C++ RenderObject类代码示例

bool isTableStructureNode(const Node *node)
{
    RenderObject *r = node->renderer();
    return (r && (r->isTableCell() || r->isTableRow() || r->isTableSection() || r->isTableCol()));
}

void SVGRenderSupport::layoutChildren(RenderObject* start, bool selfNeedsLayout)
{
    bool layoutSizeChanged = layoutSizeOfNearestViewportChanged(start);
    bool transformChanged = transformToRootChanged(start);
    HashSet<RenderObject*> notlayoutedObjects;

    for (RenderObject* child = start->firstChild(); child; child = child->nextSibling()) {
        bool needsLayout = selfNeedsLayout;
        bool childEverHadLayout = child->everHadLayout();

        if (transformChanged) {
            // If the transform changed we need to update the text metrics (note: this also happens for layoutSizeChanged=true).
            if (child->isSVGText())
                toRenderSVGText(child)->setNeedsTextMetricsUpdate();
            needsLayout = true;
        }

        if (layoutSizeChanged) {
            // When selfNeedsLayout is false and the layout size changed, we have to check whether this child uses relative lengths
            if (SVGElement* element = child->node()->isSVGElement() ? toSVGElement(child->node()) : 0) {
                if (element->hasRelativeLengths()) {
                    // When the layout size changed and when using relative values tell the RenderSVGShape to update its shape object
                    if (child->isSVGShape())
                        toRenderSVGShape(child)->setNeedsShapeUpdate();
                    else if (child->isSVGText()) {
                        toRenderSVGText(child)->setNeedsTextMetricsUpdate();
                        toRenderSVGText(child)->setNeedsPositioningValuesUpdate();
                    }

                    needsLayout = true;
                }
            }
        }

        SubtreeLayoutScope layoutScope(*child);
        // Resource containers are nasty: they can invalidate clients outside the current SubtreeLayoutScope.
        // Since they only care about viewport size changes (to resolve their relative lengths), we trigger
        // their invalidation directly from SVGSVGElement::svgAttributeChange() or at a higher
        // SubtreeLayoutScope (in RenderView::layout()).
        if (needsLayout && !child->isSVGResourceContainer())
            layoutScope.setNeedsLayout(child);

        layoutResourcesIfNeeded(child);

        if (child->needsLayout()) {
            child->layout();
            // Renderers are responsible for repainting themselves when changing, except
            // for the initial paint to avoid potential double-painting caused by non-sensical "old" bounds.
            // We could handle this in the individual objects, but for now it's easier to have
            // parent containers call repaint().  (RenderBlock::layout* has similar logic.)
            if (!childEverHadLayout && !RuntimeEnabledFeatures::repaintAfterLayoutEnabled())
                child->repaint();
        } else if (layoutSizeChanged)
            notlayoutedObjects.add(child);
    }

    if (!layoutSizeChanged) {
        ASSERT(notlayoutedObjects.isEmpty());
        return;
    }

    // If the layout size changed, invalidate all resources of all children that didn't go through the layout() code path.
    HashSet<RenderObject*>::iterator end = notlayoutedObjects.end();
    for (HashSet<RenderObject*>::iterator it = notlayoutedObjects.begin(); it != end; ++it)
        invalidateResourcesOfChildren(*it);
}

void writeSVGResourceContainer(TextStream& ts, const RenderObject& object, int indent)
{
    writeStandardPrefix(ts, object, indent);

    Element* element = toElement(object.node());
    const AtomicString& id = element->getIdAttribute();
    writeNameAndQuotedValue(ts, "id", id);    

    RenderSVGResourceContainer* resource = const_cast<RenderObject&>(object).toRenderSVGResourceContainer();
    ASSERT(resource);

    if (resource->resourceType() == MaskerResourceType) {
        RenderSVGResourceMasker* masker = static_cast<RenderSVGResourceMasker*>(resource);
        writeNameValuePair(ts, "maskUnits", masker->maskUnits());
        writeNameValuePair(ts, "maskContentUnits", masker->maskContentUnits());
        ts << "\n";
#if ENABLE(FILTERS)
    } else if (resource->resourceType() == FilterResourceType) {
        RenderSVGResourceFilter* filter = static_cast<RenderSVGResourceFilter*>(resource);
        writeNameValuePair(ts, "filterUnits", filter->filterUnits());
        writeNameValuePair(ts, "primitiveUnits", filter->primitiveUnits());
        ts << "\n";
        // Creating a placeholder filter which is passed to the builder.
        FloatRect dummyRect;
        RefPtr<SVGFilter> dummyFilter = SVGFilter::create(AffineTransform(), dummyRect, dummyRect, dummyRect, true);
        if (auto builder = filter->buildPrimitives(dummyFilter.get())) {
            if (FilterEffect* lastEffect = builder->lastEffect())
                lastEffect->externalRepresentation(ts, indent + 1);
        }
#endif
    } else if (resource->resourceType() == ClipperResourceType) {
        RenderSVGResourceClipper* clipper = static_cast<RenderSVGResourceClipper*>(resource);
        writeNameValuePair(ts, "clipPathUnits", clipper->clipPathUnits());
        ts << "\n";
    } else if (resource->resourceType() == MarkerResourceType) {
        RenderSVGResourceMarker* marker = static_cast<RenderSVGResourceMarker*>(resource);
        writeNameValuePair(ts, "markerUnits", marker->markerUnits());
        ts << " [ref at " << marker->referencePoint() << "]";
        ts << " [angle=";
        if (marker->angle() == -1)
            ts << "auto" << "]\n";
        else
            ts << marker->angle() << "]\n";
    } else if (resource->resourceType() == PatternResourceType) {
        RenderSVGResourcePattern* pattern = static_cast<RenderSVGResourcePattern*>(resource);

        // Dump final results that are used for rendering. No use in asking SVGPatternElement for its patternUnits(), as it may
        // link to other patterns using xlink:href, we need to build the full inheritance chain, aka. collectPatternProperties()
        PatternAttributes attributes;
        pattern->patternElement().collectPatternAttributes(attributes);

        writeNameValuePair(ts, "patternUnits", attributes.patternUnits());
        writeNameValuePair(ts, "patternContentUnits", attributes.patternContentUnits());

        AffineTransform transform = attributes.patternTransform();
        if (!transform.isIdentity())
            ts << " [patternTransform=" << transform << "]";
        ts << "\n";
    } else if (resource->resourceType() == LinearGradientResourceType) {
        RenderSVGResourceLinearGradient* gradient = static_cast<RenderSVGResourceLinearGradient*>(resource);

        // Dump final results that are used for rendering. No use in asking SVGGradientElement for its gradientUnits(), as it may
        // link to other gradients using xlink:href, we need to build the full inheritance chain, aka. collectGradientProperties()
        LinearGradientAttributes attributes;
        gradient->linearGradientElement().collectGradientAttributes(attributes);
        writeCommonGradientProperties(ts, attributes.spreadMethod(), attributes.gradientTransform(), attributes.gradientUnits());

        ts << " [start=" << gradient->startPoint(attributes) << "] [end=" << gradient->endPoint(attributes) << "]\n";
    }  else if (resource->resourceType() == RadialGradientResourceType) {
        RenderSVGResourceRadialGradient* gradient = static_cast<RenderSVGResourceRadialGradient*>(resource);

        // Dump final results that are used for rendering. No use in asking SVGGradientElement for its gradientUnits(), as it may
        // link to other gradients using xlink:href, we need to build the full inheritance chain, aka. collectGradientProperties()
        RadialGradientAttributes attributes;
        gradient->radialGradientElement().collectGradientAttributes(attributes);
        writeCommonGradientProperties(ts, attributes.spreadMethod(), attributes.gradientTransform(), attributes.gradientUnits());

        FloatPoint focalPoint = gradient->focalPoint(attributes);
        FloatPoint centerPoint = gradient->centerPoint(attributes);
        float radius = gradient->radius(attributes);
        float focalRadius = gradient->focalRadius(attributes);

        ts << " [center=" << centerPoint << "] [focal=" << focalPoint << "] [radius=" << radius << "] [focalRadius=" << focalRadius << "]\n";
    } else
        ts << "\n";
    writeChildren(ts, object, indent);
}

void RenderRubyAsBlock::addChild(RenderObject* child, RenderObject* beforeChild)
{
    // Insert :before and :after content before/after the RenderRubyRun(s)
    if (child->isBeforeContent()) {
        if (child->isInline()) {
            // Add generated inline content normally
            RenderBlockFlow::addChild(child, firstChild());
        } else {
            // Wrap non-inline content with an anonymous inline-block.
            RenderBlock* beforeBlock = rubyBeforeBlock(this);
            if (!beforeBlock) {
                beforeBlock = createAnonymousRubyInlineBlock(this);
                RenderBlockFlow::addChild(beforeBlock, firstChild());
            }
            beforeBlock->addChild(child);
        }
        return;
    }
    if (child->isAfterContent()) {
        if (child->isInline()) {
            // Add generated inline content normally
            RenderBlockFlow::addChild(child);
        } else {
            // Wrap non-inline content with an anonymous inline-block.
            RenderBlock* afterBlock = rubyAfterBlock(this);
            if (!afterBlock) {
                afterBlock = createAnonymousRubyInlineBlock(this);
                RenderBlockFlow::addChild(afterBlock);
            }
            afterBlock->addChild(child);
        }
        return;
    }

    // If the child is a ruby run, just add it normally.
    if (child->isRubyRun()) {
        RenderBlockFlow::addChild(child, beforeChild);
        return;
    }

    if (beforeChild && !isAfterContent(beforeChild)) {
        // insert child into run
        ASSERT(!beforeChild->isRubyRun());
        RenderObject* run = beforeChild;
        while (run && !run->isRubyRun())
            run = run->parent();
        if (run) {
            run->addChild(child, beforeChild);
            return;
        }
        ASSERT_NOT_REACHED(); // beforeChild should always have a run as parent!
        // Emergency fallback: fall through and just append.
    }

    // If the new child would be appended, try to add the child to the previous run
    // if possible, or create a new run otherwise.
    // (The RenderRubyRun object will handle the details)
    RenderRubyRun* lastRun = lastRubyRun(this);
    if (!lastRun || lastRun->hasRubyText()) {
        lastRun = RenderRubyRun::staticCreateRubyRun(this);
        RenderBlockFlow::addChild(lastRun, beforeChild);
    }
    lastRun->addChild(child);
}

void RenderTableRow::addChild(RenderObject* child, RenderObject* beforeChild)
{
    // Make sure we don't append things after :after-generated content if we have it.
    if (!beforeChild)
        beforeChild = afterPseudoElementRenderer();

    if (!child->isTableCell()) {
        RenderObject* last = beforeChild;
        if (!last)
            last = lastChild();
        if (last && last->isAnonymous() && last->isTableCell() && !last->isBeforeOrAfterContent()) {
            if (beforeChild == last)
                beforeChild = last->firstChild();
            last->addChild(child, beforeChild);
            return;
        }

        if (beforeChild && !beforeChild->isAnonymous() && beforeChild->parent() == this) {
            RenderObject* cell = beforeChild->previousSibling();
            if (cell && cell->isTableCell() && cell->isAnonymous()) {
                cell->addChild(child);
                return;
            }
        }

        // If beforeChild is inside an anonymous cell, insert into the cell.
        if (last && !last->isTableCell() && last->parent() && last->parent()->isAnonymous() && !last->parent()->isBeforeOrAfterContent()) {
            last->parent()->addChild(child, beforeChild);
            return;
        }

        RenderTableCell* cell = new (renderArena()) RenderTableCell(document() /* anonymous object */);
        RefPtr<RenderStyle> newStyle = RenderStyle::create();
        newStyle->inheritFrom(style());
        newStyle->setDisplay(TABLE_CELL);
        cell->setStyle(newStyle.release());
        addChild(cell, beforeChild);
        cell->addChild(child);
        return;
    } 
    
    // If the next renderer is actually wrapped in an anonymous table cell, we need to go up and find that.
    while (beforeChild && beforeChild->parent() != this)
        beforeChild = beforeChild->parent();

    RenderTableCell* cell = toRenderTableCell(child);

    // Generated content can result in us having a null section so make sure to null check our parent.
    if (parent())
        section()->addCell(cell, this);

    ASSERT(!beforeChild || beforeChild->isTableCell());
    RenderBox::addChild(cell, beforeChild);

    if (beforeChild || nextSibling())
        section()->setNeedsCellRecalc();
}

void RenderTableRow::addChild(RenderObject* child, RenderObject* beforeChild)
{
    // Make sure we don't append things after :after-generated content if we have it.
    if (!beforeChild)
        beforeChild = afterPseudoElementRenderer();

    if (!child->isTableCell()) {
        RenderObject* last = beforeChild;
        if (!last)
            last = lastChild();
        if (last && last->isAnonymous() && last->isTableCell() && !last->isBeforeOrAfterContent()) {
            if (beforeChild == last)
                beforeChild = last->firstChild();
            last->addChild(child, beforeChild);
            return;
        }

        if (beforeChild && !beforeChild->isAnonymous() && beforeChild->parent() == this) {
            RenderObject* cell = beforeChild->previousSibling();
            if (cell && cell->isTableCell() && cell->isAnonymous()) {
                cell->addChild(child);
                return;
            }
        }

        // If beforeChild is inside an anonymous cell, insert into the cell.
        if (last && !last->isTableCell() && last->parent() && last->parent()->isAnonymous() && !last->parent()->isBeforeOrAfterContent()) {
            last->parent()->addChild(child, beforeChild);
            return;
        }

        RenderTableCell* cell = RenderTableCell::createAnonymousWithParentRenderer(this);
        addChild(cell, beforeChild);
        cell->addChild(child);
        return;
    } 

    if (beforeChild && beforeChild->parent() != this)
        beforeChild = splitAnonymousBoxesAroundChild(beforeChild);    

    RenderTableCell* cell = toRenderTableCell(child);

    // Generated content can result in us having a null section so make sure to null check our parent.
    if (parent())
        section()->addCell(cell, this);

    ASSERT(!beforeChild || beforeChild->isTableCell());
    RenderBox::addChild(cell, beforeChild);

    if (beforeChild || nextSibling())
        section()->setNeedsCellRecalc();
}

void RenderTheme::paintSliderTicks(RenderObject* o, const PaintInfo& paintInfo, const IntRect& rect)
{
    Node* node = o->node();
    if (!node)
        return;

    HTMLInputElement* input = node->toInputElement();
    if (!input)
        return;

    HTMLDataListElement* dataList = static_cast<HTMLDataListElement*>(input->list());
    if (!dataList)
        return;

    double min = input->minimum();
    double max = input->maximum();
    ControlPart part = o->style()->appearance();
    // We don't support ticks on alternate sliders like MediaVolumeSliders.
    if (part !=  SliderHorizontalPart && part != SliderVerticalPart)
        return;
    bool isHorizontal = part ==  SliderHorizontalPart;

    IntSize thumbSize;
    RenderObject* thumbRenderer = input->sliderThumbElement()->renderer();
    if (thumbRenderer) {
        RenderStyle* thumbStyle = thumbRenderer->style();
        int thumbWidth = thumbStyle->width().intValue();
        int thumbHeight = thumbStyle->height().intValue();
        thumbSize.setWidth(isHorizontal ? thumbWidth : thumbHeight);
        thumbSize.setHeight(isHorizontal ? thumbHeight : thumbWidth);
    }

    IntSize tickSize = sliderTickSize();
    float zoomFactor = o->style()->effectiveZoom();
    FloatRect tickRect;
    int tickRegionSideMargin = 0;
    int tickRegionWidth = 0;
    IntRect trackBounds;
    RenderObject* trackRenderer = input->sliderTrackElement()->renderer();
    // We can ignoring transforms because transform is handled by the graphics context.
    if (trackRenderer)
        trackBounds = trackRenderer->absoluteBoundingBoxRectIgnoringTransforms();
    IntRect sliderBounds = o->absoluteBoundingBoxRectIgnoringTransforms();

    // Make position relative to the transformed ancestor element.
    trackBounds.setX(trackBounds.x() - sliderBounds.x() + rect.x());
    trackBounds.setY(trackBounds.y() - sliderBounds.y() + rect.y());

    if (isHorizontal) {
        tickRect.setWidth(floor(tickSize.width() * zoomFactor));
        tickRect.setHeight(floor(tickSize.height() * zoomFactor));
        tickRect.setY(floor(rect.y() + rect.height() / 2.0 + sliderTickOffsetFromTrackCenter() * zoomFactor));
        tickRegionSideMargin = trackBounds.x() + (thumbSize.width() - tickSize.width() * zoomFactor) / 2.0;
        tickRegionWidth = trackBounds.width() - thumbSize.width();
    } else {
        tickRect.setWidth(floor(tickSize.height() * zoomFactor));
        tickRect.setHeight(floor(tickSize.width() * zoomFactor));
        tickRect.setX(floor(rect.x() + rect.width() / 2.0 + sliderTickOffsetFromTrackCenter() * zoomFactor));
        tickRegionSideMargin = trackBounds.y() + (thumbSize.width() - tickSize.width() * zoomFactor) / 2.0;
        tickRegionWidth = trackBounds.height() - thumbSize.width();
    }
    RefPtr<HTMLCollection> options = dataList->options();
    GraphicsContextStateSaver stateSaver(*paintInfo.context);
    paintInfo.context->setFillColor(o->style()->visitedDependentColor(CSSPropertyColor), ColorSpaceDeviceRGB);
    for (unsigned i = 0; Node* node = options->item(i); i++) {
        ASSERT(node->hasTagName(optionTag));
        HTMLOptionElement* optionElement = toHTMLOptionElement(node);
        String value = optionElement->value();
        if (!input->isValidValue(value))
            continue;
        double parsedValue = parseToDoubleForNumberType(input->sanitizeValue(value));
        double tickFraction = (parsedValue - min) / (max - min);
        double tickRatio = isHorizontal && o->style()->isLeftToRightDirection() ? tickFraction : 1.0 - tickFraction;
        double tickPosition = round(tickRegionSideMargin + tickRegionWidth * tickRatio);
        if (isHorizontal)
            tickRect.setX(tickPosition);
        else
            tickRect.setY(tickPosition);
        paintInfo.context->fillRect(tickRect);
    }
}

void SVGResourcesCycleSolver::resolveCycles()
{
    ASSERT(m_allResources.isEmpty());

#if DEBUG_CYCLE_DETECTION > 0
    fprintf(stderr, "\nBefore cycle detection:\n");
    m_resources->dump(m_renderer);
#endif

    // Stash all resources into a HashSet for the ease of traversing.
    HashSet<RenderSVGResourceContainer*> localResources;
    m_resources->buildSetOfResources(localResources);
    ASSERT(!localResources.isEmpty());

    // Add all parent resource containers to the HashSet.
    HashSet<RenderSVGResourceContainer*> parentResources;
    RenderObject* parent = m_renderer->parent();
    while (parent) {
        if (parent->isSVGResourceContainer())
            parentResources.add(toRenderSVGResourceContainer(parent));
        parent = parent->parent();
    }

#if DEBUG_CYCLE_DETECTION > 0
    fprintf(stderr, "\nDetecting wheter any resources references any of following objects:\n");
    {
        fprintf(stderr, "Local resources:\n");
        HashSet<RenderSVGResourceContainer*>::iterator end = localResources.end();
        for (HashSet<RenderSVGResourceContainer*>::iterator it = localResources.begin(); it != end; ++it)
            fprintf(stderr, "|> %s: object=%p (node=%p)\n", (*it)->renderName(), *it, (*it)->node());

        fprintf(stderr, "Parent resources:\n");
        end = parentResources.end();
        for (HashSet<RenderSVGResourceContainer*>::iterator it = parentResources.begin(); it != end; ++it)
            fprintf(stderr, "|> %s: object=%p (node=%p)\n", (*it)->renderName(), *it, (*it)->node());
    }
#endif

    // Build combined set of local and parent resources.
    m_allResources = localResources;
    HashSet<RenderSVGResourceContainer*>::iterator end = parentResources.end();
    for (HashSet<RenderSVGResourceContainer*>::iterator it = parentResources.begin(); it != end; ++it)
        m_allResources.add(*it);

    // If we're a resource, add ourselves to the HashSet.
    if (m_renderer->isSVGResourceContainer())
        m_allResources.add(toRenderSVGResourceContainer(m_renderer));

    ASSERT(!m_allResources.isEmpty());

    // The job of this function is to determine wheter any of the 'resources' associated with the given 'renderer'
    // references us (or wheter any of its kids references us) -> that's a cycle, we need to find and break it.
    end = localResources.end();
    for (HashSet<RenderSVGResourceContainer*>::iterator it = localResources.begin(); it != end; ++it) {
        RenderSVGResourceContainer* resource = *it;
        if (parentResources.contains(resource) || resourceContainsCycles(resource))
            breakCycle(resource);
    }

#if DEBUG_CYCLE_DETECTION > 0
    fprintf(stderr, "\nAfter cycle detection:\n");
    m_resources->dump(m_renderer);
#endif

    m_allResources.clear();
}

bool RenderThemeGtk::paintCapsLockIndicator(const RenderObject& renderObject, const PaintInfo& paintInfo, const IntRect& rect)
{
    // The other paint methods don't need to check whether painting is disabled because RenderTheme already checks it
    // before calling them, but paintCapsLockIndicator() is called by RenderTextControlSingleLine which doesn't check it.
    if (paintInfo.context->paintingDisabled())
        return true;

    int iconSize = std::min(rect.width(), rect.height());
    GRefPtr<GdkPixbuf> icon = getStockIconForWidgetType(GTK_TYPE_ENTRY, GTK_STOCK_CAPS_LOCK_WARNING, gtkTextDirection(renderObject.style().direction()), 0, getIconSizeForPixelSize(iconSize));

    // Only re-scale the icon when it's smaller than the minimum icon size.
    if (iconSize >= gtkIconSizeMenu)
        iconSize = gdk_pixbuf_get_height(icon.get());

    // GTK+ locates the icon right aligned in the entry. The given rectangle is already
    // centered vertically by RenderTextControlSingleLine.
    IntRect iconRect(rect.x() + rect.width() - iconSize,
                     rect.y() + (rect.height() - iconSize) / 2,
                     iconSize, iconSize);
    paintGdkPixbuf(paintInfo.context, icon.get(), iconRect);
    return true;
}

RenderRubyBase* RenderRubyRun::rubyBase() const
{
    RenderObject* child = lastChild();
    return child && child->isRubyBase() ? static_cast<RenderRubyBase*>(child) : 0;
}

void RenderNamedFlowThread::getRanges(Vector<RefPtr<Range> >& rangeObjects, const RenderRegion* region) const
{
    LayoutUnit logicalTopForRegion;
    LayoutUnit logicalBottomForRegion;

    // extend the first region top to contain everything up to its logical height
    if (region->isFirstRegion())
        logicalTopForRegion = LayoutUnit::min();
    else
        logicalTopForRegion =  region->logicalTopForFlowThreadContent();

    // extend the last region to contain everything above its y()
    if (region->isLastRegion())
        logicalBottomForRegion = LayoutUnit::max();
    else
        logicalBottomForRegion = region->logicalBottomForFlowThreadContent();

    Vector<Element*> elements;
    // eliminate the contentElements that are descendants of other contentElements
    for (auto it = contentElements().begin(), end = contentElements().end(); it != end; ++it) {
        Element* element = *it;
        if (!isContainedInElements(elements, element))
            elements.append(element);
    }

    for (size_t i = 0; i < elements.size(); i++) {
        Element* contentElement = elements.at(i);
        if (!contentElement->renderer())
            continue;

        RefPtr<Range> range = Range::create(&contentElement->document());
        bool foundStartPosition = false;
        bool startsAboveRegion = true;
        bool endsBelowRegion = true;
        bool skipOverOutsideNodes = false;
        Node* lastEndNode = 0;

        for (Node* node = contentElement; node; node = nextNodeInsideContentElement(node, contentElement)) {
            RenderObject* renderer = node->renderer();
            if (!renderer)
                continue;

            LayoutRect boundingBox;
            if (renderer->isRenderInline())
                boundingBox = toRenderInline(renderer)->linesBoundingBox();
            else if (renderer->isText())
                boundingBox = toRenderText(renderer)->linesBoundingBox();
            else {
                boundingBox =  toRenderBox(renderer)->frameRect();
                if (toRenderBox(renderer)->isRelPositioned())
                    boundingBox.move(toRenderBox(renderer)->relativePositionLogicalOffset());
            }

            LayoutUnit offsetTop = renderer->containingBlock()->offsetFromLogicalTopOfFirstPage();
            const LayoutPoint logicalOffsetFromTop(isHorizontalWritingMode() ? LayoutUnit() :  offsetTop,
                isHorizontalWritingMode() ? offsetTop : LayoutUnit());

            boundingBox.moveBy(logicalOffsetFromTop);

            LayoutUnit logicalTopForRenderer = region->logicalTopOfFlowThreadContentRect(boundingBox);
            LayoutUnit logicalBottomForRenderer = region->logicalBottomOfFlowThreadContentRect(boundingBox);

            // if the bounding box of the current element doesn't intersect the region box
            // close the current range only if the start element began inside the region,
            // otherwise just move the start position after this node and keep skipping them until we found a proper start position.
            if (!boxIntersectsRegion(logicalTopForRenderer, logicalBottomForRenderer, logicalTopForRegion, logicalBottomForRegion)) {
                if (foundStartPosition) {
                    if (!startsAboveRegion) {
                        if (range->intersectsNode(node, IGNORE_EXCEPTION))
                            range->setEndBefore(node, IGNORE_EXCEPTION);
                        rangeObjects.append(range->cloneRange(IGNORE_EXCEPTION));
                        range = Range::create(&contentElement->document());
                        startsAboveRegion = true;
                    } else
                        skipOverOutsideNodes = true;
                }
                if (skipOverOutsideNodes)
                    range->setStartAfter(node, IGNORE_EXCEPTION);
                foundStartPosition = false;
                continue;
            }

            // start position
            if (logicalTopForRenderer < logicalTopForRegion && startsAboveRegion) {
                if (renderer->isText()) { // Text crosses region top
                    // for Text elements, just find the last textbox that is contained inside the region and use its start() offset as start position
                    RenderText* textRenderer = toRenderText(renderer);
                    for (InlineTextBox* box = textRenderer->firstTextBox(); box; box = box->nextTextBox()) {
                        if (offsetTop + box->logicalBottom() < logicalTopForRegion)
                            continue;
                        range->setStart(Position(toText(node), box->start()));
                        startsAboveRegion = false;
                        break;
                    }
                } else { // node crosses region top
                    // for all elements, except Text, just set the start position to be before their children
                    startsAboveRegion = true;
                    range->setStart(Position(node, Position::PositionIsBeforeChildren));
                }
            } else { // node starts inside region
//.........这里部分代码省略.........

static RenderObject* getParentOfFirstLineBox(RenderBlock* curr, RenderObject* marker)
{
    RenderObject* firstChild = curr->firstChild();
    if (!firstChild)
        return 0;

    for (RenderObject* currChild = firstChild; currChild; currChild = currChild->nextSibling()) {
        if (currChild == marker)
            continue;

        if (currChild->isInline() && (!currChild->isInlineFlow() || curr->generatesLineBoxesForInlineChild(currChild)))
            return curr;

        if (currChild->isFloating() || currChild->isPositioned())
            continue;

        if (currChild->isTable() || !currChild->isRenderBlock())
            break;

        if (curr->isListItem() && currChild->style()->htmlHacks() && currChild->element() &&
            (currChild->element()->hasTagName(ulTag)|| currChild->element()->hasTagName(olTag)))
            break;

        RenderObject* lineBox = getParentOfFirstLineBox(static_cast<RenderBlock*>(currChild), marker);
        if (lineBox)
            return lineBox;
    }

    return 0;
}

bool Text::textRendererIsNeeded(const NodeRenderingContext& context)
{
    if (isEditingText())
        return true;

    if (!length())
        return false;

    if (context.style()->display() == NONE)
        return false;

    bool onlyWS = containsOnlyWhitespace();
    if (!onlyWS)
        return true;

    RenderObject* parent = context.parentRenderer();
    if (parent->isTable() || parent->isTableRow() || parent->isTableSection() || parent->isRenderTableCol() || parent->isFrameSet())
        return false;
    
    if (context.style()->preserveNewline()) // pre/pre-wrap/pre-line always make renderers.
        return true;
    
    RenderObject* prev = context.previousRenderer();
    if (prev && prev->isBR()) // <span><br/> <br/></span>
        return false;
        
    if (parent->isRenderInline()) {
        // <span><div/> <div/></span>
        if (prev && !prev->isInline())
            return false;
    } else {
        if (parent->isRenderBlock() && !parent->childrenInline() && (!prev || !prev->isInline()))
            return false;
        
        RenderObject* first = parent->firstChild();
        while (first && first->isFloatingOrOutOfFlowPositioned())
            first = first->nextSibling();
        if (!first || context.nextRenderer() == first) {
            // Whitespace at the start of a block just goes away.  Don't even
            // make a render object for this text.
            return false;
        }
    }
    
    return true;
}

int caretMinOffset(const Node* n)
{
    RenderObject* r = n->renderer();
    ASSERT(!n->isCharacterDataNode() || !r || r->isText()); // FIXME: This was a runtime check that seemingly couldn't fail; changed it to an assertion for now.
    return r ? r->caretMinOffset() : 0;
}

void RenderInline::splitInlines(RenderBlock* fromBlock, RenderBlock* toBlock,
                                RenderBlock* middleBlock,
                                RenderObject* beforeChild, RenderFlow* oldCont)
{
    // Create a clone of this inline.
    RenderInline* clone = cloneInline(this);
    clone->setContinuation(oldCont);

    // Now take all of the children from beforeChild to the end and remove
    // them from |this| and place them in the clone.
    RenderObject* o = beforeChild;
    while (o) {
        RenderObject* tmp = o;
        o = tmp->nextSibling();
        clone->addChildToFlow(removeChildNode(tmp), 0);
        tmp->setNeedsLayoutAndPrefWidthsRecalc();
    }

    // Hook |clone| up as the continuation of the middle block.
    middleBlock->setContinuation(clone);

    // We have been reparented and are now under the fromBlock.  We need
    // to walk up our inline parent chain until we hit the containing block.
    // Once we hit the containing block we're done.
    RenderFlow* curr = static_cast<RenderFlow*>(parent());
    RenderFlow* currChild = this;
    
    // FIXME: Because splitting is O(n^2) as tags nest pathologically, we cap the depth at which we're willing to clone.
    // There will eventually be a better approach to this problem that will let us nest to a much
    // greater depth (see bugzilla bug 13430) but for now we have a limit.  This *will* result in
    // incorrect rendering, but the alternative is to hang forever.
    unsigned splitDepth = 1;
    const unsigned cMaxSplitDepth = 200; 
    while (curr && curr != fromBlock) {
        if (splitDepth < cMaxSplitDepth) {
            // Create a new clone.
            RenderInline* cloneChild = clone;
            clone = cloneInline(curr);

            // Insert our child clone as the first child.
            clone->addChildToFlow(cloneChild, 0);

            // Hook the clone up as a continuation of |curr|.
            RenderFlow* oldCont = curr->continuation();
            curr->setContinuation(clone);
            clone->setContinuation(oldCont);

            // Someone may have indirectly caused a <q> to split.  When this happens, the :after content
            // has to move into the inline continuation.  Call updateBeforeAfterContent to ensure that the inline's :after
            // content gets properly destroyed.
            if (document()->usesBeforeAfterRules())
                curr->updateBeforeAfterContent(RenderStyle::AFTER);

            // Now we need to take all of the children starting from the first child
            // *after* currChild and append them all to the clone.
            o = currChild->nextSibling();
            while (o) {
                RenderObject* tmp = o;
                o = tmp->nextSibling();
                clone->addChildToFlow(curr->removeChildNode(tmp), 0);
                tmp->setNeedsLayoutAndPrefWidthsRecalc();
            }
        }
        
        // Keep walking up the chain.
        currChild = curr;
        curr = static_cast<RenderFlow*>(curr->parent());
        splitDepth++;
    }

    // Now we are at the block level. We need to put the clone into the toBlock.
    toBlock->appendChildNode(clone);

    // Now take all the children after currChild and remove them from the fromBlock
    // and put them in the toBlock.
    o = currChild->nextSibling();
    while (o) {
        RenderObject* tmp = o;
        o = tmp->nextSibling();
        toBlock->appendChildNode(fromBlock->removeChildNode(tmp));
    }
}