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/*
* Copyright (C) 2011 Apple Inc. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
*/
#include "config.h"
#include "RenderCombineText.h"
#include "RenderBlock.h"
#include "StyleInheritedData.h"
#include <wtf/NeverDestroyed.h>
namespace WebCore {
const float textCombineMargin = 1.15f; // Allow em + 15% margin
RenderCombineText::RenderCombineText(Text& textNode, const String& string)
: RenderText(textNode, string)
, m_isCombined(false)
, m_needsFontUpdate(false)
{
}
void RenderCombineText::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle)
{
// FIXME: This is pretty hackish.
// Only cache a new font style if our old one actually changed. We do this to avoid
// clobbering width variants and shrink-to-fit changes, since we won't recombine when
// the font doesn't change.
if (!oldStyle || oldStyle->fontCascade() != style().fontCascade())
m_combineFontStyle = RenderStyle::clone(&style());
RenderText::styleDidChange(diff, oldStyle);
if (m_isCombined && selfNeedsLayout()) {
// Layouts cause the text to be recombined; therefore, only only un-combine when the style diff causes a layout.
RenderText::setRenderedText(originalText()); // This RenderCombineText has been combined once. Restore the original text for the next combineText().
m_isCombined = false;
}
m_needsFontUpdate = true;
}
void RenderCombineText::setRenderedText(const String& text)
{
RenderText::setRenderedText(text);
m_needsFontUpdate = true;
}
float RenderCombineText::width(unsigned from, unsigned length, const FontCascade& font, float xPosition, HashSet<const Font*>* fallbackFonts, GlyphOverflow* glyphOverflow) const
{
if (m_isCombined)
return !length ? 0 : font.size();
return RenderText::width(from, length, font, xPosition, fallbackFonts, glyphOverflow);
}
Optional<FloatPoint> RenderCombineText::computeTextOrigin(const FloatRect& boxRect) const
{
if (!m_isCombined)
return Nullopt;
// Visually center m_combinedTextWidth/Ascent/Descent within boxRect
FloatPoint result = boxRect.minXMaxYCorner();
FloatSize combinedTextSize(m_combinedTextWidth, m_combinedTextAscent + m_combinedTextDescent);
result.move((boxRect.size().transposedSize() - combinedTextSize) / 2);
result.move(0, m_combinedTextAscent);
return result;
}
void RenderCombineText::getStringToRender(int start, String& string, int& length) const
{
ASSERT(start >= 0);
if (m_isCombined) {
string = originalText();
length = string.length();
return;
}
string = text();
string = string.substringSharingImpl(static_cast<unsigned>(start), length);
}
void RenderCombineText::combineText()
{
if (!m_needsFontUpdate)
return;
// An ancestor element may trigger us to lay out again, even when we're already combined.
if (m_isCombined)
RenderText::setRenderedText(originalText());
m_isCombined = false;
m_needsFontUpdate = false;
// CSS3 spec says text-combine works only in vertical writing mode.
if (style().isHorizontalWritingMode())
return;
auto description = originalFont().fontDescription();
float emWidth = description.computedSize() * textCombineMargin;
bool shouldUpdateFont = false;
FontSelector* fontSelector = style().fontCascade().fontSelector();
description.setOrientation(Horizontal); // We are going to draw combined text horizontally.
FontCascade horizontalFont(description, style().fontCascade().letterSpacing(), style().fontCascade().wordSpacing());
horizontalFont.update(fontSelector);
GlyphOverflow glyphOverflow;
glyphOverflow.computeBounds = true;
float combinedTextWidth = width(0, textLength(), horizontalFont, 0, nullptr, &glyphOverflow);
float bestFitDelta = combinedTextWidth - emWidth;
auto bestFitDescription = description;
m_isCombined = combinedTextWidth <= emWidth;
if (m_isCombined)
shouldUpdateFont = m_combineFontStyle->setFontDescription(description); // Need to change font orientation to horizontal.
else {
// Need to try compressed glyphs.
static const FontWidthVariant widthVariants[] = { HalfWidth, ThirdWidth, QuarterWidth };
for (size_t i = 0 ; i < WTF_ARRAY_LENGTH(widthVariants) ; ++i) {
description.setWidthVariant(widthVariants[i]); // When modifying this, make sure to keep it in sync with FontPlatformData::isForTextCombine()!
FontCascade compressedFont(description, style().fontCascade().letterSpacing(), style().fontCascade().wordSpacing());
compressedFont.update(fontSelector);
glyphOverflow.left = glyphOverflow.top = glyphOverflow.right = glyphOverflow.bottom = 0;
float runWidth = RenderText::width(0, textLength(), compressedFont, 0, nullptr, &glyphOverflow);
if (runWidth <= emWidth) {
combinedTextWidth = runWidth;
m_isCombined = true;
// Replace my font with the new one.
shouldUpdateFont = m_combineFontStyle->setFontDescription(description);
break;
}
float widthDelta = runWidth - emWidth;
if (widthDelta < bestFitDelta) {
bestFitDelta = widthDelta;
bestFitDescription = description;
}
}
}
if (!m_isCombined) {
float scaleFactor = std::max(0.4f, emWidth / (emWidth + bestFitDelta));
float originalSize = bestFitDescription.computedSize();
do {
float computedSize = originalSize * scaleFactor;
bestFitDescription.setComputedSize(computedSize);
shouldUpdateFont = m_combineFontStyle->setFontDescription(bestFitDescription);
FontCascade compressedFont(bestFitDescription, style().fontCascade().letterSpacing(), style().fontCascade().wordSpacing());
compressedFont.update(fontSelector);
glyphOverflow.left = glyphOverflow.top = glyphOverflow.right = glyphOverflow.bottom = 0;
float runWidth = RenderText::width(0, textLength(), compressedFont, 0, nullptr, &glyphOverflow);
if (runWidth <= emWidth) {
combinedTextWidth = runWidth;
m_isCombined = true;
break;
}
scaleFactor -= 0.05f;
} while (scaleFactor >= 0.4f);
}
if (shouldUpdateFont)
m_combineFontStyle->fontCascade().update(fontSelector);
if (m_isCombined) {
static NeverDestroyed<String> objectReplacementCharacterString(&objectReplacementCharacter, 1);
RenderText::setRenderedText(objectReplacementCharacterString.get());
m_combinedTextWidth = combinedTextWidth;
m_combinedTextAscent = glyphOverflow.top;
m_combinedTextDescent = glyphOverflow.bottom;
}
}
} // namespace WebCore
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