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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 "core/layout/LayoutTextCombine.h"
#include "platform/graphics/GraphicsContext.h"
namespace blink {
const float textCombineMargin = 1.1f; // Allow em + 10% margin
LayoutTextCombine::LayoutTextCombine(Node* node, PassRefPtr<StringImpl> string)
: LayoutText(node, std::move(string)),
m_combinedTextWidth(0),
m_scaleX(1.0f),
m_isCombined(false),
m_needsFontUpdate(false) {}
void LayoutTextCombine::styleDidChange(StyleDifference diff,
const ComputedStyle* oldStyle) {
setStyleInternal(ComputedStyle::clone(styleRef()));
LayoutText::styleDidChange(diff, oldStyle);
updateIsCombined();
}
void LayoutTextCombine::setTextInternal(PassRefPtr<StringImpl> text) {
LayoutText::setTextInternal(std::move(text));
updateIsCombined();
}
float LayoutTextCombine::width(unsigned from,
unsigned length,
const Font& font,
LayoutUnit xPosition,
TextDirection direction,
HashSet<const SimpleFontData*>* fallbackFonts,
FloatRect* glyphBounds) const {
if (!length)
return 0;
if (hasEmptyText())
return 0;
if (m_isCombined)
return font.getFontDescription().computedSize();
return LayoutText::width(from, length, font, xPosition, direction,
fallbackFonts, glyphBounds);
}
void scaleHorizontallyAndTranslate(GraphicsContext& context,
float scaleX,
float centerX,
float offsetX,
float offsetY) {
context.concatCTM(AffineTransform(
scaleX, 0, 0, 1, centerX * (1.0f - scaleX) + offsetX * scaleX, offsetY));
}
void LayoutTextCombine::transformToInlineCoordinates(GraphicsContext& context,
const LayoutRect& boxRect,
bool clip) const {
DCHECK_EQ(m_needsFontUpdate, false);
DCHECK(m_isCombined);
// On input, the |boxRect| is:
// 1. Horizontal flow, rotated from the main vertical flow coordinate using
// TextPainter::rotation().
// 2. height() is cell-height, which includes internal leading. This equals
// to A+D, and to em+internal leading.
// 3. width() is the same as m_combinedTextWidth.
// 4. Left is (right-edge - height()).
// 5. Top is where char-top (not include internal leading) should be.
// See https://support.microsoft.com/en-us/kb/32667.
// We move it so that it comes to the center of em excluding internal
// leading.
float cellHeight = boxRect.height();
float internalLeading = styleRef().font().primaryFont()->internalLeading();
float offsetY = -internalLeading / 2;
float width;
if (m_scaleX >= 1.0f) {
// Fast path, more than 90% of cases
DCHECK_EQ(m_scaleX, 1.0f);
float offsetX = (cellHeight - m_combinedTextWidth) / 2;
context.concatCTM(AffineTransform::translation(offsetX, offsetY));
width = boxRect.width();
} else {
DCHECK_GE(m_scaleX, 0.0f);
float centerX = boxRect.x() + cellHeight / 2;
width = m_combinedTextWidth / m_scaleX;
float offsetX = (cellHeight - width) / 2;
scaleHorizontallyAndTranslate(context, m_scaleX, centerX, offsetX, offsetY);
}
if (clip)
context.clip(FloatRect(boxRect.x(), boxRect.y(), width, cellHeight));
}
void LayoutTextCombine::updateIsCombined() {
// CSS3 spec says text-combine works only in vertical writing mode.
m_isCombined = !style()->isHorizontalWritingMode()
// Nothing to combine.
&& !hasEmptyText();
if (m_isCombined)
m_needsFontUpdate = true;
}
void LayoutTextCombine::updateFont() {
if (!m_needsFontUpdate)
return;
m_needsFontUpdate = false;
if (!m_isCombined)
return;
unsigned offset = 0;
TextRun run = constructTextRun(originalFont(), this, offset, textLength(),
styleRef(), style()->direction());
FontDescription description = originalFont().getFontDescription();
float emWidth = description.computedSize();
if (!(style()->textDecorationsInEffect() &
(TextDecorationUnderline | TextDecorationOverline)))
emWidth *= textCombineMargin;
// We are going to draw combined text horizontally.
description.setOrientation(FontOrientation::Horizontal);
m_combinedTextWidth = originalFont().width(run);
FontSelector* fontSelector = style()->font().getFontSelector();
bool shouldUpdateFont = mutableStyleRef().setFontDescription(
description); // Need to change font orientation to horizontal.
if (m_combinedTextWidth <= emWidth) {
m_scaleX = 1.0f;
} 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]);
Font compressedFont = Font(description);
compressedFont.update(fontSelector);
float runWidth = compressedFont.width(run);
if (runWidth <= emWidth) {
m_combinedTextWidth = runWidth;
// Replace my font with the new one.
shouldUpdateFont = mutableStyleRef().setFontDescription(description);
break;
}
}
// If width > ~1em, shrink to fit within ~1em, otherwise render without
// scaling (no expansion).
// http://dev.w3.org/csswg/css-writing-modes-3/#text-combine-compression
if (m_combinedTextWidth > emWidth) {
m_scaleX = emWidth / m_combinedTextWidth;
m_combinedTextWidth = emWidth;
} else {
m_scaleX = 1.0f;
}
}
if (shouldUpdateFont)
style()->font().update(fontSelector);
}
} // namespace blink
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