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