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      1 // Copyright 2016 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 #include "public/fpdf_structtree.h"
      6 
      7 #include <memory>
      8 
      9 #include "core/fpdfapi/page/cpdf_page.h"
     10 #include "core/fpdfapi/parser/cpdf_dictionary.h"
     11 #include "core/fpdfdoc/fpdf_tagged.h"
     12 #include "fpdfsdk/fsdk_define.h"
     13 
     14 namespace {
     15 
     16 IPDF_StructTree* ToStructTree(FPDF_STRUCTTREE struct_tree) {
     17   return reinterpret_cast<IPDF_StructTree*>(struct_tree);
     18 }
     19 
     20 IPDF_StructElement* ToStructTreeElement(FPDF_STRUCTELEMENT struct_element) {
     21   return reinterpret_cast<IPDF_StructElement*>(struct_element);
     22 }
     23 
     24 }  // namespace
     25 
     26 DLLEXPORT FPDF_STRUCTTREE STDCALL FPDF_StructTree_GetForPage(FPDF_PAGE page) {
     27   CPDF_Page* pPage = CPDFPageFromFPDFPage(page);
     28   if (!pPage)
     29     return nullptr;
     30   return IPDF_StructTree::LoadPage(pPage->m_pDocument, pPage->m_pFormDict)
     31       .release();
     32 }
     33 
     34 DLLEXPORT void STDCALL FPDF_StructTree_Close(FPDF_STRUCTTREE struct_tree) {
     35   std::unique_ptr<IPDF_StructTree>(ToStructTree(struct_tree));
     36 }
     37 
     38 DLLEXPORT int STDCALL
     39 FPDF_StructTree_CountChildren(FPDF_STRUCTTREE struct_tree) {
     40   IPDF_StructTree* tree = ToStructTree(struct_tree);
     41   return tree ? tree->CountTopElements() : -1;
     42 }
     43 
     44 DLLEXPORT FPDF_STRUCTELEMENT STDCALL
     45 FPDF_StructTree_GetChildAtIndex(FPDF_STRUCTTREE struct_tree, int index) {
     46   IPDF_StructTree* tree = ToStructTree(struct_tree);
     47   if (!tree || index < 0 || index >= tree->CountTopElements())
     48     return nullptr;
     49   return tree->GetTopElement(index);
     50 }
     51 
     52 DLLEXPORT unsigned long STDCALL
     53 FPDF_StructElement_GetAltText(FPDF_STRUCTELEMENT struct_element,
     54                               void* buffer,
     55                               unsigned long buflen) {
     56   IPDF_StructElement* elem = ToStructTreeElement(struct_element);
     57   if (!elem)
     58     return 0;
     59 
     60   CPDF_Dictionary* dict = elem->GetDict();
     61   if (!dict)
     62     return 0;
     63 
     64   CFX_WideString str = elem->GetDict()->GetUnicodeTextFor("Alt");
     65   if (str.IsEmpty())
     66     return 0;
     67 
     68   CFX_ByteString encodedStr = str.UTF16LE_Encode();
     69   const unsigned long len = encodedStr.GetLength();
     70   if (buffer && len <= buflen)
     71     FXSYS_memcpy(buffer, encodedStr.c_str(), len);
     72   return len;
     73 }
     74 
     75 DLLEXPORT int STDCALL
     76 FPDF_StructElement_CountChildren(FPDF_STRUCTELEMENT struct_element) {
     77   IPDF_StructElement* elem = ToStructTreeElement(struct_element);
     78   return elem ? elem->CountKids() : -1;
     79 }
     80 
     81 DLLEXPORT FPDF_STRUCTELEMENT STDCALL
     82 FPDF_StructElement_GetChildAtIndex(FPDF_STRUCTELEMENT struct_element,
     83                                    int index) {
     84   IPDF_StructElement* elem = ToStructTreeElement(struct_element);
     85   if (!elem || index < 0 || index >= elem->CountKids())
     86     return nullptr;
     87 
     88   return elem->GetKidIfElement(index);
     89 }
     90