1/*
2 * Copyright (C) 2007, 2008 Nikolas Zimmermann <zimmermann@kde.org>
3 * Copyright (C) Research In Motion Limited 2010-2011. All rights reserved.
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Library General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13 * Library General Public License for more details.
14 *
15 * You should have received a copy of the GNU Library General Public License
16 * along with this library; see the file COPYING.LIB.  If not, write to
17 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
18 * Boston, MA 02110-1301, USA.
19 */
20
21#include "config.h"
22
23#if ENABLE(SVG_FONTS)
24#include "platform/fonts/SVGGlyph.h"
25
26#include "wtf/unicode/Unicode.h"
27
28using namespace WTF::Unicode;
29
30namespace blink {
31
32// Helper functions to determine the arabic character forms (initial, medial, terminal, isolated)
33enum ArabicCharShapingMode {
34    SNone = 0,
35    SRight = 1,
36    SDual = 2
37};
38
39static const ArabicCharShapingMode s_arabicCharShapingMode[222] = {
40    SRight, SRight, SRight, SRight, SDual , SRight, SDual , SRight, SDual , SDual , SDual , SDual , SDual , SRight,                 /* 0x0622 - 0x062F */
41    SRight, SRight, SRight, SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , SNone , SNone , SNone , SNone , SNone , /* 0x0630 - 0x063F */
42    SNone , SDual , SDual , SDual , SDual , SDual , SDual , SRight, SDual , SDual , SNone , SNone , SNone , SNone , SNone , SNone , /* 0x0640 - 0x064F */
43    SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , /* 0x0650 - 0x065F */
44    SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , /* 0x0660 - 0x066F */
45    SNone , SRight, SRight, SRight, SNone , SRight, SRight, SRight, SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , /* 0x0670 - 0x067F */
46    SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , SRight, SRight, SRight, SRight, SRight, SRight, SRight, SRight, /* 0x0680 - 0x068F */
47    SRight, SRight, SRight, SRight, SRight, SRight, SRight, SRight, SRight, SRight, SDual , SDual , SDual , SDual , SDual , SDual , /* 0x0690 - 0x069F */
48    SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , /* 0x06A0 - 0x06AF */
49    SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , SDual , /* 0x06B0 - 0x06BF */
50    SRight, SDual , SRight, SRight, SRight, SRight, SRight, SRight, SRight, SRight, SRight, SRight, SDual , SRight, SDual , SRight, /* 0x06C0 - 0x06CF */
51    SDual , SDual , SRight, SRight, SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , /* 0x06D0 - 0x06DF */
52    SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , /* 0x06E0 - 0x06EF */
53    SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SNone , SDual , SDual , SDual , SNone , SNone , SNone   /* 0x06F0 - 0x06FF */
54};
55
56static inline SVGGlyph::ArabicForm processArabicFormDetection(const UChar& curChar, bool& lastCharShapesRight, SVGGlyph::ArabicForm* prevForm)
57{
58    SVGGlyph::ArabicForm curForm;
59
60    ArabicCharShapingMode shapingMode = SNone;
61    if (curChar >= 0x0622 && curChar <= 0x06FF)
62        shapingMode = s_arabicCharShapingMode[curChar - 0x0622];
63
64    // Use a simple state machine to identify the actual arabic form
65    // It depends on the order of the arabic form enum:
66    // enum ArabicForm { None = 0, Isolated, Terminal, Initial, Medial };
67
68    if (lastCharShapesRight && shapingMode == SDual) {
69        if (prevForm) {
70            int correctedForm = (int) *prevForm + 1;
71            ASSERT(correctedForm >= SVGGlyph::None && correctedForm <= SVGGlyph::Medial);
72            *prevForm = static_cast<SVGGlyph::ArabicForm>(correctedForm);
73        }
74
75        curForm = SVGGlyph::Initial;
76    } else
77        curForm = shapingMode == SNone ? SVGGlyph::None : SVGGlyph::Isolated;
78
79    lastCharShapesRight = shapingMode != SNone;
80    return curForm;
81}
82
83Vector<SVGGlyph::ArabicForm> charactersWithArabicForm(const String& input, bool rtl)
84{
85    Vector<SVGGlyph::ArabicForm> forms;
86    unsigned length = input.length();
87
88    bool containsArabic = false;
89    for (unsigned i = 0; i < length; ++i) {
90        if (isArabicChar(input[i])) {
91            containsArabic = true;
92            break;
93        }
94    }
95
96    if (!containsArabic)
97        return forms;
98
99    bool lastCharShapesRight = false;
100
101    // Start identifying arabic forms
102    if (rtl) {
103        for (int i = length - 1; i >= 0; --i)
104            forms.prepend(processArabicFormDetection(input[i], lastCharShapesRight, forms.isEmpty() ? 0 : &forms.first()));
105    } else {
106        for (unsigned i = 0; i < length; ++i)
107            forms.append(processArabicFormDetection(input[i], lastCharShapesRight, forms.isEmpty() ? 0 : &forms.last()));
108    }
109
110    return forms;
111}
112
113static inline bool isCompatibleArabicForm(const SVGGlyph& identifier, const Vector<SVGGlyph::ArabicForm>& chars, unsigned startPosition, unsigned endPosition)
114{
115    if (chars.isEmpty())
116        return true;
117
118    Vector<SVGGlyph::ArabicForm>::const_iterator realEnd = chars.end();
119    Vector<SVGGlyph::ArabicForm>::const_iterator it = chars.begin() + startPosition;
120    if (it >= realEnd)
121        return true;
122
123    Vector<SVGGlyph::ArabicForm>::const_iterator end = chars.begin() + endPosition;
124    if (end >= realEnd)
125        end = realEnd;
126
127    for (; it != end; ++it) {
128        if (*it != static_cast<SVGGlyph::ArabicForm>(identifier.arabicForm) && *it != SVGGlyph::None)
129            return false;
130    }
131
132    return true;
133}
134
135bool isCompatibleGlyph(const SVGGlyph& identifier, bool isVerticalText, const String& language,
136                       const Vector<SVGGlyph::ArabicForm>& chars, unsigned startPosition, unsigned endPosition)
137{
138    bool valid = true;
139
140    // Check wheter orientation if glyph fits within the request
141    switch (identifier.orientation) {
142    case SVGGlyph::Vertical:
143        valid = isVerticalText;
144        break;
145    case SVGGlyph::Horizontal:
146        valid = !isVerticalText;
147        break;
148    case SVGGlyph::Both:
149        break;
150    }
151
152    if (!valid)
153        return false;
154
155    // Check wheter languages are compatible
156    if (!identifier.languages.isEmpty()) {
157        // This glyph exists only in certain languages, if we're not specifying a
158        // language on the referencing element we're unable to use this glyph.
159        if (language.isEmpty())
160            return false;
161
162        // Split subcode from language, if existant.
163        String languagePrefix;
164
165        size_t subCodeSeparator = language.find('-');
166        if (subCodeSeparator != kNotFound)
167            languagePrefix = language.left(subCodeSeparator);
168
169        Vector<String>::const_iterator it = identifier.languages.begin();
170        Vector<String>::const_iterator end = identifier.languages.end();
171
172        bool found = false;
173        for (; it != end; ++it) {
174            const String& cur = *it;
175            if (cur == language || cur == languagePrefix) {
176                found = true;
177                break;
178            }
179        }
180
181        if (!found)
182            return false;
183    }
184
185    // Check wheter arabic form is compatible
186    return isCompatibleArabicForm(identifier, chars, startPosition, endPosition);
187}
188
189} // namespace blink
190
191#endif
192