1/*
2 * Copyright (C) 2011 Apple Inc. All rights reserved.
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
21#include "config.h"
22#include "core/rendering/RenderCombineText.h"
23
24#include "core/rendering/TextRunConstructor.h"
25
26namespace blink {
27
28const float textCombineMargin = 1.1f; // Allow em + 10% margin
29
30RenderCombineText::RenderCombineText(Node* node, PassRefPtr<StringImpl> string)
31     : RenderText(node, string)
32     , m_combinedTextWidth(0)
33     , m_isCombined(false)
34     , m_needsFontUpdate(false)
35{
36}
37
38void RenderCombineText::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle)
39{
40    setStyleInternal(RenderStyle::clone(style()));
41    RenderText::styleDidChange(diff, oldStyle);
42
43    if (m_isCombined) {
44        RenderText::setTextInternal(originalText()); // This RenderCombineText has been combined once. Restore the original text for the next combineText().
45        m_isCombined = false;
46    }
47
48    m_needsFontUpdate = true;
49}
50
51void RenderCombineText::setTextInternal(PassRefPtr<StringImpl> text)
52{
53    RenderText::setTextInternal(text);
54
55    m_needsFontUpdate = true;
56}
57
58float RenderCombineText::width(unsigned from, unsigned length, const Font& font, float xPosition, TextDirection direction, HashSet<const SimpleFontData*>* fallbackFonts, GlyphOverflow* glyphOverflow) const
59{
60    if (!length)
61        return 0;
62
63    if (hasEmptyText())
64        return 0;
65
66    if (m_isCombined)
67        return font.fontDescription().computedSize();
68
69    return RenderText::width(from, length, font, xPosition, direction, fallbackFonts, glyphOverflow);
70}
71
72void RenderCombineText::adjustTextOrigin(FloatPoint& textOrigin, const FloatRect& boxRect) const
73{
74    if (m_isCombined)
75        textOrigin.move(boxRect.height() / 2 - ceilf(m_combinedTextWidth) / 2, style()->font().fontDescription().computedPixelSize());
76}
77
78void RenderCombineText::getStringToRender(int start, StringView& string, int& length) const
79{
80    ASSERT(start >= 0);
81    if (m_isCombined) {
82        string = StringView(m_renderingText.impl());
83        length = string.length();
84        return;
85    }
86
87    string = text().createView(start, length);
88}
89
90void RenderCombineText::combineText()
91{
92    if (!m_needsFontUpdate)
93        return;
94
95    m_isCombined = false;
96    m_needsFontUpdate = false;
97
98    // CSS3 spec says text-combine works only in vertical writing mode.
99    if (style()->isHorizontalWritingMode())
100        return;
101
102    TextRun run = constructTextRun(this, originalFont(), this, style(), style()->direction());
103    FontDescription description = originalFont().fontDescription();
104    float emWidth = description.computedSize() * textCombineMargin;
105    bool shouldUpdateFont = false;
106
107    description.setOrientation(Horizontal); // We are going to draw combined text horizontally.
108    m_combinedTextWidth = originalFont().width(run);
109    m_isCombined = m_combinedTextWidth <= emWidth;
110
111    FontSelector* fontSelector = style()->font().fontSelector();
112
113    if (m_isCombined)
114        shouldUpdateFont = style()->setFontDescription(description); // Need to change font orientation to horizontal.
115    else {
116        // Need to try compressed glyphs.
117        static const FontWidthVariant widthVariants[] = { HalfWidth, ThirdWidth, QuarterWidth };
118        for (size_t i = 0 ; i < WTF_ARRAY_LENGTH(widthVariants) ; ++i) {
119            description.setWidthVariant(widthVariants[i]);
120            Font compressedFont = Font(description);
121            compressedFont.update(fontSelector);
122            float runWidth = compressedFont.width(run);
123            if (runWidth <= emWidth) {
124                m_combinedTextWidth = runWidth;
125                m_isCombined = true;
126
127                // Replace my font with the new one.
128                shouldUpdateFont = style()->setFontDescription(description);
129                break;
130            }
131        }
132    }
133
134    if (!m_isCombined)
135        shouldUpdateFont = style()->setFontDescription(originalFont().fontDescription());
136
137    if (shouldUpdateFont)
138        style()->font().update(fontSelector);
139
140    if (m_isCombined) {
141        DEFINE_STATIC_LOCAL(String, objectReplacementCharacterString, (&objectReplacementCharacter, 1));
142        m_renderingText = text();
143        RenderText::setTextInternal(objectReplacementCharacterString.impl());
144    }
145}
146
147} // namespace blink
148