C++ GlyphPage::setGlyphDataForCharacter方法代码示例

GlyphData SVGTextRunRenderingContext::glyphDataForCharacter(const Font& font, const TextRun& run, WidthIterator& iterator, UChar32 character, bool mirror, int currentCharacter, unsigned& advanceLength)
{
    const SimpleFontData* primaryFont = font.primaryFont();
    ASSERT(primaryFont);

    pair<GlyphData, GlyphPage*> pair = font.glyphDataAndPageForCharacter(character, mirror);
    GlyphData glyphData = pair.first;

    // Check if we have the missing glyph data, in which case we can just return.
    GlyphData missingGlyphData = primaryFont->missingGlyphData();
    if (glyphData.glyph == missingGlyphData.glyph && glyphData.fontData == missingGlyphData.fontData) {
        ASSERT(glyphData.fontData);
        return glyphData;
    }

    // Characters enclosed by an <altGlyph> element, may not be registered in the GlyphPage.
    const SimpleFontData* originalFontData = glyphData.fontData;
    if (glyphData.fontData && !glyphData.fontData->isSVGFont()) {
        if (TextRun::RenderingContext* renderingContext = run.renderingContext()) {
            RenderObject* renderObject = static_cast<SVGTextRunRenderingContext*>(renderingContext)->renderer();
            RenderObject* parentRenderObject = renderObject->isText() ? renderObject->parent() : renderObject;
            ASSERT(parentRenderObject);
            if (Element* parentRenderObjectElement = toElement(parentRenderObject->node())) {
                if (parentRenderObjectElement->hasTagName(SVGNames::altGlyphTag))
                    glyphData.fontData = primaryFont;
            }
        }
    }

    const SimpleFontData* fontData = glyphData.fontData;
    if (fontData) {
        if (!fontData->isSVGFont())
            return glyphData;

        SVGFontElement* fontElement = 0;
        SVGFontFaceElement* fontFaceElement = 0;

        const SVGFontData* svgFontData = svgFontAndFontFaceElementForFontData(fontData, fontFaceElement, fontElement);
        if (!fontElement || !fontFaceElement)
            return glyphData;

        // If we got here, we're dealing with a glyph defined in a SVG Font.
        // The returned glyph by glyphDataAndPageForCharacter() is a glyph stored in the SVG Font glyph table.
        // This doesn't necessarily mean the glyph is suitable for rendering/measuring in this context, its
        // arabic-form/orientation/... may not match, we have to apply SVG Glyph selection to discover that.
        if (svgFontData->applySVGGlyphSelection(iterator, glyphData, mirror, currentCharacter, advanceLength))
            return glyphData;
    }

    GlyphPage* page = pair.second;
    ASSERT(page);

    FontFallbackList* fontList = font.fontList();
    ASSERT(fontList);

    // No suitable glyph found that is compatible with the requirments (same language, arabic-form, orientation etc.)
    // Even though our GlyphPage contains an entry for eg. glyph "a", it's not compatible. So we have to temporarily
    // remove the glyph data information from the GlyphPage, and retry the lookup, which handles font fallbacks correctly.
    GlyphPageTreeNode* originalGlyphPageZero = fontList->glyphPageZero();
    const FontFallbackList::GlyphPages& originalGlyphPages = fontList->glyphPages();
    page->setGlyphDataForCharacter(character, glyphData.glyph, 0);

    // Assure that the font fallback glyph selection worked, aka. the fallbackGlyphData font data is not the same as before.
    GlyphData fallbackGlyphData = font.glyphDataForCharacter(character, mirror);
    ASSERT(fallbackGlyphData.fontData != fontData);

    // Restore original state of the SVG Font glyph table and the current font fallback list,
    // to assure the next lookup of the same glyph won't immediately return the fallback glyph.
    page->setGlyphDataForCharacter(character, glyphData.glyph, originalFontData);
    fontList->setGlyphPageZero(originalGlyphPageZero);
    fontList->setGlyphPages(originalGlyphPages);
    ASSERT(fallbackGlyphData.fontData);
    return fallbackGlyphData;
}

GlyphData SVGTextRunRenderingContext::glyphDataForCharacter(const Font& font, WidthIterator& iterator, UChar32 character, bool mirror, int currentCharacter, unsigned& advanceLength)
{
    const SimpleFontData* primaryFont = font.primaryFont();
    ASSERT(primaryFont);

    std::pair<GlyphData, GlyphPage*> pair = font.glyphDataAndPageForCharacter(character, mirror, AutoVariant);
    GlyphData glyphData = pair.first;

    // Check if we have the missing glyph data, in which case we can just return.
    GlyphData missingGlyphData = primaryFont->missingGlyphData();
    if (glyphData.glyph == missingGlyphData.glyph && glyphData.fontData == missingGlyphData.fontData) {
        ASSERT(glyphData.fontData);
        return glyphData;
    }

    // Save data fromt he font fallback list because we may modify it later. Do this before the
    // potential change to glyphData.fontData below.
    FontGlyphs* glyph = font.glyphs();
    ASSERT(glyph);
    FontGlyphs::GlyphPagesStateSaver glyphPagesSaver(*glyph);

    // Characters enclosed by an <altGlyph> element, may not be registered in the GlyphPage.
    const SimpleFontData* originalFontData = glyphData.fontData;
    if (glyphData.fontData && !glyphData.fontData->isSVGFont()) {
        auto& elementRenderer = renderer().isRenderElement() ? toRenderElement(renderer()) : *renderer().parent();
        if (Element* parentRendererElement = elementRenderer.element()) {
            if (parentRendererElement->hasTagName(SVGNames::altGlyphTag))
                glyphData.fontData = primaryFont;
        }
    }

    const SimpleFontData* fontData = glyphData.fontData;
    if (fontData) {
        if (!fontData->isSVGFont())
            return glyphData;

        SVGFontElement* fontElement = 0;
        SVGFontFaceElement* fontFaceElement = 0;

        const SVGFontData* svgFontData = svgFontAndFontFaceElementForFontData(fontData, fontFaceElement, fontElement);
        if (!fontElement || !fontFaceElement)
            return glyphData;

        // If we got here, we're dealing with a glyph defined in a SVG Font.
        // The returned glyph by glyphDataAndPageForCharacter() is a glyph stored in the SVG Font glyph table.
        // This doesn't necessarily mean the glyph is suitable for rendering/measuring in this context, its
        // arabic-form/orientation/... may not match, we have to apply SVG Glyph selection to discover that.
        if (svgFontData->applySVGGlyphSelection(iterator, glyphData, mirror, currentCharacter, advanceLength))
            return glyphData;
    }

    GlyphPage* page = pair.second;
    ASSERT(page);

    // No suitable glyph found that is compatible with the requirments (same language, arabic-form, orientation etc.)
    // Even though our GlyphPage contains an entry for eg. glyph "a", it's not compatible. So we have to temporarily
    // remove the glyph data information from the GlyphPage, and retry the lookup, which handles font fallbacks correctly.
    page->setGlyphDataForCharacter(character, 0, 0);

    // Assure that the font fallback glyph selection worked, aka. the fallbackGlyphData font data is not the same as before.
    GlyphData fallbackGlyphData = font.glyphDataForCharacter(character, mirror);
    ASSERT(fallbackGlyphData.fontData != fontData);

    // Restore original state of the SVG Font glyph table and the current font fallback list,
    // to assure the next lookup of the same glyph won't immediately return the fallback glyph.
    page->setGlyphDataForCharacter(character, glyphData.glyph, originalFontData);
    ASSERT(fallbackGlyphData.fontData);
    return fallbackGlyphData;
}

//.........这里部分代码省略.........
        while (true) {
            page = node->page();
            if (page) {
                GlyphData data = page->glyphDataForCharacter(c);
                if (data.fontData) {
                    // The variantFontData function should not normally return 0.
                    // But if it does, we will just render the capital letter big.
                    RefPtr<SimpleFontData> variantFontData = data.fontData->variantFontData(description, variant);
                    if (!variantFontData)
                        return std::make_pair(data, page);

                    GlyphPageTreeNode* variantNode = GlyphPageTreeNode::getRootChild(variantFontData.get(), pageNumber);
                    GlyphPage* variantPage = variantNode->page();
                    if (variantPage) {
                        GlyphData data = variantPage->glyphDataForCharacter(c);
                        if (data.fontData)
                            return std::make_pair(data, variantPage);
                    }

                    // Do not attempt system fallback off the variantFontData. This is the very unlikely case that
                    // a font has the lowercase character but the small caps font does not have its uppercase version.
                    return std::make_pair(variantFontData->missingGlyphData(), page);
                }

                if (node->isSystemFallback())
                    break;
            }

            node = node->getChild(realizeFontDataAt(description, node->level()), pageNumber);
            if (pageNumber)
                m_pages.set(pageNumber, node);
            else
                m_pageZero = node;
        }
    }

    ASSERT(page);
    ASSERT(node->isSystemFallback());

    // System fallback is character-dependent. When we get here, we
    // know that the character in question isn't in the system fallback
    // font's glyph page. Try to lazily create it here.
    UChar codeUnits[2];
    int codeUnitsLength;
    if (c <= 0xFFFF) {
        codeUnits[0] = Font::normalizeSpaces(c);
        codeUnitsLength = 1;
    } else {
        codeUnits[0] = U16_LEAD(c);
        codeUnits[1] = U16_TRAIL(c);
        codeUnitsLength = 2;
    }
    const SimpleFontData* originalFontData = primaryFontData(description)->fontDataForCharacter(c);
    RefPtr<SimpleFontData> characterFontData = fontCache().systemFallbackForCharacters(description, originalFontData, m_isForPlatformFont, codeUnits, codeUnitsLength);
    if (characterFontData) {
        if (characterFontData->platformData().orientation() == Vertical && !characterFontData->hasVerticalGlyphs() && Font::isCJKIdeographOrSymbol(c))
            variant = BrokenIdeographVariant;
        if (variant != NormalVariant)
            characterFontData = characterFontData->variantFontData(description, variant);
    }
    if (characterFontData) {
        // Got the fallback glyph and font.
        GlyphPage* fallbackPage = GlyphPageTreeNode::getRootChild(characterFontData.get(), pageNumber)->page();
        GlyphData data = fallbackPage && fallbackPage->fontDataForCharacter(c) ? fallbackPage->glyphDataForCharacter(c) : characterFontData->missingGlyphData();
        // Cache it so we don't have to do system fallback again next time.
        if (variant == NormalVariant) {
#if OS(WINCE)
            // missingGlyphData returns a null character, which is not suitable for GDI to display.
            // Also, sometimes we cannot map a font for the character on WINCE, but GDI can still
            // display the character, probably because the font package is not installed correctly.
            // So we just always set the glyph to be same as the character, and let GDI solve it.
            page->setGlyphDataForCharacter(c, c, characterFontData.get());
            characterFontData->setMaxGlyphPageTreeLevel(std::max(characterFontData->maxGlyphPageTreeLevel(), node->level()));
            return std::make_pair(page->glyphDataForCharacter(c), page);
#else
            page->setGlyphDataForCharacter(c, data.glyph, data.fontData);
            data.fontData->setMaxGlyphPageTreeLevel(std::max(data.fontData->maxGlyphPageTreeLevel(), node->level()));
            if (!Font::isCJKIdeographOrSymbol(c) && data.fontData->platformData().orientation() != Horizontal && !data.fontData->isTextOrientationFallback())
                return glyphDataAndPageForNonCJKCharacterWithGlyphOrientation(c, description.nonCJKGlyphOrientation(), data, fallbackPage, pageNumber);
#endif
        }
        return std::make_pair(data, page);
    }

    // Even system fallback can fail; use the missing glyph in that case.
    // FIXME: It would be nicer to use the missing glyph from the last resort font instead.
    GlyphData data = primarySimpleFontData(description)->missingGlyphData();
    if (variant == NormalVariant) {
#if OS(WINCE)
        // See comment about WINCE GDI handling near setGlyphDataForCharacter above.
        page->setGlyphDataForCharacter(c, c, data.fontData);
        data.fontData->setMaxGlyphPageTreeLevel(std::max(data.fontData->maxGlyphPageTreeLevel(), node->level()));
        return std::make_pair(page->glyphDataForCharacter(c), page);
#else
        page->setGlyphDataForCharacter(c, data.glyph, data.fontData);
        data.fontData->setMaxGlyphPageTreeLevel(std::max(data.fontData->maxGlyphPageTreeLevel(), node->level()));
#endif
    }
    return std::make_pair(data, page);
}

//.........这里部分代码省略.........
                    } else {
                        return glyphDataAndPageForNonCJKCharacterWithGlyphOrientation(c, m_fontDescription.nonCJKGlyphOrientation(), data, page, pageNumber);
                    }

                    return make_pair(data, page);
                }

                if (node->isSystemFallback())
                    break;
            }

            // Proceed with the fallback list.
            node = node->getChild(fontDataAt(node->level()), pageNumber);
            if (pageNumber)
                m_fontFallbackList->m_pages.set(pageNumber, node);
            else
                m_fontFallbackList->m_pageZero = node;
        }
    }
    if (variant != NormalVariant) {
        while (true) {
            page = node->page();
            if (page) {
                GlyphData data = page->glyphDataForCharacter(c);
                if (data.fontData) {
                    // The variantFontData function should not normally return 0.
                    // But if it does, we will just render the capital letter big.
                    RefPtr<SimpleFontData> variantFontData = data.fontData->variantFontData(m_fontDescription, variant);
                    if (!variantFontData)
                        return make_pair(data, page);

                    GlyphPageTreeNode* variantNode = GlyphPageTreeNode::getRootChild(variantFontData.get(), pageNumber);
                    GlyphPage* variantPage = variantNode->page();
                    if (variantPage) {
                        GlyphData data = variantPage->glyphDataForCharacter(c);
                        if (data.fontData)
                            return make_pair(data, variantPage);
                    }

                    // Do not attempt system fallback off the variantFontData. This is the very unlikely case that
                    // a font has the lowercase character but the small caps font does not have its uppercase version.
                    return make_pair(variantFontData->missingGlyphData(), page);
                }

                if (node->isSystemFallback())
                    break;
            }

            // Proceed with the fallback list.
            node = node->getChild(fontDataAt(node->level()), pageNumber);
            if (pageNumber)
                m_fontFallbackList->m_pages.set(pageNumber, node);
            else
                m_fontFallbackList->m_pageZero = node;
        }
    }

    ASSERT(page);
    ASSERT(node->isSystemFallback());

    // System fallback is character-dependent. When we get here, we
    // know that the character in question isn't in the system fallback
    // font's glyph page. Try to lazily create it here.

    // FIXME: Unclear if this should normalizeSpaces above 0xFFFF.
    // Doing so changes fast/text/international/plane2-diffs.html
    UChar32 characterToRender = c;
    if (characterToRender <=  0xFFFF)
        characterToRender = Character::normalizeSpaces(characterToRender);
    const SimpleFontData* fontDataToSubstitute = fontDataAt(0)->fontDataForCharacter(characterToRender);
    RefPtr<SimpleFontData> characterFontData = FontCache::fontCache()->platformFallbackForCharacter(m_fontDescription, characterToRender, fontDataToSubstitute);
    if (characterFontData) {
        if (characterFontData->platformData().orientation() == Vertical && !characterFontData->hasVerticalGlyphs() && Character::isCJKIdeographOrSymbol(c))
            variant = BrokenIdeographVariant;
        if (variant != NormalVariant)
            characterFontData = characterFontData->variantFontData(m_fontDescription, variant);
    }
    if (characterFontData) {
        // Got the fallback glyph and font.
        GlyphPage* fallbackPage = GlyphPageTreeNode::getRootChild(characterFontData.get(), pageNumber)->page();
        GlyphData data = fallbackPage && fallbackPage->fontDataForCharacter(c) ? fallbackPage->glyphDataForCharacter(c) : characterFontData->missingGlyphData();
        // Cache it so we don't have to do system fallback again next time.
        if (variant == NormalVariant) {
            page->setGlyphDataForCharacter(c, data.glyph, data.fontData);
            data.fontData->setMaxGlyphPageTreeLevel(max(data.fontData->maxGlyphPageTreeLevel(), node->level()));
            if (!Character::isCJKIdeographOrSymbol(c) && data.fontData->platformData().orientation() != Horizontal && !data.fontData->isTextOrientationFallback())
                return glyphDataAndPageForNonCJKCharacterWithGlyphOrientation(c, m_fontDescription.nonCJKGlyphOrientation(), data, fallbackPage, pageNumber);
        }
        return make_pair(data, page);
    }

    // Even system fallback can fail; use the missing glyph in that case.
    // FIXME: It would be nicer to use the missing glyph from the last resort font instead.
    GlyphData data = primaryFont()->missingGlyphData();
    if (variant == NormalVariant) {
        page->setGlyphDataForCharacter(c, data.glyph, data.fontData);
        data.fontData->setMaxGlyphPageTreeLevel(max(data.fontData->maxGlyphPageTreeLevel(), node->level()));
    }
    return make_pair(data, page);
}

//.........这里部分代码省略.........
    GlyphPage* page;
    if (!useSmallCapsFont) {
        // Fastest loop, for the common case (not small caps).
        while (true) {
            page = node->page();
            if (page) {
                const GlyphData& data = page->glyphDataForCharacter(c);
                if (data.fontData)
                    return data;
                if (node->isSystemFallback())
                    break;
            }

            // Proceed with the fallback list.
            node = node->getChild(fontDataAt(node->level()), pageNumber);
            if (pageNumber)
                m_pages.set(pageNumber, node);
            else
                m_pageZero = node;
        }
    } else {
        while (true) {
            page = node->page();
            if (page) {
                const GlyphData& data = page->glyphDataForCharacter(c);
                if (data.fontData) {
                    // The smallCapsFontData function should not normally return 0.
                    // But if it does, we will just render the capital letter big.
                    const SimpleFontData* smallCapsFontData = data.fontData->smallCapsFontData(m_fontDescription);
                    if (!smallCapsFontData)
                        return data;

                    GlyphPageTreeNode* smallCapsNode = GlyphPageTreeNode::getRootChild(smallCapsFontData, pageNumber);
                    const GlyphPage* smallCapsPage = smallCapsNode->page();
                    if (smallCapsPage) {
                        const GlyphData& data = smallCapsPage->glyphDataForCharacter(c);
                        if (data.fontData)
                            return data;
                    }

                    // Do not attempt system fallback off the smallCapsFontData. This is the very unlikely case that
                    // a font has the lowercase character but the small caps font does not have its uppercase version.
                    return smallCapsFontData->missingGlyphData();
                }

                if (node->isSystemFallback())
                    break;
            }

            // Proceed with the fallback list.
            node = node->getChild(fontDataAt(node->level()), pageNumber);
            if (pageNumber)
                m_pages.set(pageNumber, node);
            else
                m_pageZero = node;
        }
    }

    ASSERT(page);
    ASSERT(node->isSystemFallback());

    // System fallback is character-dependent. When we get here, we
    // know that the character in question isn't in the system fallback
    // font's glyph page. Try to lazily create it here.
    UChar codeUnits[2];
    int codeUnitsLength;
    if (c <= 0xFFFF) {
        UChar c16 = c;
        if (Font::treatAsSpace(c16))
            codeUnits[0] = ' ';
        else if (Font::treatAsZeroWidthSpace(c16))
            codeUnits[0] = zeroWidthSpace;
        else
            codeUnits[0] = c16;
        codeUnitsLength = 1;
    } else {
        codeUnits[0] = U16_LEAD(c);
        codeUnits[1] = U16_TRAIL(c);
        codeUnitsLength = 2;
    }
    const SimpleFontData* characterFontData = FontCache::getFontDataForCharacters(*this, codeUnits, codeUnitsLength);
    if (useSmallCapsFont)
        characterFontData = characterFontData->smallCapsFontData(m_fontDescription);
    if (characterFontData) {
        // Got the fallback glyph and font.
        GlyphPage* fallbackPage = GlyphPageTreeNode::getRootChild(characterFontData, pageNumber)->page();
        const GlyphData& data = fallbackPage && fallbackPage->glyphDataForCharacter(c).fontData ? fallbackPage->glyphDataForCharacter(c) : characterFontData->missingGlyphData();
        // Cache it so we don't have to do system fallback again next time.
        if (!useSmallCapsFont)
            page->setGlyphDataForCharacter(c, data.glyph, data.fontData);
        return data;
    }

    // Even system fallback can fail; use the missing glyph in that case.
    // FIXME: It would be nicer to use the missing glyph from the last resort font instead.
    const GlyphData& data = primaryFont()->missingGlyphData();
    if (!useSmallCapsFont)
        page->setGlyphDataForCharacter(c, data.glyph, data.fontData);
    return data;
}

// FIXME: It is unfortunate that this function needs to be passed the original cluster.
// It is only required for the platform's FontCache::getFontDataForCharacters(), and it means
// that this function is not correct if it transforms the character to uppercase and calls
// FontCache::getFontDataForCharacters() afterwards.
const GlyphData& Font::glyphDataForCharacter(UChar32 c, const UChar* cluster, unsigned clusterLength, bool mirror, bool attemptFontSubstitution) const
{
    bool smallCaps = false;

    if (m_fontDescription.smallCaps() && !Unicode::isUpper(c)) {
        // Convert lowercase to upper.
        UChar32 upperC = Unicode::toUpper(c);
        if (upperC != c) {
            c = upperC;
            smallCaps = true;
        }
    }

    if (mirror)
        c = mirroredChar(c);

    unsigned pageNumber = (c / GlyphPage::size);

    GlyphPageTreeNode* node = pageNumber ? m_pages.get(pageNumber) : m_pageZero;
    if (!node) {
        node = GlyphPageTreeNode::getRootChild(primaryFont(), pageNumber);
        if (pageNumber)
            m_pages.set(pageNumber, node);
        else
            m_pageZero = node;
    }

    if (!attemptFontSubstitution && node->level() != 1)
        node = GlyphPageTreeNode::getRootChild(primaryFont(), pageNumber);

    while (true) {
        GlyphPage* page = node->page();

        if (page) {
            const GlyphData& data = page->glyphDataForCharacter(c);
            if (data.glyph || !attemptFontSubstitution) {
                if (!smallCaps)
                    return data;  // We have a glyph for the character in question in the current page (or we've been told not to fall back).

                const FontData* smallCapsFontData = data.fontData->smallCapsFontData(m_fontDescription);

                if (!smallCapsFontData)
                    // This should not happen, but if it does, we will return a big cap.
                    return data;

                GlyphPageTreeNode* smallCapsNode = GlyphPageTreeNode::getRootChild(smallCapsFontData, pageNumber);
                GlyphPage* smallCapsPage = smallCapsNode->page();

                if (smallCapsPage) {
                    const GlyphData& data = smallCapsPage->glyphDataForCharacter(c);
                    if (data.glyph || !attemptFontSubstitution)
                        return data;
                }
                // Not attempting system fallback off the smallCapsFontData. This is the very unlikely case that
                // a font has the lowercase character but not its uppercase version.
                return smallCapsFontData->missingGlyphData();
            }
        } else if (!attemptFontSubstitution) {
            if (smallCaps) {
                if (const FontData* smallCapsFontData = primaryFont()->smallCapsFontData(m_fontDescription))
                    return smallCapsFontData->missingGlyphData();
            }
            return primaryFont()->missingGlyphData();
        }

        if (node->isSystemFallback()) {
            // System fallback is character-dependent. When we get here, we
            // know that the character in question isn't in the system fallback
            // font's glyph page. Try to lazily create it here.

            // Convert characters that shouldn't render to zero width spaces when asking what font is
            // appropriate.
            const FontData* characterFontData;
            if (clusterLength == 1 && Font::treatAsZeroWidthSpace(cluster[0]))
#ifdef __OWB__
                characterFontData = FontCache::getFontDataForCharacters(*this, &WebCore::zeroWidthSpace, 1);
#else
                characterFontData = FontCache::getFontDataForCharacters(*this, &zeroWidthSpace, 1);
#endif //__OWB__
            else
                characterFontData = FontCache::getFontDataForCharacters(*this, cluster, clusterLength);
            if (smallCaps)
                characterFontData = characterFontData->smallCapsFontData(m_fontDescription);
            if (characterFontData) {
                // Got the fallback font, return the glyph page associated with
                // it. We also store the FontData for the glyph in the fallback
                // page for future use (it's lazily populated by us).
                GlyphPage* fallbackPage = GlyphPageTreeNode::getRootChild(characterFontData, pageNumber)->page();
                const GlyphData& data = fallbackPage ? fallbackPage->glyphDataForCharacter(c) : characterFontData->missingGlyphData();
                if (!smallCaps)
                    page->setGlyphDataForCharacter(c, data.glyph, characterFontData);
                return data;
            }
            // Even system fallback can fail.
            // FIXME: Should the last resort font be used?
            const GlyphData& data = primaryFont()->missingGlyphData();
//.........这里部分代码省略.........

//.........这里部分代码省略.........
            }

            // Proceed with the fallback list.
            node = node->getChild(fontDataAt(node->level()), pageNumber);
            if (pageNumber)
                m_fontList->m_pages.set(pageNumber, node);
            else
                m_fontList->m_pageZero = node;
        }
    } else {
        while (true) {
            page = node->page();
            if (page) {
                GlyphData data = page->glyphDataForCharacter(c);
                if (data.fontData) {
                    // The smallCapsFontData function should not normally return 0.
                    // But if it does, we will just render the capital letter big.
                    const SimpleFontData* smallCapsFontData = data.fontData->smallCapsFontData(m_fontDescription);
                    if (!smallCapsFontData)
                        return data;

                    GlyphPageTreeNode* smallCapsNode = GlyphPageTreeNode::getRootChild(smallCapsFontData, pageNumber);
                    const GlyphPage* smallCapsPage = smallCapsNode->page();
                    if (smallCapsPage) {
                        GlyphData data = smallCapsPage->glyphDataForCharacter(c);
                        if (data.fontData)
                            return data;
                    }

                    // Do not attempt system fallback off the smallCapsFontData. This is the very unlikely case that
                    // a font has the lowercase character but the small caps font does not have its uppercase version.
                    return smallCapsFontData->missingGlyphData();
                }

                if (node->isSystemFallback())
                    break;
            }

            // Proceed with the fallback list.
            node = node->getChild(fontDataAt(node->level()), pageNumber);
            if (pageNumber)
                m_fontList->m_pages.set(pageNumber, node);
            else
                m_fontList->m_pageZero = node;
        }
    }

    ASSERT(page);
    ASSERT(node->isSystemFallback());

    // System fallback is character-dependent. When we get here, we
    // know that the character in question isn't in the system fallback
    // font's glyph page. Try to lazily create it here.
    UChar codeUnits[2];
    int codeUnitsLength;
    if (c <= 0xFFFF) {
        codeUnits[0] = Font::normalizeSpaces(c);
        codeUnitsLength = 1;
    } else {
        codeUnits[0] = U16_LEAD(c);
        codeUnits[1] = U16_TRAIL(c);
        codeUnitsLength = 2;
    }
    const SimpleFontData* characterFontData = fontCache()->getFontDataForCharacters(*this, codeUnits, codeUnitsLength);
    if (useSmallCapsFont && characterFontData)
        characterFontData = characterFontData->smallCapsFontData(m_fontDescription);
    if (characterFontData) {
        // Got the fallback glyph and font.
        GlyphPage* fallbackPage = GlyphPageTreeNode::getRootChild(characterFontData, pageNumber)->page();
        GlyphData data = fallbackPage && fallbackPage->fontDataForCharacter(c) ? fallbackPage->glyphDataForCharacter(c) : characterFontData->missingGlyphData();
        // Cache it so we don't have to do system fallback again next time.
        if (!useSmallCapsFont) {
#if OS(WINCE)
            // missingGlyphData returns a null character, which is not suitable for GDI to display.
            // Also, sometimes we cannot map a font for the character on WINCE, but GDI can still
            // display the character, probably because the font package is not installed correctly.
            // So we just always set the glyph to be same as the character, and let GDI solve it.
            page->setGlyphDataForCharacter(c, c, characterFontData);
            return page->glyphDataForCharacter(c);
#else
            page->setGlyphDataForCharacter(c, data.glyph, data.fontData);
#endif
        }
        return data;
    }

    // Even system fallback can fail; use the missing glyph in that case.
    // FIXME: It would be nicer to use the missing glyph from the last resort font instead.
    GlyphData data = primaryFont()->missingGlyphData();
    if (!useSmallCapsFont) {
#if OS(WINCE)
        // See comment about WINCE GDI handling near setGlyphDataForCharacter above.
        page->setGlyphDataForCharacter(c, c, data.fontData);
        return page->glyphDataForCharacter(c);
#else
        page->setGlyphDataForCharacter(c, data.glyph, data.fontData);
#endif
    }
    return data;
}