Font.cpp   [plain text]

/*
 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
 *           (C) 1999 Antti Koivisto (koivisto@kde.org)
 *           (C) 2000 Dirk Mueller (mueller@kde.org)
 * Copyright (C) 2003, 2006, 2010, 2011 Apple Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#include "config.h"
#include "Font.h"

#include "FloatRect.h"
#include "FontCache.h"
#include "FontTranscoder.h"
#include "IntPoint.h"
#include "GlyphBuffer.h"
#include "TextRun.h"
#include "WidthIterator.h"
#include <wtf/MainThread.h>
#include <wtf/MathExtras.h>
#include <wtf/text/StringBuilder.h>

using namespace WTF;
using namespace Unicode;

namespace WTF {

// allow compilation of OwnPtr<TextLayout> in source files that don't have access to the TextLayout class definition
template <> void deleteOwnedPtr<WebCore::TextLayout>(WebCore::TextLayout* ptr)
{
    WebCore::Font::deleteLayout(ptr);
}

}

namespace WebCore {

const uint8_t Font::s_roundingHackCharacterTable[256] = {
    0, 0, 0, 0, 0, 0, 0, 0, 0, 1 /*\t*/, 1 /*\n*/, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    1 /*space*/, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 /*-*/, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1 /*?*/,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    1 /*no-break space*/, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

Font::CodePath Font::s_codePath = Auto;

TypesettingFeatures Font::s_defaultTypesettingFeatures = 0;

// ============================================================================================
// Font Implementation (Cross-Platform Portion)
// ============================================================================================

Font::Font()
    : m_letterSpacing(0)
    , m_wordSpacing(0)
    , m_needsTranscoding(false)
    , m_typesettingFeatures(0)
{
}

Font::Font(const FontDescription& fd, short letterSpacing, short wordSpacing) 
    : m_fontDescription(fd)
    , m_letterSpacing(letterSpacing)
    , m_wordSpacing(wordSpacing)
    , m_needsTranscoding(fontTranscoder().needsTranscoding(fd))
    , m_typesettingFeatures(computeTypesettingFeatures())
{
}

Font::Font(const FontPlatformData& fontData, bool isPrinterFont, FontSmoothingMode fontSmoothingMode)
    : m_glyphs(FontGlyphs::createForPlatformFont(fontData))
    , m_letterSpacing(0)
    , m_wordSpacing(0)
    , m_typesettingFeatures(computeTypesettingFeatures())
{
    m_fontDescription.setUsePrinterFont(isPrinterFont);
    m_fontDescription.setFontSmoothing(fontSmoothingMode);
    m_needsTranscoding = fontTranscoder().needsTranscoding(fontDescription());
}

Font::Font(const Font& other)
    : m_fontDescription(other.m_fontDescription)
    , m_glyphs(other.m_glyphs)
    , m_letterSpacing(other.m_letterSpacing)
    , m_wordSpacing(other.m_wordSpacing)
    , m_needsTranscoding(other.m_needsTranscoding)
    , m_typesettingFeatures(computeTypesettingFeatures())
{
}

Font& Font::operator=(const Font& other)
{
    m_fontDescription = other.m_fontDescription;
    m_glyphs = other.m_glyphs;
    m_letterSpacing = other.m_letterSpacing;
    m_wordSpacing = other.m_wordSpacing;
    m_needsTranscoding = other.m_needsTranscoding;
    m_typesettingFeatures = other.m_typesettingFeatures;
    return *this;
}

bool Font::operator==(const Font& other) const
{
    // Our FontData don't have to be checked, since checking the font description will be fine.
    // FIXME: This does not work if the font was made with the FontPlatformData constructor.
    if (loadingCustomFonts() || other.loadingCustomFonts())
        return false;

    if (m_fontDescription != other.m_fontDescription || m_letterSpacing != other.m_letterSpacing || m_wordSpacing != other.m_wordSpacing)
        return false;
    if (m_glyphs == other.m_glyphs)
        return true;
    if (!m_glyphs || !other.m_glyphs)
        return false;
    if (m_glyphs->fontSelector() != other.m_glyphs->fontSelector())
        return false;
    // Can these cases actually somehow occur? All fonts should get wiped out by full style recalc.
    if (m_glyphs->fontSelectorVersion() != other.m_glyphs->fontSelectorVersion())
        return false;
    if (m_glyphs->generation() != other.m_glyphs->generation())
        return false;
    return true;
}

struct FontGlyphsCacheKey {
    // This part of the key is shared with the lower level FontCache (caching FontData objects).
    FontDescriptionFontDataCacheKey fontDescriptionCacheKey;
    Vector<AtomicString, 3> families;
    unsigned fontSelectorId;
    unsigned fontSelectorVersion;
    unsigned fontSelectorFlags;
};

struct FontGlyphsCacheEntry {
    WTF_MAKE_FAST_ALLOCATED;
public:
    FontGlyphsCacheKey key;
    RefPtr<FontGlyphs> glyphs;
};

typedef HashMap<unsigned, OwnPtr<FontGlyphsCacheEntry>, AlreadyHashed> FontGlyphsCache;

static bool operator==(const FontGlyphsCacheKey& a, const FontGlyphsCacheKey& b)
{
    if (a.fontDescriptionCacheKey != b.fontDescriptionCacheKey)
        return false;
    if (a.families != b.families)
        return false;
    if (a.fontSelectorId != b.fontSelectorId || a.fontSelectorVersion != b.fontSelectorVersion || a.fontSelectorFlags != b.fontSelectorFlags)
        return false;
    return true;
}

static FontGlyphsCache& fontGlyphsCache()
{
    DEFINE_STATIC_LOCAL(FontGlyphsCache, cache, ());
    return cache;
}

void invalidateFontGlyphsCache()
{
    fontGlyphsCache().clear();
}

static unsigned makeFontSelectorFlags(const FontDescription& description)
{
    return static_cast<unsigned>(description.script()) << 1 | static_cast<unsigned>(description.smallCaps());
}

static void makeFontGlyphsCacheKey(FontGlyphsCacheKey& key, const FontDescription& description, FontSelector* fontSelector)
{
    key.fontDescriptionCacheKey = FontDescriptionFontDataCacheKey(description);
    for (unsigned i = 0; i < description.familyCount(); ++i)
        key.families.append(description.familyAt(i).lower());
    key.fontSelectorId = fontSelector ? fontSelector->uniqueId() : 0;
    key.fontSelectorVersion = fontSelector ? fontSelector->version() : 0;
    key.fontSelectorFlags = fontSelector && fontSelector->resolvesFamilyFor(description) ? makeFontSelectorFlags(description) : 0;
}

static unsigned computeFontGlyphsCacheHash(const FontGlyphsCacheKey& key)
{
    unsigned hashCodes[5] = {
        StringHasher::hashMemory(key.families.data(), key.families.size() * sizeof(key.families[0])),
        key.fontDescriptionCacheKey.computeHash(),
        key.fontSelectorId,
        key.fontSelectorVersion,
        key.fontSelectorFlags
    };
    return StringHasher::hashMemory<sizeof(hashCodes)>(hashCodes);
}

void pruneUnreferencedEntriesFromFontGlyphsCache()
{
    Vector<unsigned, 50> toRemove;
    FontGlyphsCache::iterator end = fontGlyphsCache().end();
    for (FontGlyphsCache::iterator it = fontGlyphsCache().begin(); it != end; ++it) {
        if (it->value->glyphs->hasOneRef())
            toRemove.append(it->key);
    }
    for (unsigned i = 0; i < toRemove.size(); ++i)
        fontGlyphsCache().remove(toRemove[i]);
}

static PassRefPtr<FontGlyphs> retrieveOrAddCachedFontGlyphs(const FontDescription& fontDescription, PassRefPtr<FontSelector> fontSelector)
{
    FontGlyphsCacheKey key;
    makeFontGlyphsCacheKey(key, fontDescription, fontSelector.get());

    unsigned hash = computeFontGlyphsCacheHash(key);
    FontGlyphsCache::AddResult addResult = fontGlyphsCache().add(hash, PassOwnPtr<FontGlyphsCacheEntry>());
    if (!addResult.isNewEntry && addResult.iterator->value->key == key)
        return addResult.iterator->value->glyphs;

    OwnPtr<FontGlyphsCacheEntry>& newEntry = addResult.iterator->value;
    newEntry = adoptPtr(new FontGlyphsCacheEntry);
    newEntry->glyphs = FontGlyphs::create(fontSelector);
    newEntry->key = key;
    RefPtr<FontGlyphs> glyphs = newEntry->glyphs;

    static const unsigned unreferencedPruneInterval = 50;
    static const int maximumEntries = 400;
    static unsigned pruneCounter;
    // Referenced FontGlyphs would exist anyway so pruning them saves little memory.
    if (!(++pruneCounter % unreferencedPruneInterval))
        pruneUnreferencedEntriesFromFontGlyphsCache();
    // Prevent pathological growth.
    if (fontGlyphsCache().size() > maximumEntries)
        fontGlyphsCache().remove(fontGlyphsCache().begin());
    return glyphs;
}

void Font::update(PassRefPtr<FontSelector> fontSelector) const
{
    m_glyphs = retrieveOrAddCachedFontGlyphs(m_fontDescription, fontSelector.get());
    m_typesettingFeatures = computeTypesettingFeatures();
}

void Font::drawText(GraphicsContext* context, const TextRun& run, const FloatPoint& point, int from, int to, CustomFontNotReadyAction customFontNotReadyAction) const
{
    // Don't draw anything while we are using custom fonts that are in the process of loading,
    // except if the 'force' argument is set to true (in which case it will use a fallback
    // font).
    if (loadingCustomFonts() && customFontNotReadyAction == DoNotPaintIfFontNotReady)
        return;
    
    to = (to == -1 ? run.length() : to);

    CodePath codePathToUse = codePath(run);
    // FIXME: Use the fast code path once it handles partial runs with kerning and ligatures. See http://webkit.org/b/100050
    if (codePathToUse != Complex && typesettingFeatures() && (from || to != run.length()) && !run.renderingContext())
        codePathToUse = Complex;

    if (codePathToUse != Complex)
        return drawSimpleText(context, run, point, from, to);

    return drawComplexText(context, run, point, from, to);
}

void Font::drawEmphasisMarks(GraphicsContext* context, const TextRun& run, const AtomicString& mark, const FloatPoint& point, int from, int to) const
{
    if (loadingCustomFonts())
        return;

    if (to < 0)
        to = run.length();

    CodePath codePathToUse = codePath(run);
    // FIXME: Use the fast code path once it handles partial runs with kerning and ligatures. See http://webkit.org/b/100050
    if (codePathToUse != Complex && typesettingFeatures() && (from || to != run.length()) && !run.renderingContext())
        codePathToUse = Complex;

    if (codePathToUse != Complex)
        drawEmphasisMarksForSimpleText(context, run, mark, point, from, to);
    else
        drawEmphasisMarksForComplexText(context, run, mark, point, from, to);
}

float Font::width(const TextRun& run, HashSet<const SimpleFontData*>* fallbackFonts, GlyphOverflow* glyphOverflow) const
{
    CodePath codePathToUse = codePath(run);
    if (codePathToUse != Complex) {
        // The complex path is more restrictive about returning fallback fonts than the simple path, so we need an explicit test to make their behaviors match.
        if (!canReturnFallbackFontsForComplexText())
            fallbackFonts = 0;
        // The simple path can optimize the case where glyph overflow is not observable.
        if (codePathToUse != SimpleWithGlyphOverflow && (glyphOverflow && !glyphOverflow->computeBounds))
            glyphOverflow = 0;
    }

    bool hasKerningOrLigatures = typesettingFeatures() & (Kerning | Ligatures);
    bool hasWordSpacingOrLetterSpacing = wordSpacing() | letterSpacing();
    float* cacheEntry = m_glyphs->widthCache().add(run, std::numeric_limits<float>::quiet_NaN(), hasKerningOrLigatures, hasWordSpacingOrLetterSpacing, glyphOverflow);
    if (cacheEntry && !std::isnan(*cacheEntry))
        return *cacheEntry;

    HashSet<const SimpleFontData*> localFallbackFonts;
    if (!fallbackFonts)
        fallbackFonts = &localFallbackFonts;

    float result;
    if (codePathToUse == Complex)
        result = floatWidthForComplexText(run, fallbackFonts, glyphOverflow);
    else
        result = floatWidthForSimpleText(run, fallbackFonts, glyphOverflow);

    if (cacheEntry && fallbackFonts->isEmpty())
        *cacheEntry = result;
    return result;
}

float Font::width(const TextRun& run, int& charsConsumed, String& glyphName) const
{
#if ENABLE(SVG_FONTS)
    if (TextRun::RenderingContext* renderingContext = run.renderingContext())
        return renderingContext->floatWidthUsingSVGFont(*this, run, charsConsumed, glyphName);
#endif

    charsConsumed = run.length();
    glyphName = "";
    return width(run);
}

#if !PLATFORM(MAC)
PassOwnPtr<TextLayout> Font::createLayout(RenderText*, float, bool) const
{
    return nullptr;
}

void Font::deleteLayout(TextLayout*)
{
}

float Font::width(TextLayout&, unsigned, unsigned, HashSet<const SimpleFontData*>*)
{
    ASSERT_NOT_REACHED();
    return 0;
}
#endif

FloatRect Font::selectionRectForText(const TextRun& run, const FloatPoint& point, int h, int from, int to) const
{
    to = (to == -1 ? run.length() : to);

    CodePath codePathToUse = codePath(run);
    // FIXME: Use the fast code path once it handles partial runs with kerning and ligatures. See http://webkit.org/b/100050
    if (codePathToUse != Complex && typesettingFeatures() && (from || to != run.length()) && !run.renderingContext())
        codePathToUse = Complex;

    if (codePathToUse != Complex)
        return selectionRectForSimpleText(run, point, h, from, to);

    return selectionRectForComplexText(run, point, h, from, to);
}

int Font::offsetForPosition(const TextRun& run, float x, bool includePartialGlyphs) const
{
    // FIXME: Use the fast code path once it handles partial runs with kerning and ligatures. See http://webkit.org/b/100050
    if (codePath(run) != Complex && !typesettingFeatures())
        return offsetForPositionForSimpleText(run, x, includePartialGlyphs);

    return offsetForPositionForComplexText(run, x, includePartialGlyphs);
}

template <typename CharacterType>
static inline String normalizeSpacesInternal(const CharacterType* characters, unsigned length)
{
    StringBuilder normalized;
    normalized.reserveCapacity(length);

    for (unsigned i = 0; i < length; ++i)
        normalized.append(Font::normalizeSpaces(characters[i]));

    return normalized.toString();
}

String Font::normalizeSpaces(const LChar* characters, unsigned length)
{
    return normalizeSpacesInternal(characters, length);
}

String Font::normalizeSpaces(const UChar* characters, unsigned length)
{
    return normalizeSpacesInternal(characters, length);
}

static bool shouldUseFontSmoothing = true;

void Font::setShouldUseSmoothing(bool shouldUseSmoothing)
{
    ASSERT(isMainThread());
    shouldUseFontSmoothing = shouldUseSmoothing;
}

bool Font::shouldUseSmoothing()
{
    return shouldUseFontSmoothing;
}

void Font::setCodePath(CodePath p)
{
    s_codePath = p;
}

Font::CodePath Font::codePath()
{
    return s_codePath;
}

void Font::setDefaultTypesettingFeatures(TypesettingFeatures typesettingFeatures)
{
    s_defaultTypesettingFeatures = typesettingFeatures;
}

TypesettingFeatures Font::defaultTypesettingFeatures()
{
    return s_defaultTypesettingFeatures;
}

Font::CodePath Font::codePath(const TextRun& run) const
{
    if (s_codePath != Auto)
        return s_codePath;

#if ENABLE(SVG_FONTS)
    if (run.renderingContext())
        return Simple;
#endif

    if (m_fontDescription.featureSettings() && m_fontDescription.featureSettings()->size() > 0)
        return Complex;
    
    if (run.length() > 1 && !WidthIterator::supportsTypesettingFeatures(*this))
        return Complex;

    if (!run.characterScanForCodePath())
        return Simple;

    if (run.is8Bit())
        return Simple;

    // Start from 0 since drawing and highlighting also measure the characters before run->from.
    return characterRangeCodePath(run.characters16(), run.length());
}

Font::CodePath Font::characterRangeCodePath(const UChar* characters, unsigned len)
{
    // FIXME: Should use a UnicodeSet in ports where ICU is used. Note that we 
    // can't simply use UnicodeCharacter Property/class because some characters
    // are not 'combining', but still need to go to the complex path.
    // Alternatively, we may as well consider binary search over a sorted
    // list of ranges.
    CodePath result = Simple;
    for (unsigned i = 0; i < len; i++) {
        const UChar c = characters[i];
        if (c < 0x2E5) // U+02E5 through U+02E9 (Modifier Letters : Tone letters)  
            continue;
        if (c <= 0x2E9) 
            return Complex;

        if (c < 0x300) // U+0300 through U+036F Combining diacritical marks
            continue;
        if (c <= 0x36F)
            return Complex;

        if (c < 0x0591 || c == 0x05BE) // U+0591 through U+05CF excluding U+05BE Hebrew combining marks, Hebrew punctuation Paseq, Sof Pasuq and Nun Hafukha
            continue;
        if (c <= 0x05CF)
            return Complex;

        // U+0600 through U+109F Arabic, Syriac, Thaana, NKo, Samaritan, Mandaic,
        // Devanagari, Bengali, Gurmukhi, Gujarati, Oriya, Tamil, Telugu, Kannada, 
        // Malayalam, Sinhala, Thai, Lao, Tibetan, Myanmar
        if (c < 0x0600) 
            continue;
        if (c <= 0x109F)
            return Complex;

        // U+1100 through U+11FF Hangul Jamo (only Ancient Korean should be left here if you precompose;
        // Modern Korean will be precomposed as a result of step A)
        if (c < 0x1100)
            continue;
        if (c <= 0x11FF)
            return Complex;

        if (c < 0x135D) // U+135D through U+135F Ethiopic combining marks
            continue;
        if (c <= 0x135F)
            return Complex;

        if (c < 0x1700) // U+1780 through U+18AF Tagalog, Hanunoo, Buhid, Taghanwa,Khmer, Mongolian
            continue;
        if (c <= 0x18AF)
            return Complex;

        if (c < 0x1900) // U+1900 through U+194F Limbu (Unicode 4.0)
            continue;
        if (c <= 0x194F)
            return Complex;

        if (c < 0x1980) // U+1980 through U+19DF New Tai Lue
            continue;
        if (c <= 0x19DF)
            return Complex;

        if (c < 0x1A00) // U+1A00 through U+1CFF Buginese, Tai Tham, Balinese, Batak, Lepcha, Vedic
            continue;
        if (c <= 0x1CFF)
            return Complex;

        if (c < 0x1DC0) // U+1DC0 through U+1DFF Comining diacritical mark supplement
            continue;
        if (c <= 0x1DFF)
            return Complex;

        // U+1E00 through U+2000 characters with diacritics and stacked diacritics
        if (c <= 0x2000) {
            result = SimpleWithGlyphOverflow;
            continue;
        }

        if (c < 0x20D0) // U+20D0 through U+20FF Combining marks for symbols
            continue;
        if (c <= 0x20FF)
            return Complex;

        if (c < 0x2CEF) // U+2CEF through U+2CF1 Combining marks for Coptic
            continue;
        if (c <= 0x2CF1)
            return Complex;

        if (c < 0x302A) // U+302A through U+302F Ideographic and Hangul Tone marks
            continue;
        if (c <= 0x302F)
            return Complex;

        if (c < 0xA67C) // U+A67C through U+A67D Combining marks for old Cyrillic
            continue;
        if (c <= 0xA67D)
            return Complex;

        if (c < 0xA6F0) // U+A6F0 through U+A6F1 Combining mark for Bamum
            continue;
        if (c <= 0xA6F1)
            return Complex;

       // U+A800 through U+ABFF Nagri, Phags-pa, Saurashtra, Devanagari Extended,
       // Hangul Jamo Ext. A, Javanese, Myanmar Extended A, Tai Viet, Meetei Mayek,
        if (c < 0xA800) 
            continue;
        if (c <= 0xABFF)
            return Complex;

        if (c < 0xD7B0) // U+D7B0 through U+D7FF Hangul Jamo Ext. B
            continue;
        if (c <= 0xD7FF)
            return Complex;

        if (c <= 0xDBFF) {
            // High surrogate

            if (i == len - 1)
                continue;

            UChar next = characters[++i];
            if (!U16_IS_TRAIL(next))
                continue;

            UChar32 supplementaryCharacter = U16_GET_SUPPLEMENTARY(c, next);

            if (supplementaryCharacter < 0x1F1E6) // U+1F1E6 through U+1F1FF Regional Indicator Symbols
                continue;
            if (supplementaryCharacter <= 0x1F1FF)
                return Complex;

            if (supplementaryCharacter < 0xE0100) // U+E0100 through U+E01EF Unicode variation selectors.
                continue;
            if (supplementaryCharacter <= 0xE01EF)
                return Complex;

            // FIXME: Check for Brahmi (U+11000 block), Kaithi (U+11080 block) and other complex scripts
            // in plane 1 or higher.

            continue;
        }

        if (c < 0xFE00) // U+FE00 through U+FE0F Unicode variation selectors
            continue;
        if (c <= 0xFE0F)
            return Complex;

        if (c < 0xFE20) // U+FE20 through U+FE2F Combining half marks
            continue;
        if (c <= 0xFE2F)
            return Complex;
    }
    return result;
}

bool Font::isCJKIdeograph(UChar32 c)
{
    // The basic CJK Unified Ideographs block.
    if (c >= 0x4E00 && c <= 0x9FFF)
        return true;
    
    // CJK Unified Ideographs Extension A.
    if (c >= 0x3400 && c <= 0x4DBF)
        return true;
    
    // CJK Radicals Supplement.
    if (c >= 0x2E80 && c <= 0x2EFF)
        return true;
    
    // Kangxi Radicals.
    if (c >= 0x2F00 && c <= 0x2FDF)
        return true;
    
    // CJK Strokes.
    if (c >= 0x31C0 && c <= 0x31EF)
        return true;
    
    // CJK Compatibility Ideographs.
    if (c >= 0xF900 && c <= 0xFAFF)
        return true;
    
    // CJK Unified Ideographs Extension B.
    if (c >= 0x20000 && c <= 0x2A6DF)
        return true;
        
    // CJK Unified Ideographs Extension C.
    if (c >= 0x2A700 && c <= 0x2B73F)
        return true;
    
    // CJK Unified Ideographs Extension D.
    if (c >= 0x2B740 && c <= 0x2B81F)
        return true;
    
    // CJK Compatibility Ideographs Supplement.
    if (c >= 0x2F800 && c <= 0x2FA1F)
        return true;

    return false;
}

bool Font::isCJKIdeographOrSymbol(UChar32 c)
{
    // 0x2C7 Caron, Mandarin Chinese 3rd Tone
    // 0x2CA Modifier Letter Acute Accent, Mandarin Chinese 2nd Tone
    // 0x2CB Modifier Letter Grave Access, Mandarin Chinese 4th Tone 
    // 0x2D9 Dot Above, Mandarin Chinese 5th Tone 
    if ((c == 0x2C7) || (c == 0x2CA) || (c == 0x2CB) || (c == 0x2D9))
        return true;

    if ((c == 0x2020) || (c == 0x2021) || (c == 0x2030) || (c == 0x203B) || (c == 0x203C)
        || (c == 0x2042) || (c == 0x2047) || (c == 0x2048) || (c == 0x2049) || (c == 0x2051)
        || (c == 0x20DD) || (c == 0x20DE) || (c == 0x2100) || (c == 0x2103) || (c == 0x2105)
        || (c == 0x2109) || (c == 0x210A) || (c == 0x2113) || (c == 0x2116) || (c == 0x2121)
        || (c == 0x212B) || (c == 0x213B) || (c == 0x2150) || (c == 0x2151) || (c == 0x2152))
        return true;

    if (c >= 0x2156 && c <= 0x215A)
        return true;

    if (c >= 0x2160 && c <= 0x216B)
        return true;

    if (c >= 0x2170 && c <= 0x217B)
        return true;

    if ((c == 0x217F) || (c == 0x2189) || (c == 0x2307) || (c == 0x2312) || (c == 0x23BE) || (c == 0x23BF))
        return true;

    if (c >= 0x23C0 && c <= 0x23CC)
        return true;

    if ((c == 0x23CE) || (c == 0x2423))
        return true;

    if (c >= 0x2460 && c <= 0x2492)
        return true;

    if (c >= 0x249C && c <= 0x24FF)
        return true;

    if ((c == 0x25A0) || (c == 0x25A1) || (c == 0x25A2) || (c == 0x25AA) || (c == 0x25AB))
        return true;

    if ((c == 0x25B1) || (c == 0x25B2) || (c == 0x25B3) || (c == 0x25B6) || (c == 0x25B7) || (c == 0x25BC) || (c == 0x25BD))
        return true;
    
    if ((c == 0x25C0) || (c == 0x25C1) || (c == 0x25C6) || (c == 0x25C7) || (c == 0x25C9) || (c == 0x25CB) || (c == 0x25CC))
        return true;

    if (c >= 0x25CE && c <= 0x25D3)
        return true;

    if (c >= 0x25E2 && c <= 0x25E6)
        return true;

    if (c == 0x25EF)
        return true;

    if (c >= 0x2600 && c <= 0x2603)
        return true;

    if ((c == 0x2605) || (c == 0x2606) || (c == 0x260E) || (c == 0x2616) || (c == 0x2617) || (c == 0x2640) || (c == 0x2642))
        return true;

    if (c >= 0x2660 && c <= 0x266F)
        return true;

    if (c >= 0x2672 && c <= 0x267D)
        return true;

    if ((c == 0x26A0) || (c == 0x26BD) || (c == 0x26BE) || (c == 0x2713) || (c == 0x271A) || (c == 0x273F) || (c == 0x2740) || (c == 0x2756))
        return true;

    if (c >= 0x2776 && c <= 0x277F)
        return true;

    if (c == 0x2B1A)
        return true;

    // Ideographic Description Characters.
    if (c >= 0x2FF0 && c <= 0x2FFF)
        return true;
    
    // CJK Symbols and Punctuation, excluding 0x3030.
    if (c >= 0x3000 && c < 0x3030)
        return true;

    if (c > 0x3030 && c <= 0x303F)
        return true;

    // Hiragana
    if (c >= 0x3040 && c <= 0x309F)
        return true;

    // Katakana 
    if (c >= 0x30A0 && c <= 0x30FF)
        return true;

    // Bopomofo
    if (c >= 0x3100 && c <= 0x312F)
        return true;

    if (c >= 0x3190 && c <= 0x319F)
        return true;

    // Bopomofo Extended
    if (c >= 0x31A0 && c <= 0x31BF)
        return true;
 
    // Enclosed CJK Letters and Months.
    if (c >= 0x3200 && c <= 0x32FF)
        return true;
    
    // CJK Compatibility.
    if (c >= 0x3300 && c <= 0x33FF)
        return true;

    if (c >= 0xF860 && c <= 0xF862)
        return true;

    // CJK Compatibility Forms.
    if (c >= 0xFE30 && c <= 0xFE4F)
        return true;

    if ((c == 0xFE10) || (c == 0xFE11) || (c == 0xFE12) || (c == 0xFE19))
        return true;

    if ((c == 0xFF0D) || (c == 0xFF1B) || (c == 0xFF1C) || (c == 0xFF1E))
        return false;

    // Halfwidth and Fullwidth Forms
    // Usually only used in CJK
    if (c >= 0xFF00 && c <= 0xFFEF)
        return true;

    // Emoji.
    if (c == 0x1F100)
        return true;

    if (c >= 0x1F110 && c <= 0x1F129)
        return true;

    if (c >= 0x1F130 && c <= 0x1F149)
        return true;

    if (c >= 0x1F150 && c <= 0x1F169)
        return true;

    if (c >= 0x1F170 && c <= 0x1F189)
        return true;

    if (c >= 0x1F200 && c <= 0x1F6F)
        return true;

    return isCJKIdeograph(c);
}

unsigned Font::expansionOpportunityCount(const LChar* characters, size_t length, TextDirection direction, bool& isAfterExpansion)
{
    unsigned count = 0;
    if (direction == LTR) {
        for (size_t i = 0; i < length; ++i) {
            if (treatAsSpace(characters[i])) {
                count++;
                isAfterExpansion = true;
            } else
                isAfterExpansion = false;
        }
    } else {
        for (size_t i = length; i > 0; --i) {
            if (treatAsSpace(characters[i - 1])) {
                count++;
                isAfterExpansion = true;
            } else
                isAfterExpansion = false;
        }
    }
    return count;
}

unsigned Font::expansionOpportunityCount(const UChar* characters, size_t length, TextDirection direction, bool& isAfterExpansion)
{
    static bool expandAroundIdeographs = canExpandAroundIdeographsInComplexText();
    unsigned count = 0;
    if (direction == LTR) {
        for (size_t i = 0; i < length; ++i) {
            UChar32 character = characters[i];
            if (treatAsSpace(character)) {
                count++;
                isAfterExpansion = true;
                continue;
            }
            if (U16_IS_LEAD(character) && i + 1 < length && U16_IS_TRAIL(characters[i + 1])) {
                character = U16_GET_SUPPLEMENTARY(character, characters[i + 1]);
                i++;
            }
            if (expandAroundIdeographs && isCJKIdeographOrSymbol(character)) {
                if (!isAfterExpansion)
                    count++;
                count++;
                isAfterExpansion = true;
                continue;
            }
            isAfterExpansion = false;
        }
    } else {
        for (size_t i = length; i > 0; --i) {
            UChar32 character = characters[i - 1];
            if (treatAsSpace(character)) {
                count++;
                isAfterExpansion = true;
                continue;
            }
            if (U16_IS_TRAIL(character) && i > 1 && U16_IS_LEAD(characters[i - 2])) {
                character = U16_GET_SUPPLEMENTARY(characters[i - 2], character);
                i--;
            }
            if (expandAroundIdeographs && isCJKIdeographOrSymbol(character)) {
                if (!isAfterExpansion)
                    count++;
                count++;
                isAfterExpansion = true;
                continue;
            }
            isAfterExpansion = false;
        }
    }
    return count;
}

bool Font::canReceiveTextEmphasis(UChar32 c)
{
    CharCategory category = Unicode::category(c);
    if (category & (Separator_Space | Separator_Line | Separator_Paragraph | Other_NotAssigned | Other_Control | Other_Format))
        return false;

    // Additional word-separator characters listed in CSS Text Level 3 Editor's Draft 3 November 2010.
    if (c == ethiopicWordspace || c == aegeanWordSeparatorLine || c == aegeanWordSeparatorDot
        || c == ugariticWordDivider || c == tibetanMarkIntersyllabicTsheg || c == tibetanMarkDelimiterTshegBstar)
        return false;

    return true;
}

}