3 files changed, 90 insertions, 20 deletions

diff --git a/core/fpdfapi/page/cpdf_page.cpp b/core/fpdfapi/page/cpdf_page.cpp
index e730aee668..4cd58dddaa 100644
--- a/core/fpdfapi/page/cpdf_page.cpp
+++ b/core/fpdfapi/page/cpdf_page.cpp
@@ -75,6 +75,26 @@ CPDF_Page::CPDF_Page(CPDF_Document* pDocument,
 
 CPDF_Page::~CPDF_Page() {}
 
+CPDF_Page* CPDF_Page::AsPDFPage() {
+  return this;
+}
+
+CPDFXFA_Page* CPDF_Page::AsXFAPage() {
+  return nullptr;
+}
+
+CPDF_Document* CPDF_Page::GetDocument() const {
+  return GetPDFDocument();
+}
+
+float CPDF_Page::GetPageWidth() const {
+  return m_PageSize.width;
+}
+
+float CPDF_Page::GetPageHeight() const {
+  return m_PageSize.height;
+}
+
 bool CPDF_Page::IsPage() const {
   return true;
 }
diff --git a/core/fpdfapi/page/cpdf_page.h b/core/fpdfapi/page/cpdf_page.h
index 1d0186181a..44bb6d8798 100644
--- a/core/fpdfapi/page/cpdf_page.h
+++ b/core/fpdfapi/page/cpdf_page.h
@@ -10,6 +10,7 @@
 #include <memory>
 
 #include "core/fpdfapi/page/cpdf_pageobjectholder.h"
+#include "core/fpdfapi/page/ipdf_page.h"
 #include "core/fxcrt/fx_coordinates.h"
 #include "core/fxcrt/fx_system.h"
 #include "core/fxcrt/retain_ptr.h"
@@ -22,45 +23,43 @@ class CPDF_Object;
 class CPDF_PageRenderCache;
 class CPDF_PageRenderContext;
 
-class CPDF_Page : public Retainable, public CPDF_PageObjectHolder {
+class CPDF_Page : public IPDF_Page, public CPDF_PageObjectHolder {
  public:
   class View {};  // Caller implements as desired, empty here due to layering.
-  class Extension : public Retainable {};  // XFA page parent class, layering.
 
   template <typename T, typename... Args>
   friend RetainPtr<T> pdfium::MakeRetain(Args&&... args);
 
+  // IPDF_Page:
+  CPDF_Page* AsPDFPage() override;
+  CPDFXFA_Page* AsXFAPage() override;
+  CPDF_Document* GetDocument() const override;
+  float GetPageWidth() const override;
+  float GetPageHeight() const override;
+  CFX_Matrix GetDisplayMatrix(const FX_RECT& rect, int iRotate) const override;
+  Optional<CFX_PointF> DeviceToPage(
+      const FX_RECT& rect,
+      int rotate,
+      const CFX_PointF& device_point) const override;
+  Optional<CFX_PointF> PageToDevice(
+      const FX_RECT& rect,
+      int rotate,
+      const CFX_PointF& page_point) const override;
+
   // CPDF_PageObjectHolder:
   bool IsPage() const override;
 
   void ParseContent();
-
-  Optional<CFX_PointF> DeviceToPage(const FX_RECT& rect,
-                                    int rotate,
-                                    const CFX_PointF& device_point) const;
-  Optional<CFX_PointF> PageToDevice(const FX_RECT& rect,
-                                    int rotate,
-                                    const CFX_PointF& page_point) const;
-
-  CFX_Matrix GetDisplayMatrix(const FX_RECT& rect, int iRotate) const;
-
-  float GetPageWidth() const { return m_PageSize.width; }
-  float GetPageHeight() const { return m_PageSize.height; }
   const CFX_SizeF& GetPageSize() const { return m_PageSize; }
-
   int GetPageRotation() const;
   CPDF_PageRenderCache* GetRenderCache() const { return m_pPageRender.get(); }
-
   CPDF_PageRenderContext* GetRenderContext() const {
     return m_pRenderContext.get();
   }
   void SetRenderContext(std::unique_ptr<CPDF_PageRenderContext> pContext);
-
   CPDF_Document* GetPDFDocument() const { return m_pPDFDocument.Get(); }
   View* GetView() const { return m_pView.Get(); }
   void SetView(View* pView) { m_pView = pView; }
-  Extension* GetPageExtension() const { return m_pPageExtension.Get(); }
-  void SetPageExtension(Extension* pExt) { m_pPageExtension = pExt; }
 
  private:
   CPDF_Page(CPDF_Document* pDocument,
@@ -74,7 +73,6 @@ class CPDF_Page : public Retainable, public CPDF_PageObjectHolder {
   CFX_SizeF m_PageSize;
   CFX_Matrix m_PageMatrix;
   UnownedPtr<CPDF_Document> m_pPDFDocument;
-  UnownedPtr<Extension> m_pPageExtension;
   std::unique_ptr<CPDF_PageRenderCache> m_pPageRender;
   std::unique_ptr<CPDF_PageRenderContext> m_pRenderContext;
   UnownedPtr<View> m_pView;
diff --git a/core/fpdfapi/page/ipdf_page.h b/core/fpdfapi/page/ipdf_page.h
new file mode 100644
index 0000000000..7c9fce7726
--- /dev/null
+++ b/core/fpdfapi/page/ipdf_page.h
@@ -0,0 +1,52 @@
+// Copyright 2018 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
+
+#ifndef CORE_FPDFAPI_PAGE_IPDF_PAGE_H_
+#define CORE_FPDFAPI_PAGE_IPDF_PAGE_H_
+
+#include "core/fxcrt/fx_coordinates.h"
+#include "core/fxcrt/retain_ptr.h"
+#include "third_party/base/optional.h"
+
+class CPDF_Document;
+class CPDF_Page;
+
+// Small layering violation, incomplete type and always null if non-XFA.
+class CPDFXFA_Page;
+
+// Interface implemented by both page types (CPDF_Page and CPDFXFA_Page).
+class IPDF_Page : public Retainable {
+ public:
+  virtual CPDF_Page* AsPDFPage() = 0;
+  virtual CPDFXFA_Page* AsXFAPage() = 0;
+
+  virtual CPDF_Document* GetDocument() const = 0;
+
+  virtual float GetPageWidth() const = 0;
+  virtual float GetPageHeight() const = 0;
+  virtual CFX_Matrix GetDisplayMatrix(const FX_RECT& rect,
+                                      int iRotate) const = 0;
+
+  virtual Optional<CFX_PointF> DeviceToPage(
+      const FX_RECT& rect,
+      int rotate,
+      const CFX_PointF& device_point) const = 0;
+
+  virtual Optional<CFX_PointF> PageToDevice(
+      const FX_RECT& rect,
+      int rotate,
+      const CFX_PointF& page_point) const = 0;
+};
+
+inline CPDF_Page* ToPDFPage(IPDF_Page* pBase) {
+  return pBase ? pBase->AsPDFPage() : nullptr;
+}
+
+inline CPDFXFA_Page* ToXFAPage(IPDF_Page* pBase) {
+  return pBase ? pBase->AsXFAPage() : nullptr;
+}
+
+#endif  // CORE_FPDFAPI_PAGE_IPDF_PAGE_H_