src/cobalt/renderer/rasterizer/skia/text_shaper.cc - cobalt - Git at Google

 // Copyright 2016 Google Inc. All Rights Reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 #include "cobalt/renderer/rasterizer/skia/text_shaper.h"

 #include <algorithm>
 #include <limits>

 #include "base/i18n/char_iterator.h"
 #include "base/i18n/icu_string_conversions.h"
 #include "cobalt/base/polymorphic_downcast.h"
 #include "cobalt/base/unicode/character.h"
 #include "cobalt/base/unicode/character_values.h"
 #include "cobalt/renderer/rasterizer/skia/glyph_buffer.h"
 #include "cobalt/renderer/rasterizer/skia/harfbuzz_font.h"

 namespace cobalt {
 namespace renderer {
 namespace rasterizer {
 namespace skia {
 namespace {

 // A simple implementation of FontProvider where a single font is always used.
 class SingleFontFontProvider : public render_tree::FontProvider {
  public:
   explicit SingleFontFontProvider(const scoped_refptr<render_tree::Font>& font)
       : size_(base::polymorphic_downcast<Font*>(font.get())->size()),
         font_(font) {}

   const render_tree::FontStyle& style() const override { return style_; }
   float size() const override { return size_; }

   const scoped_refptr<render_tree::Font>& GetCharacterFont(
       int32 utf32_character, render_tree::GlyphIndex* glyph_index) override {
     *glyph_index = font_->GetGlyphForCharacter(utf32_character);
     return font_;
   }

  private:
   render_tree::FontStyle style_;
   float size_;
   scoped_refptr<render_tree::Font> font_;
 };

 void TryAddFontToUsedFonts(Font* font,
                            render_tree::FontVector* maybe_used_fonts) {
   if (!maybe_used_fonts) {
     return;
   }

   // Verify that the font has not already been added to the used fonts, before
   // adding it to the end.
   for (int i = 0; i < maybe_used_fonts->size(); ++i) {
     if ((*maybe_used_fonts)[i] == font) {
       return;
     }
   }

   maybe_used_fonts->push_back(font);
 }

 bool ShouldFakeBoldText(const render_tree::FontProvider* font_provider,
                         const Font* font) {
   // A font-weight greater than 500 indicates bold if it is available. Use
   // synthetic bolding if this is a bold weight and the selected font
   // synthesizes bold.
   // https://www.w3.org/TR/css-fonts-3/#font-weight-prop
   // https://www.w3.org/TR/css-fonts-3/#font-style-matching
   if (font_provider->style().weight > 500) {
     const sk_sp<SkTypeface_Cobalt>& typeface(font->GetSkTypeface());
     return typeface->synthesizes_bold();
   }
   return false;
 }

 }  // namespace

 TextShaper::TextShaper()
     : local_glyph_array_size_(0), local_text_buffer_size_(0) {}

 scoped_refptr<GlyphBuffer> TextShaper::CreateGlyphBuffer(
     const char16* text_buffer, size_t text_length, const std::string& language,
     bool is_rtl, render_tree::FontProvider* font_provider) {
   math::RectF bounds;
   SkTextBlobBuilder builder;
   ShapeText(text_buffer, text_length, language, is_rtl, font_provider, &builder,
             &bounds, NULL);
   return make_scoped_refptr(new GlyphBuffer(bounds, &builder));
 }

 scoped_refptr<GlyphBuffer> TextShaper::CreateGlyphBuffer(
     const std::string& utf8_string,
     const scoped_refptr<render_tree::Font>& font) {
   string16 utf16_string;
   base::CodepageToUTF16(utf8_string, base::kCodepageUTF8,
                         base::OnStringConversionError::SUBSTITUTE,
                         &utf16_string);
   SingleFontFontProvider font_provider(font);
   return CreateGlyphBuffer(utf16_string.c_str(), utf16_string.size(), "en-US",
                            false, &font_provider);
 }

 float TextShaper::GetTextWidth(const char16* text_buffer, size_t text_length,
                                const std::string& language, bool is_rtl,
                                render_tree::FontProvider* font_provider,
                                render_tree::FontVector* maybe_used_fonts) {
   return ShapeText(text_buffer, text_length, language, is_rtl, font_provider,
                    NULL, NULL, maybe_used_fonts);
 }

 void TextShaper::PurgeCaches() {
   base::AutoLock lock(shaping_mutex_);
   harfbuzz_font_provider_.PurgeCaches();
 }

 float TextShaper::ShapeText(const char16* text_buffer, size_t text_length,
                             const std::string& language, bool is_rtl,
                             render_tree::FontProvider* font_provider,
                             SkTextBlobBuilder* maybe_builder,
                             math::RectF* maybe_bounds,
                             render_tree::FontVector* maybe_used_fonts) {
   base::AutoLock lock(shaping_mutex_);
   float total_width = 0;
   VerticalBounds vertical_bounds;
   // Only set |maybe_vertical_bounds| to a non-NULL value when |maybe_bounds| is
   // non-NULL. Otherwise, the text bounds are not being calculated.
   VerticalBounds* maybe_vertical_bounds =
       maybe_bounds ? &vertical_bounds : NULL;

   // Check for if the text contains a complex script, meaning that it requires
   // HarfBuzz. If it does, then attempt to collect the scripts. In the event
   // that this fails, fall back to the simple shaper.
   ScriptRuns script_runs;
   if (base::unicode::ContainsComplexScript(text_buffer, text_length) &&
       CollectScriptRuns(text_buffer, text_length, font_provider,
                         &script_runs)) {
     // If the direction is RTL, then reverse the script runs, so that the glyphs
     // will be added in the correct order.
     if (is_rtl) {
       std::reverse(script_runs.begin(), script_runs.end());
     }

     for (int i = 0; i < script_runs.size(); ++i) {
       ScriptRun& run = script_runs[i];
       const char16* script_run_text_buffer = text_buffer + run.start_index;

       // Check to see if the script run requires HarfBuzz. Because HarfBuzz
       // shaping is much slower than simple shaping, we only want to run
       // HarfBuzz shaping on the bare minimum possible, so any script run
       // that doesn't contain complex scripts will be simply shaped.
       if (base::unicode::ContainsComplexScript(script_run_text_buffer,
                                                run.length)) {
         ShapeComplexRun(script_run_text_buffer, run, language, is_rtl,
                         font_provider, maybe_builder, maybe_vertical_bounds,
                         maybe_used_fonts, &total_width);
       } else {
         ShapeSimpleRunWithDirection(script_run_text_buffer, run.length, is_rtl,
                                     font_provider, maybe_builder,
                                     maybe_vertical_bounds, maybe_used_fonts,
                                     &total_width);
       }
     }
   } else {
     ShapeSimpleRunWithDirection(text_buffer, text_length, is_rtl, font_provider,
                                 maybe_builder, maybe_vertical_bounds,
                                 maybe_used_fonts, &total_width);
   }

   // If |maybe_bounds| has been provided, then update the width of the bounds
   // with the total width of all of the shaped glyphs. The height is already
   // correct.
   if (maybe_bounds) {
     *maybe_bounds = math::RectF(0, vertical_bounds.GetY(), total_width,
                                 vertical_bounds.GetHeight());
   }

   return total_width;
 }

 bool TextShaper::CollectScriptRuns(const char16* text_buffer,
                                    size_t text_length,
                                    render_tree::FontProvider* font_provider,
                                    ScriptRuns* runs) {
   // Initialize the next data with the first character. This allows us to avoid
   // checking for the first character case within the while loop.
   int32 next_character = base::unicode::NormalizeSpaces(
       base::i18n::UTF16CharIterator(text_buffer, text_length).get());
   render_tree::GlyphIndex next_glyph = render_tree::kInvalidGlyphIndex;
   Font* next_font = base::polymorphic_downcast<Font*>(
       font_provider->GetCharacterFont(next_character, &next_glyph).get());

   UErrorCode error_code = U_ZERO_ERROR;
   UScriptCode next_script = uscript_getScript(next_character, &error_code);
   // If we're unable to determine the script of a character, we failed to
   // successfully collect the script runs. Return failure.
   if (U_FAILURE(error_code)) {
     return false;
   }

   // Iterate for as long as the current index has not reached the end index.
   unsigned int current_index = 0;
   unsigned int end_index = text_length;
   while (current_index < end_index) {
     Font* current_font = next_font;
     UScriptCode current_script = next_script;

     // Create an iterator starting at the current index and containing the
     // remaining length.
     base::i18n::UTF16CharIterator iter(text_buffer + current_index,
                                        end_index - current_index);
     // Skip over the first character. It's already set as our current font
     // and current script.
     iter.Advance();
     size_t next_index_offset = iter.array_pos();

     for (; !iter.end(); iter.Advance(), next_index_offset = iter.array_pos()) {
       // Normalize spaces within the current character, so that we are
       // guaranteed that they will map to a consistent font and glyph.
       next_character = base::unicode::NormalizeSpaces(iter.get());
       if (next_character == base::unicode::kZeroWidthSpaceCharacter) {
         continue;
       }

       // Check for mark characters. If this is a mark character and the current
       // font contains a glyph for it, then simply add it to the current run.
       // Doing so ensures that combining character sequences will be shaped in
       // one font run if possible.
       if ((U_GET_GC_MASK(next_character) & U_GC_M_MASK) &&
           (current_font->GetGlyphForCharacter(next_character) !=
            render_tree::kInvalidGlyphIndex)) {
         continue;
       }

       next_font = base::polymorphic_downcast<Font*>(
           font_provider->GetCharacterFont(next_character, &next_glyph).get());

       next_script = uscript_getScript(next_character, &error_code);
       // If we're unable to determine the script of a character, we failed to
       // successfully collect the script runs. Return failure.
       if (U_FAILURE(error_code)) {
         return false;
       }

       // We've reached the end of the script run in two cases:
       //   1. If the characters use different fonts.
       //   2. If the characters use different scripts, the next script isn't
       //      inherited, and the next character doesn't support the current
       //      script.
       if ((current_font != next_font) ||
           ((current_script != next_script) &&
            (next_script != USCRIPT_INHERITED) &&
            (!uscript_hasScript(next_character, current_script)))) {
         break;
       }

       // If the script is inherited, then simply retain the current script.
       if (next_script == USCRIPT_INHERITED) {
         next_script = current_script;
       }
     }

     runs->push_back(ScriptRun(current_font, current_script, current_index,
                               next_index_offset));

     // Update the index where we're starting the next script run.
     current_index += next_index_offset;
   }

   return true;
 }

 void TextShaper::ShapeComplexRun(const char16* text_buffer,
                                  const ScriptRun& script_run,
                                  const std::string& language, bool is_rtl,
                                  render_tree::FontProvider* font_provider,
                                  SkTextBlobBuilder* maybe_builder,
                                  VerticalBounds* maybe_vertical_bounds,
                                  render_tree::FontVector* maybe_used_fonts,
                                  float* total_width) {
   TryAddFontToUsedFonts(script_run.font, maybe_used_fonts);

   hb_font_t* harfbuzz_font =
       harfbuzz_font_provider_.GetHarfBuzzFont(script_run.font);

   // Ensure that the local text buffer is large enough to hold the normalized
   // string.
   EnsureLocalTextBufferHasSize(script_run.length);

   // Normalize the spaces in the run before providing it to HarfBuzz.
   bool error = false;
   unsigned int normalized_buffer_length = 0;
   unsigned int buffer_position = 0;
   while (buffer_position < script_run.length) {
     UChar32 character;
     U16_NEXT(text_buffer, buffer_position, script_run.length, character);
     character = base::unicode::NormalizeSpacesInComplexScript(character);
     U16_APPEND(local_text_buffer_.get(), normalized_buffer_length,
                script_run.length, character, error);
   }

   // Create a HarfBuzz buffer and add the string to be shaped. The HarfBuzz
   // buffer holds our text, run information to be used by the shaping engine,
   // and the resulting glyph data.
   hb_buffer_t* buffer = hb_buffer_create();
   hb_buffer_add_utf16(buffer, (const uint16_t*)local_text_buffer_.get(),
                       normalized_buffer_length, 0, normalized_buffer_length);
   hb_buffer_set_script(buffer, hb_icu_script_to_script(script_run.script));
   hb_buffer_set_direction(buffer, is_rtl ? HB_DIRECTION_RTL : HB_DIRECTION_LTR);
   hb_buffer_set_language(
       buffer, hb_language_from_string(language.c_str(), language.length()));

   // Shape the text.
   hb_shape(harfbuzz_font, buffer, NULL, 0);

   // Populate the run fields with the resulting glyph data in the buffer.
   unsigned int glyph_count = 0;

   hb_glyph_info_t* infos = hb_buffer_get_glyph_infos(buffer, &glyph_count);
   hb_glyph_position_t* hb_positions =
       hb_buffer_get_glyph_positions(buffer, NULL);

   // If |maybe_builder| has been provided, the allocate enough memory within
   // the builder for the shaped glyphs.
   const SkTextBlobBuilder::RunBuffer* run_buffer = NULL;
   if (maybe_builder) {
     SkPaint paint = script_run.font->GetSkPaint();
     paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
     paint.setFakeBoldText(ShouldFakeBoldText(font_provider, script_run.font));
     run_buffer = &(maybe_builder->allocRunPos(paint, glyph_count));
   }

   // Walk each of the shaped glyphs.
   size_t pos_index = 0;
   for (size_t i = 0; i < glyph_count; ++i) {
     DCHECK_LE(infos[i].codepoint, std::numeric_limits<uint16_t>::max());
     // If |run_buffer| has been allocated, then we're populating it with the
     // glyph and position data.
     if (run_buffer) {
       run_buffer->glyphs[i] = static_cast<uint16_t>(infos[i].codepoint);
       run_buffer->pos[pos_index++] =
           *total_width + SkFixedToScalar(hb_positions[i].x_offset);
       run_buffer->pos[pos_index++] = -SkFixedToScalar(hb_positions[i].y_offset);
     }

     // If |maybe_vertical_bounds| has been provided, then we're updating it with
     // the vertical bounds of all of the shaped glyphs.
     if (maybe_vertical_bounds) {
       const math::RectF& glyph_bounds =
           script_run.font->GetGlyphBounds(infos[i].codepoint);
       float min_y =
           glyph_bounds.y() - SkFixedToScalar(hb_positions[i].y_offset);
       float max_y = min_y + glyph_bounds.height();
       maybe_vertical_bounds->IncludeRange(min_y, max_y);
     }

     // Include the shaped glyph within the total width.
     *total_width += SkFixedToFloat(hb_positions[i].x_advance);
   }

   hb_buffer_destroy(buffer);
   hb_font_destroy(harfbuzz_font);
 }

 void TextShaper::ShapeSimpleRunWithDirection(
     const char16* text_buffer, size_t text_length, bool is_rtl,
     render_tree::FontProvider* font_provider, SkTextBlobBuilder* maybe_builder,
     VerticalBounds* maybe_vertical_bounds,
     render_tree::FontVector* maybe_used_fonts, float* total_width) {
   // If the text has an RTL direction and a builder was provided, then reverse
   // the text. This ensures that the glyphs will appear in the proper order
   // within the glyph buffer. The width and bounds do not rely on the direction
   // of the text, so in the case where there is no builder, reversing the text
   // is not necessary.
   if (maybe_builder && is_rtl) {
     // Ensure that the local text buffer is large enough to hold the reversed
     // string.
     EnsureLocalTextBufferHasSize(text_length);

     // Both reverse the text and replace mirror characters so that characters
     // such as parentheses will appear in the proper direction.
     bool error = false;
     unsigned int reversed_buffer_length = 0;
     unsigned int buffer_position = text_length;
     while (buffer_position > 0) {
       UChar32 character;
       U16_PREV(text_buffer, 0, buffer_position, character);
       character = u_charMirror(character);
       U16_APPEND(local_text_buffer_.get(), reversed_buffer_length, text_length,
                  character, error);
     }

     ShapeSimpleRun(local_text_buffer_.get(), reversed_buffer_length,
                    font_provider, maybe_builder, maybe_vertical_bounds,
                    maybe_used_fonts, total_width);
   } else {
     ShapeSimpleRun(text_buffer, text_length, font_provider, maybe_builder,
                    maybe_vertical_bounds, maybe_used_fonts, total_width);
   }
 }

 void TextShaper::ShapeSimpleRun(const char16* text_buffer, size_t text_length,
                                 render_tree::FontProvider* font_provider,
                                 SkTextBlobBuilder* maybe_builder,
                                 VerticalBounds* maybe_vertical_bounds,
                                 render_tree::FontVector* maybe_used_fonts,
                                 float* total_width) {
   // If there's a builder (meaning that a glyph buffer is being generated), then
   // ensure that the local arrays are large enough to hold all of the glyphs
   // within the simple run.
   if (maybe_builder) {
     EnsureLocalGlyphArraysHaveSize(text_length);
   }

   int glyph_count = 0;
   Font* last_font = NULL;

   // Walk through each character within the run.
   for (base::i18n::UTF16CharIterator iter(text_buffer, text_length);
        !iter.end(); iter.Advance()) {
     // Retrieve the current character and normalize spaces and zero width
     // spaces before processing it.
     int32 character = base::unicode::NormalizeSpaces(iter.get());
     render_tree::GlyphIndex glyph = render_tree::kInvalidGlyphIndex;

     // If a space character is encountered, simply add to the width and continue
     // on. As an optimization, we don't add space character glyphs to the glyph
     // buffer.
     if (character == base::unicode::kSpaceCharacter) {
       *total_width += font_provider->GetCharacterFont(character, &glyph)
                           ->GetGlyphWidth(glyph);
       continue;
       // If a zero width space character is encountered, simply continue on. It
       // doesn't impact the width or shaping data.
     } else if (character == base::unicode::kZeroWidthSpaceCharacter) {
       continue;
     }

     // Look up the font and glyph for the current character.
     Font* current_font = base::polymorphic_downcast<Font*>(
         font_provider->GetCharacterFont(character, &glyph).get());

     // If there's a builder (meaning that a glyph buffer is being generated),
     // then we need to update the glyph buffer data for the new glyph.
     if (maybe_builder) {
       // If at least one glyph has previously been added and the font has
       // changed, then the current run has ended and we need to add the font run
       // into the glyph buffer.
       if (glyph_count > 0 && last_font != current_font) {
         TryAddFontToUsedFonts(last_font, maybe_used_fonts);
         AddFontRunToGlyphBuffer(font_provider, last_font, glyph_count,
                                 maybe_builder);
         glyph_count = 0;
       }

       local_glyphs_[glyph_count] = glyph;
       local_positions_[glyph_count] = *total_width;
     }

     const math::RectF& glyph_bounds = current_font->GetGlyphBounds(glyph);
     *total_width += glyph_bounds.width();

     // If |maybe_vertical_bounds| has been provided, then we're updating it with
     // the vertical bounds of all of the shaped glyphs.
     if (maybe_vertical_bounds) {
       maybe_vertical_bounds->IncludeRange(glyph_bounds.y(),
                                           glyph_bounds.bottom());
     }

     ++glyph_count;
     last_font = current_font;
   }

   // If there's a builder (meaning that a glyph buffer is being generated), and
   // at least one glyph was generated, then we need to add the final font run
   // into the glyph buffer.
   if (maybe_builder && glyph_count > 0) {
     TryAddFontToUsedFonts(last_font, maybe_used_fonts);
     AddFontRunToGlyphBuffer(font_provider, last_font, glyph_count,
                             maybe_builder);
   }
 }

 void TextShaper::AddFontRunToGlyphBuffer(
     const render_tree::FontProvider* font_provider, const Font* font,
     const int glyph_count, SkTextBlobBuilder* builder) {
   SkPaint paint = font->GetSkPaint();
   paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
   paint.setFakeBoldText(ShouldFakeBoldText(font_provider, font));

   // Allocate space within the text blob for the glyphs and copy them into the
   // blob.
   const SkTextBlobBuilder::RunBuffer& buffer =
       builder->allocRunPosH(paint, glyph_count, 0);
   std::copy(&local_glyphs_[0], &local_glyphs_[0] + glyph_count, buffer.glyphs);
   std::copy(&local_positions_[0], &local_positions_[0] + glyph_count,
             buffer.pos);
 }

 void TextShaper::EnsureLocalGlyphArraysHaveSize(size_t size) {
   if (local_glyph_array_size_ < size) {
     local_glyph_array_size_ = size;
     local_glyphs_.reset(new render_tree::GlyphIndex[size]);
     local_positions_.reset(new SkScalar[size]);
   }
 }

 void TextShaper::EnsureLocalTextBufferHasSize(size_t size) {
   if (local_text_buffer_size_ < size) {
     local_text_buffer_size_ = size;
     local_text_buffer_.reset(new char16[size]);
   }
 }

 }  // namespace skia
 }  // namespace rasterizer
 }  // namespace renderer
 }  // namespace cobalt
	// Copyright 2016 Google Inc. All Rights Reserved.
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	#include "cobalt/renderer/rasterizer/skia/text_shaper.h"

	#include <algorithm>
	#include <limits>

	#include "base/i18n/char_iterator.h"
	#include "base/i18n/icu_string_conversions.h"
	#include "cobalt/base/polymorphic_downcast.h"
	#include "cobalt/base/unicode/character.h"
	#include "cobalt/base/unicode/character_values.h"
	#include "cobalt/renderer/rasterizer/skia/glyph_buffer.h"
	#include "cobalt/renderer/rasterizer/skia/harfbuzz_font.h"

	namespace cobalt {
	namespace renderer {
	namespace rasterizer {
	namespace skia {
	namespace {

	// A simple implementation of FontProvider where a single font is always used.
	class SingleFontFontProvider : public render_tree::FontProvider {
	public:
	explicit SingleFontFontProvider(const scoped_refptr<render_tree::Font>& font)
	: size_(base::polymorphic_downcast<Font*>(font.get())->size()),
	font_(font) {}

	const render_tree::FontStyle& style() const override { return style_; }
	float size() const override { return size_; }

	const scoped_refptr<render_tree::Font>& GetCharacterFont(
	int32 utf32_character, render_tree::GlyphIndex* glyph_index) override {
	*glyph_index = font_->GetGlyphForCharacter(utf32_character);
	return font_;
	}

	private:
	render_tree::FontStyle style_;
	float size_;
	scoped_refptr<render_tree::Font> font_;
	};

	void TryAddFontToUsedFonts(Font* font,
	render_tree::FontVector* maybe_used_fonts) {
	if (!maybe_used_fonts) {
	return;
	}

	// Verify that the font has not already been added to the used fonts, before
	// adding it to the end.
	for (int i = 0; i < maybe_used_fonts->size(); ++i) {
	if ((*maybe_used_fonts)[i] == font) {
	return;
	}
	}

	maybe_used_fonts->push_back(font);
	}

	bool ShouldFakeBoldText(const render_tree::FontProvider* font_provider,
	const Font* font) {
	// A font-weight greater than 500 indicates bold if it is available. Use
	// synthetic bolding if this is a bold weight and the selected font
	// synthesizes bold.
	// https://www.w3.org/TR/css-fonts-3/#font-weight-prop
	// https://www.w3.org/TR/css-fonts-3/#font-style-matching
	if (font_provider->style().weight > 500) {
	const sk_sp<SkTypeface_Cobalt>& typeface(font->GetSkTypeface());
	return typeface->synthesizes_bold();
	}
	return false;
	}

	} // namespace

	TextShaper::TextShaper()
	: local_glyph_array_size_(0), local_text_buffer_size_(0) {}

	scoped_refptr<GlyphBuffer> TextShaper::CreateGlyphBuffer(
	const char16* text_buffer, size_t text_length, const std::string& language,
	bool is_rtl, render_tree::FontProvider* font_provider) {
	math::RectF bounds;
	SkTextBlobBuilder builder;
	ShapeText(text_buffer, text_length, language, is_rtl, font_provider, &builder,
	&bounds, NULL);
	return make_scoped_refptr(new GlyphBuffer(bounds, &builder));
	}

	scoped_refptr<GlyphBuffer> TextShaper::CreateGlyphBuffer(
	const std::string& utf8_string,
	const scoped_refptr<render_tree::Font>& font) {
	string16 utf16_string;
	base::CodepageToUTF16(utf8_string, base::kCodepageUTF8,
	base::OnStringConversionError::SUBSTITUTE,
	&utf16_string);
	SingleFontFontProvider font_provider(font);
	return CreateGlyphBuffer(utf16_string.c_str(), utf16_string.size(), "en-US",
	false, &font_provider);
	}

	float TextShaper::GetTextWidth(const char16* text_buffer, size_t text_length,
	const std::string& language, bool is_rtl,
	render_tree::FontProvider* font_provider,
	render_tree::FontVector* maybe_used_fonts) {
	return ShapeText(text_buffer, text_length, language, is_rtl, font_provider,
	NULL, NULL, maybe_used_fonts);
	}

	void TextShaper::PurgeCaches() {
	base::AutoLock lock(shaping_mutex_);
	harfbuzz_font_provider_.PurgeCaches();
	}

	float TextShaper::ShapeText(const char16* text_buffer, size_t text_length,
	const std::string& language, bool is_rtl,
	render_tree::FontProvider* font_provider,
	SkTextBlobBuilder* maybe_builder,
	math::RectF* maybe_bounds,
	render_tree::FontVector* maybe_used_fonts) {
	base::AutoLock lock(shaping_mutex_);
	float total_width = 0;
	VerticalBounds vertical_bounds;
	// Only set \|maybe_vertical_bounds\| to a non-NULL value when \|maybe_bounds\| is
	// non-NULL. Otherwise, the text bounds are not being calculated.
	VerticalBounds* maybe_vertical_bounds =
	maybe_bounds ? &vertical_bounds : NULL;

	// Check for if the text contains a complex script, meaning that it requires
	// HarfBuzz. If it does, then attempt to collect the scripts. In the event
	// that this fails, fall back to the simple shaper.
	ScriptRuns script_runs;
	if (base::unicode::ContainsComplexScript(text_buffer, text_length) &&
	CollectScriptRuns(text_buffer, text_length, font_provider,
	&script_runs)) {
	// If the direction is RTL, then reverse the script runs, so that the glyphs
	// will be added in the correct order.
	if (is_rtl) {
	std::reverse(script_runs.begin(), script_runs.end());
	}

	for (int i = 0; i < script_runs.size(); ++i) {
	ScriptRun& run = script_runs[i];
	const char16* script_run_text_buffer = text_buffer + run.start_index;

	// Check to see if the script run requires HarfBuzz. Because HarfBuzz
	// shaping is much slower than simple shaping, we only want to run
	// HarfBuzz shaping on the bare minimum possible, so any script run
	// that doesn't contain complex scripts will be simply shaped.
	if (base::unicode::ContainsComplexScript(script_run_text_buffer,
	run.length)) {
	ShapeComplexRun(script_run_text_buffer, run, language, is_rtl,
	font_provider, maybe_builder, maybe_vertical_bounds,
	maybe_used_fonts, &total_width);
	} else {
	ShapeSimpleRunWithDirection(script_run_text_buffer, run.length, is_rtl,
	font_provider, maybe_builder,
	maybe_vertical_bounds, maybe_used_fonts,
	&total_width);
	}
	}
	} else {
	ShapeSimpleRunWithDirection(text_buffer, text_length, is_rtl, font_provider,
	maybe_builder, maybe_vertical_bounds,
	maybe_used_fonts, &total_width);
	}

	// If \|maybe_bounds\| has been provided, then update the width of the bounds
	// with the total width of all of the shaped glyphs. The height is already
	// correct.
	if (maybe_bounds) {
	*maybe_bounds = math::RectF(0, vertical_bounds.GetY(), total_width,
	vertical_bounds.GetHeight());
	}

	return total_width;
	}

	bool TextShaper::CollectScriptRuns(const char16* text_buffer,
	size_t text_length,
	render_tree::FontProvider* font_provider,
	ScriptRuns* runs) {
	// Initialize the next data with the first character. This allows us to avoid
	// checking for the first character case within the while loop.
	int32 next_character = base::unicode::NormalizeSpaces(
	base::i18n::UTF16CharIterator(text_buffer, text_length).get());
	render_tree::GlyphIndex next_glyph = render_tree::kInvalidGlyphIndex;
	Font* next_font = base::polymorphic_downcast<Font*>(
	font_provider->GetCharacterFont(next_character, &next_glyph).get());

	UErrorCode error_code = U_ZERO_ERROR;
	UScriptCode next_script = uscript_getScript(next_character, &error_code);
	// If we're unable to determine the script of a character, we failed to
	// successfully collect the script runs. Return failure.
	if (U_FAILURE(error_code)) {
	return false;
	}

	// Iterate for as long as the current index has not reached the end index.
	unsigned int current_index = 0;
	unsigned int end_index = text_length;
	while (current_index < end_index) {
	Font* current_font = next_font;
	UScriptCode current_script = next_script;

	// Create an iterator starting at the current index and containing the
	// remaining length.
	base::i18n::UTF16CharIterator iter(text_buffer + current_index,
	end_index - current_index);
	// Skip over the first character. It's already set as our current font
	// and current script.
	iter.Advance();
	size_t next_index_offset = iter.array_pos();

	for (; !iter.end(); iter.Advance(), next_index_offset = iter.array_pos()) {
	// Normalize spaces within the current character, so that we are
	// guaranteed that they will map to a consistent font and glyph.
	next_character = base::unicode::NormalizeSpaces(iter.get());
	if (next_character == base::unicode::kZeroWidthSpaceCharacter) {
	continue;
	}

	// Check for mark characters. If this is a mark character and the current
	// font contains a glyph for it, then simply add it to the current run.
	// Doing so ensures that combining character sequences will be shaped in
	// one font run if possible.
	if ((U_GET_GC_MASK(next_character) & U_GC_M_MASK) &&
	(current_font->GetGlyphForCharacter(next_character) !=
	render_tree::kInvalidGlyphIndex)) {
	continue;
	}

	next_font = base::polymorphic_downcast<Font*>(
	font_provider->GetCharacterFont(next_character, &next_glyph).get());

	next_script = uscript_getScript(next_character, &error_code);
	// If we're unable to determine the script of a character, we failed to
	// successfully collect the script runs. Return failure.
	if (U_FAILURE(error_code)) {
	return false;
	}

	// We've reached the end of the script run in two cases:
	// 1. If the characters use different fonts.
	// 2. If the characters use different scripts, the next script isn't
	// inherited, and the next character doesn't support the current
	// script.
	if ((current_font != next_font) \|\|
	((current_script != next_script) &&
	(next_script != USCRIPT_INHERITED) &&
	(!uscript_hasScript(next_character, current_script)))) {
	break;
	}

	// If the script is inherited, then simply retain the current script.
	if (next_script == USCRIPT_INHERITED) {
	next_script = current_script;
	}
	}

	runs->push_back(ScriptRun(current_font, current_script, current_index,
	next_index_offset));

	// Update the index where we're starting the next script run.
	current_index += next_index_offset;
	}

	return true;
	}

	void TextShaper::ShapeComplexRun(const char16* text_buffer,
	const ScriptRun& script_run,
	const std::string& language, bool is_rtl,
	render_tree::FontProvider* font_provider,
	SkTextBlobBuilder* maybe_builder,
	VerticalBounds* maybe_vertical_bounds,
	render_tree::FontVector* maybe_used_fonts,
	float* total_width) {
	TryAddFontToUsedFonts(script_run.font, maybe_used_fonts);

	hb_font_t* harfbuzz_font =
	harfbuzz_font_provider_.GetHarfBuzzFont(script_run.font);

	// Ensure that the local text buffer is large enough to hold the normalized
	// string.
	EnsureLocalTextBufferHasSize(script_run.length);

	// Normalize the spaces in the run before providing it to HarfBuzz.
	bool error = false;
	unsigned int normalized_buffer_length = 0;
	unsigned int buffer_position = 0;
	while (buffer_position < script_run.length) {
	UChar32 character;
	U16_NEXT(text_buffer, buffer_position, script_run.length, character);
	character = base::unicode::NormalizeSpacesInComplexScript(character);
	U16_APPEND(local_text_buffer_.get(), normalized_buffer_length,
	script_run.length, character, error);
	}

	// Create a HarfBuzz buffer and add the string to be shaped. The HarfBuzz
	// buffer holds our text, run information to be used by the shaping engine,
	// and the resulting glyph data.
	hb_buffer_t* buffer = hb_buffer_create();
	hb_buffer_add_utf16(buffer, (const uint16_t*)local_text_buffer_.get(),
	normalized_buffer_length, 0, normalized_buffer_length);
	hb_buffer_set_script(buffer, hb_icu_script_to_script(script_run.script));
	hb_buffer_set_direction(buffer, is_rtl ? HB_DIRECTION_RTL : HB_DIRECTION_LTR);
	hb_buffer_set_language(
	buffer, hb_language_from_string(language.c_str(), language.length()));

	// Shape the text.
	hb_shape(harfbuzz_font, buffer, NULL, 0);

	// Populate the run fields with the resulting glyph data in the buffer.
	unsigned int glyph_count = 0;

	hb_glyph_info_t* infos = hb_buffer_get_glyph_infos(buffer, &glyph_count);
	hb_glyph_position_t* hb_positions =
	hb_buffer_get_glyph_positions(buffer, NULL);

	// If \|maybe_builder\| has been provided, the allocate enough memory within
	// the builder for the shaped glyphs.
	const SkTextBlobBuilder::RunBuffer* run_buffer = NULL;
	if (maybe_builder) {
	SkPaint paint = script_run.font->GetSkPaint();
	paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
	paint.setFakeBoldText(ShouldFakeBoldText(font_provider, script_run.font));
	run_buffer = &(maybe_builder->allocRunPos(paint, glyph_count));
	}

	// Walk each of the shaped glyphs.
	size_t pos_index = 0;
	for (size_t i = 0; i < glyph_count; ++i) {
	DCHECK_LE(infos[i].codepoint, std::numeric_limits<uint16_t>::max());
	// If \|run_buffer\| has been allocated, then we're populating it with the
	// glyph and position data.
	if (run_buffer) {
	run_buffer->glyphs[i] = static_cast<uint16_t>(infos[i].codepoint);
	run_buffer->pos[pos_index++] =
	*total_width + SkFixedToScalar(hb_positions[i].x_offset);
	run_buffer->pos[pos_index++] = -SkFixedToScalar(hb_positions[i].y_offset);
	}

	// If \|maybe_vertical_bounds\| has been provided, then we're updating it with
	// the vertical bounds of all of the shaped glyphs.
	if (maybe_vertical_bounds) {
	const math::RectF& glyph_bounds =
	script_run.font->GetGlyphBounds(infos[i].codepoint);
	float min_y =
	glyph_bounds.y() - SkFixedToScalar(hb_positions[i].y_offset);
	float max_y = min_y + glyph_bounds.height();
	maybe_vertical_bounds->IncludeRange(min_y, max_y);
	}

	// Include the shaped glyph within the total width.
	*total_width += SkFixedToFloat(hb_positions[i].x_advance);
	}

	hb_buffer_destroy(buffer);
	hb_font_destroy(harfbuzz_font);
	}

	void TextShaper::ShapeSimpleRunWithDirection(
	const char16* text_buffer, size_t text_length, bool is_rtl,
	render_tree::FontProvider* font_provider, SkTextBlobBuilder* maybe_builder,
	VerticalBounds* maybe_vertical_bounds,
	render_tree::FontVector* maybe_used_fonts, float* total_width) {
	// If the text has an RTL direction and a builder was provided, then reverse
	// the text. This ensures that the glyphs will appear in the proper order
	// within the glyph buffer. The width and bounds do not rely on the direction
	// of the text, so in the case where there is no builder, reversing the text
	// is not necessary.
	if (maybe_builder && is_rtl) {
	// Ensure that the local text buffer is large enough to hold the reversed
	// string.
	EnsureLocalTextBufferHasSize(text_length);

	// Both reverse the text and replace mirror characters so that characters
	// such as parentheses will appear in the proper direction.
	bool error = false;
	unsigned int reversed_buffer_length = 0;
	unsigned int buffer_position = text_length;
	while (buffer_position > 0) {
	UChar32 character;
	U16_PREV(text_buffer, 0, buffer_position, character);
	character = u_charMirror(character);
	U16_APPEND(local_text_buffer_.get(), reversed_buffer_length, text_length,
	character, error);
	}

	ShapeSimpleRun(local_text_buffer_.get(), reversed_buffer_length,
	font_provider, maybe_builder, maybe_vertical_bounds,
	maybe_used_fonts, total_width);
	} else {
	ShapeSimpleRun(text_buffer, text_length, font_provider, maybe_builder,
	maybe_vertical_bounds, maybe_used_fonts, total_width);
	}
	}

	void TextShaper::ShapeSimpleRun(const char16* text_buffer, size_t text_length,
	render_tree::FontProvider* font_provider,
	SkTextBlobBuilder* maybe_builder,
	VerticalBounds* maybe_vertical_bounds,
	render_tree::FontVector* maybe_used_fonts,
	float* total_width) {
	// If there's a builder (meaning that a glyph buffer is being generated), then
	// ensure that the local arrays are large enough to hold all of the glyphs
	// within the simple run.
	if (maybe_builder) {
	EnsureLocalGlyphArraysHaveSize(text_length);
	}

	int glyph_count = 0;
	Font* last_font = NULL;

	// Walk through each character within the run.
	for (base::i18n::UTF16CharIterator iter(text_buffer, text_length);
	!iter.end(); iter.Advance()) {
	// Retrieve the current character and normalize spaces and zero width
	// spaces before processing it.
	int32 character = base::unicode::NormalizeSpaces(iter.get());
	render_tree::GlyphIndex glyph = render_tree::kInvalidGlyphIndex;

	// If a space character is encountered, simply add to the width and continue
	// on. As an optimization, we don't add space character glyphs to the glyph
	// buffer.
	if (character == base::unicode::kSpaceCharacter) {
	*total_width += font_provider->GetCharacterFont(character, &glyph)
	->GetGlyphWidth(glyph);
	continue;
	// If a zero width space character is encountered, simply continue on. It
	// doesn't impact the width or shaping data.
	} else if (character == base::unicode::kZeroWidthSpaceCharacter) {
	continue;
	}

	// Look up the font and glyph for the current character.
	Font* current_font = base::polymorphic_downcast<Font*>(
	font_provider->GetCharacterFont(character, &glyph).get());

	// If there's a builder (meaning that a glyph buffer is being generated),
	// then we need to update the glyph buffer data for the new glyph.
	if (maybe_builder) {
	// If at least one glyph has previously been added and the font has
	// changed, then the current run has ended and we need to add the font run
	// into the glyph buffer.
	if (glyph_count > 0 && last_font != current_font) {
	TryAddFontToUsedFonts(last_font, maybe_used_fonts);
	AddFontRunToGlyphBuffer(font_provider, last_font, glyph_count,
	maybe_builder);
	glyph_count = 0;
	}

	local_glyphs_[glyph_count] = glyph;
	local_positions_[glyph_count] = *total_width;
	}

	const math::RectF& glyph_bounds = current_font->GetGlyphBounds(glyph);
	*total_width += glyph_bounds.width();

	// If \|maybe_vertical_bounds\| has been provided, then we're updating it with
	// the vertical bounds of all of the shaped glyphs.
	if (maybe_vertical_bounds) {
	maybe_vertical_bounds->IncludeRange(glyph_bounds.y(),
	glyph_bounds.bottom());
	}

	++glyph_count;
	last_font = current_font;
	}

	// If there's a builder (meaning that a glyph buffer is being generated), and
	// at least one glyph was generated, then we need to add the final font run
	// into the glyph buffer.
	if (maybe_builder && glyph_count > 0) {
	TryAddFontToUsedFonts(last_font, maybe_used_fonts);
	AddFontRunToGlyphBuffer(font_provider, last_font, glyph_count,
	maybe_builder);
	}
	}

	void TextShaper::AddFontRunToGlyphBuffer(
	const render_tree::FontProvider* font_provider, const Font* font,
	const int glyph_count, SkTextBlobBuilder* builder) {
	SkPaint paint = font->GetSkPaint();
	paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
	paint.setFakeBoldText(ShouldFakeBoldText(font_provider, font));

	// Allocate space within the text blob for the glyphs and copy them into the
	// blob.
	const SkTextBlobBuilder::RunBuffer& buffer =
	builder->allocRunPosH(paint, glyph_count, 0);
	std::copy(&local_glyphs_[0], &local_glyphs_[0] + glyph_count, buffer.glyphs);
	std::copy(&local_positions_[0], &local_positions_[0] + glyph_count,
	buffer.pos);
	}

	void TextShaper::EnsureLocalGlyphArraysHaveSize(size_t size) {
	if (local_glyph_array_size_ < size) {
	local_glyph_array_size_ = size;
	local_glyphs_.reset(new render_tree::GlyphIndex[size]);
	local_positions_.reset(new SkScalar[size]);
	}
	}

	void TextShaper::EnsureLocalTextBufferHasSize(size_t size) {
	if (local_text_buffer_size_ < size) {
	local_text_buffer_size_ = size;
	local_text_buffer_.reset(new char16[size]);
	}
	}

	} // namespace skia
	} // namespace rasterizer
	} // namespace renderer
	} // namespace cobalt