Introduce CPDFPageFromFPDFPage()

fpdfsdk/src/fpdfview.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/fxcodec/fx_codec.h"
 #include "../../core/include/fxcrt/fx_safe_types.h"
 #include "../../public/fpdf_ext.h"
 #include "../../public/fpdf_progressive.h"
 #include "../../public/fpdfview.h"
 #include "../../third_party/base/nonstd_unique_ptr.h"
 #include "../../third_party/base/numerics/safe_conversions_impl.h"
 #include "../include/fsdk_define.h"
 #include "../include/fsdk_mgr.h"
 #include "../include/fsdk_rendercontext.h"
 #include "../include/javascript/IJavaScript.h"
 
 CPDF_Document* CPDFDocumentFromFPDFDocument(FPDF_DOCUMENT doc) {
   return static_cast<CPDF_Document*>(doc);
 }
 
+CPDF_Page* CPDFPageFromFPDFPage(FPDF_PAGE page) {
+  return static_cast<CPDF_Page*>(page);
+}
+
 CPDF_CustomAccess::CPDF_CustomAccess(FPDF_FILEACCESS* pFileAccess) {
   if (pFileAccess)
     m_FileAccess = *pFileAccess;
 }
 
 FX_BOOL CPDF_CustomAccess::ReadBlock(void* buffer,
                                      FX_FILESIZE offset,
                                      size_t size) {
   if (offset < 0) {
     return FALSE;
@@ skipping 244 matching lines @@
   CPDF_Dictionary* pDict = pDoc->GetPage(page_index);
   if (pDict == NULL)
     return NULL;
   CPDF_Page* pPage = new CPDF_Page;
   pPage->Load(pDoc, pDict);
   pPage->ParseContent();
   return pPage;
 }
 
 DLLEXPORT double STDCALL FPDF_GetPageWidth(FPDF_PAGE page) {
-  if (!page)
-    return 0.0;
-  return ((CPDF_Page*)page)->GetPageWidth();
+  CPDF_Page* pPage = CPDFPageFromFPDFPage(page);
+  return pPage ? pPage->GetPageWidth() : 0.0;
 }
 
 DLLEXPORT double STDCALL FPDF_GetPageHeight(FPDF_PAGE page) {
-  if (!page)
-    return 0.0;
-  return ((CPDF_Page*)page)->GetPageHeight();
+  CPDF_Page* pPage = CPDFPageFromFPDFPage(page);
+  return pPage ? pPage->GetPageHeight() : 0.0;
 }
 
 void DropContext(void* data) {
   delete (CRenderContext*)data;
 }
 
 #if defined(_DEBUG) || defined(DEBUG)
 #define DEBUG_TRACE
 #endif
 
 #if defined(_WIN32)
 DLLEXPORT void STDCALL FPDF_RenderPage(HDC dc,
                                        FPDF_PAGE page,
                                        int start_x,
                                        int start_y,
                                        int size_x,
                                        int size_y,
                                        int rotate,
                                        int flags) {
-  if (page == NULL)
+  CPDF_Page* pPage = CPDFPageFromFPDFPage(page);
+  if (!pPage)
     return;
-  CPDF_Page* pPage = (CPDF_Page*)page;
 
   CRenderContext* pContext = new CRenderContext;
   pPage->SetPrivateData((void*)1, pContext, DropContext);
 
 #ifndef _WIN32_WCE
   CFX_DIBitmap* pBitmap = NULL;
   FX_BOOL bBackgroundAlphaNeeded = FALSE;
   bBackgroundAlphaNeeded = pPage->BackgroundAlphaNeeded();
   if (bBackgroundAlphaNeeded) {
     pBitmap = new CFX_DIBitmap;
@@ skipping 137 matching lines @@
 #endif
 
 DLLEXPORT void STDCALL FPDF_RenderPageBitmap(FPDF_BITMAP bitmap,
                                              FPDF_PAGE page,
                                              int start_x,
                                              int start_y,
                                              int size_x,
                                              int size_y,
                                              int rotate,
                                              int flags) {
-  if (bitmap == NULL || page == NULL)
+  if (!bitmap)
     return;
-  CPDF_Page* pPage = (CPDF_Page*)page;
-
+  CPDF_Page* pPage = CPDFPageFromFPDFPage(page);
+  if (!pPage)
+    return;
   CRenderContext* pContext = new CRenderContext;
   pPage->SetPrivateData((void*)1, pContext, DropContext);
 #ifdef _SKIA_SUPPORT_
   pContext->m_pDevice = new CFX_SkiaDevice;
 
   if (flags & FPDF_REVERSE_BYTE_ORDER)
     ((CFX_SkiaDevice*)pContext->m_pDevice)
         ->Attach((CFX_DIBitmap*)bitmap, 0, TRUE);
   else
     ((CFX_SkiaDevice*)pContext->m_pDevice)->Attach((CFX_DIBitmap*)bitmap);
@@ skipping 74 matching lines @@
 DLLEXPORT void STDCALL FPDF_PageToDevice(FPDF_PAGE page,
                                          int start_x,
                                          int start_y,
                                          int size_x,
                                          int size_y,
                                          int rotate,
                                          double page_x,
                                          double page_y,
                                          int* device_x,
                                          int* device_y) {
-  if (page == NULL || device_x == NULL || device_y == NULL)
+  if (!device_x || !device_y)
     return;
-  CPDF_Page* pPage = (CPDF_Page*)page;
-
+  CPDF_Page* pPage = CPDFPageFromFPDFPage(page);
+  if (!pPage)
+    return;
   CPDF_Matrix page2device;
   pPage->GetDisplayMatrix(page2device, start_x, start_y, size_x, size_y,
                           rotate);
 
   FX_FLOAT device_x_f, device_y_f;
   page2device.Transform(((FX_FLOAT)page_x), ((FX_FLOAT)page_y), device_x_f,
                         device_y_f);
 
   *device_x = FXSYS_round(device_x_f);
   *device_y = FXSYS_round(device_y_f);
@@ skipping 87 matching lines @@
 void FPDF_RenderPage_Retail(CRenderContext* pContext,
                             FPDF_PAGE page,
                             int start_x,
                             int start_y,
                             int size_x,
                             int size_y,
                             int rotate,
                             int flags,
                             FX_BOOL bNeedToRestore,
                             IFSDK_PAUSE_Adapter* pause) {
-  CPDF_Page* pPage = (CPDF_Page*)page;
-  if (pPage == NULL)
+  CPDF_Page* pPage = CPDFPageFromFPDFPage(page);
+  if (!pPage)
     return;
 
   if (!pContext->m_pOptions)
     pContext->m_pOptions = new CPDF_RenderOptions;
 
   if (flags & FPDF_LCD_TEXT)
     pContext->m_pOptions->m_Flags |= RENDER_CLEARTYPE;
   else
     pContext->m_pOptions->m_Flags &= ~RENDER_CLEARTYPE;
   if (flags & FPDF_NO_NATIVETEXT)
@@ skipping 194 matching lines @@
   if (!buffer) {
     *buflen = len;
   } else if (*buflen >= len) {
     memcpy(buffer, utf16Name.c_str(), len);
     *buflen = len;
   } else {
     *buflen = -1;
   }
   return (FPDF_DEST)pDestObj;
 }