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/*
* Copyright (C) Research In Motion Limited 2010. 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 "core/layout/svg/SVGTextLayoutEngineBaseline.h"
#include "core/style/SVGComputedStyle.h"
#include "core/svg/SVGLengthContext.h"
#include "platform/fonts/Font.h"
namespace blink {
SVGTextLayoutEngineBaseline::SVGTextLayoutEngineBaseline(const Font& font,
float effectiveZoom)
: m_font(font), m_effectiveZoom(effectiveZoom) {
ASSERT(m_effectiveZoom);
}
float SVGTextLayoutEngineBaseline::calculateBaselineShift(
const ComputedStyle& style) const {
const SVGComputedStyle& svgStyle = style.svgStyle();
const SimpleFontData* fontData = m_font.primaryFont();
DCHECK(fontData);
if (!fontData)
return 0;
DCHECK(m_effectiveZoom);
switch (svgStyle.baselineShift()) {
case BS_LENGTH:
return SVGLengthContext::valueForLength(
svgStyle.baselineShiftValue(), style,
m_font.getFontDescription().computedPixelSize() / m_effectiveZoom);
case BS_SUB:
return -fontData->getFontMetrics().floatHeight() / 2 / m_effectiveZoom;
case BS_SUPER:
return fontData->getFontMetrics().floatHeight() / 2 / m_effectiveZoom;
default:
ASSERT_NOT_REACHED();
return 0;
}
}
EAlignmentBaseline
SVGTextLayoutEngineBaseline::dominantBaselineToAlignmentBaseline(
bool isVerticalText,
LineLayoutItem textLineLayout) const {
ASSERT(textLineLayout);
ASSERT(textLineLayout.style());
const SVGComputedStyle& style = textLineLayout.style()->svgStyle();
EDominantBaseline baseline = style.dominantBaseline();
if (baseline == DB_AUTO) {
if (isVerticalText)
baseline = DB_CENTRAL;
else
baseline = DB_ALPHABETIC;
}
switch (baseline) {
case DB_USE_SCRIPT:
// TODO(fs): The dominant-baseline and the baseline-table components
// are set by determining the predominant script of the character data
// content.
return AB_ALPHABETIC;
case DB_NO_CHANGE:
ASSERT(textLineLayout.parent());
return dominantBaselineToAlignmentBaseline(isVerticalText,
textLineLayout.parent());
case DB_RESET_SIZE:
ASSERT(textLineLayout.parent());
return dominantBaselineToAlignmentBaseline(isVerticalText,
textLineLayout.parent());
case DB_IDEOGRAPHIC:
return AB_IDEOGRAPHIC;
case DB_ALPHABETIC:
return AB_ALPHABETIC;
case DB_HANGING:
return AB_HANGING;
case DB_MATHEMATICAL:
return AB_MATHEMATICAL;
case DB_CENTRAL:
return AB_CENTRAL;
case DB_MIDDLE:
return AB_MIDDLE;
case DB_TEXT_AFTER_EDGE:
return AB_TEXT_AFTER_EDGE;
case DB_TEXT_BEFORE_EDGE:
return AB_TEXT_BEFORE_EDGE;
default:
ASSERT_NOT_REACHED();
return AB_AUTO;
}
}
float SVGTextLayoutEngineBaseline::calculateAlignmentBaselineShift(
bool isVerticalText,
LineLayoutItem textLineLayout) const {
ASSERT(textLineLayout);
ASSERT(textLineLayout.style());
ASSERT(textLineLayout.parent());
LineLayoutItem textLineLayoutParent = textLineLayout.parent();
ASSERT(textLineLayoutParent);
EAlignmentBaseline baseline =
textLineLayout.style()->svgStyle().alignmentBaseline();
if (baseline == AB_AUTO || baseline == AB_BASELINE) {
baseline = dominantBaselineToAlignmentBaseline(isVerticalText,
textLineLayoutParent);
ASSERT(baseline != AB_AUTO && baseline != AB_BASELINE);
}
const SimpleFontData* fontData = m_font.primaryFont();
DCHECK(fontData);
if (!fontData)
return 0;
const FontMetrics& fontMetrics = fontData->getFontMetrics();
float ascent = fontMetrics.floatAscent() / m_effectiveZoom;
float descent = fontMetrics.floatDescent() / m_effectiveZoom;
float xheight = fontMetrics.xHeight() / m_effectiveZoom;
// Note: http://wiki.apache.org/xmlgraphics-fop/LineLayout/AlignmentHandling
switch (baseline) {
case AB_BEFORE_EDGE:
case AB_TEXT_BEFORE_EDGE:
return ascent;
case AB_MIDDLE:
return xheight / 2;
case AB_CENTRAL:
return (ascent - descent) / 2;
case AB_AFTER_EDGE:
case AB_TEXT_AFTER_EDGE:
case AB_IDEOGRAPHIC:
return -descent;
case AB_ALPHABETIC:
return 0;
case AB_HANGING:
return ascent * 8 / 10.f;
case AB_MATHEMATICAL:
return ascent / 2;
case AB_BASELINE:
default:
ASSERT_NOT_REACHED();
return 0;
}
}
} // namespace blink
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