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      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/RenderBlock.h"
     25 
     26 namespace WebCore {
     27 
     28 const float textCombineMargin = 1.1f; // Allow em + 10% margin
     29 
     30 RenderCombineText::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 
     38 void 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 
     51 void RenderCombineText::setTextInternal(PassRefPtr<StringImpl> text)
     52 {
     53     RenderText::setTextInternal(text);
     54 
     55     m_needsFontUpdate = true;
     56 }
     57 
     58 float RenderCombineText::width(unsigned from, unsigned length, const Font& font, float xPosition, HashSet<const SimpleFontData*>* fallbackFonts, GlyphOverflow* glyphOverflow) const
     59 {
     60     if (hasEmptyText())
     61         return 0;
     62 
     63     if (m_isCombined)
     64         return font.size();
     65 
     66     return RenderText::width(from, length, font, xPosition, fallbackFonts, glyphOverflow);
     67 }
     68 
     69 void RenderCombineText::adjustTextOrigin(FloatPoint& textOrigin, const FloatRect& boxRect) const
     70 {
     71     if (m_isCombined)
     72         textOrigin.move(boxRect.height() / 2 - ceilf(m_combinedTextWidth) / 2, style()->font().pixelSize());
     73 }
     74 
     75 void RenderCombineText::getStringToRender(int start, StringView& string, int& length) const
     76 {
     77     ASSERT(start >= 0);
     78     if (m_isCombined) {
     79         string = StringView(originalText());
     80         length = string.length();
     81         return;
     82     }
     83 
     84     string = text().createView(start, length);
     85 }
     86 
     87 void RenderCombineText::combineText()
     88 {
     89     if (!m_needsFontUpdate)
     90         return;
     91 
     92     m_isCombined = false;
     93     m_needsFontUpdate = false;
     94 
     95     // CSS3 spec says text-combine works only in vertical writing mode.
     96     if (style()->isHorizontalWritingMode())
     97         return;
     98 
     99     TextRun run = RenderBlock::constructTextRun(this, originalFont(), this, style());
    100     FontDescription description = originalFont().fontDescription();
    101     float emWidth = description.computedSize() * textCombineMargin;
    102     bool shouldUpdateFont = false;
    103 
    104     description.setOrientation(Horizontal); // We are going to draw combined text horizontally.
    105     m_combinedTextWidth = originalFont().width(run);
    106     m_isCombined = m_combinedTextWidth <= emWidth;
    107 
    108     FontSelector* fontSelector = style()->font().fontSelector();
    109 
    110     if (m_isCombined)
    111         shouldUpdateFont = style()->setFontDescription(description); // Need to change font orientation to horizontal.
    112     else {
    113         // Need to try compressed glyphs.
    114         static const FontWidthVariant widthVariants[] = { HalfWidth, ThirdWidth, QuarterWidth };
    115         for (size_t i = 0 ; i < WTF_ARRAY_LENGTH(widthVariants) ; ++i) {
    116             description.setWidthVariant(widthVariants[i]);
    117             Font compressedFont = Font(description, style()->font().letterSpacing(), style()->font().wordSpacing());
    118             compressedFont.update(fontSelector);
    119             float runWidth = compressedFont.width(run);
    120             if (runWidth <= emWidth) {
    121                 m_combinedTextWidth = runWidth;
    122                 m_isCombined = true;
    123 
    124                 // Replace my font with the new one.
    125                 shouldUpdateFont = style()->setFontDescription(description);
    126                 break;
    127             }
    128         }
    129     }
    130 
    131     if (!m_isCombined)
    132         shouldUpdateFont = style()->setFontDescription(originalFont().fontDescription());
    133 
    134     if (shouldUpdateFont)
    135         style()->font().update(fontSelector);
    136 
    137     if (m_isCombined) {
    138         DEFINE_STATIC_LOCAL(String, objectReplacementCharacterString, (&objectReplacementCharacter, 1));
    139         RenderText::setTextInternal(objectReplacementCharacterString.impl());
    140     }
    141 }
    142 
    143 } // namespace WebCore
    144