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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/TextRunConstructor.h"
     25 
     26 namespace blink {
     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, 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 
     72 void 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 
     78 void 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 
     90 void 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