Introduce CPDF_Document::FromFPDFDocument().

fpdfsdk/src/fpdfdoc.cpp

Index: fpdfsdk/src/fpdfdoc.cpp
diff --git a/fpdfsdk/src/fpdfdoc.cpp b/fpdfsdk/src/fpdfdoc.cpp
index 4e2e7f3d0bf34d63a3f1ab32b28ff88ac23370db..ffdad281c647f4992b52ebf5e0abbc78ed152737 100644
--- a/fpdfsdk/src/fpdfdoc.cpp
+++ b/fpdfsdk/src/fpdfdoc.cpp
@@ -52,9 +52,9 @@ CPDF_LinkList* GetLinkList(CPDF_Page* page) {
 
 DLLEXPORT FPDF_BOOKMARK STDCALL
 FPDFBookmark_GetFirstChild(FPDF_DOCUMENT document, FPDF_BOOKMARK pDict) {
-  if (!document)
-    return NULL;
-  CPDF_Document* pDoc = (CPDF_Document*)document;
+  CPDF_Document* pDoc = CPDF_Document::FromFPDFDocument(document);
+  if (!pDoc)
+    return nullptr;
   CPDF_BookmarkTree tree(pDoc);
   CPDF_Bookmark bookmark = CPDF_Bookmark((CPDF_Dictionary*)pDict);
   return tree.GetFirstChild(bookmark).GetDict();
@@ -62,9 +62,11 @@ FPDFBookmark_GetFirstChild(FPDF_DOCUMENT document, FPDF_BOOKMARK pDict) {
 
 DLLEXPORT FPDF_BOOKMARK STDCALL
 FPDFBookmark_GetNextSibling(FPDF_DOCUMENT document, FPDF_BOOKMARK pDict) {
-  if (!document || !pDict)
-    return NULL;
-  CPDF_Document* pDoc = (CPDF_Document*)document;
+  if (!pDict)
+    return nullptr;
+  CPDF_Document* pDoc = CPDF_Document::FromFPDFDocument(document);
+  if (!pDoc)
+    return nullptr;
   CPDF_BookmarkTree tree(pDoc);
   CPDF_Bookmark bookmark = CPDF_Bookmark((CPDF_Dictionary*)pDict);
   return tree.GetNextSibling(bookmark).GetDict();
@@ -87,11 +89,11 @@ DLLEXPORT unsigned long STDCALL FPDFBookmark_GetTitle(FPDF_BOOKMARK pDict,
 
 DLLEXPORT FPDF_BOOKMARK STDCALL FPDFBookmark_Find(FPDF_DOCUMENT document,
                                                   FPDF_WIDESTRING title) {
-  if (!document)
-    return NULL;
   if (!title || title[0] == 0)
-    return NULL;
-  CPDF_Document* pDoc = (CPDF_Document*)document;
+    return nullptr;
+  CPDF_Document* pDoc = CPDF_Document::FromFPDFDocument(document);
+  if (!pDoc)
+    return nullptr;
   CPDF_BookmarkTree tree(pDoc);
   FX_STRSIZE len = CFX_WideString::WStringLength(title);
   CFX_WideString encodedTitle = CFX_WideString::FromUTF16LE(title, len);
@@ -100,12 +102,12 @@ DLLEXPORT FPDF_BOOKMARK STDCALL FPDFBookmark_Find(FPDF_DOCUMENT document,
 
 DLLEXPORT FPDF_DEST STDCALL FPDFBookmark_GetDest(FPDF_DOCUMENT document,
                                                  FPDF_BOOKMARK pDict) {
-  if (!document)
-    return NULL;
   if (!pDict)
-    return NULL;
+    return nullptr;
+  CPDF_Document* pDoc = CPDF_Document::FromFPDFDocument(document);
+  if (!pDoc)
+    return nullptr;
   CPDF_Bookmark bookmark((CPDF_Dictionary*)pDict);
-  CPDF_Document* pDoc = (CPDF_Document*)document;
   CPDF_Dest dest = bookmark.GetDest(pDoc);
   if (dest)
     return dest.GetObject();
@@ -113,7 +115,7 @@ DLLEXPORT FPDF_DEST STDCALL FPDFBookmark_GetDest(FPDF_DOCUMENT document,
   // action
   CPDF_Action action = bookmark.GetAction();
   if (!action)
-    return NULL;
+    return nullptr;
   return action.GetDest(pDoc).GetObject();
 }
 
@@ -146,10 +148,11 @@ DLLEXPORT unsigned long STDCALL FPDFAction_GetType(FPDF_ACTION pDict) {
 
 DLLEXPORT FPDF_DEST STDCALL FPDFAction_GetDest(FPDF_DOCUMENT document,
                                                FPDF_ACTION pDict) {
-  if (!document || !pDict)
+  if (!pDict)
+    return nullptr;
+  CPDF_Document* pDoc = CPDF_Document::FromFPDFDocument(document);
+  if (!pDoc)
     return nullptr;
-
-  CPDF_Document* pDoc = (CPDF_Document*)document;
   CPDF_Action action((CPDF_Dictionary*)pDict);
   return action.GetDest(pDoc).GetObject();
 }
@@ -172,10 +175,11 @@ DLLEXPORT unsigned long STDCALL FPDFAction_GetURIPath(FPDF_DOCUMENT document,
                                                       FPDF_ACTION pDict,
                                                       void* buffer,
                                                       unsigned long buflen) {
-  if (!document || !pDict)
+  if (!pDict)
+    return 0;
+  CPDF_Document* pDoc = CPDF_Document::FromFPDFDocument(document);
+  if (!pDoc)
     return 0;
-
-  CPDF_Document* pDoc = (CPDF_Document*)document;
   CPDF_Action action((CPDF_Dictionary*)pDict);
   CFX_ByteString path = action.GetURI(pDoc);
   unsigned long len = path.GetLength() + 1;
@@ -186,10 +190,11 @@ DLLEXPORT unsigned long STDCALL FPDFAction_GetURIPath(FPDF_DOCUMENT document,
 
 DLLEXPORT unsigned long STDCALL FPDFDest_GetPageIndex(FPDF_DOCUMENT document,
                                                       FPDF_DEST pDict) {
-  if (!document || !pDict)
+  if (!pDict)
+    return 0;
+  CPDF_Document* pDoc = CPDF_Document::FromFPDFDocument(document);
+  if (!pDoc)
     return 0;
-
-  CPDF_Document* pDoc = (CPDF_Document*)document;
   CPDF_Dest dest((CPDF_Array*)pDict);
   return dest.GetPageIndex(pDoc);
 }
@@ -219,10 +224,11 @@ FPDFLink_GetLinkZOrderAtPoint(FPDF_PAGE page, double x, double y) {
 
 DLLEXPORT FPDF_DEST STDCALL FPDFLink_GetDest(FPDF_DOCUMENT document,
                                              FPDF_LINK pDict) {
-  if (!document || !pDict)
+  if (!pDict)
+    return nullptr;
+  CPDF_Document* pDoc = CPDF_Document::FromFPDFDocument(document);
+  if (!pDoc)
     return nullptr;
-
-  CPDF_Document* pDoc = (CPDF_Document*)document;
   CPDF_Link link((CPDF_Dictionary*)pDict);
   FPDF_DEST dest = link.GetDest(pDoc).GetObject();
   if (dest)
@@ -317,10 +323,11 @@ DLLEXPORT unsigned long STDCALL FPDF_GetMetaText(FPDF_DOCUMENT doc,
                                                  FPDF_BYTESTRING tag,
                                                  void* buffer,
                                                  unsigned long buflen) {
-  if (!doc || !tag)
+  if (!tag)
+    return 0;
+  CPDF_Document* pDoc = CPDF_Document::FromFPDFDocument(doc);
+  if (!pDoc)
     return 0;
-  CPDF_Document* pDoc = (CPDF_Document*)doc;
-  // Get info dictionary
   CPDF_Dictionary* pInfo = pDoc->GetInfo();
   if (!pInfo)
     return 0;