C++ TextRun::expansion方法代码示例

UniscribeHelperTextRun::UniscribeHelperTextRun(const TextRun& run,
                                               const Font& font)
    : UniscribeHelper(0, run.length(), run.rtl(),
                      font.primaryFont()->platformData().hfont(),
                      font.primaryFont()->platformData().scriptCache(),
                      font.primaryFont()->platformData().scriptFontProperties(),
                      font.primaryFont()->spaceGlyph())
    , m_font(&font)
    , m_fontIndex(0)
{
    if (run.is8Bit()) {
        m_stringFor8BitRun = String::make16BitFrom8BitSource(run.characters8(), run.length());
        setInput(m_stringFor8BitRun.characters16());
    } else {
        setInput(run.characters16());
    }

    setDirectionalOverride(run.directionalOverride());
    setLetterSpacing(font.letterSpacing());
    setSpaceWidth(font.spaceWidth());
    setWordSpacing(font.wordSpacing());
    setAscent(font.fontMetrics().ascent());
    setRangeProperties(font.fontDescription().featureSettings());

    init();

    // Expansion is the amount to add to make justification happen. This
    // should be done after Init() so all the runs are already measured.
    if (run.expansion() > 0)
        justify(run.expansion());
}

void Font::drawComplexText(GraphicsContext* gc, const TextRun& run,
                           const FloatPoint& point, int from, int to) const
{
    if (!run.length())
        return;

    SkCanvas* canvas = gc->platformContext()->canvas();
    TextDrawingModeFlags textMode = gc->platformContext()->getTextDrawingMode();
    bool fill = textMode & TextModeFill;
    bool stroke = (textMode & TextModeStroke)
               && gc->platformContext()->getStrokeStyle() != NoStroke
               && gc->platformContext()->getStrokeThickness() > 0;

    if (!fill && !stroke)
        return;

    SkPaint strokePaint, fillPaint;
    if (fill) {
        gc->platformContext()->setupPaintForFilling(&fillPaint);
        setupForTextPainting(&fillPaint, gc->fillColor().rgb());
    }
    if (stroke) {
        gc->platformContext()->setupPaintForStroking(&strokePaint, 0, 0);
        setupForTextPainting(&strokePaint, gc->strokeColor().rgb());
    }

    ComplexTextController controller(run, point.x(), point.y(), this);
    controller.setWordSpacingAdjustment(wordSpacing());
    controller.setLetterSpacingAdjustment(letterSpacing());
    controller.setPadding(run.expansion());

    if (run.rtl()) {
        // FIXME: this causes us to shape the text twice -- once to compute the width and then again
        // below when actually rendering.  Change ComplexTextController to match platform/mac and
        // platform/chromium/win by having it store the shaped runs, so we can reuse the results.
        controller.reset(point.x() + controller.widthOfFullRun());
        // We need to set the padding again because ComplexTextController layout consumed the value.
        // Fixing the above problem would help here too.
        controller.setPadding(run.expansion());
    }

    while (controller.nextScriptRun()) {
        if (fill) {
            controller.fontPlatformDataForScriptRun()->setupPaint(&fillPaint);
            adjustTextRenderMode(&fillPaint, gc->platformContext());
            canvas->drawPosText(controller.glyphs(), controller.length() << 1, controller.positions(), fillPaint);
        }

        if (stroke) {
            controller.fontPlatformDataForScriptRun()->setupPaint(&strokePaint);
            adjustTextRenderMode(&strokePaint, gc->platformContext());
            canvas->drawPosText(controller.glyphs(), controller.length() << 1, controller.positions(), strokePaint);
        }
    }
}

// Return the code point index for the given |x| offset into the text run.
int Font::offsetForPositionForComplexText(const TextRun& run, float xFloat,
                                          bool includePartialGlyphs) const
{
    // FIXME: This truncation is not a problem for HTML, but only affects SVG, which passes floating-point numbers
    // to Font::offsetForPosition(). Bug http://webkit.org/b/40673 tracks fixing this problem.
    int targetX = static_cast<int>(xFloat);

    // (Mac code ignores includePartialGlyphs, and they don't know what it's
    // supposed to do, so we just ignore it as well.)
    ComplexTextController controller(run, 0, 0, this);
    controller.setWordSpacingAdjustment(wordSpacing());
    controller.setLetterSpacingAdjustment(letterSpacing());
    controller.setPadding(run.expansion());
    if (run.rtl()) {
        // See FIXME in drawComplexText.
        controller.reset(controller.widthOfFullRun());
        controller.setPadding(run.expansion());
    }

    unsigned basePosition = 0;

    int x = controller.offsetX();
    while (controller.nextScriptRun()) {
        int nextX = controller.offsetX();

        if (std::min(x, nextX) <= targetX && targetX <= std::max(x, nextX)) {
            // The x value in question is within this script run.
            const int glyphIndex = glyphIndexForXPositionInScriptRun(controller, targetX);

            // Now that we have a glyph index, we have to turn that into a
            // code-point index. Because of ligatures, several code-points may
            // have gone into a single glyph. We iterate over the clusters log
            // and find the first code-point which contributed to the glyph.

            // Some shapers (i.e. Khmer) will produce cluster logs which report
            // that /no/ code points contributed to certain glyphs. Because of
            // this, we take any code point which contributed to the glyph in
            // question, or any subsequent glyph. If we run off the end, then
            // we take the last code point.
            const unsigned short* log = controller.logClusters();
            for (unsigned j = 0; j < controller.numCodePoints(); ++j) {
                if (log[j] >= glyphIndex)
                    return basePosition + j;
            }

            return basePosition + controller.numCodePoints() - 1;
        }

        basePosition += controller.numCodePoints();
    }

    return basePosition;
}

// Return the rectangle for selecting the given range of code-points in the TextRun.
FloatRect Font::selectionRectForComplexText(const TextRun& run,
                                            const FloatPoint& point, int height,
                                            int from, int to) const
{
    int fromX = -1, toX = -1;
    ComplexTextController controller(run, 0, 0, this);
    controller.setWordSpacingAdjustment(wordSpacing());
    controller.setLetterSpacingAdjustment(letterSpacing());
    controller.setPadding(run.expansion());
    if (run.rtl()) {
        // See FIXME in drawComplexText.
        controller.reset(controller.widthOfFullRun());
        controller.setPadding(run.expansion());
    }

    // Iterate through the script runs in logical order, searching for the run covering the positions of interest.
    while (controller.nextScriptRun() && (fromX == -1 || toX == -1)) {
        if (fromX == -1 && from >= 0 && static_cast<unsigned>(from) < controller.numCodePoints()) {
            // |from| is within this script run. So we index the clusters log to
            // find which glyph this code-point contributed to and find its x
            // position.
            int glyph = controller.logClusters()[from];
            fromX = controller.positions()[glyph].x();
            if (controller.rtl())
                fromX += truncateFixedPointToInteger(controller.advances()[glyph]);
        } else
            from -= controller.numCodePoints();

        if (toX == -1 && to >= 0 && static_cast<unsigned>(to) < controller.numCodePoints()) {
            int glyph = controller.logClusters()[to];
            toX = controller.positions()[glyph].x();
            if (controller.rtl())
                toX += truncateFixedPointToInteger(controller.advances()[glyph]);
        } else
            to -= controller.numCodePoints();
    }

    // The position in question might be just after the text.
    if (fromX == -1)
        fromX = controller.offsetX();
    if (toX == -1)
        toX = controller.offsetX();

    ASSERT(fromX != -1 && toX != -1);

    if (fromX < toX)
        return FloatRect(point.x() + fromX, point.y(), toX - fromX, height);

    return FloatRect(point.x() + toX, point.y(), fromX - toX, height);
}

static QTextLine setupLayout(QTextLayout* layout, const TextRun& style)
{
    int flags = style.rtl() ? Qt::TextForceRightToLeft : Qt::TextForceLeftToRight;
    if (style.expansion())
        flags |= Qt::TextJustificationForced;
    layout->setFlags(flags);
    layout->beginLayout();
    QTextLine line = layout->createLine();
    line.setLineWidth(INT_MAX/256);
    if (style.expansion())
        line.setLineWidth(line.naturalTextWidth() + style.expansion());
    layout->endLayout();
    return line;
}

// FIXME: Rearchitect this to be more like WidthIterator in Font.cpp.  Have an advance() method
// that does stuff in that method instead of doing everything in the constructor.  Have advance()
// take the GlyphBuffer as an arg so that we don't have to populate the glyph buffer when
// measuring.
UniscribeController::UniscribeController(const Font* font, const TextRun& run, HashSet<const SimpleFontData*>* fallbackFonts)
    : m_font(*font)
    , m_run(run)
    , m_fallbackFonts(fallbackFonts)
    , m_minGlyphBoundingBoxX(numeric_limits<float>::max())
    , m_maxGlyphBoundingBoxX(numeric_limits<float>::min())
    , m_minGlyphBoundingBoxY(numeric_limits<float>::max())
    , m_maxGlyphBoundingBoxY(numeric_limits<float>::min())
    , m_end(run.length())
    , m_currentCharacter(0)
    , m_runWidthSoFar(0)
    , m_padding(run.expansion())
    , m_computingOffsetPosition(false)
    , m_includePartialGlyphs(false)
    , m_offsetX(0)
    , m_offsetPosition(0)
{
    if (!m_padding)
        m_padPerSpace = 0;
    else {
        float numSpaces = 0;
        for (int s = 0; s < m_run.length(); s++) {
            if (Font::treatAsSpace(m_run[s]))
                numSpaces++;
        }

        if (numSpaces == 0)
            m_padPerSpace = 0;
        else
            m_padPerSpace = m_padding / numSpaces;
    }

    // Null out our uniscribe structs
    resetControlAndState();
}

float Font::floatWidthForComplexText(const TextRun& run, HashSet<const SimpleFontData*>* /* fallbackFonts */, GlyphOverflow* /* glyphOverflow */) const
{
    ComplexTextController controller(run, 0, 0, this);
    controller.setWordSpacingAdjustment(wordSpacing());
    controller.setLetterSpacingAdjustment(letterSpacing());
    controller.setPadding(run.expansion());
    return controller.widthOfFullRun();
}

float Font::floatWidthForComplexText(const TextRun& run, HashSet<const SimpleFontData*>*, GlyphOverflow*) const
{
    if (!primaryFont()->platformData().size())
        return 0;

    if (!run.length())
        return 0;

    if (run.length() == 1 && treatAsSpace(run[0]))
        return QFontMetrics(font()).width(space) + run.expansion();

    String sanitized = Font::normalizeSpaces(run.characters(), run.length());
    QString string = fromRawDataWithoutRef(sanitized);

    int w = QFontMetrics(font()).width(string);
    // WebKit expects us to ignore word spacing on the first character (as opposed to what Qt does)
    if (treatAsSpace(run[0]))
        w -= m_wordSpacing;

    return w + run.expansion();
}

UniscribeHelperTextRun::UniscribeHelperTextRun(const TextRun& run,
                                               const Font& font)
    : UniscribeHelper(run.characters(), run.length(), run.rtl(),
                      font.primaryFont()->platformData().hfont(),
                      font.primaryFont()->platformData().scriptCache(),
                      font.primaryFont()->platformData().scriptFontProperties(),
                      font.primaryFont()->spaceGlyph())
    , m_font(&font)
    , m_fontIndex(0)
{
    setDirectionalOverride(run.directionalOverride());
    setLetterSpacing(font.letterSpacing());
    setSpaceWidth(font.spaceWidth());
    setWordSpacing(font.wordSpacing());
    setAscent(font.fontMetrics().ascent());

    init();

    // Expansion is the amount to add to make justification happen. This
    // should be done after Init() so all the runs are already measured.
    if (run.expansion() > 0)
        justify(run.expansion());
}

void Font::drawComplexText(GraphicsContext* gc, TextRun const& run,
                           FloatPoint const& point, int, int) const
{
    if (!run.length())
        return;

    int mode = gc->textDrawingMode();
    bool fill = mode & TextModeFill;
    bool stroke = mode & TextModeStroke;
    if (!fill && !stroke)
        return;

    SkPaint fillPaint, strokePaint;
    if (fill)
        setupFill(&fillPaint, gc, primaryFont());
    if (stroke)
        setupStroke(&strokePaint, gc, primaryFont());

    SkCanvas* canvas = gc->platformContext()->recordingCanvas();

    bool haveMultipleLayers = isCanvasMultiLayered(canvas);
    TextRunWalker walker(run, point.x(), point.y(), this);
    walker.setWordAndLetterSpacing(wordSpacing(), letterSpacing());
    walker.setPadding(run.expansion());

    while (walker.nextScriptRun()) {
        if (fill) {
            walker.fontPlatformDataForScriptRun()->setupPaint(&fillPaint);
            adjustTextRenderMode(&fillPaint, haveMultipleLayers);
            canvas->drawPosText(walker.glyphs(), walker.length() << 1,
                                walker.positions(), fillPaint);
        }
        if (stroke) {
            walker.fontPlatformDataForScriptRun()->setupPaint(&strokePaint);
            adjustTextRenderMode(&strokePaint, haveMultipleLayers);
            canvas->drawPosText(walker.glyphs(), walker.length() << 1,
                                walker.positions(), strokePaint);
        }
    }

    gc->platformContext()->endRecording();
}

ShapeResultSpacing::ShapeResultSpacing(const TextRun& run,
    const FontDescription& fontDescription)
    : m_textRun(run)
    , m_letterSpacing(fontDescription.letterSpacing())
    , m_wordSpacing(fontDescription.wordSpacing())
    , m_expansion(run.expansion())
    , m_expansionPerOpportunity(0)
    , m_expansionOpportunityCount(0)
    , m_textJustify(TextJustify::TextJustifyAuto)
    , m_hasSpacing(false)
    , m_normalizeSpace(run.normalizeSpace())
    , m_allowTabs(run.allowTabs())
    , m_isAfterExpansion(false)
    , m_isVerticalOffset(fontDescription.isVerticalAnyUpright())
{
    if (m_textRun.spacingDisabled())
        return;

    if (!m_letterSpacing && !m_wordSpacing && !m_expansion)
        return;

    m_hasSpacing = true;

    if (!m_expansion)
        return;

    // Setup for justifications (expansions.)
    m_textJustify = run.getTextJustify();
    m_isAfterExpansion = !run.allowsLeadingExpansion();

    bool isAfterExpansion = m_isAfterExpansion;
    m_expansionOpportunityCount = Character::expansionOpportunityCount(run,
        isAfterExpansion);
    if (isAfterExpansion && !run.allowsTrailingExpansion()) {
        ASSERT(m_expansionOpportunityCount > 0);
        --m_expansionOpportunityCount;
    }

    if (m_expansionOpportunityCount)
        m_expansionPerOpportunity = m_expansion / m_expansionOpportunityCount;
}

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 PLATFORM(QT) && !HAVE(QRAWFONT)
    if (run.expansion() || run.rtl() || isSmallCaps() || wordSpacing() || letterSpacing())
        return Complex;
#endif

    if (m_fontDescription.featureSettings() && m_fontDescription.featureSettings()->size() > 0)
        return Complex;

    CodePath result = Simple;

    // Start from 0 since drawing and highlighting also measure the characters before run->from
    // 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.
    for (int i = 0; i < run.length(); i++) {
        const UChar c = run[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
//.........这里部分代码省略.........

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

#if PLATFORM(QT)
    if (run.expansion() || run.rtl() || isSmallCaps() || wordSpacing() || letterSpacing())
        return Complex;
#endif

    CodePath result = Simple;

    // Start from 0 since drawing and highlighting also measure the characters before run->from
    for (int i = 0; i < run.length(); i++) {
        const UChar c = run[i];
        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;

        if (c < 0x0600) // U+0600 through U+1059 Arabic, Syriac, Thaana, Devanagari, Bengali, Gurmukhi, Gujarati, Oriya, Tamil, Telugu, Kannada, Malayalam, Sinhala, Thai, Lao, Tibetan, Myanmar
            continue;
        if (c <= 0x1059)
            return Complex;

        if (c < 0x1100) // 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)
            continue;
        if (c <= 0x11FF)
            return Complex;

        if (c < 0x1780) // U+1780 through U+18AF 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 < 0x1E00) // U+1E00 through U+2000 characters with diacritics and stacked diacritics
            continue;
        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 < 0xFE20) // U+FE20 through U+FE2F Combining half marks
            continue;
        if (c <= 0xFE2F)
            return Complex;
    }

#if ENABLE(SAMSUNG_WEBKIT_PERFORMANCE_PATCH)
    // SAMSUNG CHANGE : Webkit Performance Patch Merge + r94303
    if (run.length() > 1 && typesettingFeatures())
#else
    if (typesettingFeatures())
    // SAMSUNG CHANGE : Webkit Performance Patch Merge -
#endif
        return Complex;

    return result;
}

static void drawTextCommon(GraphicsContext* ctx, const TextRun& run, const FloatPoint& point, int from, int to, const QFont& font, bool isComplexText)
{
    if (to < 0)
        to = run.length();

    QPainter *p = ctx->platformContext();

    QPen textFillPen;
    if (ctx->textDrawingMode() & TextModeFill)
        textFillPen = fillPenForContext(ctx);

    QPen textStrokePen;
    if (ctx->textDrawingMode() & TextModeStroke)
        textStrokePen = strokePenForContext(ctx);

    String sanitized = Font::normalizeSpaces(run.characters(), run.length());
    QString string = fromRawDataWithoutRef(sanitized);
    QPointF pt(point.x(), point.y());

    if (from > 0 || to < run.length()) {
        if (isComplexText) {
            QTextLayout layout(string, font);
            QTextLine line = setupLayout(&layout, run);
            float x1 = line.cursorToX(from);
            float x2 = line.cursorToX(to);
            if (x2 < x1)
                qSwap(x1, x2);

            QFontMetrics fm(font);
            int ascent = fm.ascent();
            QRectF boundingRect(point.x() + x1, point.y() - ascent, x2 - x1, fm.height());
            QRectF clip = boundingRect;

            ContextShadow* ctxShadow = ctx->contextShadow();

            if (ctxShadow->m_type != ContextShadow::NoShadow) {
                qreal dx1 = 0, dx2 = 0, dy1 = 0, dy2 = 0;
                if (ctxShadow->offset().x() > 0)
                    dx2 = ctxShadow->offset().x();
                else
                    dx1 = -ctxShadow->offset().x();
                if (ctxShadow->offset().y() > 0)
                    dy2 = ctxShadow->offset().y();
                else
                    dy1 = -ctxShadow->offset().y();
                // expand the clip rect to include the text shadow as well
                clip.adjust(dx1, dx2, dy1, dy2);
                clip.adjust(-ctxShadow->m_blurDistance, -ctxShadow->m_blurDistance, ctxShadow->m_blurDistance, ctxShadow->m_blurDistance);
            }
            p->save();
            p->setClipRect(clip.toRect(), Qt::IntersectClip);
            pt.setY(pt.y() - ascent);

            if (ctxShadow->m_type != ContextShadow::NoShadow) {
                ContextShadow* ctxShadow = ctx->contextShadow();
                if (!ctxShadow->mustUseContextShadow(ctx)) {
                    p->save();
                    p->setPen(ctxShadow->m_color);
                    p->translate(ctxShadow->offset());
                    line.draw(p, pt);
                    p->restore();
                } else {
                    QPainter* shadowPainter = ctxShadow->beginShadowLayer(ctx, boundingRect);
                    if (shadowPainter) {
                        // Since it will be blurred anyway, we don't care about render hints.
                        shadowPainter->setFont(p->font());
                        shadowPainter->setPen(ctxShadow->m_color);
                        line.draw(shadowPainter, pt);
                        ctxShadow->endShadowLayer(ctx);
                    }
                }
            }
            p->setPen(textFillPen);
            line.draw(p, pt);
            p->restore();
            return;
        }
        int skipWidth = QFontMetrics(font).width(string, from, Qt::TextBypassShaping);
        pt.setX(pt.x() + skipWidth);
        string = fromRawDataWithoutRef(sanitized, from, to - from);
    }

    p->setFont(font);

    int flags = run.rtl() ? Qt::TextForceRightToLeft : Qt::TextForceLeftToRight;
    if (!isComplexText && !(ctx->textDrawingMode() & TextModeStroke))
        flags |= Qt::TextBypassShaping;

    QPainterPath textStrokePath;
    if (ctx->textDrawingMode() & TextModeStroke)
        textStrokePath.addText(pt, font, string);

    ContextShadow* ctxShadow = ctx->contextShadow();
    if (ctxShadow->m_type != ContextShadow::NoShadow) {
        if (ctx->textDrawingMode() & TextModeFill) {
            if (ctxShadow->m_type != ContextShadow::BlurShadow) {
                p->save();
                p->setPen(ctxShadow->m_color);
                p->translate(ctxShadow->offset());
                p->drawText(pt, string, flags, run.expansion());
//.........这里部分代码省略.........

static int generateComponents(TextRunComponents* components, const Font &font, const TextRun &run)
{
    int letterSpacing = font.letterSpacing();
    int wordSpacing = font.wordSpacing();
    int padding = run.expansion();
    int numSpaces = 0;
    if (padding) {
        for (int i = 0; i < run.length(); i++)
            if (Font::treatAsSpace(run[i]))
                ++numSpaces;
    }

    int offset = 0;
    if (letterSpacing) {
        // need to draw every letter on it's own
        int start = 0;
        if (Font::treatAsSpace(run[0])) {
            int add = 0;
            if (numSpaces) {
                add = padding/numSpaces;
                padding -= add;
                --numSpaces;
            }
            components->append(TextRunComponent(1, font, offset));
            offset += add + letterSpacing + components->last().m_width;
            start = 1;
        }
        for (int i = 1; i < run.length(); ++i) {
            UChar ch = run[i];
            if (U16_IS_LEAD(ch) && U16_IS_TRAIL(run[i-1]))
                ch = U16_GET_SUPPLEMENTARY(ch, run[i-1]);
            if (U16_IS_TRAIL(ch) || U_GET_GC_MASK(ch) & U_GC_MN_MASK)
                continue;
            if (Font::treatAsSpace(run[i])) {
                int add = 0;
                if (i - start > 0) {
                    components->append(TextRunComponent(run.characters16() + start, i - start,
                                                        run, font, offset));
                    offset += components->last().m_width + letterSpacing;
                }
                if (numSpaces) {
                    add = padding/numSpaces;
                    padding -= add;
                    --numSpaces;
                }
                components->append(TextRunComponent(1, font, offset));
                offset += wordSpacing + add + components->last().m_width + letterSpacing;
                start = i + 1;
                continue;
            }
            if (i - start > 0) {
                components->append(TextRunComponent(run.characters16() + start, i - start,
                                                    run,
                                                    font, offset));
                offset += components->last().m_width + letterSpacing;
            }
            start = i;
        }
        if (run.length() - start > 0) {
            components->append(TextRunComponent(run.characters16() + start, run.length() - start,
                                                run,
                                                font, offset));
            offset += components->last().m_width;
        }
        offset += letterSpacing;
    } else {
        int start = 0;
        for (int i = 0; i < run.length(); ++i) {
            if (Font::treatAsSpace(run[i])) {
                if (i - start > 0) {
                    components->append(TextRunComponent(run.characters16() + start, i - start,
                                                        run,
                                                        font, offset));
                    offset += components->last().m_width;
                }
                int add = 0;
                if (numSpaces) {
                    add = padding/numSpaces;
                    padding -= add;
                    --numSpaces;
                }
                components->append(TextRunComponent(1, font, offset));
                offset += add + components->last().m_width;
                if (i)
                    offset += wordSpacing;
                start = i + 1;
            }
        }
        if (run.length() - start > 0) {
            components->append(TextRunComponent(run.characters16() + start, run.length() - start,
                                                run,
                                                font, offset));
            offset += components->last().m_width;
        }
    }
    return offset;
}