Make CPDF_Document cache CPDF_Pages

We cache pages not by page number, which can bounce around as pages
are inserted or removed, but by page dictionary's object number.

Since the page may be created under one function and used under
another, we can't take the shortcut of not instantiating a render
cache nor not parsing the page.

Change-Id: I9a325cda8b3141153544ac53e78a51a44e6b411a
Reviewed-on: https://pdfium-review.googlesource.com/32830
Commit-Queue: Tom Sepez <tsepez@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>

2 files changed, 7 insertions, 4 deletions

diff --git a/core/fpdfapi/page/cpdf_page.cpp b/core/fpdfapi/page/cpdf_page.cpp
index 7c0a3234c9..c5c85635b2 100644
--- a/core/fpdfapi/page/cpdf_page.cpp
+++ b/core/fpdfapi/page/cpdf_page.cpp
@@ -21,11 +21,11 @@
 
 CPDF_Page::CPDF_Page(CPDF_Document* pDocument,
                      CPDF_Dictionary* pPageDict,
-                     bool bPageCache)
+                     bool bUseRenderCache)
     : CPDF_PageObjectHolder(pDocument, pPageDict),
       m_PageSize(100, 100),
       m_pPDFDocument(pDocument) {
-  if (bPageCache)
+  if (bUseRenderCache)
     m_pPageRender = pdfium::MakeUnique<CPDF_PageRenderCache>(this);
   if (!pPageDict)
     return;
diff --git a/core/fpdfapi/page/cpdf_page.h b/core/fpdfapi/page/cpdf_page.h
index 0bb99b73f1..b94326e47b 100644
--- a/core/fpdfapi/page/cpdf_page.h
+++ b/core/fpdfapi/page/cpdf_page.h
@@ -12,6 +12,7 @@
 #include "core/fpdfapi/page/cpdf_pageobjectholder.h"
 #include "core/fxcrt/fx_coordinates.h"
 #include "core/fxcrt/fx_system.h"
+#include "core/fxcrt/observable.h"
 #include "core/fxcrt/retain_ptr.h"
 #include "core/fxcrt/unowned_ptr.h"
 #include "third_party/base/optional.h"
@@ -22,7 +23,9 @@ class CPDF_Object;
 class CPDF_PageRenderCache;
 class CPDF_PageRenderContext;
 
-class CPDF_Page : public Retainable, public CPDF_PageObjectHolder {
+class CPDF_Page : public Retainable,
+                  public Observable<CPDF_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.
@@ -66,7 +69,7 @@ class CPDF_Page : public Retainable, public CPDF_PageObjectHolder {
  private:
   CPDF_Page(CPDF_Document* pDocument,
             CPDF_Dictionary* pPageDict,
-            bool bPageCache);
+            bool bUseRenderCache);
   ~CPDF_Page() override;
 
   void StartParse();