C++ LayoutMultiColumnFlowThread::blockOffsetInEnclosingFragmentationContext方法代码示例

void InitialColumnHeightFinder::examineBoxAfterEntering(
    const LayoutBox& box,
    EBreak previousBreakAfterValue) {
  if (isLogicalTopWithinBounds(flowThreadOffset() - box.paginationStrut())) {
    if (box.needsForcedBreakBefore(previousBreakAfterValue)) {
      addContentRun(flowThreadOffset());
    } else {
      ASSERT(isFirstAfterBreak(flowThreadOffset()) || !box.paginationStrut());
      if (isFirstAfterBreak(flowThreadOffset())) {
        // This box is first after a soft break.
        recordStrutBeforeOffset(flowThreadOffset(), box.paginationStrut());
      }
    }
  }

  if (box.getPaginationBreakability() != LayoutBox::AllowAnyBreaks) {
    LayoutUnit unsplittableLogicalHeight = box.logicalHeight();
    if (box.isFloating())
      unsplittableLogicalHeight += box.marginBefore() + box.marginAfter();
    m_tallestUnbreakableLogicalHeight =
        std::max(m_tallestUnbreakableLogicalHeight, unsplittableLogicalHeight);
    return;
  }
  // Need to examine inner multicol containers to find their tallest unbreakable
  // piece of content.
  if (!box.isLayoutBlockFlow())
    return;
  LayoutMultiColumnFlowThread* innerFlowThread =
      toLayoutBlockFlow(box).multiColumnFlowThread();
  if (!innerFlowThread || innerFlowThread->isLayoutPagedFlowThread())
    return;
  LayoutUnit offsetInInnerFlowThread =
      flowThreadOffset() -
      innerFlowThread->blockOffsetInEnclosingFragmentationContext();
  LayoutUnit innerUnbreakableHeight =
      innerFlowThread->tallestUnbreakableLogicalHeight(offsetInInnerFlowThread);
  m_tallestUnbreakableLogicalHeight =
      std::max(m_tallestUnbreakableLogicalHeight, innerUnbreakableHeight);
}

LayoutSize MultiColumnFragmentainerGroup::flowThreadTranslationAtOffset(LayoutUnit offsetInFlowThread) const
{
    LayoutMultiColumnFlowThread* flowThread = m_columnSet.multiColumnFlowThread();
    unsigned columnIndex = columnIndexAtOffset(offsetInFlowThread);
    LayoutRect portionRect(flowThreadPortionRectAt(columnIndex));
    flowThread->flipForWritingMode(portionRect);
    LayoutRect columnRect(columnRectAt(columnIndex));
    m_columnSet.flipForWritingMode(columnRect);
    LayoutSize translationRelativeToGroup = columnRect.location() - portionRect.location();

    LayoutSize enclosingTranslation;
    if (LayoutMultiColumnFlowThread* enclosingFlowThread = flowThread->enclosingFlowThread()) {
        // Translation that would map points in the coordinate space of the outermost flow thread to
        // visual points in the first column in the first fragmentainer group (row) in our multicol
        // container.
        LayoutSize enclosingTranslationOrigin = enclosingFlowThread->flowThreadTranslationAtOffset(flowThread->blockOffsetInEnclosingFragmentationContext());

        // Translation that would map points in the coordinate space of the outermost flow thread to
        // visual points in the first column in this fragmentainer group.
        enclosingTranslation = enclosingFlowThread->flowThreadTranslationAtOffset(blockOffsetInEnclosingFragmentationContext());

        // What we ultimately return from this method is a translation that maps points in the
        // coordinate space of our flow thread to a visual point in a certain column in this
        // fragmentainer group. We had to go all the way up to the outermost flow thread, since this
        // fragmentainer group may be in a different outer column than the first outer column that
        // this multicol container lives in. It's the visual distance between the first
        // fragmentainer group and this fragmentainer group that we need to add to the translation.
        enclosingTranslation -= enclosingTranslationOrigin;
    }

    return enclosingTranslation + translationRelativeToGroup + offsetFromColumnSet() + m_columnSet.topLeftLocationOffset() - flowThread->topLeftLocationOffset();
}