Ejemplo n.º 1
0
LayoutState::LayoutState(RenderBox& renderer, const LayoutSize& offset, LayoutUnit pageLogicalHeight, bool pageLogicalHeightChanged, ColumnInfo* columnInfo, bool containingBlockLogicalWidthChanged)
    : m_containingBlockLogicalWidthChanged(containingBlockLogicalWidthChanged)
    , m_columnInfo(columnInfo)
    , m_next(renderer.view()->layoutState())
    , m_renderer(renderer)
{
    m_flowThread = renderer.isRenderFlowThread() ? toRenderFlowThread(&renderer) : m_next->flowThread();
    renderer.view()->pushLayoutState(*this);
    bool fixed = renderer.isOutOfFlowPositioned() && renderer.style()->position() == FixedPosition;
    if (fixed) {
        // FIXME: This doesn't work correctly with transforms.
        FloatPoint fixedOffset = renderer.view()->localToAbsolute(FloatPoint(), IsFixed);
        m_layoutOffset = LayoutSize(fixedOffset.x(), fixedOffset.y()) + offset;
    } else {
        m_layoutOffset = m_next->m_layoutOffset + offset;
    }

    if (renderer.isOutOfFlowPositioned() && !fixed) {
        if (RenderObject* container = renderer.container()) {
            if (container->style()->hasInFlowPosition() && container->isRenderInline())
                m_layoutOffset += toRenderInline(container)->offsetForInFlowPositionedInline(renderer);
        }
    }
    // If we establish a new page height, then cache the offset to the top of the first page.
    // We can compare this later on to figure out what part of the page we're actually on,
    if (pageLogicalHeight || m_columnInfo || renderer.isRenderFlowThread()) {
        m_pageLogicalHeight = pageLogicalHeight;
        bool isFlipped = renderer.style()->isFlippedBlocksWritingMode();
        m_pageOffset = LayoutSize(m_layoutOffset.width() + (!isFlipped ? renderer.borderLeft() + renderer.paddingLeft() : renderer.borderRight() + renderer.paddingRight()),
            m_layoutOffset.height() + (!isFlipped ? renderer.borderTop() + renderer.paddingTop() : renderer.borderBottom() + renderer.paddingBottom()));
        m_pageLogicalHeightChanged = pageLogicalHeightChanged;
        m_isPaginated = true;
    } else {
        // If we don't establish a new page height, then propagate the old page height and offset down.
        m_pageLogicalHeight = m_next->m_pageLogicalHeight;
        m_pageLogicalHeightChanged = m_next->m_pageLogicalHeightChanged;
        m_pageOffset = m_next->m_pageOffset;

        // Disable pagination for objects we don't support. For now this includes overflow:scroll/auto, inline blocks and
        // writing mode roots.
        if (renderer.isUnsplittableForPagination()) {
            m_pageLogicalHeight = 0;
            m_isPaginated = false;
        } else {
            m_isPaginated = m_pageLogicalHeight || m_next->m_columnInfo || renderer.flowThreadContainingBlock();
        }
    }

    if (!m_columnInfo)
        m_columnInfo = m_next->m_columnInfo;

    // FIXME: <http://bugs.webkit.org/show_bug.cgi?id=13443> Apply control clip if present.
}
static bool isValidColumnSpanner(RenderMultiColumnFlowThread* flowThread, RenderObject* descendant)
{
    // We assume that we're inside the flow thread. This function is not to be called otherwise.
    ASSERT(descendant->isDescendantOf(flowThread));

    // First make sure that the renderer itself has the right properties for becoming a spanner.
    RenderStyle& style = descendant->style();
    if (style.columnSpan() != ColumnSpanAll || !descendant->isBox() || descendant->isFloatingOrOutOfFlowPositioned())
        return false;

    RenderBlock* container = descendant->containingBlock();
    if (!container->isRenderBlockFlow() || container->childrenInline()) {
        // Needs to be block-level.
        return false;
    }

    // This looks like a spanner, but if we're inside something unbreakable, it's not to be treated as one.
    for (RenderBox* ancestor = toRenderBox(descendant)->parentBox(); ancestor; ancestor = ancestor->parentBox()) {
        if (ancestor->isRenderFlowThread()) {
            // Don't allow any intervening non-multicol fragmentation contexts. The spec doesn't say
            // anything about disallowing this, but it's just going to be too complicated to
            // implement (not to mention specify behavior).
            return ancestor == flowThread;
        }
        ASSERT(ancestor->style().columnSpan() != ColumnSpanAll || !isValidColumnSpanner(flowThread, ancestor));
        if (ancestor->isUnsplittableForPagination())
            return false;
    }
    ASSERT_NOT_REACHED();
    return false;
}