src/core/SkFontMgr.cpp - skia - Git at Google

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 #include "SkFontDescriptor.h"
 #include "SkFontMgr.h"
 #include "SkOnce.h"
 #include "SkStream.h"
 #include "SkTypes.h"

 class SkFontStyle;
 class SkTypeface;

 class SkEmptyFontStyleSet : public SkFontStyleSet {
 public:
     int count() override { return 0; }
     void getStyle(int, SkFontStyle*, SkString*) override {
         SkDEBUGFAIL("SkFontStyleSet::getStyle called on empty set");
     }
     SkTypeface* createTypeface(int index) override {
         SkDEBUGFAIL("SkFontStyleSet::createTypeface called on empty set");
         return nullptr;
     }
     SkTypeface* matchStyle(const SkFontStyle&) override {
         return nullptr;
     }
 };

 SkFontStyleSet* SkFontStyleSet::CreateEmpty() { return new SkEmptyFontStyleSet; }

 ///////////////////////////////////////////////////////////////////////////////

 class SkEmptyFontMgr : public SkFontMgr {
 protected:
     int onCountFamilies() const override {
         return 0;
     }
     void onGetFamilyName(int index, SkString* familyName) const override {
         SkDEBUGFAIL("onGetFamilyName called with bad index");
     }
     SkFontStyleSet* onCreateStyleSet(int index) const override {
         SkDEBUGFAIL("onCreateStyleSet called with bad index");
         return nullptr;
     }
     SkFontStyleSet* onMatchFamily(const char[]) const override {
         return SkFontStyleSet::CreateEmpty();
     }

     SkTypeface* onMatchFamilyStyle(const char[], const SkFontStyle&) const override {
         return nullptr;
     }
     SkTypeface* onMatchFamilyStyleCharacter(const char familyName[],
                                             const SkFontStyle& style,
                                             const char* bcp47[],
                                             int bcp47Count,
                                             SkUnichar character) const override {
         return nullptr;
     }
     SkTypeface* onMatchFaceStyle(const SkTypeface*, const SkFontStyle&) const override {
         return nullptr;
     }

     sk_sp<SkTypeface> onMakeFromData(sk_sp<SkData>, int) const override {
         return nullptr;
     }
     sk_sp<SkTypeface> onMakeFromStreamIndex(std::unique_ptr<SkStreamAsset>, int) const override {
         return nullptr;
     }
     sk_sp<SkTypeface> onMakeFromStreamArgs(std::unique_ptr<SkStreamAsset>,
                                            const SkFontArguments&) const override {
         return nullptr;
     }
     sk_sp<SkTypeface> onMakeFromFontData(std::unique_ptr<SkFontData>) const override {
         return nullptr;
     }
     sk_sp<SkTypeface> onMakeFromFile(const char[], int) const override {
         return nullptr;
     }
     sk_sp<SkTypeface> onLegacyMakeTypeface(const char [], SkFontStyle) const override {
         return nullptr;
     }
 };

 static SkFontStyleSet* emptyOnNull(SkFontStyleSet* fsset) {
     if (nullptr == fsset) {
         fsset = SkFontStyleSet::CreateEmpty();
     }
     return fsset;
 }

 int SkFontMgr::countFamilies() const {
     return this->onCountFamilies();
 }

 void SkFontMgr::getFamilyName(int index, SkString* familyName) const {
     this->onGetFamilyName(index, familyName);
 }

 SkFontStyleSet* SkFontMgr::createStyleSet(int index) const {
     return emptyOnNull(this->onCreateStyleSet(index));
 }

 SkFontStyleSet* SkFontMgr::matchFamily(const char familyName[]) const {
     return emptyOnNull(this->onMatchFamily(familyName));
 }

 SkTypeface* SkFontMgr::matchFamilyStyle(const char familyName[],
                                         const SkFontStyle& fs) const {
     return this->onMatchFamilyStyle(familyName, fs);
 }

 SkTypeface* SkFontMgr::matchFamilyStyleCharacter(const char familyName[], const SkFontStyle& style,
                                                  const char* bcp47[], int bcp47Count,
                                                  SkUnichar character) const {
     return this->onMatchFamilyStyleCharacter(familyName, style, bcp47, bcp47Count, character);
 }

 SkTypeface* SkFontMgr::matchFaceStyle(const SkTypeface* face,
                                       const SkFontStyle& fs) const {
     return this->onMatchFaceStyle(face, fs);
 }

 sk_sp<SkTypeface> SkFontMgr::makeFromData(sk_sp<SkData> data, int ttcIndex) const {
     if (nullptr == data) {
         return nullptr;
     }
     return this->onMakeFromData(std::move(data), ttcIndex);
 }

 sk_sp<SkTypeface> SkFontMgr::makeFromStream(std::unique_ptr<SkStreamAsset> stream,
                                             int ttcIndex) const {
     if (nullptr == stream) {
         return nullptr;
     }
     return this->onMakeFromStreamIndex(std::move(stream), ttcIndex);
 }

 sk_sp<SkTypeface> SkFontMgr::makeFromStream(std::unique_ptr<SkStreamAsset> stream,
                                             const SkFontArguments& args) const {
     if (nullptr == stream) {
         return nullptr;
     }
     return this->onMakeFromStreamArgs(std::move(stream), args);
 }

 sk_sp<SkTypeface> SkFontMgr::makeFromFontData(std::unique_ptr<SkFontData> data) const {
     if (nullptr == data) {
         return nullptr;
     }
     return this->onMakeFromFontData(std::move(data));
 }

 sk_sp<SkTypeface> SkFontMgr::makeFromFile(const char path[], int ttcIndex) const {
     if (nullptr == path) {
         return nullptr;
     }
     return this->onMakeFromFile(path, ttcIndex);
 }

 sk_sp<SkTypeface> SkFontMgr::legacyMakeTypeface(const char familyName[], SkFontStyle style) const {
     return this->onLegacyMakeTypeface(familyName, style);
 }

 sk_sp<SkTypeface> SkFontMgr::onMakeFromStreamArgs(std::unique_ptr<SkStreamAsset> stream,
                                                   const SkFontArguments& args) const {
     return this->makeFromStream(std::move(stream), args.getCollectionIndex());
 }
 sk_sp<SkTypeface> SkFontMgr::onMakeFromFontData(std::unique_ptr<SkFontData> data) const {
     return this->makeFromStream(data->detachStream(), data->getIndex());
 }

 // A global function pointer that's not declared, but can be overriden at startup by test tools.
 sk_sp<SkFontMgr> (*gSkFontMgr_DefaultFactory)() = nullptr;

 sk_sp<SkFontMgr> SkFontMgr::RefDefault() {
     static SkOnce once;
     static sk_sp<SkFontMgr> singleton;

     once([]{
         sk_sp<SkFontMgr> fm = gSkFontMgr_DefaultFactory ? gSkFontMgr_DefaultFactory()
                                                         : SkFontMgr::Factory();
         singleton = fm ? std::move(fm) : sk_make_sp<SkEmptyFontMgr>();
     });
     return singleton;
 }

 /**
 * Width has the greatest priority.
 * If the value of pattern.width is 5 (normal) or less,
 *    narrower width values are checked first, then wider values.
 * If the value of pattern.width is greater than 5 (normal),
 *    wider values are checked first, followed by narrower values.
 *
 * Italic/Oblique has the next highest priority.
 * If italic requested and there is some italic font, use it.
 * If oblique requested and there is some oblique font, use it.
 * If italic requested and there is some oblique font, use it.
 * If oblique requested and there is some italic font, use it.
 *
 * Exact match.
 * If pattern.weight < 400, weights below pattern.weight are checked
 *   in descending order followed by weights above pattern.weight
 *   in ascending order until a match is found.
 * If pattern.weight > 500, weights above pattern.weight are checked
 *   in ascending order followed by weights below pattern.weight
 *   in descending order until a match is found.
 * If pattern.weight is 400, 500 is checked first
 *   and then the rule for pattern.weight < 400 is used.
 * If pattern.weight is 500, 400 is checked first
 *   and then the rule for pattern.weight < 400 is used.
 */
 SkTypeface* SkFontStyleSet::matchStyleCSS3(const SkFontStyle& pattern) {
     int count = this->count();
     if (0 == count) {
         return nullptr;
     }

     struct Score {
         int score;
         int index;
         Score& operator +=(int rhs) { this->score += rhs; return *this; }
         Score& operator <<=(int rhs) { this->score <<= rhs; return *this; }
         bool operator <(const Score& that) { return this->score < that.score; }
     };

     Score maxScore = { 0, 0 };
     for (int i = 0; i < count; ++i) {
         SkFontStyle current;
         this->getStyle(i, &current, nullptr);
         Score currentScore = { 0, i };

         // CSS stretch / SkFontStyle::Width
         // Takes priority over everything else.
         if (pattern.width() <= SkFontStyle::kNormal_Width) {
             if (current.width() <= pattern.width()) {
                 currentScore += 10 - pattern.width() + current.width();
             } else {
                 currentScore += 10 - current.width();
             }
         } else {
             if (current.width() > pattern.width()) {
                 currentScore += 10 + pattern.width() - current.width();
             } else {
                 currentScore += current.width();
             }
         }
         currentScore <<= 8;

         // CSS style (normal, italic, oblique) / SkFontStyle::Slant (upright, italic, oblique)
         // Takes priority over all valid weights.
         static_assert(SkFontStyle::kUpright_Slant == 0 &&
                       SkFontStyle::kItalic_Slant  == 1 &&
                       SkFontStyle::kOblique_Slant == 2,
                       "SkFontStyle::Slant values not as required.");
         SkASSERT(0 <= pattern.slant() && pattern.slant() <= 2 &&
                  0 <= current.slant() && current.slant() <= 2);
         static const int score[3][3] = {
             /*               Upright Italic Oblique  [current]*/
             /*   Upright */ {   3   ,  1   ,   2   },
             /*   Italic  */ {   1   ,  3   ,   2   },
             /*   Oblique */ {   1   ,  2   ,   3   },
             /* [pattern] */
         };
         currentScore += score[pattern.slant()][current.slant()];
         currentScore <<= 8;

         // Synthetics (weight, style) [no stretch synthetic?]

         // CSS weight / SkFontStyle::Weight
         // The 'closer' to the target weight, the higher the score.
         // 1000 is the 'heaviest' recognized weight
         if (pattern.weight() == current.weight()) {
             currentScore += 1000;
         } else if (pattern.weight() <= 500) {
             if (400 <= pattern.weight() && pattern.weight() < 450) {
                 if (450 <= current.weight() && current.weight() <= 500) {
                     // Artificially boost the 500 weight.
                     // TODO: determine correct number to use.
                     currentScore += 500;
                 }
             }
             if (current.weight() <= pattern.weight()) {
                 currentScore += 1000 - pattern.weight() + current.weight();
             } else {
                 currentScore += 1000 - current.weight();
             }
         } else if (pattern.weight() > 500) {
             if (current.weight() > pattern.weight()) {
                 currentScore += 1000 + pattern.weight() - current.weight();
             } else {
                 currentScore += current.weight();
             }
         }

         if (maxScore < currentScore) {
             maxScore = currentScore;
         }
     }

     return this->createTypeface(maxScore.index);
 }
	/*
	* Copyright 2015 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#include "SkFontDescriptor.h"
	#include "SkFontMgr.h"
	#include "SkOnce.h"
	#include "SkStream.h"
	#include "SkTypes.h"

	class SkFontStyle;
	class SkTypeface;

	class SkEmptyFontStyleSet : public SkFontStyleSet {
	public:
	int count() override { return 0; }
	void getStyle(int, SkFontStyle, SkString) override {
	SkDEBUGFAIL("SkFontStyleSet::getStyle called on empty set");
	}
	SkTypeface* createTypeface(int index) override {
	SkDEBUGFAIL("SkFontStyleSet::createTypeface called on empty set");
	return nullptr;
	}
	SkTypeface* matchStyle(const SkFontStyle&) override {
	return nullptr;
	}
	};

	SkFontStyleSet* SkFontStyleSet::CreateEmpty() { return new SkEmptyFontStyleSet; }

	///////////////////////////////////////////////////////////////////////////////

	class SkEmptyFontMgr : public SkFontMgr {
	protected:
	int onCountFamilies() const override {
	return 0;
	}
	void onGetFamilyName(int index, SkString* familyName) const override {
	SkDEBUGFAIL("onGetFamilyName called with bad index");
	}
	SkFontStyleSet* onCreateStyleSet(int index) const override {
	SkDEBUGFAIL("onCreateStyleSet called with bad index");
	return nullptr;
	}
	SkFontStyleSet* onMatchFamily(const char[]) const override {
	return SkFontStyleSet::CreateEmpty();
	}

	SkTypeface* onMatchFamilyStyle(const char[], const SkFontStyle&) const override {
	return nullptr;
	}
	SkTypeface* onMatchFamilyStyleCharacter(const char familyName[],
	const SkFontStyle& style,
	const char* bcp47[],
	int bcp47Count,
	SkUnichar character) const override {
	return nullptr;
	}
	SkTypeface* onMatchFaceStyle(const SkTypeface*, const SkFontStyle&) const override {
	return nullptr;
	}

	sk_sp<SkTypeface> onMakeFromData(sk_sp<SkData>, int) const override {
	return nullptr;
	}
	sk_sp<SkTypeface> onMakeFromStreamIndex(std::unique_ptr<SkStreamAsset>, int) const override {
	return nullptr;
	}
	sk_sp<SkTypeface> onMakeFromStreamArgs(std::unique_ptr<SkStreamAsset>,
	const SkFontArguments&) const override {
	return nullptr;
	}
	sk_sp<SkTypeface> onMakeFromFontData(std::unique_ptr<SkFontData>) const override {
	return nullptr;
	}
	sk_sp<SkTypeface> onMakeFromFile(const char[], int) const override {
	return nullptr;
	}
	sk_sp<SkTypeface> onLegacyMakeTypeface(const char [], SkFontStyle) const override {
	return nullptr;
	}
	};

	static SkFontStyleSet* emptyOnNull(SkFontStyleSet* fsset) {
	if (nullptr == fsset) {
	fsset = SkFontStyleSet::CreateEmpty();
	}
	return fsset;
	}

	int SkFontMgr::countFamilies() const {
	return this->onCountFamilies();
	}

	void SkFontMgr::getFamilyName(int index, SkString* familyName) const {
	this->onGetFamilyName(index, familyName);
	}

	SkFontStyleSet* SkFontMgr::createStyleSet(int index) const {
	return emptyOnNull(this->onCreateStyleSet(index));
	}

	SkFontStyleSet* SkFontMgr::matchFamily(const char familyName[]) const {
	return emptyOnNull(this->onMatchFamily(familyName));
	}

	SkTypeface* SkFontMgr::matchFamilyStyle(const char familyName[],
	const SkFontStyle& fs) const {
	return this->onMatchFamilyStyle(familyName, fs);
	}

	SkTypeface* SkFontMgr::matchFamilyStyleCharacter(const char familyName[], const SkFontStyle& style,
	const char* bcp47[], int bcp47Count,
	SkUnichar character) const {
	return this->onMatchFamilyStyleCharacter(familyName, style, bcp47, bcp47Count, character);
	}

	SkTypeface* SkFontMgr::matchFaceStyle(const SkTypeface* face,
	const SkFontStyle& fs) const {
	return this->onMatchFaceStyle(face, fs);
	}

	sk_sp<SkTypeface> SkFontMgr::makeFromData(sk_sp<SkData> data, int ttcIndex) const {
	if (nullptr == data) {
	return nullptr;
	}
	return this->onMakeFromData(std::move(data), ttcIndex);
	}

	sk_sp<SkTypeface> SkFontMgr::makeFromStream(std::unique_ptr<SkStreamAsset> stream,
	int ttcIndex) const {
	if (nullptr == stream) {
	return nullptr;
	}
	return this->onMakeFromStreamIndex(std::move(stream), ttcIndex);
	}

	sk_sp<SkTypeface> SkFontMgr::makeFromStream(std::unique_ptr<SkStreamAsset> stream,
	const SkFontArguments& args) const {
	if (nullptr == stream) {
	return nullptr;
	}
	return this->onMakeFromStreamArgs(std::move(stream), args);
	}

	sk_sp<SkTypeface> SkFontMgr::makeFromFontData(std::unique_ptr<SkFontData> data) const {
	if (nullptr == data) {
	return nullptr;
	}
	return this->onMakeFromFontData(std::move(data));
	}

	sk_sp<SkTypeface> SkFontMgr::makeFromFile(const char path[], int ttcIndex) const {
	if (nullptr == path) {
	return nullptr;
	}
	return this->onMakeFromFile(path, ttcIndex);
	}

	sk_sp<SkTypeface> SkFontMgr::legacyMakeTypeface(const char familyName[], SkFontStyle style) const {
	return this->onLegacyMakeTypeface(familyName, style);
	}

	sk_sp<SkTypeface> SkFontMgr::onMakeFromStreamArgs(std::unique_ptr<SkStreamAsset> stream,
	const SkFontArguments& args) const {
	return this->makeFromStream(std::move(stream), args.getCollectionIndex());
	}
	sk_sp<SkTypeface> SkFontMgr::onMakeFromFontData(std::unique_ptr<SkFontData> data) const {
	return this->makeFromStream(data->detachStream(), data->getIndex());
	}

	// A global function pointer that's not declared, but can be overriden at startup by test tools.
	sk_sp<SkFontMgr> (*gSkFontMgr_DefaultFactory)() = nullptr;

	sk_sp<SkFontMgr> SkFontMgr::RefDefault() {
	static SkOnce once;
	static sk_sp<SkFontMgr> singleton;

	once([]{
	sk_sp<SkFontMgr> fm = gSkFontMgr_DefaultFactory ? gSkFontMgr_DefaultFactory()
	: SkFontMgr::Factory();
	singleton = fm ? std::move(fm) : sk_make_sp<SkEmptyFontMgr>();
	});
	return singleton;
	}

	/**
	* Width has the greatest priority.
	* If the value of pattern.width is 5 (normal) or less,
	* narrower width values are checked first, then wider values.
	* If the value of pattern.width is greater than 5 (normal),
	* wider values are checked first, followed by narrower values.
	*
	* Italic/Oblique has the next highest priority.
	* If italic requested and there is some italic font, use it.
	* If oblique requested and there is some oblique font, use it.
	* If italic requested and there is some oblique font, use it.
	* If oblique requested and there is some italic font, use it.
	*
	* Exact match.
	* If pattern.weight < 400, weights below pattern.weight are checked
	* in descending order followed by weights above pattern.weight
	* in ascending order until a match is found.
	* If pattern.weight > 500, weights above pattern.weight are checked
	* in ascending order followed by weights below pattern.weight
	* in descending order until a match is found.
	* If pattern.weight is 400, 500 is checked first
	* and then the rule for pattern.weight < 400 is used.
	* If pattern.weight is 500, 400 is checked first
	* and then the rule for pattern.weight < 400 is used.
	*/
	SkTypeface* SkFontStyleSet::matchStyleCSS3(const SkFontStyle& pattern) {
	int count = this->count();
	if (0 == count) {
	return nullptr;
	}

	struct Score {
	int score;
	int index;
	Score& operator +=(int rhs) { this->score += rhs; return *this; }
	Score& operator <<=(int rhs) { this->score <<= rhs; return *this; }
	bool operator <(const Score& that) { return this->score < that.score; }
	};

	Score maxScore = { 0, 0 };
	for (int i = 0; i < count; ++i) {
	SkFontStyle current;
	this->getStyle(i, &current, nullptr);
	Score currentScore = { 0, i };

	// CSS stretch / SkFontStyle::Width
	// Takes priority over everything else.
	if (pattern.width() <= SkFontStyle::kNormal_Width) {
	if (current.width() <= pattern.width()) {
	currentScore += 10 - pattern.width() + current.width();
	} else {
	currentScore += 10 - current.width();
	}
	} else {
	if (current.width() > pattern.width()) {
	currentScore += 10 + pattern.width() - current.width();
	} else {
	currentScore += current.width();
	}
	}
	currentScore <<= 8;

	// CSS style (normal, italic, oblique) / SkFontStyle::Slant (upright, italic, oblique)
	// Takes priority over all valid weights.
	static_assert(SkFontStyle::kUpright_Slant == 0 &&
	SkFontStyle::kItalic_Slant == 1 &&
	SkFontStyle::kOblique_Slant == 2,
	"SkFontStyle::Slant values not as required.");
	SkASSERT(0 <= pattern.slant() && pattern.slant() <= 2 &&
	0 <= current.slant() && current.slant() <= 2);
	static const int score[3][3] = {
	/* Upright Italic Oblique [current]*/
	/* Upright */ { 3 , 1 , 2 },
	/* Italic */ { 1 , 3 , 2 },
	/* Oblique */ { 1 , 2 , 3 },
	/* [pattern] */
	};
	currentScore += score[pattern.slant()][current.slant()];
	currentScore <<= 8;

	// Synthetics (weight, style) [no stretch synthetic?]

	// CSS weight / SkFontStyle::Weight
	// The 'closer' to the target weight, the higher the score.
	// 1000 is the 'heaviest' recognized weight
	if (pattern.weight() == current.weight()) {
	currentScore += 1000;
	} else if (pattern.weight() <= 500) {
	if (400 <= pattern.weight() && pattern.weight() < 450) {
	if (450 <= current.weight() && current.weight() <= 500) {
	// Artificially boost the 500 weight.
	// TODO: determine correct number to use.
	currentScore += 500;
	}
	}
	if (current.weight() <= pattern.weight()) {
	currentScore += 1000 - pattern.weight() + current.weight();
	} else {
	currentScore += 1000 - current.weight();
	}
	} else if (pattern.weight() > 500) {
	if (current.weight() > pattern.weight()) {
	currentScore += 1000 + pattern.weight() - current.weight();
	} else {
	currentScore += current.weight();
	}
	}

	if (maxScore < currentScore) {
	maxScore = currentScore;
	}
	}

	return this->createTypeface(maxScore.index);
	}