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 "SVGAltGlyphDefElement.h"
24
25#include "ElementIterator.h"
26#include "SVGAltGlyphItemElement.h"
27#include "SVGGlyphRefElement.h"
28#include "SVGNames.h"
29
30namespace WebCore {
31
32inline SVGAltGlyphDefElement::SVGAltGlyphDefElement(const QualifiedName& tagName, Document& document)
33    : SVGElement(tagName, document)
34{
35    ASSERT(hasTagName(SVGNames::altGlyphDefTag));
36}
37
38PassRefPtr<SVGAltGlyphDefElement> SVGAltGlyphDefElement::create(const QualifiedName& tagName, Document& document)
39{
40    return adoptRef(new SVGAltGlyphDefElement(tagName, document));
41}
42
43bool SVGAltGlyphDefElement::hasValidGlyphElements(Vector<String>& glyphNames) const
44{
45    // Spec: http://www.w3.org/TR/SVG/text.html#AltGlyphDefElement
46    // An 'altGlyphDef' can contain either of the following:
47    //
48    // 1. In the simplest case, an 'altGlyphDef' contains one or more 'glyphRef' elements.
49    // Each 'glyphRef' element references a single glyph within a particular font.
50    // If all of the referenced glyphs are available, then these glyphs are rendered
51    // instead of the character(s) inside of the referencing 'altGlyph' element.
52    // If any of the referenced glyphs are unavailable, then the character(s) that are
53    // inside of the 'altGlyph' element are rendered as if there were not an 'altGlyph'
54    // element surrounding those characters.
55    //
56    // 2. In the more complex case, an 'altGlyphDef' contains one or more 'altGlyphItem' elements.
57    // Each 'altGlyphItem' represents a candidate set of substitute glyphs. Each 'altGlyphItem'
58    // contains one or more 'glyphRef' elements. Each 'glyphRef' element references a single
59    // glyph within a particular font. The first 'altGlyphItem' in which all referenced glyphs
60    // are available is chosen. The glyphs referenced from this 'altGlyphItem' are rendered
61    // instead of the character(s) that are inside of the referencing 'altGlyph' element.
62    // If none of the 'altGlyphItem' elements result in a successful match (i.e., none of the
63    // 'altGlyphItem' elements has all of its referenced glyphs available), then the character(s)
64    // that are inside of the 'altGlyph' element are rendered as if there were not an 'altGlyph'
65    // element surrounding those characters.
66    //
67    // The spec doesn't tell how to deal with the mixing of <glyphRef> and <altGlyItem>.
68    // However, we determine content model by the the type of the first appearing element
69    // just like Opera 11 does. After the content model is determined we skip elements
70    // which don't comform to it. For example:
71    // a.    <altGlyphDef>
72    //         <glyphRef id="g1" />
73    //         <altGlyphItem id="i1"> ... </altGlyphItem>
74    //         <glyphRef id="g2" />
75    //       </altGlyphDef>
76    //
77    // b.    <altGlyphDef>
78    //         <altGlyphItem id="i1"> ... </altGlyphItem>
79    //         <altGlyphItem id="i2"> ... </altGlyphItem>
80    //         <glyphRef id="g1" />
81    //         <glyphRef id="g2" />
82    //       </altGlyphDef>
83    // For a), the content model is 1), so we will use "g1" and "g2" if they are all valid
84    // and "i1" is skipped.
85    // For b), the content model is 2), so we will use <glyphRef> elements contained in
86    // "i1" if they are valid and "g1" and "g2" are skipped.
87
88    // These 2 variables are used to determine content model.
89    bool fountFirstGlyphRef = false;
90    bool foundFirstAltGlyphItem = false;
91
92    for (auto& child : childrenOfType<SVGElement>(*this)) {
93        if (!foundFirstAltGlyphItem && isSVGGlyphRefElement(child)) {
94            fountFirstGlyphRef = true;
95            String referredGlyphName;
96
97            if (toSVGGlyphRefElement(child).hasValidGlyphElement(referredGlyphName))
98                glyphNames.append(referredGlyphName);
99            else {
100                // As the spec says "If any of the referenced glyphs are unavailable,
101                // then the character(s) that are inside of the 'altGlyph' element are
102                // rendered as if there were not an 'altGlyph' element surrounding
103                // those characters.".
104                glyphNames.clear();
105                return false;
106            }
107        } else if (!fountFirstGlyphRef && isSVGAltGlyphItemElement(child)) {
108            foundFirstAltGlyphItem = true;
109
110            // As the spec says "The first 'altGlyphItem' in which all referenced glyphs
111            // are available is chosen."
112            if (toSVGAltGlyphItemElement(child).hasValidGlyphElements(glyphNames) && !glyphNames.isEmpty())
113                return true;
114        }
115    }
116    return !glyphNames.isEmpty();
117}
118
119}
120
121#endif
122