third_party/WebKit/Source/platform/fonts/FontDescription.cpp

/*
 * Copyright (C) 2007 Nicholas Shanks <contact@nickshanks.com>
 * Copyright (C) 2008 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "platform/fonts/FontDescription.h"

#include "platform/Language.h"
#include "platform/RuntimeEnabledFeatures.h"
#include "wtf/StringHasher.h"
#include "wtf/text/AtomicStringHash.h"
#include "wtf/text/StringHash.h"

namespace blink {

struct SameSizeAsFontDescription {
  DISALLOW_NEW();
  FontFamily familyList;
  RefPtr<FontFeatureSettings> m_featureSettings;
  RefPtr<FontVariationSettings> m_variationSettings;
  AtomicString locale;
  float sizes[6];
  FieldsAsUnsignedType bitfields;
};

static_assert(sizeof(FontDescription) == sizeof(SameSizeAsFontDescription),
              "FontDescription should stay small");

TypesettingFeatures FontDescription::s_defaultTypesettingFeatures = 0;

bool FontDescription::s_useSubpixelTextPositioning = false;

FontDescription::FontDescription()
    : m_specifiedSize(0),
      m_computedSize(0),
      m_adjustedSize(0),
      m_sizeAdjust(FontSizeAdjustNone),
      m_letterSpacing(0),
      m_wordSpacing(0) {
  m_fieldsAsUnsigned.parts[0] = 0;
  m_fieldsAsUnsigned.parts[1] = 0;
  m_fields.m_orientation = static_cast<unsigned>(FontOrientation::Horizontal);
  m_fields.m_widthVariant = RegularWidth;
  m_fields.m_style = FontStyleNormal;
  m_fields.m_variantCaps = CapsNormal;
  m_fields.m_isAbsoluteSize = false;
  m_fields.m_weight = FontWeightNormal;
  m_fields.m_stretch = FontStretchNormal;
  m_fields.m_genericFamily = NoFamily;
  m_fields.m_kerning = AutoKerning;
  m_fields.m_commonLigaturesState = NormalLigaturesState;
  m_fields.m_discretionaryLigaturesState = NormalLigaturesState;
  m_fields.m_historicalLigaturesState = NormalLigaturesState;
  m_fields.m_contextualLigaturesState = NormalLigaturesState;
  m_fields.m_keywordSize = 0;
  m_fields.m_fontSmoothing = AutoSmoothing;
  m_fields.m_textRendering = AutoTextRendering;
  m_fields.m_syntheticBold = false;
  m_fields.m_syntheticItalic = false;
  m_fields.m_subpixelTextPosition = s_useSubpixelTextPositioning;
  m_fields.m_typesettingFeatures = s_defaultTypesettingFeatures;
  m_fields.m_variantNumeric = FontVariantNumeric().m_fieldsAsUnsigned;
  m_fields.m_subpixelAscentDescent = false;
}

FontDescription::FontDescription(const FontDescription&) = default;

FontDescription& FontDescription::operator=(const FontDescription&) = default;

bool FontDescription::operator==(const FontDescription& other) const {
  return m_familyList == other.m_familyList && m_locale == other.m_locale &&
         m_specifiedSize == other.m_specifiedSize &&
         m_computedSize == other.m_computedSize &&
         m_adjustedSize == other.m_adjustedSize &&
         m_sizeAdjust == other.m_sizeAdjust &&
         m_letterSpacing == other.m_letterSpacing &&
         m_wordSpacing == other.m_wordSpacing &&
         m_fieldsAsUnsigned.parts[0] == other.m_fieldsAsUnsigned.parts[0] &&
         m_fieldsAsUnsigned.parts[1] == other.m_fieldsAsUnsigned.parts[1] &&
         (m_featureSettings == other.m_featureSettings ||
          (m_featureSettings && other.m_featureSettings &&
           *m_featureSettings == *other.m_featureSettings)) &&
         (m_variationSettings == other.m_variationSettings ||
          (m_variationSettings && other.m_variationSettings &&
           *m_variationSettings == *other.m_variationSettings));
}

FontWeight FontDescription::lighterWeight(FontWeight weight) {
  switch (weight) {
    case FontWeight100:
    case FontWeight200:
    case FontWeight300:
    case FontWeight400:
    case FontWeight500:
      return FontWeight100;

    case FontWeight600:
    case FontWeight700:
      return FontWeight400;

    case FontWeight800:
    case FontWeight900:
      return FontWeight700;
  }
  ASSERT_NOT_REACHED();
  return FontWeightNormal;
}

FontWeight FontDescription::bolderWeight(FontWeight weight) {
  switch (weight) {
    case FontWeight100:
    case FontWeight200:
    case FontWeight300:
      return FontWeight400;

    case FontWeight400:
    case FontWeight500:
      return FontWeight700;

    case FontWeight600:
    case FontWeight700:
    case FontWeight800:
    case FontWeight900:
      return FontWeight900;
  }
  ASSERT_NOT_REACHED();
  return FontWeightNormal;
}

FontDescription::Size FontDescription::largerSize(const Size& size) {
  return Size(0, size.value * 1.2, size.isAbsolute);
}

FontDescription::Size FontDescription::smallerSize(const Size& size) {
  return Size(0, size.value / 1.2, size.isAbsolute);
}

FontTraits FontDescription::traits() const {
  return FontTraits(style(), weight(), stretch());
}

FontDescription::VariantLigatures FontDescription::getVariantLigatures() const {
  VariantLigatures ligatures;

  ligatures.common = commonLigaturesState();
  ligatures.discretionary = discretionaryLigaturesState();
  ligatures.historical = historicalLigaturesState();
  ligatures.contextual = contextualLigaturesState();

  return ligatures;
}

void FontDescription::setTraits(FontTraits traits) {
  setStyle(traits.style());
  setWeight(traits.weight());
  setStretch(traits.stretch());
}

void FontDescription::setVariantCaps(FontVariantCaps variantCaps) {
  m_fields.m_variantCaps = variantCaps;

  updateTypesettingFeatures();
}

void FontDescription::setVariantLigatures(const VariantLigatures& ligatures) {
  m_fields.m_commonLigaturesState = ligatures.common;
  m_fields.m_discretionaryLigaturesState = ligatures.discretionary;
  m_fields.m_historicalLigaturesState = ligatures.historical;
  m_fields.m_contextualLigaturesState = ligatures.contextual;

  updateTypesettingFeatures();
}

void FontDescription::setVariantNumeric(
    const FontVariantNumeric& variantNumeric) {
  m_fields.m_variantNumeric = variantNumeric.m_fieldsAsUnsigned;

  updateTypesettingFeatures();
}

float FontDescription::effectiveFontSize() const {
  // Ensure that the effective precision matches the font-cache precision.
  // This guarantees that the same precision is used regardless of cache status.
  float computedOrAdjustedSize =
      hasSizeAdjust() ? adjustedSize() : computedSize();
  return floorf(computedOrAdjustedSize * FontCacheKey::precisionMultiplier()) /
         FontCacheKey::precisionMultiplier();
}

FontCacheKey FontDescription::cacheKey(
    const FontFaceCreationParams& creationParams,
    FontTraits desiredTraits) const {
  FontTraits fontTraits = desiredTraits.bitfield() ? desiredTraits : traits();

  unsigned options =
      static_cast<unsigned>(m_fields.m_syntheticItalic) << 6 |  // bit 7
      static_cast<unsigned>(m_fields.m_syntheticBold) << 5 |    // bit 6
      static_cast<unsigned>(m_fields.m_textRendering) << 3 |    // bits 4-5
      static_cast<unsigned>(m_fields.m_orientation) << 1 |      // bit 2-3
      static_cast<unsigned>(m_fields.m_subpixelTextPosition);   // bit 1

  return FontCacheKey(creationParams, effectiveFontSize(),
                      options | fontTraits.bitfield() << 8,
                      m_variationSettings);
}

void FontDescription::setDefaultTypesettingFeatures(
    TypesettingFeatures typesettingFeatures) {
  s_defaultTypesettingFeatures = typesettingFeatures;
}

TypesettingFeatures FontDescription::defaultTypesettingFeatures() {
  return s_defaultTypesettingFeatures;
}

void FontDescription::updateTypesettingFeatures() {
  m_fields.m_typesettingFeatures = s_defaultTypesettingFeatures;

  switch (textRendering()) {
    case AutoTextRendering:
      break;
    case OptimizeSpeed:
      m_fields.m_typesettingFeatures &= ~(blink::Kerning | Ligatures);
      break;
    case GeometricPrecision:
    case OptimizeLegibility:
      m_fields.m_typesettingFeatures |= blink::Kerning | Ligatures;
      break;
  }

  switch (getKerning()) {
    case FontDescription::NoneKerning:
      m_fields.m_typesettingFeatures &= ~blink::Kerning;
      break;
    case FontDescription::NormalKerning:
      m_fields.m_typesettingFeatures |= blink::Kerning;
      break;
    case FontDescription::AutoKerning:
      break;
  }

  // As per CSS (http://dev.w3.org/csswg/css-text-3/#letter-spacing-property),
  // When the effective letter-spacing between two characters is not zero (due
  // to either justification or non-zero computed letter-spacing), user agents
  // should not apply optional ligatures.
  if (m_letterSpacing == 0) {
    switch (commonLigaturesState()) {
      case FontDescription::DisabledLigaturesState:
        m_fields.m_typesettingFeatures &= ~blink::Ligatures;
        break;
      case FontDescription::EnabledLigaturesState:
        m_fields.m_typesettingFeatures |= blink::Ligatures;
        break;
      case FontDescription::NormalLigaturesState:
        break;
    }

    if (discretionaryLigaturesState() ==
            FontDescription::EnabledLigaturesState ||
        historicalLigaturesState() == FontDescription::EnabledLigaturesState ||
        contextualLigaturesState() == FontDescription::EnabledLigaturesState) {
      m_fields.m_typesettingFeatures |= blink::Ligatures;
    }
  }

  if (variantCaps() != CapsNormal)
    m_fields.m_typesettingFeatures |= blink::Caps;
}

static inline void addToHash(unsigned& hash, unsigned key) {
  hash = ((hash << 5) + hash) + key;  // Djb2
}

static inline void addFloatToHash(unsigned& hash, float value) {
  addToHash(hash, StringHasher::hashMemory(&value, sizeof(value)));
}

unsigned FontDescription::styleHashWithoutFamilyList() const {
  unsigned hash = 0;
  StringHasher stringHasher;
  const FontFeatureSettings* settings = featureSettings();
  if (settings) {
    unsigned numFeatures = settings->size();
    for (unsigned i = 0; i < numFeatures; ++i) {
      const AtomicString& tag = settings->at(i).tag();
      for (unsigned j = 0; j < tag.length(); j++)
        stringHasher.addCharacter(tag[j]);
      addToHash(hash, settings->at(i).value());
    }
  }

  if (variationSettings())
    addToHash(hash, variationSettings()->hash());

  if (m_locale) {
    const AtomicString& locale = m_locale->localeString();
    for (unsigned i = 0; i < locale.length(); i++)
      stringHasher.addCharacter(locale[i]);
  }
  addToHash(hash, stringHasher.hash());

  addFloatToHash(hash, m_specifiedSize);
  addFloatToHash(hash, m_computedSize);
  addFloatToHash(hash, m_adjustedSize);
  addFloatToHash(hash, m_sizeAdjust);
  addFloatToHash(hash, m_letterSpacing);
  addFloatToHash(hash, m_wordSpacing);
  addToHash(hash, m_fieldsAsUnsigned.parts[0]);
  addToHash(hash, m_fieldsAsUnsigned.parts[1]);

  return hash;
}

SkFontStyle FontDescription::skiaFontStyle() const {
  int width = static_cast<int>(stretch());
  SkFontStyle::Slant slant = SkFontStyle::kUpright_Slant;
  switch (style()) {
    case FontStyleNormal:
      slant = SkFontStyle::kUpright_Slant;
      break;
    case FontStyleItalic:
      slant = SkFontStyle::kItalic_Slant;
      break;
    case FontStyleOblique:
      slant = SkFontStyle::kOblique_Slant;
      break;
    default:
      NOTREACHED();
      break;
  }
  return SkFontStyle(numericFontWeight(weight()), width, slant);
  static_assert(
      static_cast<int>(FontStretchUltraCondensed) ==
          static_cast<int>(SkFontStyle::kUltraCondensed_Width),
      "FontStretchUltraCondensed should map to kUltraCondensed_Width");
  static_assert(static_cast<int>(FontStretchNormal) ==
                    static_cast<int>(SkFontStyle::kNormal_Width),
                "FontStretchNormal should map to kNormal_Width");
  static_assert(static_cast<int>(FontStretchUltraExpanded) ==
                    static_cast<int>(SkFontStyle::kUltraExpanded_Width),
                "FontStretchUltraExpanded should map to kUltraExpanded_Width");
}

}  // namespace blink