1 // Copyright 2017 PDFium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
6
7 #include "core/fpdfdoc/cpdf_structtree.h"
8
9 #include "core/fpdfapi/parser/cpdf_array.h"
10 #include "core/fpdfapi/parser/cpdf_dictionary.h"
11 #include "core/fpdfapi/parser/cpdf_document.h"
12 #include "core/fpdfapi/parser/cpdf_number.h"
13 #include "core/fpdfapi/parser/cpdf_reference.h"
14 #include "core/fpdfdoc/cpdf_numbertree.h"
15 #include "core/fpdfdoc/cpdf_structelement.h"
16 #include "third_party/base/ptr_util.h"
17
18 namespace {
19
IsTagged(const CPDF_Document * pDoc)20 bool IsTagged(const CPDF_Document* pDoc) {
21 const CPDF_Dictionary* pCatalog = pDoc->GetRoot();
22 const CPDF_Dictionary* pMarkInfo = pCatalog->GetDictFor("MarkInfo");
23 return pMarkInfo && pMarkInfo->GetIntegerFor("Marked");
24 }
25
26 } // namespace
27
28 // static
LoadPage(const CPDF_Document * pDoc,const CPDF_Dictionary * pPageDict)29 std::unique_ptr<CPDF_StructTree> CPDF_StructTree::LoadPage(
30 const CPDF_Document* pDoc,
31 const CPDF_Dictionary* pPageDict) {
32 if (!IsTagged(pDoc))
33 return nullptr;
34
35 auto pTree = pdfium::MakeUnique<CPDF_StructTree>(pDoc);
36 pTree->LoadPageTree(pPageDict);
37 return pTree;
38 }
39
CPDF_StructTree(const CPDF_Document * pDoc)40 CPDF_StructTree::CPDF_StructTree(const CPDF_Document* pDoc)
41 : m_pTreeRoot(pDoc->GetRoot()->GetDictFor("StructTreeRoot")),
42 m_pRoleMap(m_pTreeRoot ? m_pTreeRoot->GetDictFor("RoleMap") : nullptr) {}
43
44 CPDF_StructTree::~CPDF_StructTree() = default;
45
LoadPageTree(const CPDF_Dictionary * pPageDict)46 void CPDF_StructTree::LoadPageTree(const CPDF_Dictionary* pPageDict) {
47 m_pPage.Reset(pPageDict);
48 if (!m_pTreeRoot)
49 return;
50
51 const CPDF_Object* pKids = m_pTreeRoot->GetDirectObjectFor("K");
52 if (!pKids)
53 return;
54
55 uint32_t dwKids = 0;
56 if (pKids->IsDictionary())
57 dwKids = 1;
58 else if (const CPDF_Array* pArray = pKids->AsArray())
59 dwKids = pArray->size();
60 else
61 return;
62
63 m_Kids.clear();
64 m_Kids.resize(dwKids);
65 const CPDF_Dictionary* pParentTree = m_pTreeRoot->GetDictFor("ParentTree");
66 if (!pParentTree)
67 return;
68
69 CPDF_NumberTree parent_tree(pParentTree);
70 int parents_id = pPageDict->GetIntegerFor("StructParents", -1);
71 if (parents_id < 0)
72 return;
73
74 const CPDF_Array* pParentArray = ToArray(parent_tree.LookupValue(parents_id));
75 if (!pParentArray)
76 return;
77
78 StructElementMap element_map;
79 for (size_t i = 0; i < pParentArray->size(); i++) {
80 if (const CPDF_Dictionary* pParent = pParentArray->GetDictAt(i))
81 AddPageNode(pParent, &element_map, 0);
82 }
83 }
84
AddPageNode(const CPDF_Dictionary * pDict,StructElementMap * map,int nLevel)85 RetainPtr<CPDF_StructElement> CPDF_StructTree::AddPageNode(
86 const CPDF_Dictionary* pDict,
87 StructElementMap* map,
88 int nLevel) {
89 static constexpr int kStructTreeMaxRecursion = 32;
90 if (nLevel > kStructTreeMaxRecursion)
91 return nullptr;
92
93 auto it = map->find(pDict);
94 if (it != map->end())
95 return it->second;
96
97 auto pElement = pdfium::MakeRetain<CPDF_StructElement>(this, nullptr, pDict);
98 (*map)[pDict] = pElement;
99 const CPDF_Dictionary* pParent = pDict->GetDictFor("P");
100 if (!pParent || pParent->GetStringFor("Type") == "StructTreeRoot") {
101 if (!AddTopLevelNode(pDict, pElement))
102 map->erase(pDict);
103 return pElement;
104 }
105
106 RetainPtr<CPDF_StructElement> pParentElement =
107 AddPageNode(pParent, map, nLevel + 1);
108 bool bSave = false;
109 for (CPDF_StructKid& kid : *pParentElement->GetKids()) {
110 if (kid.m_Type == CPDF_StructKid::kElement && kid.m_pDict == pDict) {
111 kid.m_pElement = pElement;
112 bSave = true;
113 }
114 }
115 if (!bSave)
116 map->erase(pDict);
117 return pElement;
118 }
119
AddTopLevelNode(const CPDF_Dictionary * pDict,const RetainPtr<CPDF_StructElement> & pElement)120 bool CPDF_StructTree::AddTopLevelNode(
121 const CPDF_Dictionary* pDict,
122 const RetainPtr<CPDF_StructElement>& pElement) {
123 const CPDF_Object* pObj = m_pTreeRoot->GetDirectObjectFor("K");
124 if (!pObj)
125 return false;
126
127 if (pObj->IsDictionary()) {
128 if (pObj->GetObjNum() != pDict->GetObjNum())
129 return false;
130 m_Kids[0] = pElement;
131 }
132
133 const CPDF_Array* pTopKids = pObj->AsArray();
134 if (!pTopKids)
135 return true;
136
137 bool bSave = false;
138 for (size_t i = 0; i < pTopKids->size(); i++) {
139 const CPDF_Reference* pKidRef = ToReference(pTopKids->GetObjectAt(i));
140 if (pKidRef && pKidRef->GetRefObjNum() == pDict->GetObjNum()) {
141 m_Kids[i] = pElement;
142 bSave = true;
143 }
144 }
145 return bSave;
146 }
147