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      1 /*
      2  * Copyright (C) 2007 Eric Seidel <eric (at) webkit.org>
      3  * Copyright (C) 2007 Nikolas Zimmermann <zimmermann (at) kde.org>
      4  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
      5  *
      6  * This library is free software; you can redistribute it and/or
      7  * modify it under the terms of the GNU Library General Public
      8  * License as published by the Free Software Foundation; either
      9  * version 2 of the License, or (at your option) any later version.
     10  *
     11  * This library is distributed in the hope that it will be useful,
     12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
     13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     14  * Library General Public License for more details.
     15  *
     16  * You should have received a copy of the GNU Library General Public License
     17  * along with this library; see the file COPYING.LIB.  If not, write to
     18  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     19  * Boston, MA 02110-1301, USA.
     20  */
     21 
     22 #include "config.h"
     23 
     24 #if ENABLE(SVG_FONTS)
     25 #include "core/svg/SVGFontElement.h"
     26 
     27 #include "core/frame/UseCounter.h"
     28 #include "core/svg/SVGGlyphElement.h"
     29 #include "core/svg/SVGHKernElement.h"
     30 #include "core/svg/SVGMissingGlyphElement.h"
     31 #include "core/svg/SVGVKernElement.h"
     32 #include "wtf/ASCIICType.h"
     33 
     34 namespace WebCore {
     35 
     36 // Animated property definitions
     37 DEFINE_ANIMATED_BOOLEAN(SVGFontElement, SVGNames::externalResourcesRequiredAttr, ExternalResourcesRequired, externalResourcesRequired)
     38 
     39 BEGIN_REGISTER_ANIMATED_PROPERTIES(SVGFontElement)
     40     REGISTER_LOCAL_ANIMATED_PROPERTY(externalResourcesRequired)
     41     REGISTER_PARENT_ANIMATED_PROPERTIES(SVGElement)
     42 END_REGISTER_ANIMATED_PROPERTIES
     43 
     44 inline SVGFontElement::SVGFontElement(Document& document)
     45     : SVGElement(SVGNames::fontTag, document)
     46     , m_missingGlyph(0)
     47     , m_isGlyphCacheValid(false)
     48 {
     49     ScriptWrappable::init(this);
     50     registerAnimatedPropertiesForSVGFontElement();
     51 
     52     UseCounter::count(document, UseCounter::SVGFontElement);
     53 }
     54 
     55 PassRefPtr<SVGFontElement> SVGFontElement::create(Document& document)
     56 {
     57     return adoptRef(new SVGFontElement(document));
     58 }
     59 
     60 void SVGFontElement::invalidateGlyphCache()
     61 {
     62     if (m_isGlyphCacheValid) {
     63         m_glyphMap.clear();
     64         m_horizontalKerningPairs.clear();
     65         m_verticalKerningPairs.clear();
     66     }
     67     m_isGlyphCacheValid = false;
     68 }
     69 
     70 SVGMissingGlyphElement* SVGFontElement::firstMissingGlyphElement() const
     71 {
     72     for (Node* child = firstChild(); child; child = child->nextSibling()) {
     73         if (child->hasTagName(SVGNames::missing_glyphTag))
     74             return toSVGMissingGlyphElement(child);
     75     }
     76 
     77     return 0;
     78 }
     79 
     80 void SVGFontElement::registerLigaturesInGlyphCache(Vector<String>& ligatures)
     81 {
     82     ASSERT(!ligatures.isEmpty());
     83 
     84     // Register each character of a ligature in the map, if not present.
     85     // Eg. If only a "fi" ligature is present, but not "f" and "i", the
     86     // GlyphPage will not contain any entries for "f" and "i", so the
     87     // SVGFont is not used to render the text "fi1234". Register an
     88     // empty SVGGlyph with the character, so the SVG Font will be used
     89     // to render the text. If someone tries to render "f2" the SVG Font
     90     // will not be able to find a glyph for "f", but handles the fallback
     91     // character substitution properly through glyphDataForCharacter().
     92     Vector<SVGGlyph> glyphs;
     93     size_t ligaturesSize = ligatures.size();
     94     for (size_t i = 0; i < ligaturesSize; ++i) {
     95         const String& unicode = ligatures[i];
     96 
     97         unsigned unicodeLength = unicode.length();
     98         ASSERT(unicodeLength > 1);
     99 
    100         for (unsigned i = 0; i < unicodeLength; ++i) {
    101             String lookupString = unicode.substring(i, 1);
    102             m_glyphMap.collectGlyphsForString(lookupString, glyphs);
    103             if (!glyphs.isEmpty()) {
    104                 glyphs.clear();
    105                 continue;
    106             }
    107 
    108             // This glyph is never meant to be used for rendering, only as identifier as a part of a ligature.
    109             SVGGlyph newGlyphPart;
    110             newGlyphPart.isPartOfLigature = true;
    111             m_glyphMap.addGlyph(String(), lookupString, newGlyphPart);
    112         }
    113     }
    114 }
    115 
    116 void SVGFontElement::ensureGlyphCache()
    117 {
    118     if (m_isGlyphCacheValid)
    119         return;
    120 
    121     SVGMissingGlyphElement* firstMissingGlyphElement = 0;
    122     Vector<String> ligatures;
    123     for (Node* child = firstChild(); child; child = child->nextSibling()) {
    124         if (child->hasTagName(SVGNames::glyphTag)) {
    125             SVGGlyphElement* glyph = toSVGGlyphElement(child);
    126             AtomicString unicode = glyph->fastGetAttribute(SVGNames::unicodeAttr);
    127             AtomicString glyphId = glyph->getIdAttribute();
    128             if (glyphId.isEmpty() && unicode.isEmpty())
    129                 continue;
    130 
    131             m_glyphMap.addGlyph(glyphId, unicode, glyph->buildGlyphIdentifier());
    132 
    133             // Register ligatures, if needed, don't mix up with surrogate pairs though!
    134             if (unicode.length() > 1 && !U16_IS_SURROGATE(unicode[0]))
    135                 ligatures.append(unicode.string());
    136         } else if (child->hasTagName(SVGNames::hkernTag)) {
    137             toSVGHKernElement(child)->buildHorizontalKerningPair(m_horizontalKerningPairs);
    138         } else if (child->hasTagName(SVGNames::vkernTag)) {
    139             toSVGVKernElement(child)->buildVerticalKerningPair(m_verticalKerningPairs);
    140         } else if (child->hasTagName(SVGNames::missing_glyphTag) && !firstMissingGlyphElement) {
    141             firstMissingGlyphElement = toSVGMissingGlyphElement(child);
    142         }
    143     }
    144 
    145     // Register each character of each ligature, if needed.
    146     if (!ligatures.isEmpty())
    147         registerLigaturesInGlyphCache(ligatures);
    148 
    149     // Register missing-glyph element, if present.
    150     if (firstMissingGlyphElement) {
    151         SVGGlyph svgGlyph = SVGGlyphElement::buildGenericGlyphIdentifier(firstMissingGlyphElement);
    152         m_glyphMap.appendToGlyphTable(svgGlyph);
    153         m_missingGlyph = svgGlyph.tableEntry;
    154         ASSERT(m_missingGlyph > 0);
    155     }
    156 
    157     m_isGlyphCacheValid = true;
    158 }
    159 
    160 static bool stringMatchesUnicodeRange(const String& unicodeString, const UnicodeRanges& ranges, const HashSet<String>& unicodeValues)
    161 {
    162     if (unicodeString.isEmpty())
    163         return false;
    164 
    165     if (!ranges.isEmpty()) {
    166         UChar firstChar = unicodeString[0];
    167         const UnicodeRanges::const_iterator end = ranges.end();
    168         for (UnicodeRanges::const_iterator it = ranges.begin(); it != end; ++it) {
    169             if (firstChar >= it->first && firstChar <= it->second)
    170                 return true;
    171         }
    172     }
    173 
    174     if (!unicodeValues.isEmpty())
    175         return unicodeValues.contains(unicodeString);
    176 
    177     return false;
    178 }
    179 
    180 static bool stringMatchesGlyphName(const String& glyphName, const HashSet<String>& glyphValues)
    181 {
    182     if (glyphName.isEmpty())
    183         return false;
    184 
    185     if (!glyphValues.isEmpty())
    186         return glyphValues.contains(glyphName);
    187 
    188     return false;
    189 }
    190 
    191 static bool matches(const String& u1, const String& g1, const String& u2, const String& g2, const SVGKerningPair& kerningPair)
    192 {
    193     if (!stringMatchesUnicodeRange(u1, kerningPair.unicodeRange1, kerningPair.unicodeName1)
    194         && !stringMatchesGlyphName(g1, kerningPair.glyphName1))
    195         return false;
    196 
    197     if (!stringMatchesUnicodeRange(u2, kerningPair.unicodeRange2, kerningPair.unicodeName2)
    198         && !stringMatchesGlyphName(g2, kerningPair.glyphName2))
    199         return false;
    200 
    201     return true;
    202 }
    203 
    204 static float kerningForPairOfStringsAndGlyphs(const KerningPairVector& kerningPairs, const String& u1, const String& g1, const String& u2, const String& g2)
    205 {
    206     KerningPairVector::const_iterator it = kerningPairs.end() - 1;
    207     const KerningPairVector::const_iterator begin = kerningPairs.begin() - 1;
    208     for (; it != begin; --it) {
    209         if (matches(u1, g1, u2, g2, *it))
    210             return it->kerning;
    211     }
    212 
    213     return 0;
    214 }
    215 
    216 float SVGFontElement::horizontalKerningForPairOfStringsAndGlyphs(const String& u1, const String& g1, const String& u2, const String& g2) const
    217 {
    218     if (m_horizontalKerningPairs.isEmpty())
    219         return 0;
    220 
    221     return kerningForPairOfStringsAndGlyphs(m_horizontalKerningPairs, u1, g1, u2, g2);
    222 }
    223 
    224 float SVGFontElement::verticalKerningForPairOfStringsAndGlyphs(const String& u1, const String& g1, const String& u2, const String& g2) const
    225 {
    226     if (m_verticalKerningPairs.isEmpty())
    227         return 0;
    228 
    229     return kerningForPairOfStringsAndGlyphs(m_verticalKerningPairs, u1, g1, u2, g2);
    230 }
    231 
    232 void SVGFontElement::collectGlyphsForString(const String& string, Vector<SVGGlyph>& glyphs)
    233 {
    234     ensureGlyphCache();
    235     m_glyphMap.collectGlyphsForString(string, glyphs);
    236 }
    237 
    238 void SVGFontElement::collectGlyphsForGlyphName(const String& glyphName, Vector<SVGGlyph>& glyphs)
    239 {
    240     ensureGlyphCache();
    241     // FIXME: We only support glyphName -> single glyph mapping so far.
    242     glyphs.append(m_glyphMap.glyphIdentifierForGlyphName(glyphName));
    243 }
    244 
    245 SVGGlyph SVGFontElement::svgGlyphForGlyph(Glyph glyph)
    246 {
    247     ensureGlyphCache();
    248     return m_glyphMap.svgGlyphForGlyph(glyph);
    249 }
    250 
    251 Glyph SVGFontElement::missingGlyph()
    252 {
    253     ensureGlyphCache();
    254     return m_missingGlyph;
    255 }
    256 
    257 }
    258 
    259 #endif // ENABLE(SVG_FONTS)
    260