Split CPDF_PageObjectHolder off from CPDF_PageObjectList

Eventually, we're going to expose an iterator over
CPDF_PageObjectList that we don't want to be inherited by
the CPDF_PageObjectHolder sub-classes: page and form.

Also, the operations that the object holder performs dealing
with inquiring about masks and such seem beyond the scope of
what a list would provide.  Hence the "Holder" name.

R=thestig@chromium.org

Review URL: https://codereview.chromium.org/1701073002 .

3 files changed, 27 insertions, 30 deletions

diff --git a/core/include/fpdfapi/fpdf_module.h b/core/include/fpdfapi/fpdf_module.h
index 6888e81000..4856184932 100644
--- a/core/include/fpdfapi/fpdf_module.h
+++ b/core/include/fpdfapi/fpdf_module.h
@@ -24,7 +24,6 @@ class CPDF_Document;
 class CPDF_FontGlobals;
 class CPDF_Image;
 class CPDF_Page;
-class CPDF_PageObjectList;
 class CPDF_PageRenderCache;
 class CPDF_RenderOptions;
 class CPDF_Stream;
diff --git a/core/include/fpdfapi/fpdf_page.h b/core/include/fpdfapi/fpdf_page.h
index 20030e7dea..fb951280a2 100644
--- a/core/include/fpdfapi/fpdf_page.h
+++ b/core/include/fpdfapi/fpdf_page.h
@@ -22,50 +22,46 @@ class CPDF_StreamFilter;
 class CPDF_AllStates;
 class CPDF_ContentParser;
 class CPDF_StreamContentParser;
+
 #define PDFTRANS_GROUP 0x0100
 #define PDFTRANS_ISOLATED 0x0200
 #define PDFTRANS_KNOCKOUT 0x0400
 
-class CPDF_PageObjectList {
+class CPDF_PageObjectList : public CFX_PtrList {
  public:
-  CPDF_PageObjectList();
-  ~CPDF_PageObjectList();
-
-  void ContinueParse(IFX_Pause* pPause);
-
-  FX_BOOL IsParsed() const { return m_ParseState == CONTENT_PARSED; }
-
-  FX_POSITION GetFirstObjectPosition() const {
-    return m_ObjectList.GetHeadPosition();
-  }
-
-  FX_POSITION GetLastObjectPosition() const {
-    return m_ObjectList.GetTailPosition();
-  }
+  explicit CPDF_PageObjectList(int nBlockSize) : CFX_PtrList(nBlockSize) {}
 
   CPDF_PageObject* GetNextObject(FX_POSITION& pos) const {
-    return (CPDF_PageObject*)m_ObjectList.GetNext(pos);
+    return static_cast<CPDF_PageObject*>(GetNext(pos));
   }
 
   CPDF_PageObject* GetPrevObject(FX_POSITION& pos) const {
-    return (CPDF_PageObject*)m_ObjectList.GetPrev(pos);
+    return static_cast<CPDF_PageObject*>(GetPrev(pos));
   }
 
   CPDF_PageObject* GetObjectAt(FX_POSITION pos) const {
-    return (CPDF_PageObject*)m_ObjectList.GetAt(pos);
+    return static_cast<CPDF_PageObject*>(GetAt(pos));
   }
 
-  void AddTail(CPDF_PageObject* obj) { m_ObjectList.AddTail(obj); }
-  FX_DWORD CountObjects() const { return m_ObjectList.GetCount(); }
-
-  int GetObjectIndex(CPDF_PageObject* pObj) const;
-
+  // Linear complexity, to be avoided except as needed by public APIs.
   CPDF_PageObject* GetObjectByIndex(int index) const;
 
   FX_POSITION InsertObject(FX_POSITION posInsertAfter,
                            CPDF_PageObject* pNewObject);
+};
 
-  void Transform(const CFX_Matrix& matrix);
+class CPDF_PageObjectHolder {
+ public:
+  CPDF_PageObjectHolder();
+  ~CPDF_PageObjectHolder();
+
+  void ContinueParse(IFX_Pause* pPause);
+  FX_BOOL IsParsed() const { return m_ParseState == CONTENT_PARSED; }
+
+  CPDF_PageObjectList* GetPageObjectList() { return &m_PageObjectList; }
+  const CPDF_PageObjectList* GetPageObjectList() const {
+    return &m_PageObjectList;
+  }
 
   FX_BOOL BackgroundAlphaNeeded() const { return m_bBackgroundAlphaNeeded; }
   void SetBackgroundAlphaNeeded(FX_BOOL needed) {
@@ -74,6 +70,8 @@ class CPDF_PageObjectList {
 
   FX_BOOL HasImageMask() const { return m_bHasImageMask; }
   void SetHasImageMask(FX_BOOL value) { m_bHasImageMask = value; }
+
+  void Transform(const CFX_Matrix& matrix);
   CFX_FloatRect CalcBoundingBox() const;
 
   CPDF_Dictionary* m_pFormDict;
@@ -93,10 +91,10 @@ class CPDF_PageObjectList {
   FX_BOOL m_bHasImageMask;
   ParseState m_ParseState;
   std::unique_ptr<CPDF_ContentParser> m_pParser;
-  CFX_PtrList m_ObjectList;
+  CPDF_PageObjectList m_PageObjectList;
 };
 
-class CPDF_Page : public CPDF_PageObjectList, public CFX_PrivateData {
+class CPDF_Page : public CPDF_PageObjectHolder, public CFX_PrivateData {
  public:
   CPDF_Page();
   ~CPDF_Page();
@@ -142,7 +140,7 @@ class CPDF_ParseOptions {
 
   FX_BOOL m_bDecodeInlineImage;
 };
-class CPDF_Form : public CPDF_PageObjectList {
+class CPDF_Form : public CPDF_PageObjectHolder {
  public:
   CPDF_Form(CPDF_Document* pDocument,
             CPDF_Dictionary* pPageResources,
diff --git a/core/include/fpdfapi/fpdf_render.h b/core/include/fpdfapi/fpdf_render.h
index ec5d151914..fc0f68afe8 100644
--- a/core/include/fpdfapi/fpdf_render.h
+++ b/core/include/fpdfapi/fpdf_render.h
@@ -74,7 +74,7 @@ class CPDF_RenderContext {
  public:
   class Layer {
    public:
-    CPDF_PageObjectList* m_pObjectList;
+    CPDF_PageObjectHolder* m_pObjectHolder;
     CFX_Matrix m_Matrix;
   };
 
@@ -82,7 +82,7 @@ class CPDF_RenderContext {
   CPDF_RenderContext(CPDF_Document* pDoc, CPDF_PageRenderCache* pPageCache);
   ~CPDF_RenderContext();
 
-  void AppendLayer(CPDF_PageObjectList* pObjectList,
+  void AppendLayer(CPDF_PageObjectHolder* pObjectHolder,
                    const CFX_Matrix* pObject2Device);
 
   void Render(CFX_RenderDevice* pDevice,