1/*
2 * Copyright (C) 2011 Leo Yang <leoyang@webkit.org>
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Library General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
8 *
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12 * Library General Public License for more details.
13 *
14 * You should have received a copy of the GNU Library General Public License
15 * along with this library; see the file COPYING.LIB.  If not, write to
16 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
17 * Boston, MA 02110-1301, USA.
18 */
19
20#include "config.h"
21
22#if ENABLE(SVG_FONTS)
23#include "core/svg/SVGAltGlyphDefElement.h"
24
25#include "SVGNames.h"
26#include "core/svg/SVGAltGlyphItemElement.h"
27#include "core/svg/SVGGlyphRefElement.h"
28
29namespace WebCore {
30
31inline SVGAltGlyphDefElement::SVGAltGlyphDefElement(Document& document)
32    : SVGElement(SVGNames::altGlyphDefTag, document)
33{
34    ScriptWrappable::init(this);
35}
36
37PassRefPtr<SVGAltGlyphDefElement> SVGAltGlyphDefElement::create(Document& document)
38{
39    return adoptRef(new SVGAltGlyphDefElement(document));
40}
41
42bool SVGAltGlyphDefElement::hasValidGlyphElements(Vector<String>& glyphNames) const
43{
44    // Spec: http://www.w3.org/TR/SVG/text.html#AltGlyphDefElement
45    // An 'altGlyphDef' can contain either of the following:
46    //
47    // 1. In the simplest case, an 'altGlyphDef' contains one or more 'glyphRef' elements.
48    // Each 'glyphRef' element references a single glyph within a particular font.
49    // If all of the referenced glyphs are available, then these glyphs are rendered
50    // instead of the character(s) inside of the referencing 'altGlyph' element.
51    // If any of the referenced glyphs are unavailable, then the character(s) that are
52    // inside of the 'altGlyph' element are rendered as if there were not an 'altGlyph'
53    // element surrounding those characters.
54    //
55    // 2. In the more complex case, an 'altGlyphDef' contains one or more 'altGlyphItem' elements.
56    // Each 'altGlyphItem' represents a candidate set of substitute glyphs. Each 'altGlyphItem'
57    // contains one or more 'glyphRef' elements. Each 'glyphRef' element references a single
58    // glyph within a particular font. The first 'altGlyphItem' in which all referenced glyphs
59    // are available is chosen. The glyphs referenced from this 'altGlyphItem' are rendered
60    // instead of the character(s) that are inside of the referencing 'altGlyph' element.
61    // If none of the 'altGlyphItem' elements result in a successful match (i.e., none of the
62    // 'altGlyphItem' elements has all of its referenced glyphs available), then the character(s)
63    // that are inside of the 'altGlyph' element are rendered as if there were not an 'altGlyph'
64    // element surrounding those characters.
65    //
66    // The spec doesn't tell how to deal with the mixing of <glyphRef> and <altGlyItem>.
67    // However, we determine content model by the the type of the first appearing element
68    // just like Opera 11 does. After the content model is determined we skip elements
69    // which don't comform to it. For example:
70    // a.    <altGlyphDef>
71    //         <glyphRef id="g1" />
72    //         <altGlyphItem id="i1"> ... </altGlyphItem>
73    //         <glyphRef id="g2" />
74    //       </altGlyphDef>
75    //
76    // b.    <altGlyphDef>
77    //         <altGlyphItem id="i1"> ... </altGlyphItem>
78    //         <altGlyphItem id="i2"> ... </altGlyphItem>
79    //         <glyphRef id="g1" />
80    //         <glyphRef id="g2" />
81    //       </altGlyphDef>
82    // For a), the content model is 1), so we will use "g1" and "g2" if they are all valid
83    // and "i1" is skipped.
84    // For b), the content model is 2), so we will use <glyphRef> elements contained in
85    // "i1" if they are valid and "g1" and "g2" are skipped.
86
87    // These 2 variables are used to determine content model.
88    bool fountFirstGlyphRef = false;
89    bool foundFirstAltGlyphItem = false;
90
91    for (Node* child = firstChild(); child; child = child->nextSibling()) {
92        if (!foundFirstAltGlyphItem && child->hasTagName(SVGNames::glyphRefTag)) {
93            fountFirstGlyphRef = true;
94            String referredGlyphName;
95
96            if (toSVGGlyphRefElement(child)->hasValidGlyphElement(referredGlyphName))
97                glyphNames.append(referredGlyphName);
98            else {
99                // As the spec says "If any of the referenced glyphs are unavailable,
100                // then the character(s) that are inside of the 'altGlyph' element are
101                // rendered as if there were not an 'altGlyph' element surrounding
102                // those characters.".
103                glyphNames.clear();
104                return false;
105            }
106        } else if (!fountFirstGlyphRef && child->hasTagName(SVGNames::altGlyphItemTag)) {
107            foundFirstAltGlyphItem = true;
108            Vector<String> referredGlyphNames;
109
110            // As the spec says "The first 'altGlyphItem' in which all referenced glyphs
111            // are available is chosen."
112            if (static_cast<SVGAltGlyphItemElement*>(child)->hasValidGlyphElements(glyphNames) && !glyphNames.isEmpty())
113                return true;
114        }
115    }
116    return !glyphNames.isEmpty();
117}
118
119}
120
121#endif
122