renderobject.cpp

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    RenderObject* o;
    if (!(o = nextSibling())) {
        o = parent();
        while (o && !o->nextSibling()) {
            if (o == stayWithin)
                return 0;
            o = o->parent();
        }
        if (o)
            o = o->nextSibling();
    }

    return o;
}

RenderObject* RenderObject::previousInPreOrder() const
{
    if (RenderObject* o = previousSibling()) {
        while (o->lastChild())
            o = o->lastChild();
        return o;
    }

    return parent();
}

RenderObject* RenderObject::childAt(unsigned index) const
{
    RenderObject* child = firstChild();
    for (unsigned i = 0; child && i < index; i++)
        child = child->nextSibling();
    return child;
}

RenderObject* RenderObject::firstLeafChild() const
{
    RenderObject* r = firstChild();
    while (r) {
        RenderObject* n = 0;
        n = r->firstChild();
        if (!n)
            break;
        r = n;
    }
    return r;
}

RenderObject* RenderObject::lastLeafChild() const
{
    RenderObject* r = lastChild();
    while (r) {
        RenderObject* n = 0;
        n = r->lastChild();
        if (!n)
            break;
        r = n;
    }
    return r;
}

static void addLayers(RenderObject* obj, RenderLayer* parentLayer, RenderObject*& newObject,
                      RenderLayer*& beforeChild)
{
    if (obj->hasLayer()) {
        if (!beforeChild && newObject) {
            // We need to figure out the layer that follows newObject.  We only do
            // this the first time we find a child layer, and then we update the
            // pointer values for newObject and beforeChild used by everyone else.
            beforeChild = newObject->parent()->findNextLayer(parentLayer, newObject);
            newObject = 0;
        }
        parentLayer->addChild(toRenderBoxModelObject(obj)->layer(), beforeChild);
        return;
    }

    for (RenderObject* curr = obj->firstChild(); curr; curr = curr->nextSibling())
        addLayers(curr, parentLayer, newObject, beforeChild);
}

void RenderObject::addLayers(RenderLayer* parentLayer, RenderObject* newObject)
{
    if (!parentLayer)
        return;

    RenderObject* object = newObject;
    RenderLayer* beforeChild = 0;
    WebCore::addLayers(this, parentLayer, object, beforeChild);
}

void RenderObject::removeLayers(RenderLayer* parentLayer)
{
    if (!parentLayer)
        return;

    if (hasLayer()) {
        parentLayer->removeChild(toRenderBoxModelObject(this)->layer());
        return;
    }

    for (RenderObject* curr = firstChild(); curr; curr = curr->nextSibling())
        curr->removeLayers(parentLayer);
}

void RenderObject::moveLayers(RenderLayer* oldParent, RenderLayer* newParent)
{
    if (!newParent)
        return;

    if (hasLayer()) {
        RenderLayer* layer = toRenderBoxModelObject(this)->layer();
        if (oldParent)
            oldParent->removeChild(layer);
        newParent->addChild(layer);
        return;
    }

    for (RenderObject* curr = firstChild(); curr; curr = curr->nextSibling())
        curr->moveLayers(oldParent, newParent);
}

RenderLayer* RenderObject::findNextLayer(RenderLayer* parentLayer, RenderObject* startPoint,
                                         bool checkParent)
{
    // Error check the parent layer passed in.  If it's null, we can't find anything.
    if (!parentLayer)
        return 0;

    // Step 1: If our layer is a child of the desired parent, then return our layer.
    RenderLayer* ourLayer = hasLayer() ? toRenderBoxModelObject(this)->layer() : 0;
    if (ourLayer && ourLayer->parent() == parentLayer)
        return ourLayer;

    // Step 2: If we don't have a layer, or our layer is the desired parent, then descend
    // into our siblings trying to find the next layer whose parent is the desired parent.
    if (!ourLayer || ourLayer == parentLayer) {
        for (RenderObject* curr = startPoint ? startPoint->nextSibling() : firstChild();
             curr; curr = curr->nextSibling()) {
            RenderLayer* nextLayer = curr->findNextLayer(parentLayer, 0, false);
            if (nextLayer)
                return nextLayer;
        }
    }

    // Step 3: If our layer is the desired parent layer, then we're finished.  We didn't
    // find anything.
    if (parentLayer == ourLayer)
        return 0;

    // Step 4: If |checkParent| is set, climb up to our parent and check its siblings that
    // follow us to see if we can locate a layer.
    if (checkParent && parent())
        return parent()->findNextLayer(parentLayer, this, true);

    return 0;
}

RenderLayer* RenderObject::enclosingLayer() const
{
    const RenderObject* curr = this;
    while (curr) {
        RenderLayer* layer = curr->hasLayer() ? toRenderBoxModelObject(curr)->layer() : 0;
        if (layer)
            return layer;
        curr = curr->parent();
    }
    return 0;
}

RenderBox* RenderObject::enclosingBox() const
{
    RenderObject* curr = const_cast<RenderObject*>(this);
    while (curr) {
        if (curr->isBox())
            return toRenderBox(curr);
        curr = curr->parent();
    }
    
    ASSERT_NOT_REACHED();
    return 0;
}

RenderBlock* RenderObject::firstLineBlock() const
{
    return 0;
}

void RenderObject::setPrefWidthsDirty(bool b, bool markParents)
{
    bool alreadyDirty = m_prefWidthsDirty;
    m_prefWidthsDirty = b;
    if (b && !alreadyDirty && markParents && (isText() || (style()->position() != FixedPosition && style()->position() != AbsolutePosition)))
        invalidateContainerPrefWidths();
}

void RenderObject::invalidateContainerPrefWidths()
{
    // In order to avoid pathological behavior when inlines are deeply nested, we do include them
    // in the chain that we mark dirty (even though they're kind of irrelevant).
    RenderObject* o = isTableCell() ? containingBlock() : container();
    while (o && !o->m_prefWidthsDirty) {
        o->m_prefWidthsDirty = true;
        if (o->style()->position() == FixedPosition || o->style()->position() == AbsolutePosition)
            // A positioned object has no effect on the min/max width of its containing block ever.
            // We can optimize this case and not go up any further.
            break;
        o = o->isTableCell() ? o->containingBlock() : o->container();
    }
}

void RenderObject::setLayerNeedsFullRepaint()
{
    ASSERT(hasLayer());
    toRenderBoxModelObject(this)->layer()->setNeedsFullRepaint(true);
}

RenderBlock* RenderObject::containingBlock() const
{
    if (isTableCell()) {
        const RenderTableCell* cell = static_cast<const RenderTableCell*>(this);
        if (parent() && cell->section())
            return cell->table();
        return 0;
    }

    if (isRenderView())
        return const_cast<RenderView*>(toRenderView(this));

    RenderObject* o = parent();
    if (!isText() && m_style->position() == FixedPosition) {
        while (o && !o->isRenderView() && !(o->hasTransform() && o->isRenderBlock()))
            o = o->parent();
    } else if (!isText() && m_style->position() == AbsolutePosition) {
        while (o && (o->style()->position() == StaticPosition || (o->isInline() && !o->isReplaced())) && !o->isRenderView() && !(o->hasTransform() && o->isRenderBlock())) {
            // For relpositioned inlines, we return the nearest enclosing block.  We don't try
            // to return the inline itself.  This allows us to avoid having a positioned objects
            // list in all RenderInlines and lets us return a strongly-typed RenderBlock* result
            // from this method.  The container() method can actually be used to obtain the
            // inline directly.
            if (o->style()->position() == RelativePosition && o->isInline() && !o->isReplaced())
                return o->containingBlock();
            o = o->parent();
        }
    } else {
        while (o && ((o->isInline() && !o->isReplaced()) || o->isTableRow() || o->isTableSection()
                     || o->isTableCol() || o->isFrameSet() || o->isMedia()
#if ENABLE(SVG)
                     || o->isSVGContainer() || o->isSVGRoot()
#endif
                     ))
            o = o->parent();
    }

    if (!o || !o->isRenderBlock())
        return 0; // Probably doesn't happen any more, but leave just in case. -dwh

    return toRenderBlock(o);
}

static bool mustRepaintFillLayers(const RenderObject* renderer, const FillLayer* layer)
{
    // Nobody will use multiple layers without wanting fancy positioning.
    if (layer->next())
        return true;

    // Make sure we have a valid image.
    StyleImage* img = layer->image();
    bool shouldPaintBackgroundImage = img && img->canRender(renderer->style()->effectiveZoom());

    // These are always percents or auto.
    if (shouldPaintBackgroundImage &&
        (!layer->xPosition().isZero() || !layer->yPosition().isZero() ||
         layer->size().width().isPercent() || layer->size().height().isPercent()))
        // The image will shift unpredictably if the size changes.
        return true;

    return false;
}

bool RenderObject::mustRepaintBackgroundOrBorder() const
{
    if (hasMask() && mustRepaintFillLayers(this, style()->maskLayers()))
        return true;

    // If we don't have a background/border/mask, then nothing to do.
    if (!hasBoxDecorations())
        return false;

    if (mustRepaintFillLayers(this, style()->backgroundLayers()))
        return true;
     
    // Our fill layers are ok.  Let's check border.
    if (style()->hasBorder()) {
        // Border images are not ok.
        StyleImage* borderImage = style()->borderImage().image();
        bool shouldPaintBorderImage = borderImage && borderImage->canRender(style()->effectiveZoom());

        // If the image hasn't loaded, we're still using the normal border style.
        if (shouldPaintBorderImage && borderImage->isLoaded())
            return true;
    }

    return false;
}

void RenderObject::drawLineForBoxSide(GraphicsContext* graphicsContext, int x1, int y1, int x2, int y2,
                                      BoxSide s, Color c, const Color& textcolor, EBorderStyle style,
                                      int adjbw1, int adjbw2)
{
    int width = (s == BSTop || s == BSBottom ? y2 - y1 : x2 - x1);

    if (style == DOUBLE && width < 3)
        style = SOLID;

    if (!c.isValid()) {
        if (style == INSET || style == OUTSET || style == RIDGE || style == GROOVE)
            c.setRGB(238, 238, 238);
        else
            c = textcolor;
    }

    switch (style) {
        case BNONE:
        case BHIDDEN:
            return;
        case DOTTED:
        case DASHED:
            graphicsContext->setStrokeColor(c);
            graphicsContext->setStrokeThickness(width);
            graphicsContext->setStrokeStyle(style == DASHED ? DashedStroke : DottedStroke);

            if (width > 0)
                switch (s) {
                    case BSBottom:
                    case BSTop:
                        graphicsContext->drawLine(IntPoint(x1, (y1 + y2) / 2), IntPoint(x2, (y1 + y2) / 2));
                        break;
                    case BSRight:
                    case BSLeft:
                        graphicsContext->drawLine(IntPoint((x1 + x2) / 2, y1), IntPoint((x1 + x2) / 2, y2));
                        break;
                }
            break;
        case DOUBLE: {
            int third = (width + 1) / 3;

            if (adjbw1 == 0 && adjbw2 == 0) {
                graphicsContext->setStrokeStyle(NoStroke);
                graphicsContext->setFillColor(c);
                switch (s) {
                    case BSTop:
                    case BSBottom:
                        graphicsContext->drawRect(IntRect(x1, y1, x2 - x1, third));
                        graphicsContext->drawRect(IntRect(x1, y2 - third, x2 - x1, third));