C++ RenderObject::hasBackground方法代码示例

static bool isDeletableElement(const Node* node)
{
    if (!node || !node->isHTMLElement() || !node->inDocument() || !node->rendererIsEditable())
        return false;

    // In general we want to only draw the UI around object of a certain area, but we still keep the min width/height to
    // make sure we don't end up with very thin or very short elements getting the UI.
    const int minimumArea = 2500;
    const int minimumWidth = 48;
    const int minimumHeight = 16;
    const unsigned minimumVisibleBorders = 1;

    RenderObject* renderer = node->renderer();
    if (!renderer || !renderer->isBox())
        return false;

    // Disallow the body element since it isn't practical to delete, and the deletion UI would be clipped.
    if (node->hasTagName(bodyTag))
        return false;

    // Disallow elements with any overflow clip, since the deletion UI would be clipped as well. <rdar://problem/6840161>
    if (renderer->hasOverflowClip())
        return false;

    // Disallow Mail blockquotes since the deletion UI would get in the way of editing for these.
    if (isMailBlockquote(node))
        return false;

    RenderBox* box = toRenderBox(renderer);
    IntRect borderBoundingBox = box->borderBoundingBox();
    if (borderBoundingBox.width() < minimumWidth || borderBoundingBox.height() < minimumHeight)
        return false;

    if ((borderBoundingBox.width() * borderBoundingBox.height()) < minimumArea)
        return false;

    if (renderer->isTable())
        return true;

    if (node->hasTagName(ulTag) || node->hasTagName(olTag) || node->hasTagName(iframeTag))
        return true;

    if (renderer->isOutOfFlowPositioned())
        return true;

    if (renderer->isRenderBlock() && !renderer->isTableCell()) {
        RenderStyle* style = renderer->style();
        if (!style)
            return false;

        // Allow blocks that have background images
        if (style->hasBackgroundImage()) {
            for (const FillLayer* background = style->backgroundLayers(); background; background = background->next()) {
                if (background->image() && background->image()->canRender(renderer, 1))
                    return true;
            }
        }

        // Allow blocks with a minimum number of non-transparent borders
        unsigned visibleBorders = style->borderTop().isVisible() + style->borderBottom().isVisible() + style->borderLeft().isVisible() + style->borderRight().isVisible();
        if (visibleBorders >= minimumVisibleBorders)
            return true;

        // Allow blocks that have a different background from it's parent
        ContainerNode* parentNode = node->parentNode();
        if (!parentNode)
            return false;

        RenderObject* parentRenderer = parentNode->renderer();
        if (!parentRenderer)
            return false;

        RenderStyle* parentStyle = parentRenderer->style();
        if (!parentStyle)
            return false;

        if (renderer->hasBackground() && (!parentRenderer->hasBackground() || style->visitedDependentColor(CSSPropertyBackgroundColor) != parentStyle->visitedDependentColor(CSSPropertyBackgroundColor)))
            return true;
    }

    return false;
}