Method Layer

src/pdf/PDFDocumentImpl.cpp:132–162

    int fPageObjectDescendantCount;

    static std::vector<PageTreeNode> Layer(std::vector<PageTreeNode> vec, PDFDocumentImpl* doc) {
      std::vector<PageTreeNode> result;
      static constexpr size_t kMaxNodeSize = 8;
      const size_t n = vec.size();
      DEBUG_ASSERT(n >= 1);
      const size_t result_len = ((n - 1) / kMaxNodeSize) + 1;
      DEBUG_ASSERT(result_len >= 1);
      DEBUG_ASSERT((n == 1 || result_len < n));
      result.reserve(result_len);
      size_t index = 0;
      for (size_t i = 0; i < result_len; ++i) {
        if (n != 1 && index + 1 == n) {  // No need to create a new node.
          result.push_back(std::move(vec[index++]));
          continue;
        }
        PDFIndirectReference parent = doc->reserveRef();
        auto kids_list = MakePDFArray();
        int descendantCount = 0;
        for (size_t j = 0; j < kMaxNodeSize && index < n; ++j) {
          PageTreeNode& node = vec[index++];
          node.fNode->insertRef("Parent", parent);
          kids_list->appendRef(doc->emit(*node.fNode, node.fReservedRef));
          descendantCount += node.fPageObjectDescendantCount;
        }
        auto next = PDFDictionary::Make("Pages");
        next->insertInt("Count", descendantCount);
        next->insertObject("Kids", std::move(kids_list));
        result.push_back(PageTreeNode{std::move(next), parent, descendantCount});
      }
      return result;
    }
  };
  std::vector<PageTreeNode> currentLayer;
  currentLayer.reserve(pages.size());