text: // Copyright 2016 PDFium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
  
  #include "core/fpdfdoc/cpdf_linklist.h"
  
  #include "core/fpdfapi/page/cpdf_page.h"
  #include "core/fpdfapi/parser/cpdf_array.h"
  
  CPDF_LinkList::CPDF_LinkList() {}
  
  CPDF_LinkList::~CPDF_LinkList() {}
  
  const std::vector<CPDF_Dictionary*>* CPDF_LinkList::GetPageLinks(
      CPDF_Page* pPage) {
    uint32_t objnum = pPage->m_pFormDict->GetObjNum();
    if (objnum == 0)
      return nullptr;
  
    auto it = m_PageMap.find(objnum);
    if (it != m_PageMap.end())
      return &it->second;
  
    // std::map::operator[] forces the creation of a map entry.
    std::vector<CPDF_Dictionary*>& page_link_list = m_PageMap[objnum];
    LoadPageLinks(pPage, &page_link_list);
    return &page_link_list;
  }
  
  CPDF_Link CPDF_LinkList::GetLinkAtPoint(CPDF_Page* pPage,
                                          FX_FLOAT pdf_x,
                                          FX_FLOAT pdf_y,
                                          int* z_order) {
    const std::vector<CPDF_Dictionary*>* pPageLinkList = GetPageLinks(pPage);
    if (!pPageLinkList)
      return CPDF_Link();
  
    for (size_t i = pPageLinkList->size(); i > 0; --i) {
      size_t annot_index = i - 1;
      CPDF_Dictionary* pAnnot = (*pPageLinkList)[annot_index];
      if (!pAnnot)
        continue;
  
      CPDF_Link link(pAnnot);
      CFX_FloatRect rect = link.GetRect();
      if (!rect.Contains(pdf_x, pdf_y))
        continue;
  
      if (z_order)
        *z_order = annot_index;
      return link;
    }
    return CPDF_Link();
  }
  
  void CPDF_LinkList::LoadPageLinks(CPDF_Page* pPage,
                                    std::vector<CPDF_Dictionary*>* pList) {
    CPDF_Array* pAnnotList = pPage->m_pFormDict->GetArrayFor("Annots");
    if (!pAnnotList)
      return;
  
    for (size_t i = 0; i < pAnnotList->GetCount(); ++i) {
      CPDF_Dictionary* pAnnot = pAnnotList->GetDictAt(i);
      bool add_link = (pAnnot && pAnnot->GetStringFor("Subtype") == "Link");
      // Add non-links as nullptrs to preserve z-order.
      pList->push_back(add_link ? pAnnot : nullptr);
    }
  }
  