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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 "third_party/blink/renderer/core/layout/layout_text_combine.h"
#include "base/stl_util.h"
#include "third_party/blink/renderer/platform/graphics/graphics_context.h"
namespace blink {
const float kTextCombineMargin = 1.1f; // Allow em + 10% margin
LayoutTextCombine::LayoutTextCombine(Node* node,
scoped_refptr<StringImpl> string)
: LayoutText(node, std::move(string)),
combined_text_width_(0),
scale_x_(1.0f),
is_combined_(false) {}
void LayoutTextCombine::StyleDidChange(StyleDifference diff,
const ComputedStyle* old_style) {
NOT_DESTROYED();
LayoutText::StyleDidChange(diff, old_style);
UpdateIsCombined();
if (!IsCombined())
return;
// We need to call LayoutText::StyleDidChange before updating combined text
// font because StyleDidChange may change the text through text-transform.
UpdateFontStyleForCombinedText();
}
void LayoutTextCombine::TextDidChange() {
NOT_DESTROYED();
LayoutText::TextDidChange();
bool was_combined = IsCombined();
UpdateIsCombined();
// SetTextInternal may be called on construction for applying text-transform
// in which case Parent() is nullptr. However, was_combined should be false
// since it initially is.
DCHECK(!was_combined || Parent());
if (was_combined) {
// Re-set the ComputedStyle from the parent to base the measurements in
// UpdateFontStyleForCombinedText on the original font and not what was
// previously set for combined text. If IsCombined() is now false, we are
// simply resetting the style to the parent style.
SetStyle(Parent()->Style());
} else if (IsCombined()) {
// If the text was previously not combined, SetStyle would have been a no-op
// since the before and after style would be the same ComputedStyle
// instance and StyleDidChange would not be called. Instead, call
// UpdateFontStyleForCombinedText directly.
UpdateFontStyleForCombinedText();
}
}
float LayoutTextCombine::Width(unsigned from,
unsigned length,
const Font& font,
LayoutUnit x_position,
TextDirection direction,
HashSet<const SimpleFontData*>* fallback_fonts,
FloatRect* glyph_bounds,
float) const {
NOT_DESTROYED();
if (!length)
return 0;
if (HasEmptyText())
return 0;
if (is_combined_)
return font.GetFontDescription().ComputedSize();
return LayoutText::Width(from, length, font, x_position, direction,
fallback_fonts, glyph_bounds);
}
void ScaleHorizontallyAndTranslate(GraphicsContext& context,
float scale_x,
float center_x,
float offset_x,
float offset_y) {
context.ConcatCTM(AffineTransform(
scale_x, 0, 0, 1, center_x * (1.0f - scale_x) + offset_x * scale_x,
offset_y));
}
void LayoutTextCombine::TransformToInlineCoordinates(
GraphicsContext& context,
const PhysicalRect& box_rect,
bool clip) const {
NOT_DESTROYED();
DCHECK(is_combined_);
// No transform needed if we don't have a font.
if (!StyleRef().GetFont().PrimaryFont())
return;
// 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 cell_height = box_rect.Height();
float internal_leading =
StyleRef().GetFont().PrimaryFont()->InternalLeading();
float offset_y = -internal_leading / 2;
float width;
if (scale_x_ >= 1.0f) {
// Fast path, more than 90% of cases
DCHECK_EQ(scale_x_, 1.0f);
float offset_x = (cell_height - combined_text_width_) / 2;
context.ConcatCTM(AffineTransform::Translation(offset_x, offset_y));
width = box_rect.Width();
} else {
DCHECK_GE(scale_x_, 0.0f);
float center_x = box_rect.X() + cell_height / 2;
width = combined_text_width_ / scale_x_;
float offset_x = (cell_height - width) / 2;
ScaleHorizontallyAndTranslate(context, scale_x_, center_x, offset_x,
offset_y);
}
if (clip)
context.Clip(FloatRect(box_rect.X(), box_rect.Y(), width, cell_height));
}
void LayoutTextCombine::UpdateIsCombined() {
NOT_DESTROYED();
// CSS3 spec says text-combine works only in vertical writing mode.
is_combined_ = !StyleRef().IsHorizontalWritingMode()
// Nothing to combine.
&& !HasEmptyText();
}
void LayoutTextCombine::UpdateFontStyleForCombinedText() {
NOT_DESTROYED();
DCHECK(is_combined_);
scoped_refptr<ComputedStyle> style = ComputedStyle::Clone(StyleRef());
SetStyleInternal(style);
unsigned offset = 0;
TextRun run = ConstructTextRun(style->GetFont(), this, offset, TextLength(),
*style, style->Direction());
FontDescription description = style->GetFont().GetFontDescription();
float em_width = description.ComputedSize();
if (!EnumHasFlags(style->TextDecorationsInEffect(),
TextDecoration::kUnderline | TextDecoration::kOverline))
em_width *= kTextCombineMargin;
// We are going to draw combined text horizontally.
description.SetOrientation(FontOrientation::kHorizontal);
combined_text_width_ = style->GetFont().Width(run);
FontSelector* font_selector = style->GetFont().GetFontSelector();
// Need to change font orientation to horizontal.
style->SetFontDescription(description);
if (combined_text_width_ <= em_width) {
scale_x_ = 1.0f;
} else {
// Need to try compressed glyphs.
static const FontWidthVariant kWidthVariants[] = {kHalfWidth, kThirdWidth,
kQuarterWidth};
for (size_t i = 0; i < base::size(kWidthVariants); ++i) {
description.SetWidthVariant(kWidthVariants[i]);
Font compressed_font(description, font_selector);
float run_width = compressed_font.Width(run);
if (run_width <= em_width) {
combined_text_width_ = run_width;
// Replace my font with the new one.
style->SetFontDescription(description);
break;
}
}
// If width > ~1em, shrink to fit within ~1em, otherwise render without
// scaling (no expansion).
// https://drafts.csswg.org/css-writing-modes/#text-combine-compression
if (combined_text_width_ > em_width) {
scale_x_ = em_width / combined_text_width_;
combined_text_width_ = em_width;
} else {
scale_x_ = 1.0f;
}
}
}
} // namespace blink
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