void setZeroWidth(float zeroWidth) {
    m_zeroWidth = zeroWidth;
    m_hasZeroWidth = true;
  }

  bool hasZeroWidth() const { return m_hasZeroWidth; }
  void setHasZeroWidth(bool hasZeroWidth) { m_hasZeroWidth = hasZeroWidth; }

  float underlineThickness() const { return m_underlinethickness; }
  void setUnderlineThickness(float underlineThickness) {
    m_underlinethickness = underlineThickness;
  }

  float underlinePosition() const { return m_underlinePosition; }
  void setUnderlinePosition(float underlinePosition) {
    m_underlinePosition = underlinePosition;
  }

 private:
  friend class SimpleFontData;

  void reset() {
    m_unitsPerEm = gDefaultUnitsPerEm;
    m_ascent = 0;
    m_descent = 0;
    m_ascentInt = 0;
    m_descentInt = 0;
    m_lineGap = 0;
    m_lineSpacing = 0;
    m_xHeight = 0;
    m_hasXHeight = false;
    m_underlinethickness = 0;
    m_underlinePosition = 0;
  }

  unsigned m_unitsPerEm;
  float m_ascent;
  float m_descent;
  float m_lineGap;
  float m_lineSpacing;
  float m_xHeight;
  float m_zeroWidth;
  float m_underlinethickness;
  float m_underlinePosition;
  int m_ascentInt;
  int m_descentInt;
  bool m_hasXHeight;
  bool m_hasZeroWidth;
};

}  // namespace blink

#endif  // FontMetrics_h