Introduce CPDFPageFromFPDFPage()

fpdfsdk/src/fpdftext.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 "../../core/include/fpdfdoc/fpdf_doc.h"
 #include "../../core/include/fpdftext/fpdf_text.h"
 #include "../../public/fpdf_text.h"
+#include "../include/fsdk_define.h"
 
 #ifdef _WIN32
 #include <tchar.h>
 #endif
 
 DLLEXPORT FPDF_TEXTPAGE STDCALL FPDFText_LoadPage(FPDF_PAGE page) {
-  if (!page)
-    return NULL;
-  IPDF_TextPage* textpage = NULL;
-  CPDF_ViewerPreferences viewRef(((CPDF_Page*)page)->m_pDocument);
-  textpage =
-      IPDF_TextPage::CreateTextPage((CPDF_Page*)page, viewRef.IsDirectionR2L());
+  CPDF_Page* pPage = CPDFPageFromFPDFPage(page);
+  if (!pPage)
+    return nullptr;
+  CPDF_ViewerPreferences viewRef(pPage->m_pDocument);
+  IPDF_TextPage* textpage =
+      IPDF_TextPage::CreateTextPage(pPage, viewRef.IsDirectionR2L());
   textpage->ParseTextPage();
   return textpage;
 }
 DLLEXPORT void STDCALL FPDFText_ClosePage(FPDF_TEXTPAGE text_page) {
   delete (IPDF_TextPage*)text_page;
 }
 DLLEXPORT int STDCALL FPDFText_CountChars(FPDF_TEXTPAGE text_page) {
   if (!text_page)
     return -1;
   IPDF_TextPage* textpage = (IPDF_TextPage*)text_page;
@@ skipping 243 matching lines @@
     CFX_FloatRect rect = rectArray.GetAt(rect_index);
     *left = rect.left;
     *right = rect.right;
     *top = rect.top;
     *bottom = rect.bottom;
   }
 }
 DLLEXPORT void STDCALL FPDFLink_CloseWebLinks(FPDF_PAGELINK link_page) {
   delete (IPDF_LinkExtract*)link_page;
 }