third_party/WebKit/Source/platform/fonts/shaping/HarfBuzzShaper.h - chromium/src - Git at Google

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
  * copyright notice, this list of conditions and the following disclaimer
  * in the documentation and/or other materials provided with the
  * distribution.
  *     * Neither the name of Google Inc. nor the names of its
  * contributors may be used to endorse or promote products derived from
  * this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */

 #ifndef HarfBuzzShaper_h
 #define HarfBuzzShaper_h

 #include "platform/fonts/FontDescription.h"
 #include "platform/fonts/SmallCapsIterator.h"
 #include "platform/fonts/shaping/ShapeResult.h"
 #include "platform/fonts/shaping/Shaper.h"
 #include "platform/geometry/FloatPoint.h"
 #include "platform/geometry/FloatRect.h"
 #include "platform/text/TextRun.h"
 #include "wtf/Allocator.h"
 #include "wtf/Deque.h"
 #include "wtf/HashSet.h"
 #include "wtf/Vector.h"
 #include "wtf/text/CharacterNames.h"
 #include <hb.h>
 #include <memory>
 #include <unicode/uscript.h>

 namespace blink {

 class Font;
 class GlyphBuffer;
 class SimpleFontData;
 class HarfBuzzShaper;
 class UnicodeRangeSet;

 // Shaping text runs is split into several stages: Run segmentation, shaping the
 // initial segment, identify shaped and non-shaped sequences of the shaping
 // result, and processing sub-runs by trying to shape them with a fallback font
 // until the last resort font is reached.
 //
 // If caps formatting is requested, an additional lowercase/uppercase
 // segmentation stage is required. In this stage, OpenType features in the font
 // are matched against the requested formatting and formatting is synthesized as
 // required by the CSS Level 3 Fonts Module.
 //
 // Going through one example - for simplicity without caps formatting - to
 // illustrate the process: The following is a run of vertical text to be
 // shaped. After run segmentation in RunSegmenter it is split into 4
 // segments. The segments indicated by the segementation results showing the
 // script, orientation information and small caps handling of the individual
 // segment. The Japanese text at the beginning has script "Hiragana", does not
 // need rotation when laid out vertically and does not need uppercasing when
 // small caps is requested.
 //
 // 0 い
 // 1 ろ
 // 2 は USCRIPT_HIRAGANA,
 //     OrientationIterator::OrientationKeep,
 //     SmallCapsIterator::SmallCapsSameCase
 //
 // 3 a
 // 4 ̄ (Combining Macron)
 // 5 a
 // 6 A USCRIPT_LATIN,
 //     OrientationIterator::OrientationRotateSideways,
 //     SmallCapsIterator::SmallCapsUppercaseNeeded
 //
 // 7 い
 // 8 ろ
 // 9 は USCRIPT_HIRAGANA,
 //      OrientationIterator::OrientationKeep,
 //      SmallCapsIterator::SmallCapsSameCase
 //
 //
 // Let's assume the CSS for this text run is as follows:
 //     font-family: "Heiti SC", Tinos, sans-serif;
 // where Tinos is a web font, defined as a composite font, with two sub ranges,
 // one for Latin U+00-U+FF and one unrestricted unicode-range.
 //
 // FontFallbackIterator provides the shaper with Heiti SC, then Tinos of the
 // restricted unicode-range, then the unrestricted full unicode-range Tinos,
 // then a system sans-serif.
 //
 // The initial segment 0-2 to the shaper, together with the segmentation
 // properties and the initial Heiti SC font. Characters 0-2 are shaped
 // successfully with Heiti SC. The next segment, 3-5 is passed to the shaper.
 // The shaper attempts to shape it with Heiti SC, which fails for the Combining
 // Macron. So the shaping result for this segment would look similar to this.
 //
 // Glyphpos: 0 1 2 3
 // Cluster:  0 0 2 3
 // Glyph:    a x a A (where x is .notdef)
 //
 // Now in the extractShapeResults() step we notice that there is more work to
 // do, since Heiti SC does not have a glyph for the Combining Macron combined
 // with an a. So, this cluster together with a Todo item for switching to the
 // next font is put into HolesQueue.
 //
 // After shaping the initial segment, the remaining items in the HolesQueue are
 // processed, picking them from the head of the queue. So, first, the next font
 // is requested from the FontFallbackIterator. In this case, Tinos (for the
 // range U+00-U+FF) comes back. Shaping using this font, assuming it is
 // subsetted, fails again since there is no combining mark available. This
 // triggers requesting yet another font. This time, the Tinos font for the full
 // range. With this, shaping succeeds with the following HarfBuzz result:
 //
 //  Glyphpos 0 1 2 3
 //  Cluster: 0 0 2 3
 //  Glyph:   a ̄ a A (with glyph coordinates placing the ̄ above the first a)
 //
 // Now this sub run is successfully processed and can be appended to
 // ShapeResult. A new ShapeResult::RunInfo is created. The logic in
 // insertRunIntoShapeResult then takes care of merging the shape result into
 // the right position the vector of RunInfos in ShapeResult.
 //
 // Shaping then continues analogously for the remaining Hiragana Japanese
 // sub-run, and the result is inserted into ShapeResult as well.
 class PLATFORM_EXPORT HarfBuzzShaper final : public Shaper {
  public:
   HarfBuzzShaper(const Font*, const TextRun&);
   PassRefPtr<ShapeResult> shapeResult();
   ~HarfBuzzShaper() {}

   enum HolesQueueItemAction { HolesQueueNextFont, HolesQueueRange };

   struct HolesQueueItem {
     DISALLOW_NEW_EXCEPT_PLACEMENT_NEW();
     HolesQueueItemAction m_action;
     unsigned m_startIndex;
     unsigned m_numCharacters;
     HolesQueueItem(HolesQueueItemAction action, unsigned start, unsigned num)
         : m_action(action), m_startIndex(start), m_numCharacters(num){};
   };

  protected:
   using FeaturesVector = Vector<hb_feature_t, 6>;

   class CapsFeatureSettingsScopedOverlay final {
     STACK_ALLOCATED()

    public:
     CapsFeatureSettingsScopedOverlay(FeaturesVector&,
                                      FontDescription::FontVariantCaps);
     CapsFeatureSettingsScopedOverlay() = delete;
     ~CapsFeatureSettingsScopedOverlay();

    private:
     void overlayCapsFeatures(FontDescription::FontVariantCaps);
     void prependCounting(const hb_feature_t&);
     FeaturesVector& m_features;
     size_t m_countFeatures;
   };

  private:
   void setFontFeatures();

   void appendToHolesQueue(HolesQueueItemAction,
                           unsigned startIndex,
                           unsigned numCharacters);
   void prependHolesQueue(HolesQueueItemAction,
                          unsigned startIndex,
                          unsigned numCharacters);
   void splitUntilNextCaseChange(HolesQueueItem& currentQueueItem,
                                 SmallCapsIterator::SmallCapsBehavior&);
   inline bool shapeRange(hb_buffer_t* harfBuzzBuffer,
                          unsigned startIndex,
                          unsigned numCharacters,
                          const SimpleFontData* currentFont,
                          PassRefPtr<UnicodeRangeSet> currentFontRangeSet,
                          UScriptCode currentRunScript,
                          hb_language_t);
   bool extractShapeResults(hb_buffer_t* harfBuzzBuffer,
                            ShapeResult*,
                            bool& fontCycleQueued,
                            const HolesQueueItem& currentQueueItem,
                            const SimpleFontData* currentFont,
                            UScriptCode currentRunScript,
                            bool isLastResort);
   bool collectFallbackHintChars(Vector<UChar32>& hint);

   void insertRunIntoShapeResult(
       ShapeResult*,
       std::unique_ptr<ShapeResult::RunInfo> runToInsert,
       unsigned startGlyph,
       unsigned numGlyphs,
       hb_buffer_t*);

   std::unique_ptr<UChar[]> m_normalizedBuffer;
   unsigned m_normalizedBufferLength;

   FeaturesVector m_features;
   Deque<HolesQueueItem> m_holesQueue;
 };

 }  // namespace blink

 #endif  // HarfBuzzShaper_h
	/*
	* Copyright (C) 2012 Google Inc. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions are
	* met:
	*
	* * Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	* * Redistributions in binary form must reproduce the above
	* copyright notice, this list of conditions and the following disclaimer
	* in the documentation and/or other materials provided with the
	* distribution.
	* * Neither the name of Google Inc. nor the names of its
	* contributors may be used to endorse or promote products derived from
	* this software without specific prior written permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/

	#ifndef HarfBuzzShaper_h
	#define HarfBuzzShaper_h

	#include "platform/fonts/FontDescription.h"
	#include "platform/fonts/SmallCapsIterator.h"
	#include "platform/fonts/shaping/ShapeResult.h"
	#include "platform/fonts/shaping/Shaper.h"
	#include "platform/geometry/FloatPoint.h"
	#include "platform/geometry/FloatRect.h"
	#include "platform/text/TextRun.h"
	#include "wtf/Allocator.h"
	#include "wtf/Deque.h"
	#include "wtf/HashSet.h"
	#include "wtf/Vector.h"
	#include "wtf/text/CharacterNames.h"
	#include <hb.h>
	#include <memory>
	#include <unicode/uscript.h>

	namespace blink {

	class Font;
	class GlyphBuffer;
	class SimpleFontData;
	class HarfBuzzShaper;
	class UnicodeRangeSet;

	// Shaping text runs is split into several stages: Run segmentation, shaping the
	// initial segment, identify shaped and non-shaped sequences of the shaping
	// result, and processing sub-runs by trying to shape them with a fallback font
	// until the last resort font is reached.
	//
	// If caps formatting is requested, an additional lowercase/uppercase
	// segmentation stage is required. In this stage, OpenType features in the font
	// are matched against the requested formatting and formatting is synthesized as
	// required by the CSS Level 3 Fonts Module.
	//
	// Going through one example - for simplicity without caps formatting - to
	// illustrate the process: The following is a run of vertical text to be
	// shaped. After run segmentation in RunSegmenter it is split into 4
	// segments. The segments indicated by the segementation results showing the
	// script, orientation information and small caps handling of the individual
	// segment. The Japanese text at the beginning has script "Hiragana", does not
	// need rotation when laid out vertically and does not need uppercasing when
	// small caps is requested.
	//
	// 0 い
	// 1 ろ
	// 2 は USCRIPT_HIRAGANA,
	// OrientationIterator::OrientationKeep,
	// SmallCapsIterator::SmallCapsSameCase
	//
	// 3 a
	// 4 ̄ (Combining Macron)
	// 5 a
	// 6 A USCRIPT_LATIN,
	// OrientationIterator::OrientationRotateSideways,
	// SmallCapsIterator::SmallCapsUppercaseNeeded
	//
	// 7 い
	// 8 ろ
	// 9 は USCRIPT_HIRAGANA,
	// OrientationIterator::OrientationKeep,
	// SmallCapsIterator::SmallCapsSameCase
	//
	//
	// Let's assume the CSS for this text run is as follows:
	// font-family: "Heiti SC", Tinos, sans-serif;
	// where Tinos is a web font, defined as a composite font, with two sub ranges,
	// one for Latin U+00-U+FF and one unrestricted unicode-range.
	//
	// FontFallbackIterator provides the shaper with Heiti SC, then Tinos of the
	// restricted unicode-range, then the unrestricted full unicode-range Tinos,
	// then a system sans-serif.
	//
	// The initial segment 0-2 to the shaper, together with the segmentation
	// properties and the initial Heiti SC font. Characters 0-2 are shaped
	// successfully with Heiti SC. The next segment, 3-5 is passed to the shaper.
	// The shaper attempts to shape it with Heiti SC, which fails for the Combining
	// Macron. So the shaping result for this segment would look similar to this.
	//
	// Glyphpos: 0 1 2 3
	// Cluster: 0 0 2 3
	// Glyph: a x a A (where x is .notdef)
	//
	// Now in the extractShapeResults() step we notice that there is more work to
	// do, since Heiti SC does not have a glyph for the Combining Macron combined
	// with an a. So, this cluster together with a Todo item for switching to the
	// next font is put into HolesQueue.
	//
	// After shaping the initial segment, the remaining items in the HolesQueue are
	// processed, picking them from the head of the queue. So, first, the next font
	// is requested from the FontFallbackIterator. In this case, Tinos (for the
	// range U+00-U+FF) comes back. Shaping using this font, assuming it is
	// subsetted, fails again since there is no combining mark available. This
	// triggers requesting yet another font. This time, the Tinos font for the full
	// range. With this, shaping succeeds with the following HarfBuzz result:
	//
	// Glyphpos 0 1 2 3
	// Cluster: 0 0 2 3
	// Glyph: a ̄ a A (with glyph coordinates placing the ̄ above the first a)
	//
	// Now this sub run is successfully processed and can be appended to
	// ShapeResult. A new ShapeResult::RunInfo is created. The logic in
	// insertRunIntoShapeResult then takes care of merging the shape result into
	// the right position the vector of RunInfos in ShapeResult.
	//
	// Shaping then continues analogously for the remaining Hiragana Japanese
	// sub-run, and the result is inserted into ShapeResult as well.
	class PLATFORM_EXPORT HarfBuzzShaper final : public Shaper {
	public:
	HarfBuzzShaper(const Font*, const TextRun&);
	PassRefPtr<ShapeResult> shapeResult();
	~HarfBuzzShaper() {}

	enum HolesQueueItemAction { HolesQueueNextFont, HolesQueueRange };

	struct HolesQueueItem {
	DISALLOW_NEW_EXCEPT_PLACEMENT_NEW();
	HolesQueueItemAction m_action;
	unsigned m_startIndex;
	unsigned m_numCharacters;
	HolesQueueItem(HolesQueueItemAction action, unsigned start, unsigned num)
	: m_action(action), m_startIndex(start), m_numCharacters(num){};
	};

	protected:
	using FeaturesVector = Vector<hb_feature_t, 6>;

	class CapsFeatureSettingsScopedOverlay final {
	STACK_ALLOCATED()

	public:
	CapsFeatureSettingsScopedOverlay(FeaturesVector&,
	FontDescription::FontVariantCaps);
	CapsFeatureSettingsScopedOverlay() = delete;
	~CapsFeatureSettingsScopedOverlay();

	private:
	void overlayCapsFeatures(FontDescription::FontVariantCaps);
	void prependCounting(const hb_feature_t&);
	FeaturesVector& m_features;
	size_t m_countFeatures;
	};

	private:
	void setFontFeatures();

	void appendToHolesQueue(HolesQueueItemAction,
	unsigned startIndex,
	unsigned numCharacters);
	void prependHolesQueue(HolesQueueItemAction,
	unsigned startIndex,
	unsigned numCharacters);
	void splitUntilNextCaseChange(HolesQueueItem& currentQueueItem,
	SmallCapsIterator::SmallCapsBehavior&);
	inline bool shapeRange(hb_buffer_t* harfBuzzBuffer,
	unsigned startIndex,
	unsigned numCharacters,
	const SimpleFontData* currentFont,
	PassRefPtr<UnicodeRangeSet> currentFontRangeSet,
	UScriptCode currentRunScript,
	hb_language_t);
	bool extractShapeResults(hb_buffer_t* harfBuzzBuffer,
	ShapeResult*,
	bool& fontCycleQueued,
	const HolesQueueItem& currentQueueItem,
	const SimpleFontData* currentFont,
	UScriptCode currentRunScript,
	bool isLastResort);
	bool collectFallbackHintChars(Vector<UChar32>& hint);

	void insertRunIntoShapeResult(
	ShapeResult*,
	std::unique_ptr<ShapeResult::RunInfo> runToInsert,
	unsigned startGlyph,
	unsigned numGlyphs,
	hb_buffer_t*);

	std::unique_ptr<UChar[]> m_normalizedBuffer;
	unsigned m_normalizedBufferLength;

	FeaturesVector m_features;
	Deque<HolesQueueItem> m_holesQueue;
	};

	} // namespace blink

	#endif // HarfBuzzShaper_h