2 files changed, 22 insertions, 1 deletions
diff --git a/core/fpdfapi/parser/cpdf_document.cpp b/core/fpdfapi/parser/cpdf_document.cpp
index 7968d1b019..2e4baabe91 100644
--- a/core/fpdfapi/parser/cpdf_document.cpp
+++ b/core/fpdfapi/parser/cpdf_document.cpp
@@ -602,6 +602,19 @@ bool CPDF_Document::InsertNewPage(int iPage, CPDF_Dictionary* pPageDict) {
   return true;
 }
 
+RetainPtr<CPDF_Page> CPDF_Document::GetOrCreatePDFPage(
+    CPDF_Dictionary* pPageDict) {
+  std::pair<uint32_t, uint32_t> key = {pPageDict->GetObjNum(),
+                                       pPageDict->GetGenNum()};
+  if (m_PageMap[key])
+    return RetainPtr<CPDF_Page>(m_PageMap[key].Get());
+
+  auto pPage = pdfium::MakeRetain<CPDF_Page>(this, pPageDict, true);
+  pPage->ParseContent();
+  m_PageMap[key].Reset(pPage.Get());
+  return pPage;
+}
+
 void CPDF_Document::DeletePage(int iPage) {
   CPDF_Dictionary* pPages = GetPagesDict();
   if (!pPages)
diff --git a/core/fpdfapi/parser/cpdf_document.h b/core/fpdfapi/parser/cpdf_document.h
index c2774b163a..c240e77567 100644
--- a/core/fpdfapi/parser/cpdf_document.h
+++ b/core/fpdfapi/parser/cpdf_document.h
@@ -8,6 +8,7 @@
 #define CORE_FPDFAPI_PARSER_CPDF_DOCUMENT_H_
 
 #include <functional>
+#include <map>
 #include <memory>
 #include <set>
 #include <utility>
@@ -64,6 +65,7 @@ class CPDF_Document : public CPDF_IndirectObjectHolder {
   const CPDF_Dictionary* GetInfo() const { return m_pInfoDict.Get(); }
   CPDF_Dictionary* GetInfo() { return m_pInfoDict.Get(); }
 
+  RetainPtr<CPDF_Page> GetOrCreatePDFPage(CPDF_Dictionary* pPageDict);
   void DeletePage(int iPage);
   int GetPageCount() const;
   bool IsPageLoaded(int iPage) const;
@@ -167,7 +169,13 @@ class CPDF_Document : public CPDF_IndirectObjectHolder {
   std::unique_ptr<CPDF_DocRenderData> m_pDocRender;
   std::unique_ptr<JBig2_DocumentContext> m_pCodecContext;
   std::unique_ptr<CPDF_LinkList> m_pLinksContext;
-  std::vector<uint32_t> m_PageList;  // Page number to page's dict objnum.
+
+  // Page number (index) to page's dict objnum.
+  std::vector<uint32_t> m_PageList;
+
+  // Dict {objnum, gennum} to page mapping.
+  std::map<std::pair<uint32_t, uint32_t>, CPDF_Page::ObservedPtr> m_PageMap;
+
   UnownedPtr<Extension> m_pExtension;
 };