third_party/blink/renderer/core/layout/layout_text_combine.cc - chromium/src - Git at Google

 /*
  * 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 "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) {
   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::SetTextInternal(scoped_refptr<StringImpl> text) {
   LayoutText::SetTextInternal(std::move(text));

   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()->MutableStyle());
   } 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 {
   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 LayoutRect& box_rect,
                                                      bool clip) const {
   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() {
   // CSS3 spec says text-combine works only in vertical writing mode.
   is_combined_ = !StyleRef().IsHorizontalWritingMode()
                  // Nothing to combine.
                  && !HasEmptyText();
 }

 void LayoutTextCombine::UpdateFontStyleForCombinedText() {
   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.
   bool should_update_font = 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 < arraysize(kWidthVariants); ++i) {
       description.SetWidthVariant(kWidthVariants[i]);
       Font compressed_font = Font(description);
       compressed_font.Update(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.
         should_update_font = 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;
     }
   }

   if (should_update_font)
     style->GetFont().Update(font_selector);
 }

 }  // namespace blink
	/*
	* 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 "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) {
	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::SetTextInternal(scoped_refptr<StringImpl> text) {
	LayoutText::SetTextInternal(std::move(text));

	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()->MutableStyle());
	} 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 {
	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 LayoutRect& box_rect,
	bool clip) const {
	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() {
	// CSS3 spec says text-combine works only in vertical writing mode.
	is_combined_ = !StyleRef().IsHorizontalWritingMode()
	// Nothing to combine.
	&& !HasEmptyText();
	}

	void LayoutTextCombine::UpdateFontStyleForCombinedText() {
	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.
	bool should_update_font = 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 < arraysize(kWidthVariants); ++i) {
	description.SetWidthVariant(kWidthVariants[i]);
	Font compressed_font = Font(description);
	compressed_font.Update(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.
	should_update_font = 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;
	}
	}

	if (should_update_font)
	style->GetFont().Update(font_selector);
	}

	} // namespace blink