Add FPDFPage_SetRotation function

fpdfsdk/src/fpdfeditpage.cpp

 // Copyright 2014 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 "x:/pdf/fpdfapi5/include/fpdfapi.h"
 #include "../include/fsdk_define.h"
 #include "../include/fpdfedit.h"
 
@@ skipping 296 matching lines @@
                 pRectArray->SetAt(2,FX_NEW CPDF_Number(rect.right));
                 pRectArray->SetAt(3,FX_NEW CPDF_Number(rect.top));
                 pAnnot->m_pAnnotDict->SetAt("Rect",pRectArray);
 
                 //Transform AP's rectangle
                 //To Do
 
         }
 
 }
+
+DLLEXPORT void STDCALL FPDFPage_SetRotation(FPDF_PAGE page, int rotate)
+{
+        CPDF_Page* pPage = (CPDF_Page*)page;
+        if (!pPage || !pPage->m_pFormDict || !pPage->m_pFormDict->KeyExist("Type")
+                || pPage->m_pFormDict->GetElement("Type")->GetDirect()->GetString().Compare("Page"))
+        {
+                return;
+        }
+        CPDF_Dictionary* pDict = pPage->m_pFormDict;
+        rotate %=4;
+
+        pDict->SetAt("Rotate", FX_NEW CPDF_Number(rotate * 90));
+}