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/*
* Copyright (C) 2014 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "InlineTextBoxStyle.h"
#include "FontCascade.h"
#include "InlineTextBox.h"
#include "RootInlineBox.h"
namespace WebCore {
int computeUnderlineOffset(TextUnderlinePosition underlinePosition, const FontMetrics& fontMetrics, const InlineTextBox* inlineTextBox, int textDecorationThickness)
{
// This represents the gap between the baseline and the closest edge of the underline.
int gap = std::max<int>(1, ceilf(textDecorationThickness / 2.0));
// FIXME: The code for visual overflow detection passes in a null inline text box. This means it is now
// broken for the case where auto needs to behave like "under".
// According to the specification TextUnderlinePositionAuto should avoid drawing through glyphs in
// scripts where it would not be appropriate (e.g., ideographs).
// Strictly speaking this can occur whenever the line contains ideographs
// even if it is horizontal, but detecting this has performance implications. For now we only work with
// vertical text, since we already determined the baseline type to be ideographic in that
// case.
TextUnderlinePosition resolvedUnderlinePosition = underlinePosition;
if (resolvedUnderlinePosition == TextUnderlinePositionAuto) {
if (inlineTextBox)
resolvedUnderlinePosition = inlineTextBox->root().baselineType() == IdeographicBaseline ? TextUnderlinePositionUnder : TextUnderlinePositionAlphabetic;
else
resolvedUnderlinePosition = TextUnderlinePositionAlphabetic;
}
switch (resolvedUnderlinePosition) {
case TextUnderlinePositionAlphabetic:
return fontMetrics.ascent() + gap;
case TextUnderlinePositionUnder: {
ASSERT(inlineTextBox);
// Position underline relative to the bottom edge of the lowest element's content box.
const RootInlineBox& rootBox = inlineTextBox->root();
const RenderElement* decorationRenderer = inlineTextBox->parent()->renderer().enclosingRendererWithTextDecoration(TextDecorationUnderline, inlineTextBox->isFirstLine());
float offset;
if (inlineTextBox->renderer().style().isFlippedLinesWritingMode()) {
offset = inlineTextBox->logicalTop();
rootBox.minLogicalTopForTextDecorationLine(offset, decorationRenderer, TextDecorationUnderline);
offset = inlineTextBox->logicalTop() - offset;
} else {
offset = inlineTextBox->logicalBottom();
rootBox.maxLogicalBottomForTextDecorationLine(offset, decorationRenderer, TextDecorationUnderline);
offset -= inlineTextBox->logicalBottom();
}
return inlineTextBox->logicalHeight() + gap + std::max<float>(offset, 0);
}
case TextUnderlinePositionAuto:
ASSERT_NOT_REACHED();
}
ASSERT_NOT_REACHED();
return fontMetrics.ascent() + gap;
}
void getWavyStrokeParameters(float strokeThickness, float& controlPointDistance, float& step)
{
// Distance between decoration's axis and Bezier curve's control points.
// The height of the curve is based on this distance. Use a minimum of 6 pixels distance since
// the actual curve passes approximately at half of that distance, that is 3 pixels.
// The minimum height of the curve is also approximately 3 pixels. Increases the curve's height
// as strokeThickness increases to make the curve look better.
controlPointDistance = 3 * std::max<float>(2, strokeThickness);
// Increment used to form the diamond shape between start point (p1), control
// points and end point (p2) along the axis of the decoration. Makes the
// curve wider as strokeThickness increases to make the curve look better.
step = 2 * std::max<float>(2, strokeThickness);
}
static inline void extendIntToFloat(int& extendMe, float extendTo)
{
extendMe = std::max(extendMe, static_cast<int>(ceilf(extendTo)));
}
GlyphOverflow visualOverflowForDecorations(const RenderStyle& lineStyle, const InlineTextBox* inlineTextBox)
{
ASSERT(!inlineTextBox || inlineTextBox->lineStyle() == lineStyle);
TextDecoration decoration = lineStyle.textDecorationsInEffect();
if (decoration == TextDecorationNone)
return GlyphOverflow();
float strokeThickness = textDecorationStrokeThickness(lineStyle.fontSize());
float controlPointDistance = 0;
float step;
float wavyOffset = 0;
TextDecorationStyle decorationStyle = lineStyle.textDecorationStyle();
float height = lineStyle.fontCascade().fontMetrics().floatHeight();
GlyphOverflow overflowResult;
if (decorationStyle == TextDecorationStyleWavy) {
getWavyStrokeParameters(strokeThickness, controlPointDistance, step);
wavyOffset = wavyOffsetFromDecoration();
overflowResult.left = strokeThickness;
overflowResult.right = strokeThickness;
}
// These metrics must match where underlines get drawn.
if (decoration & TextDecorationUnderline) {
// Compensate for the integral ceiling in GraphicsContext::computeLineBoundsAndAntialiasingModeForText()
int underlineOffset = 1;
underlineOffset += computeUnderlineOffset(lineStyle.textUnderlinePosition(), lineStyle.fontMetrics(), inlineTextBox, strokeThickness);
if (decorationStyle == TextDecorationStyleWavy) {
extendIntToFloat(overflowResult.bottom, underlineOffset + wavyOffset + controlPointDistance + strokeThickness - height);
extendIntToFloat(overflowResult.top, -(underlineOffset + wavyOffset - controlPointDistance - strokeThickness));
} else {
extendIntToFloat(overflowResult.bottom, underlineOffset + strokeThickness - height);
extendIntToFloat(overflowResult.top, -underlineOffset);
}
}
if (decoration & TextDecorationOverline) {
if (decorationStyle == TextDecorationStyleWavy) {
extendIntToFloat(overflowResult.bottom, -wavyOffset + controlPointDistance + strokeThickness - height);
extendIntToFloat(overflowResult.top, wavyOffset + controlPointDistance + strokeThickness);
} else {
extendIntToFloat(overflowResult.bottom, strokeThickness - height);
// top is untouched
}
}
if (decoration & TextDecorationLineThrough) {
float baseline = lineStyle.fontMetrics().floatAscent();
if (decorationStyle == TextDecorationStyleWavy) {
extendIntToFloat(overflowResult.bottom, 2 * baseline / 3 + controlPointDistance + strokeThickness - height);
extendIntToFloat(overflowResult.top, -(2 * baseline / 3 - controlPointDistance - strokeThickness));
} else {
extendIntToFloat(overflowResult.bottom, 2 * baseline / 3 + strokeThickness - height);
extendIntToFloat(overflowResult.top, -(2 * baseline / 3));
}
}
return overflowResult;
}
}
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