diff --git a/core/include/fpdfdoc/fpdf_doc.h b/core/include/fpdfdoc/fpdf_doc.h
index 168d9eb..cc5cf08 100644
--- a/core/include/fpdfdoc/fpdf_doc.h
+++ b/core/include/fpdfdoc/fpdf_doc.h
@@ -394,7 +394,8 @@
 
   void GetRect(CFX_FloatRect& rect) const;
 
-  CPDF_Dictionary* GetAnnotDict();
+  const CPDF_Dictionary* GetAnnotDict() const { return m_pAnnotDict; }
+  CPDF_Dictionary* GetAnnotDict() { return m_pAnnotDict; }
 
   FX_BOOL DrawAppearance(const CPDF_Page* pPage,
                          CFX_RenderDevice* pDevice,
@@ -427,45 +428,18 @@
 
 class CPDF_AnnotList {
  public:
-  CPDF_AnnotList(CPDF_Page* pPage);
-
+  explicit CPDF_AnnotList(CPDF_Page* pPage);
   ~CPDF_AnnotList();
 
-  void GetAnnotMatrix(const CPDF_Dictionary* pAnnotDict,
-                      const CFX_Matrix* pUser2Device,
-                      CFX_Matrix& matrix) const;
-
-  void GetAnnotRect(const CPDF_Dictionary* pAnnotDict,
-                    const CFX_Matrix* pUser2Device,
-                    CPDF_Rect& rtAnnot) const;
-
-  void DisplayAnnots(const CPDF_Page* pPage,
-                     CFX_RenderDevice* pDevice,
-                     CFX_AffineMatrix* pMatrix,
-                     FX_BOOL bShowWidget,
-                     CPDF_RenderOptions* pOptions);
-
   void DisplayAnnots(const CPDF_Page* pPage,
                      CPDF_RenderContext* pContext,
                      FX_BOOL bPrinting,
                      CFX_AffineMatrix* pMatrix,
                      FX_BOOL bShowWidget,
                      CPDF_RenderOptions* pOptions) {
-    DisplayAnnots(pPage, NULL, pContext, bPrinting, pMatrix,
-                  bShowWidget ? 3 : 1, pOptions, NULL);
+    DisplayAnnots(pPage, nullptr, pContext, bPrinting, pMatrix,
+                  bShowWidget ? 3 : 1, pOptions, nullptr);
   }
-
-  void DisplayAnnots(const CPDF_Page* pPage,
-                     CPDF_RenderContext* pContext,
-                     FX_BOOL bPrinting,
-                     CFX_AffineMatrix* pMatrix,
-                     FX_BOOL bShowWidget,
-                     CPDF_RenderOptions* pOptions,
-                     FX_RECT* pClipRect) {
-    DisplayAnnots(pPage, NULL, pContext, bPrinting, pMatrix,
-                  bShowWidget ? 3 : 1, pOptions, pClipRect);
-  }
-
   void DisplayAnnots(const CPDF_Page* pPage,
                      CFX_RenderDevice* pDevice,
                      CPDF_RenderContext* pContext,
@@ -474,24 +448,12 @@
                      FX_DWORD dwAnnotFlags,
                      CPDF_RenderOptions* pOptions,
                      FX_RECT* pClipRect);
-
-  CPDF_Annot* GetAt(int index) { return (CPDF_Annot*)m_AnnotList.GetAt(index); }
-
-  int Count() { return m_AnnotList.GetSize(); }
-
-  int GetIndex(CPDF_Annot* pAnnot);
-
+  size_t Count() const { return m_AnnotList.size(); }
+  CPDF_Annot* GetAt(size_t index) const { return m_AnnotList[index]; }
+  const std::vector<CPDF_Annot*>& All() const { return m_AnnotList; }
   CPDF_Document* GetDocument() const { return m_pDocument; }
 
  protected:
-  CFX_PtrArray m_AnnotList;
-
-  CPDF_Dictionary* m_pPageDict;
-
-  CPDF_Document* m_pDocument;
-
-  CFX_PtrArray m_Borders;
-
   void DisplayPass(const CPDF_Page* pPage,
                    CFX_RenderDevice* pDevice,
                    CPDF_RenderContext* pContext,
@@ -500,8 +462,11 @@
                    FX_BOOL bWidget,
                    CPDF_RenderOptions* pOptions,
                    FX_RECT* clip_rect);
-  friend class CPDF_Annot;
+
+  CPDF_Document* const m_pDocument;
+  std::vector<CPDF_Annot*> m_AnnotList;
 };
+
 #define COLORTYPE_TRANSPARENT 0
 #define COLORTYPE_GRAY 1
 #define COLORTYPE_RGB 2
@@ -623,7 +588,7 @@
                                       FX_FLOAT pdf_y,
                                       int* z_order) const;
 
-  CPDF_FormControl* GetControlByDict(CPDF_Dictionary* pWidgetDict) const;
+  CPDF_FormControl* GetControlByDict(const CPDF_Dictionary* pWidgetDict) const;
 
   CPDF_Document* GetDocument() const { return m_pDocument; }
 
diff --git a/core/src/fpdfdoc/doc_annot.cpp b/core/src/fpdfdoc/doc_annot.cpp
index d37b1aa..ae253a0 100644
--- a/core/src/fpdfdoc/doc_annot.cpp
+++ b/core/src/fpdfdoc/doc_annot.cpp
@@ -8,25 +8,23 @@
 #include "../../include/fpdfdoc/fpdf_doc.h"
 #include "../../include/fpdfapi/fpdf_pageobj.h"
 
-CPDF_AnnotList::CPDF_AnnotList(CPDF_Page* pPage) {
-  ASSERT(pPage != NULL);
-  m_pPageDict = pPage->m_pFormDict;
-  if (m_pPageDict == NULL) {
+CPDF_AnnotList::CPDF_AnnotList(CPDF_Page* pPage)
+    : m_pDocument(pPage->m_pDocument) {
+  if (!pPage->m_pFormDict)
     return;
-  }
-  m_pDocument = pPage->m_pDocument;
-  CPDF_Array* pAnnots = m_pPageDict->GetArray("Annots");
-  if (pAnnots == NULL) {
+
+  CPDF_Array* pAnnots = pPage->m_pFormDict->GetArray("Annots");
+  if (!pAnnots)
     return;
-  }
+
   CPDF_Dictionary* pRoot = m_pDocument->GetRoot();
   CPDF_Dictionary* pAcroForm = pRoot->GetDict("AcroForm");
   FX_BOOL bRegenerateAP = pAcroForm && pAcroForm->GetBoolean("NeedAppearances");
   for (FX_DWORD i = 0; i < pAnnots->GetCount(); ++i) {
     CPDF_Dictionary* pDict = ToDictionary(pAnnots->GetElementValue(i));
-    if (!pDict) {
+    if (!pDict)
       continue;
-    }
+
     FX_DWORD dwObjNum = pDict->GetObjNum();
     if (dwObjNum == 0) {
       dwObjNum = m_pDocument->AddIndirectObject(pDict);
@@ -35,24 +33,20 @@
       pAnnots->RemoveAt(i + 1);
       pDict = pAnnots->GetDict(i);
     }
-    CPDF_Annot* pAnnot = new CPDF_Annot(pDict, this);
-    m_AnnotList.Add(pAnnot);
+    m_AnnotList.push_back(new CPDF_Annot(pDict, this));
     if (bRegenerateAP &&
-        pDict->GetConstString(FX_BSTRC("Subtype")) == FX_BSTRC("Widget"))
-      if (CPDF_InterForm::UpdatingAPEnabled()) {
-        FPDF_GenerateAP(m_pDocument, pDict);
-      }
+        pDict->GetConstString(FX_BSTRC("Subtype")) == FX_BSTRC("Widget") &&
+        CPDF_InterForm::UpdatingAPEnabled()) {
+      FPDF_GenerateAP(m_pDocument, pDict);
+    }
   }
 }
+
 CPDF_AnnotList::~CPDF_AnnotList() {
-  int i = 0;
-  for (i = 0; i < m_AnnotList.GetSize(); ++i) {
-    delete (CPDF_Annot*)m_AnnotList[i];
-  }
-  for (i = 0; i < m_Borders.GetSize(); ++i) {
-    delete (CPDF_PageObjects*)m_Borders[i];
-  }
+  for (CPDF_Annot* annot : m_AnnotList)
+    delete annot;
 }
+
 void CPDF_AnnotList::DisplayPass(const CPDF_Page* pPage,
                                  CFX_RenderDevice* pDevice,
                                  CPDF_RenderContext* pContext,
@@ -61,34 +55,32 @@
                                  FX_BOOL bWidgetPass,
                                  CPDF_RenderOptions* pOptions,
                                  FX_RECT* clip_rect) {
-  for (int i = 0; i < m_AnnotList.GetSize(); ++i) {
-    CPDF_Annot* pAnnot = (CPDF_Annot*)m_AnnotList[i];
+  for (CPDF_Annot* pAnnot : m_AnnotList) {
     FX_BOOL bWidget = pAnnot->GetSubType() == "Widget";
-    if ((bWidgetPass && !bWidget) || (!bWidgetPass && bWidget)) {
+    if ((bWidgetPass && !bWidget) || (!bWidgetPass && bWidget))
       continue;
-    }
+
     FX_DWORD annot_flags = pAnnot->GetFlags();
-    if (annot_flags & ANNOTFLAG_HIDDEN) {
+    if (annot_flags & ANNOTFLAG_HIDDEN)
       continue;
-    }
-    if (bPrinting && (annot_flags & ANNOTFLAG_PRINT) == 0) {
+
+    if (bPrinting && (annot_flags & ANNOTFLAG_PRINT) == 0)
       continue;
-    }
-    if (!bPrinting && (annot_flags & ANNOTFLAG_NOVIEW)) {
+
+    if (!bPrinting && (annot_flags & ANNOTFLAG_NOVIEW))
       continue;
-    }
-    if (pOptions != NULL) {
+
+    if (pOptions) {
       IPDF_OCContext* pOCContext = pOptions->m_pOCContext;
       CPDF_Dictionary* pAnnotDict = pAnnot->GetAnnotDict();
-      if (pOCContext != NULL && pAnnotDict != NULL &&
+      if (pOCContext && pAnnotDict &&
           !pOCContext->CheckOCGVisible(pAnnotDict->GetDict(FX_BSTRC("OC")))) {
         continue;
       }
     }
     CPDF_Rect annot_rect_f;
     pAnnot->GetRect(annot_rect_f);
-    CFX_Matrix matrix;
-    matrix = *pMatrix;
+    CFX_Matrix matrix = *pMatrix;
     if (clip_rect) {
       annot_rect_f.Transform(&matrix);
       FX_RECT annot_rect = annot_rect_f.GetOutterRect();
@@ -105,20 +97,7 @@
     }
   }
 }
-void CPDF_AnnotList::DisplayAnnots(const CPDF_Page* pPage,
-                                   CFX_RenderDevice* pDevice,
-                                   CFX_AffineMatrix* pUser2Device,
-                                   FX_BOOL bShowWidget,
-                                   CPDF_RenderOptions* pOptions) {
-  FX_RECT clip_rect;
-  if (pDevice) {
-    clip_rect = pDevice->GetClipBox();
-  }
-  FX_BOOL bPrinting = pDevice->GetDeviceClass() == FXDC_PRINTER ||
-                      (pOptions && (pOptions->m_Flags & RENDER_PRINTPREVIEW));
-  DisplayAnnots(pPage, pDevice, NULL, bPrinting, pUser2Device,
-                bShowWidget ? 3 : 1, pOptions, &clip_rect);
-}
+
 void CPDF_AnnotList::DisplayAnnots(const CPDF_Page* pPage,
                                    CFX_RenderDevice* pDevice,
                                    CPDF_RenderContext* pContext,
@@ -136,13 +115,7 @@
                 pOptions, pClipRect);
   }
 }
-int CPDF_AnnotList::GetIndex(CPDF_Annot* pAnnot) {
-  for (int i = 0; i < m_AnnotList.GetSize(); ++i)
-    if (m_AnnotList[i] == (void*)pAnnot) {
-      return i;
-    }
-  return -1;
-}
+
 CPDF_Annot::CPDF_Annot(CPDF_Dictionary* pDict, CPDF_AnnotList* pList)
     : m_pAnnotDict(pDict),
       m_pList(pList),
@@ -176,10 +149,6 @@
   return m_pAnnotDict->GetInteger("F");
 }
 
-CPDF_Dictionary* CPDF_Annot::GetAnnotDict() {
-  return m_pAnnotDict;
-}
-
 CPDF_Stream* FPDFDOC_GetAnnotAP(CPDF_Dictionary* pAnnotDict,
                                 CPDF_Annot::AppearanceMode mode) {
   CPDF_Dictionary* pAP = pAnnotDict->GetDict("AP");
@@ -217,20 +186,23 @@
   }
   return nullptr;
 }
+
 CPDF_Form* CPDF_Annot::GetAPForm(const CPDF_Page* pPage, AppearanceMode mode) {
   CPDF_Stream* pStream = FPDFDOC_GetAnnotAP(m_pAnnotDict, mode);
-  if (pStream == NULL) {
-    return NULL;
-  }
-  CPDF_Form* pForm;
-  if (m_APMap.Lookup(pStream, (void*&)pForm)) {
-    return pForm;
-  }
-  pForm = new CPDF_Form(m_pList->m_pDocument, pPage->m_pResources, pStream);
-  pForm->ParseContent(NULL, NULL, NULL, NULL);
-  m_APMap.SetAt(pStream, pForm);
-  return pForm;
+  if (!pStream)
+    return nullptr;
+
+  void* pForm;
+  if (m_APMap.Lookup(pStream, pForm))
+    return static_cast<CPDF_Form*>(pForm);
+
+  CPDF_Form* pNewForm =
+      new CPDF_Form(m_pList->GetDocument(), pPage->m_pResources, pStream);
+  pNewForm->ParseContent(nullptr, nullptr, nullptr, nullptr);
+  m_APMap.SetAt(pStream, pNewForm);
+  return pNewForm;
 }
+
 static CPDF_Form* FPDFDOC_Annot_GetMatrix(const CPDF_Page* pPage,
                                           CPDF_Annot* pAnnot,
                                           CPDF_Annot::AppearanceMode mode,
diff --git a/core/src/fpdfdoc/doc_form.cpp b/core/src/fpdfdoc/doc_form.cpp
index c155b94..5cc2a66 100644
--- a/core/src/fpdfdoc/doc_form.cpp
+++ b/core/src/fpdfdoc/doc_form.cpp
@@ -818,7 +818,7 @@
 }
 
 CPDF_FormControl* CPDF_InterForm::GetControlByDict(
-    CPDF_Dictionary* pWidgetDict) const {
+    const CPDF_Dictionary* pWidgetDict) const {
   const auto it = m_ControlMap.find(pWidgetDict);
   return it != m_ControlMap.end() ? it->second : nullptr;
 }
diff --git a/fpdfsdk/include/fsdk_baseform.h b/fpdfsdk/include/fsdk_baseform.h
index 14c8fef..bcba4c8 100644
--- a/fpdfsdk/include/fsdk_baseform.h
+++ b/fpdfsdk/include/fsdk_baseform.h
@@ -155,7 +155,7 @@
   CPDF_FormField* GetFormField() const;
   CPDF_FormControl* GetFormControl() const;
   static CPDF_FormControl* GetFormControl(CPDF_InterForm* pInterForm,
-                                          CPDF_Dictionary* pAnnotDict);
+                                          const CPDF_Dictionary* pAnnotDict);
 
   void DrawShadow(CFX_RenderDevice* pDevice, CPDFSDK_PageView* pPageView);
 
diff --git a/fpdfsdk/include/fsdk_define.h b/fpdfsdk/include/fsdk_define.h
index 2faaf01..f62234a 100644
--- a/fpdfsdk/include/fsdk_define.h
+++ b/fpdfsdk/include/fsdk_define.h
@@ -108,7 +108,7 @@
                             IFSDK_PAUSE_Adapter* pause);
 
 void CheckUnSupportError(CPDF_Document* pDoc, FX_DWORD err_code);
-void CheckUnSupportAnnot(CPDF_Document* pDoc, CPDF_Annot* pPDFAnnot);
+void CheckUnSupportAnnot(CPDF_Document* pDoc, const CPDF_Annot* pPDFAnnot);
 void ProcessParseError(FX_DWORD err_code);
 
 #endif  // FPDFSDK_INCLUDE_FSDK_DEFINE_H_
diff --git a/fpdfsdk/include/fsdk_mgr.h b/fpdfsdk/include/fsdk_mgr.h
index bfbbd63..615b585 100644
--- a/fpdfsdk/include/fsdk_mgr.h
+++ b/fpdfsdk/include/fsdk_mgr.h
@@ -538,9 +538,9 @@
                        CPDF_Matrix* pUser2Device,
                        CPDF_RenderOptions* pOptions,
                        FX_RECT* pClip = NULL);
-  CPDF_Annot* GetPDFAnnotAtPoint(FX_FLOAT pageX, FX_FLOAT pageY);
+  const CPDF_Annot* GetPDFAnnotAtPoint(FX_FLOAT pageX, FX_FLOAT pageY);
   CPDFSDK_Annot* GetFXAnnotAtPoint(FX_FLOAT pageX, FX_FLOAT pageY);
-  CPDF_Annot* GetPDFWidgetAtPoint(FX_FLOAT pageX, FX_FLOAT pageY);
+  const CPDF_Annot* GetPDFWidgetAtPoint(FX_FLOAT pageX, FX_FLOAT pageY);
   CPDFSDK_Annot* GetFXWidgetAtPoint(FX_FLOAT pageX, FX_FLOAT pageY);
   CPDFSDK_Annot* GetFocusAnnot();
   void SetFocusAnnot(CPDFSDK_Annot* pSDKAnnot, FX_UINT nFlag = 0) {
@@ -578,7 +578,7 @@
                        double deltaY,
                        const CPDF_Point& point,
                        int nFlag);
-  FX_BOOL IsValidAnnot(CPDF_Annot* p) const;
+  bool IsValidAnnot(const CPDF_Annot* p) const;
   void GetCurrentMatrix(CPDF_Matrix& matrix) { matrix = m_curMatrix; }
   void UpdateRects(CFX_RectArray& rects);
   void UpdateView(CPDFSDK_Annot* pAnnot);
diff --git a/fpdfsdk/src/fpdf_ext.cpp b/fpdfsdk/src/fpdf_ext.cpp
index 196ac99..aead361 100644
--- a/fpdfsdk/src/fpdf_ext.cpp
+++ b/fpdfsdk/src/fpdf_ext.cpp
@@ -58,12 +58,12 @@
   return TRUE;
 }
 
-void CheckUnSupportAnnot(CPDF_Document* pDoc, CPDF_Annot* pPDFAnnot) {
+void CheckUnSupportAnnot(CPDF_Document* pDoc, const CPDF_Annot* pPDFAnnot) {
   CFX_ByteString cbSubType = pPDFAnnot->GetSubType();
   if (cbSubType.Compare("3D") == 0) {
     FPDF_UnSupportError(FPDF_UNSP_ANNOT_3DANNOT);
   } else if (cbSubType.Compare("Screen") == 0) {
-    CPDF_Dictionary* pAnnotDict = pPDFAnnot->GetAnnotDict();
+    const CPDF_Dictionary* pAnnotDict = pPDFAnnot->GetAnnotDict();
     CFX_ByteString cbString;
     if (pAnnotDict->KeyExist("IT"))
       cbString = pAnnotDict->GetString("IT");
@@ -78,7 +78,7 @@
   } else if (cbSubType.Compare("FileAttachment") == 0) {
     FPDF_UnSupportError(FPDF_UNSP_ANNOT_ATTACHMENT);
   } else if (cbSubType.Compare("Widget") == 0) {
-    CPDF_Dictionary* pAnnotDict = pPDFAnnot->GetAnnotDict();
+    const CPDF_Dictionary* pAnnotDict = pPDFAnnot->GetAnnotDict();
     CFX_ByteString cbString;
     if (pAnnotDict->KeyExist("FT")) {
       cbString = pAnnotDict->GetString("FT");
diff --git a/fpdfsdk/src/fpdfeditpage.cpp b/fpdfsdk/src/fpdfeditpage.cpp
index 8b4168f..531d372 100644
--- a/fpdfsdk/src/fpdfeditpage.cpp
+++ b/fpdfsdk/src/fpdfeditpage.cpp
@@ -280,7 +280,7 @@
   if (!pPage)
     return;
   CPDF_AnnotList AnnotList(pPage);
-  for (int i = 0; i < AnnotList.Count(); i++) {
+  for (size_t i = 0; i < AnnotList.Count(); ++i) {
     CPDF_Annot* pAnnot = AnnotList.GetAt(i);
     // transformAnnots Rectangle
     CPDF_Rect rect;
diff --git a/fpdfsdk/src/fsdk_baseform.cpp b/fpdfsdk/src/fsdk_baseform.cpp
index 54b607a..e486310 100644
--- a/fpdfsdk/src/fsdk_baseform.cpp
+++ b/fpdfsdk/src/fsdk_baseform.cpp
@@ -566,37 +566,23 @@
 }
 
 CPDF_FormField* CPDFSDK_Widget::GetFormField() const {
-  ASSERT(m_pInterForm != NULL);
-
-  CPDF_FormControl* pCtrl = GetFormControl();
-  ASSERT(pCtrl != NULL);
-
-  return pCtrl->GetField();
+  return GetFormControl()->GetField();
 }
 
 CPDF_FormControl* CPDFSDK_Widget::GetFormControl() const {
-  ASSERT(m_pInterForm != NULL);
-
   CPDF_InterForm* pPDFInterForm = m_pInterForm->GetInterForm();
-  ASSERT(pPDFInterForm != NULL);
-
   return pPDFInterForm->GetControlByDict(GetAnnotDict());
 }
 
-CPDF_FormControl* CPDFSDK_Widget::GetFormControl(CPDF_InterForm* pInterForm,
-                                                 CPDF_Dictionary* pAnnotDict) {
-  ASSERT(pInterForm != NULL);
+CPDF_FormControl* CPDFSDK_Widget::GetFormControl(
+    CPDF_InterForm* pInterForm,
+    const CPDF_Dictionary* pAnnotDict) {
   ASSERT(pAnnotDict != NULL);
-
-  CPDF_FormControl* pControl = pInterForm->GetControlByDict(pAnnotDict);
-
-  return pControl;
+  return pInterForm->GetControlByDict(pAnnotDict);
 }
 
 int CPDFSDK_Widget::GetRotate() const {
   CPDF_FormControl* pCtrl = GetFormControl();
-  ASSERT(pCtrl != NULL);
-
   return pCtrl->GetRotation() % 360;
 }
 
diff --git a/fpdfsdk/src/fsdk_mgr.cpp b/fpdfsdk/src/fsdk_mgr.cpp
index 9bb603d..f12e8fb 100644
--- a/fpdfsdk/src/fsdk_mgr.cpp
+++ b/fpdfsdk/src/fsdk_mgr.cpp
@@ -696,11 +696,9 @@
   }
 }
 
-CPDF_Annot* CPDFSDK_PageView::GetPDFAnnotAtPoint(FX_FLOAT pageX,
-                                                 FX_FLOAT pageY) {
-  const int nCount = m_pAnnotList->Count();
-  for (int i = 0; i < nCount; ++i) {
-    CPDF_Annot* pAnnot = m_pAnnotList->GetAt(i);
+const CPDF_Annot* CPDFSDK_PageView::GetPDFAnnotAtPoint(FX_FLOAT pageX,
+                                                       FX_FLOAT pageY) {
+  for (const CPDF_Annot* pAnnot : m_pAnnotList->All()) {
     CFX_FloatRect annotRect;
     pAnnot->GetRect(annotRect);
     if (annotRect.Contains(pageX, pageY))
@@ -709,11 +707,9 @@
   return nullptr;
 }
 
-CPDF_Annot* CPDFSDK_PageView::GetPDFWidgetAtPoint(FX_FLOAT pageX,
-                                                  FX_FLOAT pageY) {
-  const int nCount = m_pAnnotList->Count();
-  for (int i = 0; i < nCount; ++i) {
-    CPDF_Annot* pAnnot = m_pAnnotList->GetAt(i);
+const CPDF_Annot* CPDFSDK_PageView::GetPDFWidgetAtPoint(FX_FLOAT pageX,
+                                                        FX_FLOAT pageY) {
+  for (const CPDF_Annot* pAnnot : m_pAnnotList->All()) {
     if (pAnnot->GetSubType() == "Widget") {
       CFX_FloatRect annotRect;
       pAnnot->GetRect(annotRect);
@@ -1051,8 +1047,8 @@
     m_pAnnotList.reset(new CPDF_AnnotList(pPage));
     CPDF_InterForm::EnableUpdateAP(enableAPUpdate);
 
-    const int nCount = m_pAnnotList->Count();
-    for (int i = 0; i < nCount; i++) {
+    const size_t nCount = m_pAnnotList->Count();
+    for (size_t i = 0; i < nCount; ++i) {
       CPDF_Annot* pPDFAnnot = m_pAnnotList->GetAt(i);
       CheckUnSupportAnnot(GetPDFDocument(), pPDFAnnot);
 
@@ -1094,16 +1090,12 @@
   return -1;
 }
 
-FX_BOOL CPDFSDK_PageView::IsValidAnnot(CPDF_Annot* p) const {
+bool CPDFSDK_PageView::IsValidAnnot(const CPDF_Annot* p) const {
   if (!p)
-    return FALSE;
+    return false;
 
-  const int nCount = m_pAnnotList->Count();
-  for (int i = 0; i < nCount; ++i) {
-    if (m_pAnnotList->GetAt(i) == p)
-      return TRUE;
-  }
-  return FALSE;
+  const auto& annots = m_pAnnotList->All();
+  return std::find(annots.begin(), annots.end(), p) != annots.end();
 }
 
 CPDFSDK_Annot* CPDFSDK_PageView::GetFocusAnnot() {