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

   1 /*
   2  * Copyright (C) 2007 Nicholas Shanks <contact@nickshanks.com>
   3  * Copyright (C) 2008 Apple Inc. All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  *
   9  * 1.  Redistributions of source code must retain the above copyright
  10  *     notice, this list of conditions and the following disclaimer.
  11  * 2.  Redistributions in binary form must reproduce the above copyright
  12  *     notice, this list of conditions and the following disclaimer in the
  13  *     documentation and/or other materials provided with the distribution.
  14  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
  15  *     its contributors may be used to endorse or promote products derived
  16  *     from this software without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
  19  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  20  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  21  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
  22  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  23  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  24  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  25  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28  */
  29
  30 #include "config.h"
  31 #include "platform/fonts/FontDescription.h"
  32
  33 #include "platform/RuntimeEnabledFeatures.h"
  34 #include "wtf/text/AtomicStringHash.h"
  35 #include "wtf/text/StringHash.h"
  36
  37 namespace blink {
  38
  39 struct SameSizeAsFontDescription {
  40     FontFamily familyList;
  41     RefPtr<FontFeatureSettings> m_featureSettings;
  42     AtomicString locale;
  43     float sizes[6];
  44     // FXIME: Make them fit into one word.
  45     uint32_t bitfields;
  46     uint32_t bitfields2 : 7;
  47 };
  48
  49 static_assert(sizeof(FontDescription) == sizeof(SameSizeAsFontDescription), "FontDescription should stay small");
  50
  51 TypesettingFeatures FontDescription::s_defaultTypesettingFeatures = 0;
  52
  53 bool FontDescription::s_useSubpixelTextPositioning = false;
  54
  55 FontWeight FontDescription::lighterWeight(FontWeight weight)
  56 {
  57     switch (weight) {
  58         case FontWeight100:
  59         case FontWeight200:
  60         case FontWeight300:
  61         case FontWeight400:
  62         case FontWeight500:
  63             return FontWeight100;
  64
  65         case FontWeight600:
  66         case FontWeight700:
  67             return FontWeight400;
  68
  69         case FontWeight800:
  70         case FontWeight900:
  71             return FontWeight700;
  72     }
  73     ASSERT_NOT_REACHED();
  74     return FontWeightNormal;
  75 }
  76
  77 FontWeight FontDescription::bolderWeight(FontWeight weight)
  78 {
  79     switch (weight) {
  80         case FontWeight100:
  81         case FontWeight200:
  82         case FontWeight300:
  83             return FontWeight400;
  84
  85         case FontWeight400:
  86         case FontWeight500:
  87             return FontWeight700;
  88
  89         case FontWeight600:
  90         case FontWeight700:
  91         case FontWeight800:
  92         case FontWeight900:
  93             return FontWeight900;
  94     }
  95     ASSERT_NOT_REACHED();
  96     return FontWeightNormal;
  97 }
  98
  99 FontDescription::Size FontDescription::largerSize(const Size& size)
 100 {
 101     return Size(0, size.value * 1.2, size.isAbsolute);
 102 }
 103
 104 FontDescription::Size FontDescription::smallerSize(const Size& size)
 105 {
 106     return Size(0, size.value / 1.2, size.isAbsolute);
 107 }
 108
 109 FontTraits FontDescription::traits() const
 110 {
 111     return FontTraits(style(), variant(), weight(), stretch());
 112 }
 113
 114 FontDescription::VariantLigatures FontDescription::variantLigatures() const
 115 {
 116     VariantLigatures ligatures;
 117
 118     ligatures.common = commonLigaturesState();
 119     ligatures.discretionary = discretionaryLigaturesState();
 120     ligatures.historical = historicalLigaturesState();
 121     ligatures.contextual = contextualLigaturesState();
 122
 123     return ligatures;
 124 }
 125
 126 static const AtomicString& defaultLocale()
 127 {
 128     DEFINE_STATIC_LOCAL(AtomicString, locale, ());
 129     if (locale.isNull())
 130         locale = AtomicString("en");
 131     return locale;
 132 }
 133
 134 const AtomicString& FontDescription::locale(bool includeDefault) const
 135 {
 136     if (m_locale.isNull() && includeDefault)
 137         return defaultLocale();
 138     return m_locale;
 139 }
 140
 141 void FontDescription::setTraits(FontTraits traits)
 142 {
 143     setStyle(traits.style());
 144     setVariant(traits.variant());
 145     setWeight(traits.weight());
 146     setStretch(traits.stretch());
 147 }
 148
 149 void FontDescription::setVariantLigatures(const VariantLigatures& ligatures)
 150 {
 151     m_commonLigaturesState = ligatures.common;
 152     m_discretionaryLigaturesState = ligatures.discretionary;
 153     m_historicalLigaturesState = ligatures.historical;
 154     m_contextualLigaturesState = ligatures.contextual;
 155
 156     updateTypesettingFeatures();
 157 }
 158
 159 float FontDescription::effectiveFontSize() const
 160 {
 161     // Ensure that the effective precision matches the font-cache precision.
 162     // This guarantees that the same precision is used regardless of cache status.
 163     float computedOrAdjustedSize = hasSizeAdjust() ? adjustedSize() : computedSize();
 164     return floorf(computedOrAdjustedSize * FontCacheKey::precisionMultiplier()) / FontCacheKey::precisionMultiplier();
 165 }
 166
 167 FontCacheKey FontDescription::cacheKey(const FontFaceCreationParams& creationParams, FontTraits desiredTraits) const
 168 {
 169     FontTraits fontTraits = desiredTraits.bitfield() ? desiredTraits : traits();
 170
 171     unsigned options =
 172         static_cast<unsigned>(m_syntheticItalic) << 6 | // bit 7
 173         static_cast<unsigned>(m_syntheticBold) << 5 | // bit 6
 174         static_cast<unsigned>(m_textRendering) << 3 | // bits 4-5
 175         static_cast<unsigned>(m_orientation) << 1 | // bit 2-3
 176         static_cast<unsigned>(m_subpixelTextPosition); // bit 1
 177
 178     return FontCacheKey(creationParams, effectiveFontSize(), options | fontTraits.bitfield() << 7);
 179 }
 180
 181
 182 void FontDescription::setDefaultTypesettingFeatures(TypesettingFeatures typesettingFeatures)
 183 {
 184     s_defaultTypesettingFeatures = typesettingFeatures;
 185 }
 186
 187 TypesettingFeatures FontDescription::defaultTypesettingFeatures()
 188 {
 189     return s_defaultTypesettingFeatures;
 190 }
 191
 192 void FontDescription::updateTypesettingFeatures() const
 193 {
 194     m_typesettingFeatures = s_defaultTypesettingFeatures;
 195
 196     switch (textRendering()) {
 197     case AutoTextRendering:
 198         break;
 199     case OptimizeSpeed:
 200         m_typesettingFeatures &= ~(blink::Kerning | Ligatures);
 201         break;
 202     case GeometricPrecision:
 203     case OptimizeLegibility:
 204         m_typesettingFeatures |= blink::Kerning | Ligatures;
 205         break;
 206     }
 207
 208     switch (kerning()) {
 209     case FontDescription::NoneKerning:
 210         m_typesettingFeatures &= ~blink::Kerning;
 211         break;
 212     case FontDescription::NormalKerning:
 213         m_typesettingFeatures |= blink::Kerning;
 214         break;
 215     case FontDescription::AutoKerning:
 216         break;
 217     }
 218
 219     // As per CSS (http://dev.w3.org/csswg/css-text-3/#letter-spacing-property),
 220     // When the effective letter-spacing between two characters is not zero (due to
 221     // either justification or non-zero computed letter-spacing), user agents should
 222     // not apply optional ligatures.
 223     if (m_letterSpacing == 0) {
 224         switch (commonLigaturesState()) {
 225         case FontDescription::DisabledLigaturesState:
 226             m_typesettingFeatures &= ~Ligatures;
 227             break;
 228         case FontDescription::EnabledLigaturesState:
 229             m_typesettingFeatures |= Ligatures;
 230             break;
 231         case FontDescription::NormalLigaturesState:
 232             break;
 233         }
 234
 235         if (discretionaryLigaturesState() == FontDescription::EnabledLigaturesState
 236             || historicalLigaturesState() == FontDescription::EnabledLigaturesState
 237             || contextualLigaturesState() == FontDescription::EnabledLigaturesState) {
 238             m_typesettingFeatures |= blink::Ligatures;
 239         }
 240     }
 241 }
 242
 243 } // namespace blink