glyphpagetreenode.cpp

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            if (fontData->isSegmented()) {
                haveGlyphs = false;

                const SegmentedFontData* segmentedFontData = static_cast<const SegmentedFontData*>(fontData);
                unsigned numRanges = segmentedFontData->numRanges();
                bool zeroFilled = false;
                RefPtr<GlyphPage> scratchPage;
                GlyphPage* pageToFill = m_page.get();
                for (unsigned i = 0; i < numRanges; i++) {
                    const FontDataRange& range = segmentedFontData->rangeAt(i);
                    int from = max(0, range.from() - static_cast<int>(start));
                    int to = 1 + min(range.to() - static_cast<int>(start), static_cast<int>(GlyphPage::size) - 1);
                    if (from < static_cast<int>(GlyphPage::size) && to > 0) {
                        if (haveGlyphs && !scratchPage) {
                            scratchPage = GlyphPage::create(this);
                            pageToFill = scratchPage.get();
                        }

                        if (!zeroFilled) {
                            if (from > 0 || to < static_cast<int>(GlyphPage::size)) {
                                for (unsigned i = 0; i < GlyphPage::size; i++)
                                    pageToFill->setGlyphDataForIndex(i, 0, 0);
                            }
                            zeroFilled = true;
                        }
                        haveGlyphs |= pageToFill->fill(from, to - from, buffer + from * (start < 0x10000 ? 1 : 2), (to - from) * (start < 0x10000 ? 1 : 2), range.fontData());
                        if (scratchPage) {
                            for (int j = from; j < to; j++) {
                                if (!m_page->m_glyphs[j].glyph && pageToFill->m_glyphs[j].glyph)
                                    m_page->m_glyphs[j] = pageToFill->m_glyphs[j];
                            }
                        }
                    }
                }
            } else
                haveGlyphs = m_page->fill(0, GlyphPage::size, buffer, bufferLength, static_cast<const SimpleFontData*>(fontData));

            if (!haveGlyphs)
                m_page = 0;
        } else if (parentPage && parentPage->owner() != m_parent) {
            // The page we're overriding may not be owned by our parent node.
            // This happens when our parent node provides no useful overrides
            // and just copies the pointer to an already-existing page (see
            // below).
            //
            // We want our override to be shared by all nodes that reference
            // that page to avoid duplication, and so standardize on having the
            // page's owner collect all the overrides.  Call getChild on the
            // page owner with the desired font data (this will populate
            // the page) and then reference it.
            m_page = parentPage->owner()->getChild(fontData, pageNumber)->page();
        } else {
            // Get the pure page for the fallback font (at level 1 with no
            // overrides). getRootChild will always create a page if one
            // doesn't exist, but the page doesn't necessarily have glyphs
            // (this pointer may be 0).
            GlyphPage* fallbackPage = getRootChild(fontData, pageNumber)->page();
            if (!parentPage) {
                // When the parent has no glyphs for this page, we can easily
                // override it just by supplying the glyphs from our font.
                m_page = fallbackPage;
            } else if (!fallbackPage) {
                // When our font has no glyphs for this page, we can just reference the
                // parent page.
                m_page = parentPage;
            } else {
                // Combine the parent's glyphs and ours to form a new more complete page.
                m_page = GlyphPage::create(this);

                // Overlay the parent page on the fallback page. Check if the fallback font
                // has added anything.
                bool newGlyphs = false;
                for (unsigned i = 0; i < GlyphPage::size; i++) {
                    if (parentPage->m_glyphs[i].glyph)
                        m_page->m_glyphs[i] = parentPage->m_glyphs[i];
                    else  if (fallbackPage->m_glyphs[i].glyph) {
                        m_page->m_glyphs[i] = fallbackPage->m_glyphs[i];
                        newGlyphs = true;
                    } else {
                        const GlyphData data = { 0, 0 };
                        m_page->m_glyphs[i] = data;
                    }
                }

                if (!newGlyphs)
                    // We didn't override anything, so our override is just the parent page.
                    m_page = parentPage;
            }
        }
    } else {
        m_page = GlyphPage::create(this);
        // System fallback. Initialized with the parent's page here, as individual
        // entries may use different fonts depending on character. If the Font
        // ever finds it needs a glyph out of the system fallback page, it will
        // ask the system for the best font to use and fill that glyph in for us.
        if (parentPage)
            memcpy(m_page->m_glyphs, parentPage->m_glyphs, GlyphPage::size * sizeof(m_page->m_glyphs[0]));
        else {
            const GlyphData data = { 0, 0 };
            for (unsigned i = 0; i < GlyphPage::size; i++)
                m_page->m_glyphs[i] = data;
        }
    }
}

GlyphPageTreeNode* GlyphPageTreeNode::getChild(const FontData* fontData, unsigned pageNumber)
{
    ASSERT(fontData || !m_isSystemFallback);
    ASSERT(pageNumber == m_pageNumber);

    GlyphPageTreeNode* child = fontData ? m_children.get(fontData) : m_systemFallbackChild;
    if (!child) {
        child = new GlyphPageTreeNode;
        child->m_parent = this;
        child->m_level = m_level + 1;
        if (fontData && fontData->isCustomFont()) {
            for (GlyphPageTreeNode* curr = this; curr; curr = curr->m_parent)
                curr->m_customFontCount++;
        }

#ifndef NDEBUG
        child->m_pageNumber = m_pageNumber;
#endif
        if (fontData) {
            m_children.set(fontData, child);
            fontData->setMaxGlyphPageTreeLevel(max(fontData->maxGlyphPageTreeLevel(), child->m_level));
        } else {
            m_systemFallbackChild = child;
            child->m_isSystemFallback = true;
        }
        child->initializePage(fontData, pageNumber);
    }
    return child;
}

void GlyphPageTreeNode::pruneCustomFontData(const FontData* fontData)
{
    if (!fontData || !m_customFontCount)
        return;
        
    // Prune any branch that contains this FontData.
    GlyphPageTreeNode* node = m_children.get(fontData);
    if (node) {
        m_children.remove(fontData);
        unsigned fontCount = node->m_customFontCount + 1;
        delete node;
        for (GlyphPageTreeNode* curr = this; curr; curr = curr->m_parent)
            curr->m_customFontCount -= fontCount;
    }
    
    // Check any branches that remain that still have custom fonts underneath them.
    if (!m_customFontCount)
        return;
    HashMap<const FontData*, GlyphPageTreeNode*>::iterator end = m_children.end();
    for (HashMap<const FontData*, GlyphPageTreeNode*>::iterator it = m_children.begin(); it != end; ++it)
        it->second->pruneCustomFontData(fontData);
}

void GlyphPageTreeNode::pruneFontData(const SimpleFontData* fontData, unsigned level)
{
    ASSERT(fontData);
    if (!fontData)
        return;

    // Prune any branch that contains this FontData.
    HashMap<const FontData*, GlyphPageTreeNode*>::iterator child = m_children.find(fontData);
    if (child == m_children.end()) {
        // If there is no level-1 node for fontData, then there is no deeper node for it in this tree.
        if (!level)
            return;
    } else {
        GlyphPageTreeNode* node = child->second;
        m_children.remove(fontData);
        unsigned customFontCount = node->m_customFontCount;
        delete node;
        if (customFontCount) {
            for (GlyphPageTreeNode* curr = this; curr; curr = curr->m_parent)
                curr->m_customFontCount -= customFontCount;
        }
    }

    level++;
    if (level > fontData->maxGlyphPageTreeLevel())
        return;

    HashMap<const FontData*, GlyphPageTreeNode*>::iterator end = m_children.end();
    for (HashMap<const FontData*, GlyphPageTreeNode*>::iterator it = m_children.begin(); it != end; ++it)
        it->second->pruneFontData(fontData, level);
}

}