1/*
2 * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
3 * Copyright (C) 2007 Nikolas Zimmermann <zimmermann@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/dom/ElementTraversal.h"
28#include "core/frame/UseCounter.h"
29#include "core/svg/SVGGlyphElement.h"
30#include "core/svg/SVGHKernElement.h"
31#include "core/svg/SVGMissingGlyphElement.h"
32#include "core/svg/SVGVKernElement.h"
33#include "wtf/ASCIICType.h"
34
35namespace blink {
36
37inline SVGFontElement::SVGFontElement(Document& document)
38    : SVGElement(SVGNames::fontTag, document)
39    , m_missingGlyph(0)
40    , m_isGlyphCacheValid(false)
41{
42    UseCounter::count(document, UseCounter::SVGFontElement);
43}
44
45DEFINE_NODE_FACTORY(SVGFontElement)
46
47void SVGFontElement::invalidateGlyphCache()
48{
49    if (m_isGlyphCacheValid) {
50        m_glyphMap.clear();
51        m_horizontalKerningTable.clear();
52        m_verticalKerningTable.clear();
53    }
54    m_isGlyphCacheValid = false;
55}
56
57void SVGFontElement::registerLigaturesInGlyphCache(Vector<String>& ligatures)
58{
59    ASSERT(!ligatures.isEmpty());
60
61    // Register each character of a ligature in the map, if not present.
62    // Eg. If only a "fi" ligature is present, but not "f" and "i", the
63    // GlyphPage will not contain any entries for "f" and "i", so the
64    // SVGFont is not used to render the text "fi1234". Register an
65    // empty SVGGlyph with the character, so the SVG Font will be used
66    // to render the text. If someone tries to render "f2" the SVG Font
67    // will not be able to find a glyph for "f", but handles the fallback
68    // character substitution properly through glyphDataForCharacter().
69    Vector<SVGGlyph> glyphs;
70    size_t ligaturesSize = ligatures.size();
71    for (size_t i = 0; i < ligaturesSize; ++i) {
72        const String& unicode = ligatures[i];
73
74        unsigned unicodeLength = unicode.length();
75        ASSERT(unicodeLength > 1);
76
77        for (unsigned i = 0; i < unicodeLength; ++i) {
78            String lookupString = unicode.substring(i, 1);
79            m_glyphMap.collectGlyphsForString(lookupString, glyphs);
80            if (!glyphs.isEmpty()) {
81                glyphs.clear();
82                continue;
83            }
84
85            // This glyph is never meant to be used for rendering, only as identifier as a part of a ligature.
86            SVGGlyph newGlyphPart;
87            newGlyphPart.isPartOfLigature = true;
88            m_glyphMap.addGlyph(String(), lookupString, newGlyphPart);
89        }
90    }
91}
92
93static inline KerningPairKey makeKerningPairKey(Glyph glyphId1, Glyph glyphId2)
94{
95    return glyphId1 << 16 | glyphId2;
96}
97
98Vector<SVGGlyph> SVGFontElement::buildGlyphList(const UnicodeRanges& unicodeRanges, const HashSet<String>& unicodeNames, const HashSet<String>& glyphNames) const
99{
100    Vector<SVGGlyph> glyphs;
101    if (!unicodeRanges.isEmpty()) {
102        const UnicodeRanges::const_iterator end = unicodeRanges.end();
103        for (UnicodeRanges::const_iterator it = unicodeRanges.begin(); it != end; ++it)
104            m_glyphMap.collectGlyphsForUnicodeRange(*it, glyphs);
105    }
106    if (!unicodeNames.isEmpty()) {
107        const HashSet<String>::const_iterator end = unicodeNames.end();
108        for (HashSet<String>::const_iterator it = unicodeNames.begin(); it != end; ++it)
109            m_glyphMap.collectGlyphsForStringExact(*it, glyphs);
110    }
111    if (!glyphNames.isEmpty()) {
112        const HashSet<String>::const_iterator end = glyphNames.end();
113        for (HashSet<String>::const_iterator it = glyphNames.begin(); it != end; ++it) {
114            const SVGGlyph& glyph = m_glyphMap.glyphIdentifierForGlyphName(*it);
115            if (glyph.tableEntry)
116                glyphs.append(glyph);
117        }
118    }
119    return glyphs;
120}
121
122void SVGFontElement::addPairsToKerningTable(const SVGKerningPair& kerningPair, KerningTable& kerningTable)
123{
124    Vector<SVGGlyph> glyphsLhs = buildGlyphList(kerningPair.unicodeRange1, kerningPair.unicodeName1, kerningPair.glyphName1);
125    Vector<SVGGlyph> glyphsRhs = buildGlyphList(kerningPair.unicodeRange2, kerningPair.unicodeName2, kerningPair.glyphName2);
126    if (glyphsLhs.isEmpty() || glyphsRhs.isEmpty())
127        return;
128    size_t glyphsLhsSize = glyphsLhs.size();
129    size_t glyphsRhsSize = glyphsRhs.size();
130    // Enumerate all the valid kerning pairs, and add them to the table.
131    for (size_t lhsIndex = 0; lhsIndex < glyphsLhsSize; ++lhsIndex) {
132        for (size_t rhsIndex = 0; rhsIndex < glyphsRhsSize; ++rhsIndex) {
133            Glyph glyph1 = glyphsLhs[lhsIndex].tableEntry;
134            Glyph glyph2 = glyphsRhs[rhsIndex].tableEntry;
135            ASSERT(glyph1 && glyph2);
136            kerningTable.add(makeKerningPairKey(glyph1, glyph2), kerningPair.kerning);
137        }
138    }
139}
140
141void SVGFontElement::buildKerningTable(const KerningPairVector& kerningPairs, KerningTable& kerningTable)
142{
143    size_t kerningPairsSize = kerningPairs.size();
144    for (size_t i = 0; i < kerningPairsSize; ++i)
145        addPairsToKerningTable(kerningPairs[i], kerningTable);
146}
147
148void SVGFontElement::ensureGlyphCache()
149{
150    if (m_isGlyphCacheValid)
151        return;
152
153    KerningPairVector horizontalKerningPairs;
154    KerningPairVector verticalKerningPairs;
155
156    SVGMissingGlyphElement* firstMissingGlyphElement = 0;
157    Vector<String> ligatures;
158    for (SVGElement* element = Traversal<SVGElement>::firstChild(*this); element; element = Traversal<SVGElement>::nextSibling(*element)) {
159        if (isSVGGlyphElement(*element)) {
160            SVGGlyphElement& glyph = toSVGGlyphElement(*element);
161            AtomicString unicode = glyph.fastGetAttribute(SVGNames::unicodeAttr);
162            AtomicString glyphId = glyph.getIdAttribute();
163            if (glyphId.isEmpty() && unicode.isEmpty())
164                continue;
165
166            m_glyphMap.addGlyph(glyphId, unicode, glyph.buildGlyphIdentifier());
167
168            // Register ligatures, if needed, don't mix up with surrogate pairs though!
169            if (unicode.length() > 1 && !U16_IS_SURROGATE(unicode[0]))
170                ligatures.append(unicode.string());
171        } else if (isSVGHKernElement(*element)) {
172            toSVGHKernElement(*element).buildHorizontalKerningPair(horizontalKerningPairs);
173        } else if (isSVGVKernElement(*element)) {
174            toSVGVKernElement(*element).buildVerticalKerningPair(verticalKerningPairs);
175        } else if (isSVGMissingGlyphElement(*element) && !firstMissingGlyphElement) {
176            firstMissingGlyphElement = toSVGMissingGlyphElement(element);
177        }
178    }
179
180    // Build the kerning tables.
181    buildKerningTable(horizontalKerningPairs, m_horizontalKerningTable);
182    buildKerningTable(verticalKerningPairs, m_verticalKerningTable);
183
184    // The glyph-name->glyph-id map won't be needed/used after having built the kerning table(s).
185    m_glyphMap.dropNamedGlyphMap();
186
187    // Register each character of each ligature, if needed.
188    if (!ligatures.isEmpty())
189        registerLigaturesInGlyphCache(ligatures);
190
191    // Register missing-glyph element, if present.
192    if (firstMissingGlyphElement) {
193        SVGGlyph svgGlyph = SVGGlyphElement::buildGenericGlyphIdentifier(firstMissingGlyphElement);
194        m_glyphMap.appendToGlyphTable(svgGlyph);
195        m_missingGlyph = svgGlyph.tableEntry;
196        ASSERT(m_missingGlyph > 0);
197    }
198
199    m_isGlyphCacheValid = true;
200}
201
202static float kerningForPairOfGlyphs(const KerningTable& kerningTable, Glyph glyphId1, Glyph glyphId2)
203{
204    KerningTable::const_iterator result = kerningTable.find(makeKerningPairKey(glyphId1, glyphId2));
205    if (result != kerningTable.end())
206        return result->value;
207
208    return 0;
209}
210
211float SVGFontElement::horizontalKerningForPairOfGlyphs(Glyph glyphId1, Glyph glyphId2) const
212{
213    if (m_horizontalKerningTable.isEmpty())
214        return 0;
215
216    return kerningForPairOfGlyphs(m_horizontalKerningTable, glyphId1, glyphId2);
217}
218
219float SVGFontElement::verticalKerningForPairOfGlyphs(Glyph glyphId1, Glyph glyphId2) const
220{
221    if (m_verticalKerningTable.isEmpty())
222        return 0;
223
224    return kerningForPairOfGlyphs(m_verticalKerningTable, glyphId1, glyphId2);
225}
226
227void SVGFontElement::collectGlyphsForString(const String& string, Vector<SVGGlyph>& glyphs)
228{
229    ensureGlyphCache();
230    m_glyphMap.collectGlyphsForString(string, glyphs);
231}
232
233void SVGFontElement::collectGlyphsForAltGlyphReference(const String& glyphIdentifier, Vector<SVGGlyph>& glyphs)
234{
235    ensureGlyphCache();
236    // FIXME: We only support glyphName -> single glyph mapping so far.
237    glyphs.append(m_glyphMap.glyphIdentifierForAltGlyphReference(glyphIdentifier));
238}
239
240SVGGlyph SVGFontElement::svgGlyphForGlyph(Glyph glyph)
241{
242    ensureGlyphCache();
243    return m_glyphMap.svgGlyphForGlyph(glyph);
244}
245
246Glyph SVGFontElement::missingGlyph()
247{
248    ensureGlyphCache();
249    return m_missingGlyph;
250}
251
252} // namespace blink
253
254#endif // ENABLE(SVG_FONTS)
255