238 lines
12 KiB
C++
238 lines
12 KiB
C++
/*
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* Copyright (C) 2014-2021 Apple Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "config.h"
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#include "InlineTextBoxStyle.h"
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#include "FontCascade.h"
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#include "HTMLAnchorElement.h"
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#include "HTMLNames.h"
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#include "LayoutIntegrationLineIterator.h"
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#include "LayoutIntegrationRunIterator.h"
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#include "LegacyInlineTextBox.h"
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#include "LegacyRootInlineBox.h"
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#include "RenderInline.h"
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#include "TextUnderlineOffset.h"
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namespace WebCore {
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static bool isAncestorAndWithinBlock(const RenderInline& ancestor, const RenderObject* child)
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{
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const RenderObject* object = child;
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while (object && (!object->isRenderBlock() || object->isInline())) {
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if (object == &ancestor)
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return true;
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object = object->parent();
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}
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return false;
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}
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static void minLogicalTopForTextDecorationLine(const LayoutIntegration::LineIterator& line, float& minLogicalTop, const RenderElement* decorationRenderer, OptionSet<TextDecoration> textDecoration)
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{
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for (auto run = line.firstRun(); run; run.traverseNextOnLine()) {
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if (run->renderer().isOutOfFlowPositioned())
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continue; // Positioned placeholders don't affect calculations.
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if (!(run->style().textDecorationsInEffect() & textDecoration))
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continue; // If the text decoration isn't in effect on the child, then it must be outside of |decorationRenderer|'s hierarchy.
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if (decorationRenderer && decorationRenderer->isRenderInline() && !isAncestorAndWithinBlock(downcast<RenderInline>(*decorationRenderer), &run->renderer()))
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continue;
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if (run->isText() || run->style().textDecorationSkip().isEmpty())
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minLogicalTop = std::min<float>(minLogicalTop, run->logicalTop());
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}
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}
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static void maxLogicalBottomForTextDecorationLine(const LayoutIntegration::LineIterator& line, float& maxLogicalBottom, const RenderElement* decorationRenderer, OptionSet<TextDecoration> textDecoration)
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{
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for (auto run = line.firstRun(); run; run.traverseNextOnLine()) {
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if (run->renderer().isOutOfFlowPositioned())
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continue; // Positioned placeholders don't affect calculations.
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if (!(run->style().textDecorationsInEffect() & textDecoration))
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continue; // If the text decoration isn't in effect on the child, then it must be outside of |decorationRenderer|'s hierarchy.
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if (decorationRenderer && decorationRenderer->isRenderInline() && !isAncestorAndWithinBlock(downcast<RenderInline>(*decorationRenderer), &run->renderer()))
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continue;
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if (run->isText() || run->style().textDecorationSkip().isEmpty())
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maxLogicalBottom = std::max<float>(maxLogicalBottom, run->logicalBottom());
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}
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}
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static const RenderElement* enclosingRendererWithTextDecoration(const RenderText& renderer, OptionSet<TextDecoration> textDecoration, bool firstLine)
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{
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const RenderElement* current = renderer.parent();
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do {
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if (current->isRenderBlock())
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return current;
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if (!current->isRenderInline() || current->isRubyText())
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return nullptr;
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const RenderStyle& styleToUse = firstLine ? current->firstLineStyle() : current->style();
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if (styleToUse.textDecoration() & textDecoration)
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return current;
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current = current->parent();
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} while (current && (!current->element() || (!is<HTMLAnchorElement>(*current->element()) && !current->element()->hasTagName(HTMLNames::fontTag))));
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return current;
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}
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float computeUnderlineOffset(TextUnderlinePosition underlinePosition, TextUnderlineOffset underlineOffset, const FontMetrics& fontMetrics, const LayoutIntegration::TextRunIterator& textRun, float defaultGap)
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{
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// This represents the gap between the baseline and the closest edge of the underline.
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float gap = std::max<int>(1, std::ceil(defaultGap / 2.0f));
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// FIXME: The code for visual overflow detection passes in a null inline text box. This means it is now
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// broken for the case where auto needs to behave like "under".
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// According to the specification TextUnderlinePosition::Auto should avoid drawing through glyphs in
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// scripts where it would not be appropriate (e.g., ideographs).
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// Strictly speaking this can occur whenever the line contains ideographs
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// even if it is horizontal, but detecting this has performance implications. For now we only work with
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// vertical text, since we already determined the baseline type to be ideographic in that
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// case.
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auto resolvedUnderlinePosition = underlinePosition;
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if (resolvedUnderlinePosition == TextUnderlinePosition::Auto && underlineOffset.isAuto()) {
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if (textRun)
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resolvedUnderlinePosition = textRun.line()->baselineType() == IdeographicBaseline ? TextUnderlinePosition::Under : TextUnderlinePosition::Auto;
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else
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resolvedUnderlinePosition = TextUnderlinePosition::Auto;
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}
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switch (resolvedUnderlinePosition) {
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case TextUnderlinePosition::Auto:
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if (underlineOffset.isAuto())
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return fontMetrics.ascent() + gap;
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return fontMetrics.ascent() + underlineOffset.lengthValue();
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case TextUnderlinePosition::FromFont:
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return fontMetrics.ascent() + fontMetrics.underlinePosition() + underlineOffset.lengthOr(0);
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case TextUnderlinePosition::Under: {
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ASSERT(textRun);
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// Position underline relative to the bottom edge of the lowest element's content box.
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auto line = textRun.line();
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auto* decorationRenderer = enclosingRendererWithTextDecoration(textRun->renderer(), TextDecoration::Underline, line.isFirst());
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float offset;
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if (textRun->renderer().style().isFlippedLinesWritingMode()) {
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offset = textRun->logicalTop();
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minLogicalTopForTextDecorationLine(line, offset, decorationRenderer, TextDecoration::Underline);
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offset = textRun->logicalTop() - offset;
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} else {
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offset = textRun->logicalBottom();
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maxLogicalBottomForTextDecorationLine(line, offset, decorationRenderer, TextDecoration::Underline);
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offset -= textRun->logicalBottom();
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}
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auto desiredOffset = textRun->logicalHeight() + gap + std::max(offset, 0.0f) + underlineOffset.lengthOr(0);
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return std::max<float>(desiredOffset, fontMetrics.ascent());
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}
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}
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ASSERT_NOT_REACHED();
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return fontMetrics.ascent() + gap;
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}
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WavyStrokeParameters getWavyStrokeParameters(float fontSize)
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{
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WavyStrokeParameters result;
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// More information is in the WavyStrokeParameters definition.
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result.controlPointDistance = fontSize * 1.5 / 16;
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result.step = fontSize / 4.5;
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return result;
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}
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GlyphOverflow visualOverflowForDecorations(const RenderStyle& lineStyle, const LayoutIntegration::TextRunIterator& textRun)
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{
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ASSERT(!textRun || textRun->style() == lineStyle);
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auto decoration = lineStyle.textDecorationsInEffect();
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if (decoration.isEmpty())
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return GlyphOverflow();
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float strokeThickness = lineStyle.textDecorationThickness().resolve(lineStyle.computedFontSize(), lineStyle.fontMetrics());
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WavyStrokeParameters wavyStrokeParameters;
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float wavyOffset = 0;
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TextDecorationStyle decorationStyle = lineStyle.textDecorationStyle();
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float height = lineStyle.fontCascade().fontMetrics().floatHeight();
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GlyphOverflow overflowResult;
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if (decorationStyle == TextDecorationStyle::Wavy) {
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wavyStrokeParameters = getWavyStrokeParameters(lineStyle.computedFontPixelSize());
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wavyOffset = wavyOffsetFromDecoration();
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overflowResult.left = strokeThickness;
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overflowResult.right = strokeThickness;
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}
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// These metrics must match where underlines get drawn.
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// FIXME: Share the code in TextDecorationPainter::paintTextDecoration() so we can just query it for the painted geometry.
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if (decoration & TextDecoration::Underline) {
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// Compensate for the integral ceiling in GraphicsContext::computeLineBoundsAndAntialiasingModeForText()
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int underlineOffset = 1;
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float textDecorationBaseFontSize = 16;
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auto defaultGap = lineStyle.computedFontSize() / textDecorationBaseFontSize;
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underlineOffset += computeUnderlineOffset(lineStyle.textUnderlinePosition(), lineStyle.textUnderlineOffset(), lineStyle.fontMetrics(), textRun, defaultGap);
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if (decorationStyle == TextDecorationStyle::Wavy) {
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overflowResult.extendBottom(underlineOffset + wavyOffset + wavyStrokeParameters.controlPointDistance + strokeThickness - height);
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overflowResult.extendTop(-(underlineOffset + wavyOffset - wavyStrokeParameters.controlPointDistance - strokeThickness));
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} else {
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overflowResult.extendBottom(underlineOffset + strokeThickness - height);
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overflowResult.extendTop(-underlineOffset);
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}
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}
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if (decoration & TextDecoration::Overline) {
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FloatRect rect(FloatPoint(), FloatSize(1, strokeThickness));
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float autoTextDecorationThickness = TextDecorationThickness::createWithAuto().resolve(lineStyle.computedFontSize(), lineStyle.fontMetrics());
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rect.move(0, autoTextDecorationThickness - strokeThickness - wavyOffset);
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if (decorationStyle == TextDecorationStyle::Wavy) {
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FloatBoxExtent wavyExpansion;
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wavyExpansion.setTop(wavyStrokeParameters.controlPointDistance);
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wavyExpansion.setBottom(wavyStrokeParameters.controlPointDistance);
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rect.expand(wavyExpansion);
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}
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overflowResult.extendTop(-rect.y());
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overflowResult.extendBottom(rect.maxY() - height);
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}
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if (decoration & TextDecoration::LineThrough) {
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FloatRect rect(FloatPoint(), FloatSize(1, strokeThickness));
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float autoTextDecorationThickness = TextDecorationThickness::createWithAuto().resolve(lineStyle.computedFontSize(), lineStyle.fontMetrics());
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auto center = 2 * lineStyle.fontMetrics().floatAscent() / 3 + autoTextDecorationThickness / 2;
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rect.move(0, center - strokeThickness / 2);
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if (decorationStyle == TextDecorationStyle::Wavy) {
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FloatBoxExtent wavyExpansion;
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wavyExpansion.setTop(wavyStrokeParameters.controlPointDistance);
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wavyExpansion.setBottom(wavyStrokeParameters.controlPointDistance);
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rect.expand(wavyExpansion);
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}
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overflowResult.extendTop(-rect.y());
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overflowResult.extendBottom(rect.maxY() - height);
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}
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return overflowResult;
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}
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}
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