C++ WritingMode::GetBlockDir方法代码示例

//.........这里部分代码省略.........
    }
  }

  int columnCount = 0;
  int contentBEnd = 0;
  bool reflowNext = false;

  while (child) {
    // Try to skip reflowing the child. We can't skip if the child is dirty. We also can't
    // skip if the next column is dirty, because the next column's first line(s)
    // might be pullable back to this column. We can't skip if it's the last child
    // because we need to obtain the bottom margin. We can't skip
    // if this is the last column and we're supposed to assign unbounded
    // height to it, because that could change the available height from
    // the last time we reflowed it and we should try to pull all the
    // content from its next sibling. (Note that it might be the last
    // column, but not be the last child because the desired number of columns
    // has changed.)
    bool skipIncremental = !aReflowInput.ShouldReflowAllKids()
      && !NS_SUBTREE_DIRTY(child)
      && child->GetNextSibling()
      && !(aUnboundedLastColumn && columnCount == aConfig.mBalanceColCount - 1)
      && !NS_SUBTREE_DIRTY(child->GetNextSibling());
    // If we need to pull up content from the prev-in-flow then this is not just
    // a height shrink. The prev in flow will have set the dirty bit.
    // Check the overflow rect YMost instead of just the child's content height. The child
    // may have overflowing content that cares about the available height boundary.
    // (It may also have overflowing content that doesn't care about the available height
    // boundary, but if so, too bad, this optimization is defeated.)
    // We want scrollable overflow here since this is a calculation that
    // affects layout.
    bool skipResizeBSizeShrink = false;
    if (shrinkingBSizeOnly) {
      switch (wm.GetBlockDir()) {
      case WritingMode::eBlockTB:
        if (child->GetScrollableOverflowRect().YMost() <= aConfig.mColMaxBSize) {
          skipResizeBSizeShrink = true;
        }
        break;
      case WritingMode::eBlockLR:
        if (child->GetScrollableOverflowRect().XMost() <= aConfig.mColMaxBSize) {
          skipResizeBSizeShrink = true;
        }
        break;
      case WritingMode::eBlockRL:
        // XXX not sure how to handle this, so for now just don't attempt
        // the optimization
        break;
      default:
        NS_NOTREACHED("unknown block direction");
        break;
      }
    }

    nscoord childContentBEnd = 0;
    if (!reflowNext && (skipIncremental || skipResizeBSizeShrink)) {
      // This child does not need to be reflowed, but we may need to move it
      MoveChildTo(child, childOrigin, wm, containerSize);

      // If this is the last frame then make sure we get the right status
      nsIFrame* kidNext = child->GetNextSibling();
      if (kidNext) {
        aStatus = (kidNext->GetStateBits() & NS_FRAME_IS_OVERFLOW_CONTAINER)
                  ? NS_FRAME_OVERFLOW_INCOMPLETE
                  : NS_FRAME_NOT_COMPLETE;
      } else {