Source/WebCore/platform/graphics/FontCascade.h - WebKit - Git at Google

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003-2021 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Holger Hans Peter Freyther
  *
  * 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.
  *
  */

 #pragma once

 #include "DashArray.h"
 #include "Font.h"
 #include "FontCascadeDescription.h"
 #include "FontCascadeFonts.h"
 #include "Path.h"
 #include <optional>
 #include <wtf/HashSet.h>
 #include <wtf/WeakPtr.h>
 #include <wtf/unicode/CharacterNames.h>

 // "X11/X.h" defines Complex to 0 and conflicts
 // with Complex value in CodePath enum.
 #ifdef Complex
 #undef Complex
 #endif

 namespace WebCore {

 class GraphicsContext;
 class LayoutRect;
 class RenderText;
 class TextLayout;
 class TextRun;

 namespace DisplayList {
 class InMemoryDisplayList;
 }

 struct GlyphData;

 struct GlyphOverflow {
     bool isEmpty() const
     {
         return !left && !right && !top && !bottom;
     }

     void extendTo(const GlyphOverflow& other)
     {
         left = std::max(left, other.left);
         right = std::max(right, other.right);
         top = std::max(top, other.top);
         bottom = std::max(bottom, other.bottom);
     }

     void extendTop(float extendTo)
     {
         top = std::max(top, LayoutUnit(ceilf(extendTo)));
     }

     void extendBottom(float extendTo)
     {
         bottom = std::max(bottom, LayoutUnit(ceilf(extendTo)));
     }

     bool operator!=(const GlyphOverflow& other)
     {
         // FIXME: Probably should name this rather than making it the != operator since it ignores the value of computeBounds.
         return left != other.left || right != other.right || top != other.top || bottom != other.bottom;
     }

     LayoutUnit left;
     LayoutUnit right;
     LayoutUnit top;
     LayoutUnit bottom;
     bool computeBounds { false };
 };

 #if USE(CORE_TEXT)
 AffineTransform computeBaseOverallTextMatrix(const std::optional<AffineTransform>& syntheticOblique);
 AffineTransform computeOverallTextMatrix(const Font&);
 AffineTransform computeBaseVerticalTextMatrix(const AffineTransform& previousTextMatrix);
 AffineTransform computeVerticalTextMatrix(const Font&, const AffineTransform& previousTextMatrix);
 #endif

 class TextLayoutDeleter {
 public:
     void operator()(TextLayout*) const;
 };

 class FontCascade : public CanMakeWeakPtr<FontCascade> {
 public:
     WEBCORE_EXPORT FontCascade();
     WEBCORE_EXPORT FontCascade(FontCascadeDescription&&, float letterSpacing = 0, float wordSpacing = 0);
     // This constructor is only used if the platform wants to start with a native font.
     WEBCORE_EXPORT FontCascade(const FontPlatformData&, FontSmoothingMode = FontSmoothingMode::AutoSmoothing);

     FontCascade(const FontCascade&);
     WEBCORE_EXPORT FontCascade& operator=(const FontCascade&);

     WEBCORE_EXPORT bool operator==(const FontCascade& other) const;
     bool operator!=(const FontCascade& other) const { return !(*this == other); }

     const FontCascadeDescription& fontDescription() const { return m_fontDescription; }

     int pixelSize() const { return fontDescription().computedPixelSize(); }
     float size() const { return fontDescription().computedSize(); }

     bool isCurrent(const FontSelector&) const;
     void updateFonts(Ref<FontCascadeFonts>&&) const;
     WEBCORE_EXPORT void update(RefPtr<FontSelector>&& = nullptr) const;

     enum CustomFontNotReadyAction { DoNotPaintIfFontNotReady, UseFallbackIfFontNotReady };
     WEBCORE_EXPORT FloatSize drawText(GraphicsContext&, const TextRun&, const FloatPoint&, unsigned from = 0, std::optional<unsigned> to = std::nullopt, CustomFontNotReadyAction = DoNotPaintIfFontNotReady) const;
     static void drawGlyphs(GraphicsContext&, const Font&, const GlyphBufferGlyph*, const GlyphBufferAdvance*, unsigned numGlyphs, const FloatPoint&, FontSmoothingMode);
     void drawEmphasisMarks(GraphicsContext&, const TextRun&, const AtomString& mark, const FloatPoint&, unsigned from = 0, std::optional<unsigned> to = std::nullopt) const;

     DashArray dashesForIntersectionsWithRect(const TextRun&, const FloatPoint& textOrigin, const FloatRect& lineExtents) const;

     float widthOfTextRange(const TextRun&, unsigned from, unsigned to, HashSet<const Font*>* fallbackFonts = 0, float* outWidthBeforeRange = nullptr, float* outWidthAfterRange = nullptr) const;
     WEBCORE_EXPORT float width(const TextRun&, HashSet<const Font*>* fallbackFonts = 0, GlyphOverflow* = 0) const;
     float widthForSimpleText(StringView text, TextDirection = TextDirection::LTR) const;

     std::unique_ptr<TextLayout, TextLayoutDeleter> createLayout(RenderText&, float xPos, bool collapseWhiteSpace) const;
     static float width(TextLayout&, unsigned from, unsigned len, HashSet<const Font*>* fallbackFonts = 0);
     float widthOfSpaceString() const
     {
         return width(TextRun { String { &space, 1 } });
     }

     int offsetForPosition(const TextRun&, float position, bool includePartialGlyphs) const;
     void adjustSelectionRectForText(const TextRun&, LayoutRect& selectionRect, unsigned from = 0, std::optional<unsigned> to = std::nullopt) const;

     bool isSmallCaps() const { return m_fontDescription.variantCaps() == FontVariantCaps::Small; }

     float wordSpacing() const { return m_wordSpacing; }
     float letterSpacing() const { return m_letterSpacing; }
     void setWordSpacing(float s) { m_wordSpacing = s; }
     void setLetterSpacing(float s) { m_letterSpacing = s; }
     bool isFixedPitch() const;

     FontRenderingMode renderingMode() const { return m_fontDescription.renderingMode(); }

     bool enableKerning() const { return m_enableKerning; }
     bool requiresShaping() const { return m_requiresShaping; }

     const AtomString& firstFamily() const { return m_fontDescription.firstFamily(); }
     unsigned familyCount() const { return m_fontDescription.familyCount(); }
     const AtomString& familyAt(unsigned i) const { return m_fontDescription.familyAt(i); }

     // A std::nullopt return value indicates "font-style: normal".
     std::optional<FontSelectionValue> italic() const { return m_fontDescription.italic(); }
     FontSelectionValue weight() const { return m_fontDescription.weight(); }
     FontWidthVariant widthVariant() const { return m_fontDescription.widthVariant(); }

     bool isPlatformFont() const { return m_fonts->isForPlatformFont(); }

     const FontMetrics& metricsOfPrimaryFont() const { return primaryFont().fontMetrics(); }
     float tabWidth(const Font&, const TabSize&, float, Font::SyntheticBoldInclusion) const;
     bool hasValidAverageCharWidth() const;
     bool fastAverageCharWidthIfAvailable(float &width) const; // returns true on success

     int emphasisMarkAscent(const AtomString&) const;
     int emphasisMarkDescent(const AtomString&) const;
     int emphasisMarkHeight(const AtomString&) const;

     const Font& primaryFont() const;
     const FontRanges& fallbackRangesAt(unsigned) const;
     GlyphData glyphDataForCharacter(UChar32, bool mirror, FontVariant = AutoVariant) const;

     const Font* fontForCombiningCharacterSequence(const UChar*, size_t length) const;

     static bool isCJKIdeograph(UChar32);
     static bool isCJKIdeographOrSymbol(UChar32);

     // Returns (the number of opportunities, whether the last expansion is a trailing expansion)
     // If there are no opportunities, the bool will be true iff we are forbidding leading expansions.
     static std::pair<unsigned, bool> expansionOpportunityCount(StringView, TextDirection, ExpansionBehavior);

     // Whether or not there is an expansion opportunity just before the first character
     // Note that this does not take a isAfterExpansion flag; this assumes that isAfterExpansion is false
     static bool leftExpansionOpportunity(StringView, TextDirection);
     static bool rightExpansionOpportunity(StringView, TextDirection);

     WEBCORE_EXPORT static void setShouldUseSmoothing(bool);
     WEBCORE_EXPORT static bool shouldUseSmoothing();

     static bool isSubpixelAntialiasingAvailable();

     enum class CodePath : uint8_t { Auto, Simple, Complex, SimpleWithGlyphOverflow };
     CodePath codePath(const TextRun&, std::optional<unsigned> from = std::nullopt, std::optional<unsigned> to = std::nullopt) const;
     static CodePath characterRangeCodePath(const LChar*, unsigned) { return CodePath::Simple; }
     static CodePath characterRangeCodePath(const UChar*, unsigned len);

     bool primaryFontIsSystemFont() const;

     static float syntheticObliqueAngle() { return 14; }

     std::unique_ptr<DisplayList::InMemoryDisplayList> displayListForTextRun(GraphicsContext&, const TextRun&, unsigned from = 0, std::optional<unsigned> to = { }, CustomFontNotReadyAction = CustomFontNotReadyAction::DoNotPaintIfFontNotReady) const;

     unsigned generation() const { return m_generation; }

 #if PLATFORM(WIN) && USE(CG)
     static void setFontSmoothingLevel(int);
     static uint32_t setFontSmoothingStyle(CGContextRef, bool fontAllowsSmoothing);
     static void setFontSmoothingContrast(CGFloat);
     static void systemFontSmoothingChanged();
     static void setCGContextFontRenderingStyle(CGContextRef, bool isSystemFont, bool isPrinterFont, bool usePlatformNativeGlyphs);
     static void getPlatformGlyphAdvances(CGFontRef, const CGAffineTransform&, bool isSystemFont, bool isPrinterFont, CGGlyph, CGSize& advance);
 #endif
 private:
     enum ForTextEmphasisOrNot { NotForTextEmphasis, ForTextEmphasis };

     GlyphBuffer layoutText(CodePath, const TextRun&, unsigned from, unsigned to, ForTextEmphasisOrNot = NotForTextEmphasis) const;
     GlyphBuffer layoutSimpleText(const TextRun&, unsigned from, unsigned to, ForTextEmphasisOrNot = NotForTextEmphasis) const;
     void drawGlyphBuffer(GraphicsContext&, const GlyphBuffer&, FloatPoint&, CustomFontNotReadyAction) const;
     void drawEmphasisMarks(GraphicsContext&, const GlyphBuffer&, const AtomString&, const FloatPoint&) const;
     float floatWidthForSimpleText(const TextRun&, HashSet<const Font*>* fallbackFonts = 0, GlyphOverflow* = 0) const;
     int offsetForPositionForSimpleText(const TextRun&, float position, bool includePartialGlyphs) const;
     void adjustSelectionRectForSimpleText(const TextRun&, LayoutRect& selectionRect, unsigned from, unsigned to) const;

     std::optional<GlyphData> getEmphasisMarkGlyphData(const AtomString&) const;

     static bool canReturnFallbackFontsForComplexText();
     static bool canExpandAroundIdeographsInComplexText();

     GlyphBuffer layoutComplexText(const TextRun&, unsigned from, unsigned to, ForTextEmphasisOrNot = NotForTextEmphasis) const;
     float floatWidthForComplexText(const TextRun&, HashSet<const Font*>* fallbackFonts = 0, GlyphOverflow* = 0) const;
     int offsetForPositionForComplexText(const TextRun&, float position, bool includePartialGlyphs) const;
     void adjustSelectionRectForComplexText(const TextRun&, LayoutRect& selectionRect, unsigned from, unsigned to) const;

     static std::pair<unsigned, bool> expansionOpportunityCountInternal(const LChar*, unsigned length, TextDirection, ExpansionBehavior);
     static std::pair<unsigned, bool> expansionOpportunityCountInternal(const UChar*, unsigned length, TextDirection, ExpansionBehavior);

     friend struct WidthIterator;
     friend class ComplexTextController;

 public:
 #if ENABLE(TEXT_AUTOSIZING)
     bool equalForTextAutoSizing(const FontCascade& other) const
     {
         return m_fontDescription.equalForTextAutoSizing(other.m_fontDescription)
             && m_letterSpacing == other.m_letterSpacing
             && m_wordSpacing == other.m_wordSpacing;
     }
 #endif

     // Useful for debugging the different font rendering code paths.
     WEBCORE_EXPORT static void setCodePath(CodePath);
     static CodePath codePath();
     static CodePath s_codePath;

     FontSelector* fontSelector() const;
     static bool treatAsSpace(UChar32 c) { return c == space || c == tabCharacter || c == newlineCharacter || c == noBreakSpace; }
     static bool isCharacterWhoseGlyphsShouldBeDeletedForTextRendering(UChar32 character)
     {
         // https://drafts.csswg.org/css-text-3/#white-space-processing
         // "Unsupported Default_ignorable characters must be ignored for text rendering."
         return (character >= nullCharacter && character < space)
             || (character >= deleteCharacter && character < noBreakSpace)
             || character == objectReplacementCharacter
             || u_hasBinaryProperty(character, UCHAR_DEFAULT_IGNORABLE_CODE_POINT);
     }
     // FIXME: Callers of treatAsZeroWidthSpace() and treatAsZeroWidthSpaceInComplexScript() should probably be calling isCharacterWhoseGlyphsShouldBeDeletedForTextRendering() instead.
     static bool treatAsZeroWidthSpace(UChar32 c) { return treatAsZeroWidthSpaceInComplexScript(c) || c == zeroWidthNonJoiner || c == zeroWidthJoiner; }
     static bool treatAsZeroWidthSpaceInComplexScript(UChar32 c) { return c < space || (c >= deleteCharacter && c < noBreakSpace) || c == softHyphen || c == zeroWidthSpace || (c >= leftToRightMark && c <= rightToLeftMark) || (c >= leftToRightEmbed && c <= rightToLeftOverride) || c == zeroWidthNoBreakSpace || c == objectReplacementCharacter; }
     static bool canReceiveTextEmphasis(UChar32);

     static inline UChar normalizeSpaces(UChar character)
     {
         if (treatAsSpace(character))
             return space;

         if (treatAsZeroWidthSpace(character))
             return zeroWidthSpace;

         return character;
     }

     static String normalizeSpaces(const LChar*, unsigned length);
     static String normalizeSpaces(const UChar*, unsigned length);

     bool useBackslashAsYenSymbol() const { return m_useBackslashAsYenSymbol; }
     FontCascadeFonts* fonts() const { return m_fonts.get(); }
     bool isLoadingCustomFonts() const;

 private:

     bool advancedTextRenderingMode() const
     {
         auto textRenderingMode = m_fontDescription.textRenderingMode();
         if (textRenderingMode == TextRenderingMode::GeometricPrecision || textRenderingMode == TextRenderingMode::OptimizeLegibility)
             return true;
         if (textRenderingMode == TextRenderingMode::OptimizeSpeed)
             return false;
 #if PLATFORM(COCOA) || USE(FREETYPE)
         return true;
 #else
         return false;
 #endif
     }

     bool computeEnableKerning() const
     {
         auto kerning = m_fontDescription.kerning();
         if (kerning == Kerning::Normal)
             return true;
         if (kerning == Kerning::NoShift)
             return false;
         return advancedTextRenderingMode();
     }

     bool computeRequiresShaping() const
     {
 #if PLATFORM(COCOA) || USE(FREETYPE)
         if (!m_fontDescription.variantSettings().isAllNormal())
             return true;
         if (m_fontDescription.featureSettings().size())
             return true;
 #endif
         return advancedTextRenderingMode();
     }

 #if PLATFORM(WIN) && USE(CG)
     static double s_fontSmoothingContrast;
     static uint32_t s_fontSmoothingType;
     static int s_fontSmoothingLevel;
     static uint32_t s_systemFontSmoothingType;
     static bool s_systemFontSmoothingSet;
     static bool s_systemFontSmoothingEnabled;
 #endif

     FontCascadeDescription m_fontDescription;
     mutable RefPtr<FontCascadeFonts> m_fonts;
     float m_letterSpacing { 0 };
     float m_wordSpacing { 0 };
     mutable unsigned m_generation { 0 };
     bool m_useBackslashAsYenSymbol { false };
     bool m_enableKerning { false }; // Computed from m_fontDescription.
     bool m_requiresShaping { false }; // Computed from m_fontDescription.
 };

 inline const Font& FontCascade::primaryFont() const
 {
     ASSERT(m_fonts);
     return m_fonts->primaryFont(m_fontDescription);
 }

 inline const FontRanges& FontCascade::fallbackRangesAt(unsigned index) const
 {
     ASSERT(m_fonts);
     return m_fonts->realizeFallbackRangesAt(m_fontDescription, index);
 }

 inline bool FontCascade::isFixedPitch() const
 {
     ASSERT(m_fonts);
     return m_fonts->isFixedPitch(m_fontDescription);
 }

 inline FontSelector* FontCascade::fontSelector() const
 {
     return m_fonts ? m_fonts->fontSelector() : nullptr;
 }

 inline float FontCascade::tabWidth(const Font& font, const TabSize& tabSize, float position, Font::SyntheticBoldInclusion syntheticBoldInclusion) const
 {
     float baseTabWidth = tabSize.widthInPixels(font.spaceWidth());
     float result = 0;
     if (!baseTabWidth)
         result = letterSpacing();
     else {
         float tabDeltaWidth = baseTabWidth - fmodf(position, baseTabWidth);
         result = (tabDeltaWidth < font.spaceWidth() / 2) ? baseTabWidth : tabDeltaWidth;
     }
     // If our caller passes in SyntheticBoldInclusion::Exclude, that means they're going to apply synthetic bold themselves later.
     // However, regardless of that, the space characters that are fed into the width calculation need to have their correct width, including the synthetic bold.
     // So, we've already got synthetic bold applied, so if we're supposed to exclude it, we need to subtract it out here.
     return result - (syntheticBoldInclusion == Font::SyntheticBoldInclusion::Exclude ? font.syntheticBoldOffset() : 0);
 }

 }
	/*
	* Copyright (C) 2000 Lars Knoll (knoll@kde.org)
	* (C) 2000 Antti Koivisto (koivisto@kde.org)
	* (C) 2000 Dirk Mueller (mueller@kde.org)
	* Copyright (C) 2003-2021 Apple Inc. All rights reserved.
	* Copyright (C) 2008 Holger Hans Peter Freyther
	*
	* 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.
	*
	*/

	#pragma once

	#include "DashArray.h"
	#include "Font.h"
	#include "FontCascadeDescription.h"
	#include "FontCascadeFonts.h"
	#include "Path.h"
	#include <optional>
	#include <wtf/HashSet.h>
	#include <wtf/WeakPtr.h>
	#include <wtf/unicode/CharacterNames.h>

	// "X11/X.h" defines Complex to 0 and conflicts
	// with Complex value in CodePath enum.
	#ifdef Complex
	#undef Complex
	#endif

	namespace WebCore {

	class GraphicsContext;
	class LayoutRect;
	class RenderText;
	class TextLayout;
	class TextRun;

	namespace DisplayList {
	class InMemoryDisplayList;
	}

	struct GlyphData;

	struct GlyphOverflow {
	bool isEmpty() const
	{
	return !left && !right && !top && !bottom;
	}

	void extendTo(const GlyphOverflow& other)
	{
	left = std::max(left, other.left);
	right = std::max(right, other.right);
	top = std::max(top, other.top);
	bottom = std::max(bottom, other.bottom);
	}

	void extendTop(float extendTo)
	{
	top = std::max(top, LayoutUnit(ceilf(extendTo)));
	}

	void extendBottom(float extendTo)
	{
	bottom = std::max(bottom, LayoutUnit(ceilf(extendTo)));
	}

	bool operator!=(const GlyphOverflow& other)
	{
	// FIXME: Probably should name this rather than making it the != operator since it ignores the value of computeBounds.
	return left != other.left \|\| right != other.right \|\| top != other.top \|\| bottom != other.bottom;
	}

	LayoutUnit left;
	LayoutUnit right;
	LayoutUnit top;
	LayoutUnit bottom;
	bool computeBounds { false };
	};

	#if USE(CORE_TEXT)
	AffineTransform computeBaseOverallTextMatrix(const std::optional<AffineTransform>& syntheticOblique);
	AffineTransform computeOverallTextMatrix(const Font&);
	AffineTransform computeBaseVerticalTextMatrix(const AffineTransform& previousTextMatrix);
	AffineTransform computeVerticalTextMatrix(const Font&, const AffineTransform& previousTextMatrix);
	#endif

	class TextLayoutDeleter {
	public:
	void operator()(TextLayout*) const;
	};

	class FontCascade : public CanMakeWeakPtr<FontCascade> {
	public:
	WEBCORE_EXPORT FontCascade();
	WEBCORE_EXPORT FontCascade(FontCascadeDescription&&, float letterSpacing = 0, float wordSpacing = 0);
	// This constructor is only used if the platform wants to start with a native font.
	WEBCORE_EXPORT FontCascade(const FontPlatformData&, FontSmoothingMode = FontSmoothingMode::AutoSmoothing);

	FontCascade(const FontCascade&);
	WEBCORE_EXPORT FontCascade& operator=(const FontCascade&);

	WEBCORE_EXPORT bool operator==(const FontCascade& other) const;
	bool operator!=(const FontCascade& other) const { return !(*this == other); }

	const FontCascadeDescription& fontDescription() const { return m_fontDescription; }

	int pixelSize() const { return fontDescription().computedPixelSize(); }
	float size() const { return fontDescription().computedSize(); }

	bool isCurrent(const FontSelector&) const;
	void updateFonts(Ref<FontCascadeFonts>&&) const;
	WEBCORE_EXPORT void update(RefPtr<FontSelector>&& = nullptr) const;

	enum CustomFontNotReadyAction { DoNotPaintIfFontNotReady, UseFallbackIfFontNotReady };
	WEBCORE_EXPORT FloatSize drawText(GraphicsContext&, const TextRun&, const FloatPoint&, unsigned from = 0, std::optional<unsigned> to = std::nullopt, CustomFontNotReadyAction = DoNotPaintIfFontNotReady) const;
	static void drawGlyphs(GraphicsContext&, const Font&, const GlyphBufferGlyph, const GlyphBufferAdvance, unsigned numGlyphs, const FloatPoint&, FontSmoothingMode);
	void drawEmphasisMarks(GraphicsContext&, const TextRun&, const AtomString& mark, const FloatPoint&, unsigned from = 0, std::optional<unsigned> to = std::nullopt) const;

	DashArray dashesForIntersectionsWithRect(const TextRun&, const FloatPoint& textOrigin, const FloatRect& lineExtents) const;

	float widthOfTextRange(const TextRun&, unsigned from, unsigned to, HashSet<const Font> fallbackFonts = 0, float* outWidthBeforeRange = nullptr, float* outWidthAfterRange = nullptr) const;
	WEBCORE_EXPORT float width(const TextRun&, HashSet<const Font> fallbackFonts = 0, GlyphOverflow* = 0) const;
	float widthForSimpleText(StringView text, TextDirection = TextDirection::LTR) const;

	std::unique_ptr<TextLayout, TextLayoutDeleter> createLayout(RenderText&, float xPos, bool collapseWhiteSpace) const;
	static float width(TextLayout&, unsigned from, unsigned len, HashSet<const Font> fallbackFonts = 0);
	float widthOfSpaceString() const
	{
	return width(TextRun { String { &space, 1 } });
	}

	int offsetForPosition(const TextRun&, float position, bool includePartialGlyphs) const;
	void adjustSelectionRectForText(const TextRun&, LayoutRect& selectionRect, unsigned from = 0, std::optional<unsigned> to = std::nullopt) const;

	bool isSmallCaps() const { return m_fontDescription.variantCaps() == FontVariantCaps::Small; }

	float wordSpacing() const { return m_wordSpacing; }
	float letterSpacing() const { return m_letterSpacing; }
	void setWordSpacing(float s) { m_wordSpacing = s; }
	void setLetterSpacing(float s) { m_letterSpacing = s; }
	bool isFixedPitch() const;

	FontRenderingMode renderingMode() const { return m_fontDescription.renderingMode(); }

	bool enableKerning() const { return m_enableKerning; }
	bool requiresShaping() const { return m_requiresShaping; }

	const AtomString& firstFamily() const { return m_fontDescription.firstFamily(); }
	unsigned familyCount() const { return m_fontDescription.familyCount(); }
	const AtomString& familyAt(unsigned i) const { return m_fontDescription.familyAt(i); }

	// A std::nullopt return value indicates "font-style: normal".
	std::optional<FontSelectionValue> italic() const { return m_fontDescription.italic(); }
	FontSelectionValue weight() const { return m_fontDescription.weight(); }
	FontWidthVariant widthVariant() const { return m_fontDescription.widthVariant(); }

	bool isPlatformFont() const { return m_fonts->isForPlatformFont(); }

	const FontMetrics& metricsOfPrimaryFont() const { return primaryFont().fontMetrics(); }
	float tabWidth(const Font&, const TabSize&, float, Font::SyntheticBoldInclusion) const;
	bool hasValidAverageCharWidth() const;
	bool fastAverageCharWidthIfAvailable(float &width) const; // returns true on success

	int emphasisMarkAscent(const AtomString&) const;
	int emphasisMarkDescent(const AtomString&) const;
	int emphasisMarkHeight(const AtomString&) const;

	const Font& primaryFont() const;
	const FontRanges& fallbackRangesAt(unsigned) const;
	GlyphData glyphDataForCharacter(UChar32, bool mirror, FontVariant = AutoVariant) const;

	const Font* fontForCombiningCharacterSequence(const UChar*, size_t length) const;

	static bool isCJKIdeograph(UChar32);
	static bool isCJKIdeographOrSymbol(UChar32);

	// Returns (the number of opportunities, whether the last expansion is a trailing expansion)
	// If there are no opportunities, the bool will be true iff we are forbidding leading expansions.
	static std::pair<unsigned, bool> expansionOpportunityCount(StringView, TextDirection, ExpansionBehavior);

	// Whether or not there is an expansion opportunity just before the first character
	// Note that this does not take a isAfterExpansion flag; this assumes that isAfterExpansion is false
	static bool leftExpansionOpportunity(StringView, TextDirection);
	static bool rightExpansionOpportunity(StringView, TextDirection);

	WEBCORE_EXPORT static void setShouldUseSmoothing(bool);
	WEBCORE_EXPORT static bool shouldUseSmoothing();

	static bool isSubpixelAntialiasingAvailable();

	enum class CodePath : uint8_t { Auto, Simple, Complex, SimpleWithGlyphOverflow };
	CodePath codePath(const TextRun&, std::optional<unsigned> from = std::nullopt, std::optional<unsigned> to = std::nullopt) const;
	static CodePath characterRangeCodePath(const LChar*, unsigned) { return CodePath::Simple; }
	static CodePath characterRangeCodePath(const UChar*, unsigned len);

	bool primaryFontIsSystemFont() const;

	static float syntheticObliqueAngle() { return 14; }

	std::unique_ptr<DisplayList::InMemoryDisplayList> displayListForTextRun(GraphicsContext&, const TextRun&, unsigned from = 0, std::optional<unsigned> to = { }, CustomFontNotReadyAction = CustomFontNotReadyAction::DoNotPaintIfFontNotReady) const;

	unsigned generation() const { return m_generation; }

	#if PLATFORM(WIN) && USE(CG)
	static void setFontSmoothingLevel(int);
	static uint32_t setFontSmoothingStyle(CGContextRef, bool fontAllowsSmoothing);
	static void setFontSmoothingContrast(CGFloat);
	static void systemFontSmoothingChanged();
	static void setCGContextFontRenderingStyle(CGContextRef, bool isSystemFont, bool isPrinterFont, bool usePlatformNativeGlyphs);
	static void getPlatformGlyphAdvances(CGFontRef, const CGAffineTransform&, bool isSystemFont, bool isPrinterFont, CGGlyph, CGSize& advance);
	#endif
	private:
	enum ForTextEmphasisOrNot { NotForTextEmphasis, ForTextEmphasis };

	GlyphBuffer layoutText(CodePath, const TextRun&, unsigned from, unsigned to, ForTextEmphasisOrNot = NotForTextEmphasis) const;
	GlyphBuffer layoutSimpleText(const TextRun&, unsigned from, unsigned to, ForTextEmphasisOrNot = NotForTextEmphasis) const;
	void drawGlyphBuffer(GraphicsContext&, const GlyphBuffer&, FloatPoint&, CustomFontNotReadyAction) const;
	void drawEmphasisMarks(GraphicsContext&, const GlyphBuffer&, const AtomString&, const FloatPoint&) const;
	float floatWidthForSimpleText(const TextRun&, HashSet<const Font> fallbackFonts = 0, GlyphOverflow* = 0) const;
	int offsetForPositionForSimpleText(const TextRun&, float position, bool includePartialGlyphs) const;
	void adjustSelectionRectForSimpleText(const TextRun&, LayoutRect& selectionRect, unsigned from, unsigned to) const;

	std::optional<GlyphData> getEmphasisMarkGlyphData(const AtomString&) const;

	static bool canReturnFallbackFontsForComplexText();
	static bool canExpandAroundIdeographsInComplexText();

	GlyphBuffer layoutComplexText(const TextRun&, unsigned from, unsigned to, ForTextEmphasisOrNot = NotForTextEmphasis) const;
	float floatWidthForComplexText(const TextRun&, HashSet<const Font> fallbackFonts = 0, GlyphOverflow* = 0) const;
	int offsetForPositionForComplexText(const TextRun&, float position, bool includePartialGlyphs) const;
	void adjustSelectionRectForComplexText(const TextRun&, LayoutRect& selectionRect, unsigned from, unsigned to) const;

	static std::pair<unsigned, bool> expansionOpportunityCountInternal(const LChar*, unsigned length, TextDirection, ExpansionBehavior);
	static std::pair<unsigned, bool> expansionOpportunityCountInternal(const UChar*, unsigned length, TextDirection, ExpansionBehavior);

	friend struct WidthIterator;
	friend class ComplexTextController;

	public:
	#if ENABLE(TEXT_AUTOSIZING)
	bool equalForTextAutoSizing(const FontCascade& other) const
	{
	return m_fontDescription.equalForTextAutoSizing(other.m_fontDescription)
	&& m_letterSpacing == other.m_letterSpacing
	&& m_wordSpacing == other.m_wordSpacing;
	}
	#endif

	// Useful for debugging the different font rendering code paths.
	WEBCORE_EXPORT static void setCodePath(CodePath);
	static CodePath codePath();
	static CodePath s_codePath;

	FontSelector* fontSelector() const;
	static bool treatAsSpace(UChar32 c) { return c == space \|\| c == tabCharacter \|\| c == newlineCharacter \|\| c == noBreakSpace; }
	static bool isCharacterWhoseGlyphsShouldBeDeletedForTextRendering(UChar32 character)
	{
	// https://drafts.csswg.org/css-text-3/#white-space-processing
	// "Unsupported Default_ignorable characters must be ignored for text rendering."
	return (character >= nullCharacter && character < space)
	\|\| (character >= deleteCharacter && character < noBreakSpace)
	\|\| character == objectReplacementCharacter
	\|\| u_hasBinaryProperty(character, UCHAR_DEFAULT_IGNORABLE_CODE_POINT);
	}
	// FIXME: Callers of treatAsZeroWidthSpace() and treatAsZeroWidthSpaceInComplexScript() should probably be calling isCharacterWhoseGlyphsShouldBeDeletedForTextRendering() instead.
	static bool treatAsZeroWidthSpace(UChar32 c) { return treatAsZeroWidthSpaceInComplexScript(c) \|\| c == zeroWidthNonJoiner \|\| c == zeroWidthJoiner; }
	static bool treatAsZeroWidthSpaceInComplexScript(UChar32 c) { return c < space \|\| (c >= deleteCharacter && c < noBreakSpace) \|\| c == softHyphen \|\| c == zeroWidthSpace \|\| (c >= leftToRightMark && c <= rightToLeftMark) \|\| (c >= leftToRightEmbed && c <= rightToLeftOverride) \|\| c == zeroWidthNoBreakSpace \|\| c == objectReplacementCharacter; }
	static bool canReceiveTextEmphasis(UChar32);

	static inline UChar normalizeSpaces(UChar character)
	{
	if (treatAsSpace(character))
	return space;

	if (treatAsZeroWidthSpace(character))
	return zeroWidthSpace;

	return character;
	}

	static String normalizeSpaces(const LChar*, unsigned length);
	static String normalizeSpaces(const UChar*, unsigned length);

	bool useBackslashAsYenSymbol() const { return m_useBackslashAsYenSymbol; }
	FontCascadeFonts* fonts() const { return m_fonts.get(); }
	bool isLoadingCustomFonts() const;

	private:

	bool advancedTextRenderingMode() const
	{
	auto textRenderingMode = m_fontDescription.textRenderingMode();
	if (textRenderingMode == TextRenderingMode::GeometricPrecision \|\| textRenderingMode == TextRenderingMode::OptimizeLegibility)
	return true;
	if (textRenderingMode == TextRenderingMode::OptimizeSpeed)
	return false;
	#if PLATFORM(COCOA) \|\| USE(FREETYPE)
	return true;
	#else
	return false;
	#endif
	}

	bool computeEnableKerning() const
	{
	auto kerning = m_fontDescription.kerning();
	if (kerning == Kerning::Normal)
	return true;
	if (kerning == Kerning::NoShift)
	return false;
	return advancedTextRenderingMode();
	}

	bool computeRequiresShaping() const
	{
	#if PLATFORM(COCOA) \|\| USE(FREETYPE)
	if (!m_fontDescription.variantSettings().isAllNormal())
	return true;
	if (m_fontDescription.featureSettings().size())
	return true;
	#endif
	return advancedTextRenderingMode();
	}

	#if PLATFORM(WIN) && USE(CG)
	static double s_fontSmoothingContrast;
	static uint32_t s_fontSmoothingType;
	static int s_fontSmoothingLevel;
	static uint32_t s_systemFontSmoothingType;
	static bool s_systemFontSmoothingSet;
	static bool s_systemFontSmoothingEnabled;
	#endif

	FontCascadeDescription m_fontDescription;
	mutable RefPtr<FontCascadeFonts> m_fonts;
	float m_letterSpacing { 0 };
	float m_wordSpacing { 0 };
	mutable unsigned m_generation { 0 };
	bool m_useBackslashAsYenSymbol { false };
	bool m_enableKerning { false }; // Computed from m_fontDescription.
	bool m_requiresShaping { false }; // Computed from m_fontDescription.
	};

	inline const Font& FontCascade::primaryFont() const
	{
	ASSERT(m_fonts);
	return m_fonts->primaryFont(m_fontDescription);
	}

	inline const FontRanges& FontCascade::fallbackRangesAt(unsigned index) const
	{
	ASSERT(m_fonts);
	return m_fonts->realizeFallbackRangesAt(m_fontDescription, index);
	}

	inline bool FontCascade::isFixedPitch() const
	{
	ASSERT(m_fonts);
	return m_fonts->isFixedPitch(m_fontDescription);
	}

	inline FontSelector* FontCascade::fontSelector() const
	{
	return m_fonts ? m_fonts->fontSelector() : nullptr;
	}

	inline float FontCascade::tabWidth(const Font& font, const TabSize& tabSize, float position, Font::SyntheticBoldInclusion syntheticBoldInclusion) const
	{
	float baseTabWidth = tabSize.widthInPixels(font.spaceWidth());
	float result = 0;
	if (!baseTabWidth)
	result = letterSpacing();
	else {
	float tabDeltaWidth = baseTabWidth - fmodf(position, baseTabWidth);
	result = (tabDeltaWidth < font.spaceWidth() / 2) ? baseTabWidth : tabDeltaWidth;
	}
	// If our caller passes in SyntheticBoldInclusion::Exclude, that means they're going to apply synthetic bold themselves later.
	// However, regardless of that, the space characters that are fed into the width calculation need to have their correct width, including the synthetic bold.
	// So, we've already got synthetic bold applied, so if we're supposed to exclude it, we need to subtract it out here.
	return result - (syntheticBoldInclusion == Font::SyntheticBoldInclusion::Exclude ? font.syntheticBoldOffset() : 0);
	}

	}