Remove IWFL_WidgetMgr in favor of CFWL_WidgetMgr.

The pure virtual class isn't buying us anything, and is costing
us an otherwise unneeded vtable.

Fix pre-existing presubmit warning in fwl_noteimp.cpp:88:
  If statement had no body and no else clause ...

Remove switch on enum() and make separate GetWidget() methods.

Review-Url: https://codereview.chromium.org/2004213002

15 files changed, 184 insertions, 265 deletions

diff --git a/BUILD.gn b/BUILD.gn
index 2fdaa885ba..e4ab94158f 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -1052,7 +1052,6 @@ if (pdf_enable_xfa) {
       "xfa/fwl/core/ifwl_tooltiptarget.h",
       "xfa/fwl/core/ifwl_widget.h",
       "xfa/fwl/core/ifwl_widgetdelegate.h",
-      "xfa/fwl/core/ifwl_widgetmgr.h",
       "xfa/fwl/core/include/fwl_widgethit.h",
       "xfa/fwl/core/include/ifwl_adaptertimermgr.h",
       "xfa/fwl/lightwidget/cfwl_barcode.cpp",
diff --git a/xfa.gyp b/xfa.gyp
index 7ef5791188..43b5e415a3 100644
--- a/xfa.gyp
+++ b/xfa.gyp
@@ -195,7 +195,6 @@
         "xfa/fwl/core/ifwl_tooltiptarget.h",
         "xfa/fwl/core/ifwl_widget.h",
         "xfa/fwl/core/ifwl_widgetdelegate.h",
-        "xfa/fwl/core/ifwl_widgetmgr.h",
         "xfa/fwl/core/include/fwl_widgethit.h",
         "xfa/fwl/core/include/ifwl_adaptertimermgr.h",
         "xfa/fwl/lightwidget/cfwl_barcode.cpp",
diff --git a/xfa/fwl/basewidget/fwl_checkboximp.cpp b/xfa/fwl/basewidget/fwl_checkboximp.cpp
index 574da160ee..ade6ebf155 100644
--- a/xfa/fwl/basewidget/fwl_checkboximp.cpp
+++ b/xfa/fwl/basewidget/fwl_checkboximp.cpp
@@ -368,8 +368,7 @@ void CFWL_CheckBoxImp::NextStates() {
   if (m_pProperties->m_dwStyleExes & FWL_STYLEEXT_CKB_RadioButton) {
     if ((m_pProperties->m_dwStates & FWL_STATE_CKB_CheckMask) ==
         FWL_STATE_CKB_Unchecked) {
-      CFWL_WidgetMgr* pWidgetMgr =
-          static_cast<CFWL_WidgetMgr*>(FWL_GetWidgetMgr());
+      CFWL_WidgetMgr* pWidgetMgr = CFWL_WidgetMgr::GetInstance();
       if (!pWidgetMgr->IsFormDisabled()) {
         CFX_ArrayTemplate<IFWL_Widget*> radioarr;
         pWidgetMgr->GetSameGroupRadioButton(m_pInterface, radioarr);
diff --git a/xfa/fwl/basewidget/fwl_editimp.cpp b/xfa/fwl/basewidget/fwl_editimp.cpp
index 423d0b5c28..5975062902 100644
--- a/xfa/fwl/basewidget/fwl_editimp.cpp
+++ b/xfa/fwl/basewidget/fwl_editimp.cpp
@@ -1013,8 +1013,7 @@ void CFWL_EditImp::DrawContent(CFX_Graphics* pGraphics,
       (m_pProperties->m_dwStyleExes & FWL_STYLEEXT_EDT_NoHideSel) ||
       (m_pProperties->m_dwStates & FWL_WGTSTATE_Focused);
   if (bShowSel) {
-    IFWL_Widget* pForm =
-        m_pWidgetMgr->GetWidget(m_pInterface, FWL_WGTRELATION_SystemForm);
+    IFWL_Widget* pForm = m_pWidgetMgr->GetSystemFormWidget(m_pInterface);
     if (pForm) {
       bShowSel = (pForm->GetStates() & FWL_WGTSTATE_Deactivated) !=
                  FWL_WGTSTATE_Deactivated;
diff --git a/xfa/fwl/core/fwl_appimp.cpp b/xfa/fwl/core/fwl_appimp.cpp
index d7fa8bc1c0..1b90d369b5 100644
--- a/xfa/fwl/core/fwl_appimp.cpp
+++ b/xfa/fwl/core/fwl_appimp.cpp
@@ -32,7 +32,7 @@ CXFA_FFApp* IFWL_App::GetAdapterNative() {
   return static_cast<CFWL_AppImp*>(GetImpl())->GetAdapterNative();
 }
 
-IFWL_WidgetMgr* IFWL_App::GetWidgetMgr() {
+CFWL_WidgetMgr* IFWL_App::GetWidgetMgr() {
   return static_cast<CFWL_AppImp*>(GetImpl())->GetWidgetMgr();
 }
 
@@ -76,10 +76,9 @@ CXFA_FFApp* CFWL_AppImp::GetAdapterNative() const {
   return m_pAdapterNative;
 }
 CXFA_FWLAdapterWidgetMgr* FWL_GetAdapterWidgetMgr() {
-  return static_cast<CFWL_WidgetMgr*>(FWL_GetWidgetMgr())
-      ->GetAdapterWidgetMgr();
+  return CFWL_WidgetMgr::GetInstance()->GetAdapterWidgetMgr();
 }
-IFWL_WidgetMgr* CFWL_AppImp::GetWidgetMgr() const {
+CFWL_WidgetMgr* CFWL_AppImp::GetWidgetMgr() const {
   return m_pWidgetMgr.get();
 }
 
diff --git a/xfa/fwl/core/fwl_appimp.h b/xfa/fwl/core/fwl_appimp.h
index b138ccb5be..f3377048fc 100644
--- a/xfa/fwl/core/fwl_appimp.h
+++ b/xfa/fwl/core/fwl_appimp.h
@@ -16,7 +16,6 @@ class CXFA_FFApp;
 class IFWL_App;
 class IFWL_NoteThread;
 class IFWL_ThemeProvider;
-class IFWL_WidgetMgr;
 
 class CFWL_AppImp {
  public:
@@ -29,7 +28,7 @@ class CFWL_AppImp {
   FWL_Error Initialize();
   FWL_Error Finalize();
   CXFA_FFApp* GetAdapterNative() const;
-  IFWL_WidgetMgr* GetWidgetMgr() const;
+  CFWL_WidgetMgr* GetWidgetMgr() const;
   IFWL_ThemeProvider* GetThemeProvider() const;
   void SetThemeProvider(IFWL_ThemeProvider* pThemeProvider);
   void Exit(int32_t iExitCode);
diff --git a/xfa/fwl/core/fwl_formimp.cpp b/xfa/fwl/core/fwl_formimp.cpp
index bcaba2c153..9cfd70e4c7 100644
--- a/xfa/fwl/core/fwl_formimp.cpp
+++ b/xfa/fwl/core/fwl_formimp.cpp
@@ -151,7 +151,7 @@ FWL_Error CFWL_FormImp::GetClientRect(CFX_RectF& rect) {
   }
 #ifdef FWL_UseMacSystemBorder
   rect = m_rtRelative;
-  CFWL_WidgetMgr* pWidgetMgr = static_cast<CFWL_WidgetMgr*>(FWL_GetWidgetMgr());
+  CFWL_WidgetMgr* pWidgetMgr = CFWL_WidgetMgr::GetInstance();
   if (!pWidgetMgr)
     return FWL_Error::Indefinite;
 
@@ -447,15 +447,15 @@ void CFWL_FormImp::ShowChildWidget(IFWL_Widget* pParent) {
   IFWL_App* pApp = FWL_GetApp();
   if (!pApp)
     return;
-  CFWL_WidgetMgr* pWidgetMgr =
-      static_cast<CFWL_WidgetMgr*>(pApp->GetWidgetMgr());
+
+  CFWL_WidgetMgr* pWidgetMgr = pApp->GetWidgetMgr();
   if (!pWidgetMgr)
     return;
-  IFWL_Widget* pChild =
-      pWidgetMgr->GetWidget(pParent, FWL_WGTRELATION_FirstChild);
+
+  IFWL_Widget* pChild = pWidgetMgr->GetFirstChildWidget(pParent);
   while (pChild) {
     ShowChildWidget(pChild);
-    pChild = pWidgetMgr->GetWidget(pChild, FWL_WGTRELATION_NextSibling);
+    pChild = pWidgetMgr->GetNextSiblingWidget(pChild);
   }
 }
 
@@ -616,7 +616,7 @@ void CFWL_FormImp::GetEdgeRect(CFX_RectF& rtEdge) {
 }
 void CFWL_FormImp::SetWorkAreaRect() {
   m_rtRestore = m_pProperties->m_rtWidget;
-  CFWL_WidgetMgr* pWidgetMgr = static_cast<CFWL_WidgetMgr*>(FWL_GetWidgetMgr());
+  CFWL_WidgetMgr* pWidgetMgr = CFWL_WidgetMgr::GetInstance();
   if (!pWidgetMgr)
     return;
   m_bSetMaximize = TRUE;
@@ -765,7 +765,7 @@ FX_BOOL CFWL_FormImp::HasIcon() {
   return !!pData->GetIcon(m_pInterface, FALSE);
 }
 void CFWL_FormImp::UpdateIcon() {
-  CFWL_WidgetMgr* pWidgetMgr = static_cast<CFWL_WidgetMgr*>(FWL_GetWidgetMgr());
+  CFWL_WidgetMgr* pWidgetMgr = CFWL_WidgetMgr::GetInstance();
   if (!pWidgetMgr)
     return;
   IFWL_FormDP* pData =
@@ -778,7 +778,7 @@ void CFWL_FormImp::UpdateIcon() {
     m_pSmallIcon = pSmallIcon;
 }
 void CFWL_FormImp::UpdateCaption() {
-  CFWL_WidgetMgr* pWidgetMgr = static_cast<CFWL_WidgetMgr*>(FWL_GetWidgetMgr());
+  CFWL_WidgetMgr* pWidgetMgr = CFWL_WidgetMgr::GetInstance();
   if (!pWidgetMgr)
     return;
   IFWL_FormDP* pData =
@@ -935,8 +935,7 @@ void CFWL_FormImpDelegate::OnProcessMessage(CFWL_Message* pMessage) {
       break;
     }
     case CFWL_MessageType::Size: {
-      CFWL_WidgetMgr* pWidgetMgr =
-          static_cast<CFWL_WidgetMgr*>(FWL_GetWidgetMgr());
+      CFWL_WidgetMgr* pWidgetMgr = CFWL_WidgetMgr::GetInstance();
       if (!pWidgetMgr)
         return;
 
diff --git a/xfa/fwl/core/fwl_noteimp.cpp b/xfa/fwl/core/fwl_noteimp.cpp
index 4db2d6bb5f..7d123f7560 100644
--- a/xfa/fwl/core/fwl_noteimp.cpp
+++ b/xfa/fwl/core/fwl_noteimp.cpp
@@ -83,9 +83,9 @@ void CFWL_NoteDriver::SendEvent(CFWL_Event* pNote) {
   if (CFWL_EventType::Mouse == pNote->GetClassID()) {
     CFWL_EvtMouse* pMouse = static_cast<CFWL_EvtMouse*>(pNote);
     if (FWL_MouseCommand::Hover == pMouse->m_dwCmd) {
-      if (m_pNoteLoop->GetForm() &&
-          CFWL_ToolTipContainer::getInstance()->ProcessEnter(
-              pMouse, m_pNoteLoop->GetForm()->GetInterface())) {
+      if (m_pNoteLoop->GetForm()) {
+        CFWL_ToolTipContainer::getInstance()->ProcessEnter(
+            pMouse, m_pNoteLoop->GetForm()->GetInterface());
       }
     } else if (FWL_MouseCommand::Leave == pMouse->m_dwCmd) {
       CFWL_ToolTipContainer::getInstance()->ProcessLeave(pMouse);
@@ -173,7 +173,7 @@ FX_BOOL CFWL_NoteDriver::SetFocus(IFWL_Widget* pFocus, FX_BOOL bNotify) {
   }
   if (pFocus) {
     IFWL_Widget* pWidget =
-        FWL_GetWidgetMgr()->GetWidget(pFocus, FWL_WGTRELATION_SystemForm);
+        CFWL_WidgetMgr::GetInstance()->GetSystemFormWidget(pFocus);
     CFWL_FormImp* pForm =
         pWidget ? static_cast<CFWL_FormImp*>(pWidget->GetImpl()) : nullptr;
     if (pForm) {
@@ -194,7 +194,7 @@ FX_BOOL CFWL_NoteDriver::SetFocus(IFWL_Widget* pFocus, FX_BOOL bNotify) {
   return TRUE;
 }
 FWL_Error CFWL_NoteDriver::Run() {
-  CFWL_WidgetMgr* pWidgetMgr = static_cast<CFWL_WidgetMgr*>(FWL_GetWidgetMgr());
+  CFWL_WidgetMgr* pWidgetMgr = CFWL_WidgetMgr::GetInstance();
   if (!pWidgetMgr)
     return FWL_Error::Indefinite;
 
@@ -319,7 +319,7 @@ int32_t CFWL_NoteDriver::CountLoop() {
 }
 
 FX_BOOL CFWL_NoteDriver::ProcessMessage(CFWL_Message* pMessage) {
-  CFWL_WidgetMgr* pWidgetMgr = static_cast<CFWL_WidgetMgr*>(FWL_GetWidgetMgr());
+  CFWL_WidgetMgr* pWidgetMgr = CFWL_WidgetMgr::GetInstance();
   IFWL_Widget* pMessageForm = pWidgetMgr->IsFormDisabled()
                                   ? pMessage->m_pDstTarget
                                   : GetMessageForm(pMessage->m_pDstTarget);
@@ -436,22 +436,21 @@ FX_BOOL CFWL_NoteDriver::DoDeactivate(CFWL_MsgDeactivate* pMsg,
 }
 FX_BOOL CFWL_NoteDriver::DoSetFocus(CFWL_MsgSetFocus* pMsg,
                                     IFWL_Widget* pMessageForm) {
-  CFWL_WidgetMgr* pWidgetMgr = static_cast<CFWL_WidgetMgr*>(FWL_GetWidgetMgr());
+  CFWL_WidgetMgr* pWidgetMgr = CFWL_WidgetMgr::GetInstance();
   if (pWidgetMgr->IsFormDisabled()) {
     m_pFocus = pMsg->m_pDstTarget;
     return TRUE;
-  } else {
-    IFWL_Widget* pWidget = pMsg->m_pDstTarget;
-    CFWL_FormImp* pForm =
-        pWidget ? static_cast<CFWL_FormImp*>(pWidget->GetImpl()) : nullptr;
-    if (pForm) {
-      CFWL_WidgetImp* pSubFocus = pForm->GetSubFocus();
-      if (pSubFocus && ((pSubFocus->GetStates() & FWL_WGTSTATE_Focused) == 0)) {
-        pMsg->m_pDstTarget = pSubFocus->GetInterface();
-        if (m_pFocus != pMsg->m_pDstTarget) {
-          m_pFocus = pMsg->m_pDstTarget;
-          return TRUE;
-        }
+  }
+  IFWL_Widget* pWidget = pMsg->m_pDstTarget;
+  CFWL_FormImp* pForm =
+      pWidget ? static_cast<CFWL_FormImp*>(pWidget->GetImpl()) : nullptr;
+  if (pForm) {
+    CFWL_WidgetImp* pSubFocus = pForm->GetSubFocus();
+    if (pSubFocus && ((pSubFocus->GetStates() & FWL_WGTSTATE_Focused) == 0)) {
+      pMsg->m_pDstTarget = pSubFocus->GetInterface();
+      if (m_pFocus != pMsg->m_pDstTarget) {
+        m_pFocus = pMsg->m_pDstTarget;
+        return TRUE;
       }
     }
   }
@@ -459,7 +458,7 @@ FX_BOOL CFWL_NoteDriver::DoSetFocus(CFWL_MsgSetFocus* pMsg,
 }
 FX_BOOL CFWL_NoteDriver::DoKillFocus(CFWL_MsgKillFocus* pMsg,
                                      IFWL_Widget* pMessageForm) {
-  CFWL_WidgetMgr* pWidgetMgr = static_cast<CFWL_WidgetMgr*>(FWL_GetWidgetMgr());
+  CFWL_WidgetMgr* pWidgetMgr = CFWL_WidgetMgr::GetInstance();
   if (pWidgetMgr->IsFormDisabled()) {
     if (m_pFocus == pMsg->m_pDstTarget) {
       m_pFocus = NULL;
@@ -485,21 +484,18 @@ FX_BOOL CFWL_NoteDriver::DoKey(CFWL_MsgKey* pMsg, IFWL_Widget* pMessageForm) {
 #if (_FX_OS_ != _FX_MACOSX_)
   if (pMsg->m_dwCmd == FWL_KeyCommand::KeyDown &&
       pMsg->m_dwKeyCode == FWL_VKEY_Tab) {
-    CFWL_WidgetMgr* pWidgetMgr =
-        static_cast<CFWL_WidgetMgr*>(FWL_GetWidgetMgr());
+    CFWL_WidgetMgr* pWidgetMgr = CFWL_WidgetMgr::GetInstance();
     IFWL_Widget* pForm = GetMessageForm(pMsg->m_pDstTarget);
     IFWL_Widget* pFocus = m_pFocus;
     if (m_pFocus) {
-      if (pWidgetMgr->GetWidget(m_pFocus, FWL_WGTRELATION_SystemForm) !=
-          pForm) {
-        pFocus = NULL;
-      }
+      if (pWidgetMgr->GetSystemFormWidget(m_pFocus) != pForm)
+        pFocus = nullptr;
     }
     FX_BOOL bFind = FALSE;
     IFWL_Widget* pNextTabStop = pWidgetMgr->nextTab(pForm, pFocus, bFind);
     if (!pNextTabStop) {
       bFind = FALSE;
-      pNextTabStop = pWidgetMgr->nextTab(pForm, NULL, bFind);
+      pNextTabStop = pWidgetMgr->nextTab(pForm, nullptr, bFind);
     }
     if (pNextTabStop == pFocus) {
       return TRUE;
@@ -513,8 +509,7 @@ FX_BOOL CFWL_NoteDriver::DoKey(CFWL_MsgKey* pMsg, IFWL_Widget* pMessageForm) {
   if (!m_pFocus) {
     if (pMsg->m_dwCmd == FWL_KeyCommand::KeyDown &&
         pMsg->m_dwKeyCode == FWL_VKEY_Return) {
-      CFWL_WidgetMgr* pWidgetMgr =
-          static_cast<CFWL_WidgetMgr*>(FWL_GetWidgetMgr());
+      CFWL_WidgetMgr* pWidgetMgr = CFWL_WidgetMgr::GetInstance();
       IFWL_Widget* defButton = pWidgetMgr->GetDefaultButton(pMessageForm);
       if (defButton) {
         pMsg->m_pDstTarget = defButton;
@@ -543,7 +538,7 @@ FX_BOOL CFWL_NoteDriver::DoMouse(CFWL_MsgMouse* pMsg,
 }
 FX_BOOL CFWL_NoteDriver::DoWheel(CFWL_MsgMouseWheel* pMsg,
                                  IFWL_Widget* pMessageForm) {
-  CFWL_WidgetMgr* pWidgetMgr = static_cast<CFWL_WidgetMgr*>(FWL_GetWidgetMgr());
+  CFWL_WidgetMgr* pWidgetMgr = CFWL_WidgetMgr::GetInstance();
   if (!pWidgetMgr)
     return FALSE;
 
@@ -557,7 +552,7 @@ FX_BOOL CFWL_NoteDriver::DoWheel(CFWL_MsgMouseWheel* pMsg,
   return TRUE;
 }
 FX_BOOL CFWL_NoteDriver::DoSize(CFWL_MsgSize* pMsg) {
-  CFWL_WidgetMgr* pWidgetMgr = static_cast<CFWL_WidgetMgr*>(FWL_GetWidgetMgr());
+  CFWL_WidgetMgr* pWidgetMgr = CFWL_WidgetMgr::GetInstance();
   if (!pWidgetMgr)
     return FALSE;
   pWidgetMgr->NotifySizeChanged(pMsg->m_pDstTarget, (FX_FLOAT)pMsg->m_iWidth,
@@ -574,7 +569,7 @@ FX_BOOL CFWL_NoteDriver::DoDragFiles(CFWL_MsgDropFiles* pMsg,
 }
 FX_BOOL CFWL_NoteDriver::DoMouseEx(CFWL_MsgMouse* pMsg,
                                    IFWL_Widget* pMessageForm) {
-  CFWL_WidgetMgr* pWidgetMgr = static_cast<CFWL_WidgetMgr*>(FWL_GetWidgetMgr());
+  CFWL_WidgetMgr* pWidgetMgr = CFWL_WidgetMgr::GetInstance();
   if (!pWidgetMgr)
     return FALSE;
   IFWL_Widget* pTarget = NULL;
@@ -655,12 +650,10 @@ IFWL_Widget* CFWL_NoteDriver::GetMessageForm(IFWL_Widget* pDstTarget) {
     pMessageForm = pDstTarget;
   }
   if (!pMessageForm && pDstTarget) {
-    CFWL_WidgetMgr* pWidgetMgr =
-        static_cast<CFWL_WidgetMgr*>(FWL_GetWidgetMgr());
+    CFWL_WidgetMgr* pWidgetMgr = CFWL_WidgetMgr::GetInstance();
     if (!pWidgetMgr)
       return nullptr;
-    pMessageForm =
-        pWidgetMgr->GetWidget(pDstTarget, FWL_WGTRELATION_SystemForm);
+    pMessageForm = pWidgetMgr->GetSystemFormWidget(pDstTarget);
   }
   return pMessageForm;
 }
diff --git a/xfa/fwl/core/fwl_widgetimp.cpp b/xfa/fwl/core/fwl_widgetimp.cpp
index e72a7f385a..f6e130b563 100644
--- a/xfa/fwl/core/fwl_widgetimp.cpp
+++ b/xfa/fwl/core/fwl_widgetimp.cpp
@@ -209,18 +209,20 @@ FWL_Error CFWL_WidgetImp::GetWidgetRect(CFX_RectF& rect, FX_BOOL bAutoSize) {
   }
   return FWL_Error::Succeeded;
 }
+
 FWL_Error CFWL_WidgetImp::GetGlobalRect(CFX_RectF& rect) {
-  IFWL_Widget* pForm =
-      m_pWidgetMgr->GetWidget(m_pInterface, FWL_WGTRELATION_SystemForm);
+  IFWL_Widget* pForm = m_pWidgetMgr->GetSystemFormWidget(m_pInterface);
   if (!pForm)
     return FWL_Error::Indefinite;
+
   rect.Set(0, 0, m_pProperties->m_rtWidget.width,
            m_pProperties->m_rtWidget.height);
-  if (pForm == m_pInterface) {
+  if (pForm == m_pInterface)
     return FWL_Error::Succeeded;
-  }
+
   return TransformTo(pForm, rect);
 }
+
 FWL_Error CFWL_WidgetImp::SetWidgetRect(const CFX_RectF& rect) {
   CFX_RectF rtOld = m_pProperties->m_rtWidget;
   m_pProperties->m_rtWidget = rect;
@@ -250,7 +252,7 @@ FWL_Error CFWL_WidgetImp::GetClientRect(CFX_RectF& rect) {
   return FWL_Error::Succeeded;
 }
 IFWL_Widget* CFWL_WidgetImp::GetParent() {
-  return m_pWidgetMgr->GetWidget(m_pInterface, FWL_WGTRELATION_Parent);
+  return m_pWidgetMgr->GetParentWidget(m_pInterface);
 }
 FWL_Error CFWL_WidgetImp::SetParent(IFWL_Widget* pParent) {
   m_pProperties->m_pParent = pParent;
@@ -258,7 +260,7 @@ FWL_Error CFWL_WidgetImp::SetParent(IFWL_Widget* pParent) {
   return FWL_Error::Succeeded;
 }
 IFWL_Widget* CFWL_WidgetImp::GetOwner() {
-  return m_pWidgetMgr->GetWidget(m_pInterface, FWL_WGTRELATION_Owner);
+  return m_pWidgetMgr->GetOwnerWidget(m_pInterface);
 }
 FWL_Error CFWL_WidgetImp::SetOwner(IFWL_Widget* pOwner) {
   m_pProperties->m_pOwner = pOwner;
@@ -289,14 +291,14 @@ FWL_Error CFWL_WidgetImp::ModifyStylesEx(uint32_t dwStylesExAdded,
 uint32_t CFWL_WidgetImp::GetStates() {
   return m_pProperties->m_dwStates;
 }
-static void NotifyHideChildWidget(IFWL_WidgetMgr* widgetMgr,
+static void NotifyHideChildWidget(CFWL_WidgetMgr* widgetMgr,
                                   IFWL_Widget* widget,
                                   CFWL_NoteDriver* noteDriver) {
-  IFWL_Widget* child = widgetMgr->GetWidget(widget, FWL_WGTRELATION_FirstChild);
+  IFWL_Widget* child = widgetMgr->GetFirstChildWidget(widget);
   while (child) {
     noteDriver->NotifyTargetHide(child);
     NotifyHideChildWidget(widgetMgr, child, noteDriver);
-    child = widgetMgr->GetWidget(child, FWL_WGTRELATION_NextSibling);
+    child = widgetMgr->GetNextSiblingWidget(child);
   }
 }
 
@@ -308,14 +310,13 @@ void CFWL_WidgetImp::SetStates(uint32_t dwStates, FX_BOOL bSet) {
 
   CFWL_NoteDriver* noteDriver =
       static_cast<CFWL_NoteDriver*>(GetOwnerApp()->GetNoteDriver());
-  IFWL_WidgetMgr* widgetMgr = FWL_GetWidgetMgr();
+  CFWL_WidgetMgr* widgetMgr = CFWL_WidgetMgr::GetInstance();
   noteDriver->NotifyTargetHide(m_pInterface);
-  IFWL_Widget* child =
-      widgetMgr->GetWidget(m_pInterface, FWL_WGTRELATION_FirstChild);
+  IFWL_Widget* child = widgetMgr->GetFirstChildWidget(m_pInterface);
   while (child) {
     noteDriver->NotifyTargetHide(child);
     NotifyHideChildWidget(widgetMgr, child, noteDriver);
-    child = widgetMgr->GetWidget(child, FWL_WGTRELATION_NextSibling);
+    child = widgetMgr->GetNextSiblingWidget(child);
   }
   return;
 }
@@ -391,8 +392,7 @@ FWL_Error CFWL_WidgetImp::TransformTo(IFWL_Widget* pWidget,
     GetMatrix(m, TRUE);
     m.TransformPoint(fx, fy);
   }
-  IFWL_Widget* form1 =
-      m_pWidgetMgr->GetWidget(m_pInterface, FWL_WGTRELATION_SystemForm);
+  IFWL_Widget* form1 = m_pWidgetMgr->GetSystemFormWidget(m_pInterface);
   if (!form1)
     return FWL_Error::Indefinite;
   if (!pWidget) {
@@ -401,8 +401,7 @@ FWL_Error CFWL_WidgetImp::TransformTo(IFWL_Widget* pWidget,
     fy += r.top;
     return FWL_Error::Succeeded;
   }
-  IFWL_Widget* form2 =
-      m_pWidgetMgr->GetWidget(pWidget, FWL_WGTRELATION_SystemForm);
+  IFWL_Widget* form2 = m_pWidgetMgr->GetSystemFormWidget(pWidget);
   if (!form2)
     return FWL_Error::Indefinite;
   if (form1 != form2) {
@@ -517,7 +516,7 @@ CFWL_WidgetImp::CFWL_WidgetImp(const CFWL_WidgetImpProperties& properties,
       m_pInterface(NULL),
       m_iLock(0) {
   *m_pProperties = properties;
-  m_pWidgetMgr = static_cast<CFWL_WidgetMgr*>(FWL_GetWidgetMgr());
+  m_pWidgetMgr = CFWL_WidgetMgr::GetInstance();
   ASSERT(m_pWidgetMgr != NULL);
 }
 CFWL_WidgetImp::~CFWL_WidgetImp() {
@@ -617,15 +616,13 @@ IFWL_ThemeProvider* CFWL_WidgetImp::GetAvailableTheme() {
   }
   IFWL_Widget* pUp = m_pInterface;
   do {
-    FWL_WGTRELATION relation = (pUp->GetStyles() & FWL_WGTSTYLE_Popup)
-                                   ? FWL_WGTRELATION_Owner
-                                   : FWL_WGTRELATION_Parent;
-    pUp = m_pWidgetMgr->GetWidget(pUp, relation);
+    pUp = (pUp->GetStyles() & FWL_WGTSTYLE_Popup)
+              ? m_pWidgetMgr->GetOwnerWidget(pUp)
+              : m_pWidgetMgr->GetParentWidget(pUp);
     if (pUp) {
       IFWL_ThemeProvider* pRet = pUp->GetThemeProvider();
-      if (pRet && pRet->IsValidWidget(m_pInterface)) {
+      if (pRet && pRet->IsValidWidget(m_pInterface))
         return pRet;
-      }
     }
   } while (pUp);
   return FWL_GetApp()->GetThemeProvider();
@@ -929,7 +926,7 @@ CFX_SizeF CFWL_WidgetImp::GetOffsetFromParent(IFWL_Widget* pParent) {
   if (pParent == GetInterface())
     return CFX_SizeF();
 
-  IFWL_WidgetMgr* pWidgetMgr = FWL_GetWidgetMgr();
+  CFWL_WidgetMgr* pWidgetMgr = CFWL_WidgetMgr::GetInstance();
   if (!pWidgetMgr)
     return CFX_SizeF();
 
@@ -941,7 +938,7 @@ CFX_SizeF CFWL_WidgetImp::GetOffsetFromParent(IFWL_Widget* pParent) {
     CFX_RectF rtDst;
     pDstWidget->GetWidgetRect(rtDst);
     szRet += CFX_SizeF(rtDst.left, rtDst.top);
-    pDstWidget = pWidgetMgr->GetWidget(pDstWidget, FWL_WGTRELATION_Parent);
+    pDstWidget = pWidgetMgr->GetParentWidget(pDstWidget);
   }
   return szRet;
 }
diff --git a/xfa/fwl/core/fwl_widgetmgrimp.cpp b/xfa/fwl/core/fwl_widgetmgrimp.cpp
index 93f39a98e5..98d135c96d 100644
--- a/xfa/fwl/core/fwl_widgetmgrimp.cpp
+++ b/xfa/fwl/core/fwl_widgetmgrimp.cpp
@@ -36,11 +36,10 @@ FX_BOOL FWL_UseOffscreen(IFWL_Widget* pWidget) {
 #endif
 }
 
-IFWL_WidgetMgr* FWL_GetWidgetMgr() {
+// static
+CFWL_WidgetMgr* CFWL_WidgetMgr::GetInstance() {
   IFWL_App* pApp = FWL_GetApp();
-  if (!pApp)
-    return NULL;
-  return pApp->GetWidgetMgr();
+  return pApp ? pApp->GetWidgetMgr() : nullptr;
 }
 
 CFWL_WidgetMgr::CFWL_WidgetMgr(CXFA_FFApp* pAdapterNative)
@@ -56,88 +55,68 @@ CFWL_WidgetMgr::CFWL_WidgetMgr(CXFA_FFApp* pAdapterNative)
 
 CFWL_WidgetMgr::~CFWL_WidgetMgr() {}
 
-int32_t CFWL_WidgetMgr::CountWidgets(IFWL_Widget* pParent) {
-  CFWL_WidgetMgrItem* pParentItem = GetWidgetMgrItem(pParent);
-  return TravelWidgetMgr(pParentItem, NULL, NULL);
+IFWL_Widget* CFWL_WidgetMgr::GetParentWidget(IFWL_Widget* pWidget) const {
+  CFWL_WidgetMgrItem* pItem = GetWidgetMgrItem(pWidget);
+  return pItem && pItem->pParent ? pItem->pParent->pWidget : nullptr;
 }
-IFWL_Widget* CFWL_WidgetMgr::GetWidget(int32_t nIndex, IFWL_Widget* pParent) {
-  CFWL_WidgetMgrItem* pParentItem = GetWidgetMgrItem(pParent);
-  IFWL_Widget* pWidget = NULL;
-  TravelWidgetMgr(pParentItem, &nIndex, NULL, &pWidget);
-  return pWidget;
+
+IFWL_Widget* CFWL_WidgetMgr::GetOwnerWidget(IFWL_Widget* pWidget) const {
+  CFWL_WidgetMgrItem* pItem = GetWidgetMgrItem(pWidget);
+  return pItem && pItem->pOwner ? pItem->pOwner->pWidget : nullptr;
 }
-IFWL_Widget* CFWL_WidgetMgr::GetWidget(IFWL_Widget* pWidget,
-                                       FWL_WGTRELATION eRelation) {
+
+IFWL_Widget* CFWL_WidgetMgr::GetFirstSiblingWidget(IFWL_Widget* pWidget) const {
   CFWL_WidgetMgrItem* pItem = GetWidgetMgrItem(pWidget);
-  if (!pItem) {
-    return NULL;
-  }
-  IFWL_Widget* pRet = NULL;
-  switch (eRelation) {
-    case FWL_WGTRELATION_Parent: {
-      pRet = pItem->pParent ? pItem->pParent->pWidget : NULL;
-      break;
-    }
-    case FWL_WGTRELATION_Owner: {
-      pRet = pItem->pOwner ? pItem->pOwner->pWidget : NULL;
-      break;
-    }
-    case FWL_WGTRELATION_FirstSibling: {
-      pItem = pItem->pPrevious;
-      while (pItem && pItem->pPrevious) {
-        pItem = pItem->pPrevious;
-      }
-      pRet = pItem ? pItem->pWidget : NULL;
-      break;
-    }
-    case FWL_WGTRELATION_PriorSibling: {
-      pRet = pItem->pPrevious ? pItem->pPrevious->pWidget : NULL;
-      break;
-    }
-    case FWL_WGTRELATION_NextSibling: {
-      pRet = pItem->pNext ? pItem->pNext->pWidget : NULL;
-      break;
-    }
-    case FWL_WGTRELATION_LastSibling: {
-      pItem = pItem->pNext;
-      while (pItem && pItem->pNext) {
-        pItem = pItem->pNext;
-      }
-      pRet = pItem ? pItem->pWidget : NULL;
-      break;
-    }
-    case FWL_WGTRELATION_FirstChild: {
-      pRet = pItem->pChild ? pItem->pChild->pWidget : NULL;
-      break;
-    }
-    case FWL_WGTRELATION_LastChild: {
-      pItem = pItem->pChild;
-      while (pItem && pItem->pNext) {
-        pItem = pItem->pNext;
-      }
-      pRet = pItem ? pItem->pWidget : NULL;
-      break;
-    }
-    case FWL_WGTRELATION_SystemForm: {
-      while (pItem) {
-        if (IsAbleNative(pItem->pWidget)) {
-          pRet = pItem->pWidget;
-          break;
-        }
-        pItem = pItem->pParent;
-      }
-      break;
-    }
-    default: {}
-  }
-  return pRet;
+  pItem = pItem ? pItem->pPrevious : nullptr;  // Not self.
+  while (pItem && pItem->pPrevious)
+    pItem = pItem->pPrevious;
+
+  return pItem ? pItem->pWidget : nullptr;
 }
-int32_t CFWL_WidgetMgr::GetWidgetIndex(IFWL_Widget* pWidget) {
+
+IFWL_Widget* CFWL_WidgetMgr::GetPriorSiblingWidget(IFWL_Widget* pWidget) const {
   CFWL_WidgetMgrItem* pItem = GetWidgetMgrItem(pWidget);
-  if (!pItem)
-    return -1;
-  return TravelWidgetMgr(pItem->pParent, NULL, pItem);
+  return pItem && pItem->pPrevious ? pItem->pPrevious->pWidget : nullptr;
+}
+
+IFWL_Widget* CFWL_WidgetMgr::GetNextSiblingWidget(IFWL_Widget* pWidget) const {
+  CFWL_WidgetMgrItem* pItem = GetWidgetMgrItem(pWidget);
+  return pItem && pItem->pNext ? pItem->pNext->pWidget : nullptr;
+}
+
+IFWL_Widget* CFWL_WidgetMgr::GetLastSiblingWidget(IFWL_Widget* pWidget) const {
+  CFWL_WidgetMgrItem* pItem = GetWidgetMgrItem(pWidget);
+  pItem = pItem ? pItem->pNext : nullptr;  // Not self.
+  while (pItem && pItem->pNext)
+    pItem = pItem->pNext;
+
+  return pItem ? pItem->pWidget : nullptr;
 }
+
+IFWL_Widget* CFWL_WidgetMgr::GetFirstChildWidget(IFWL_Widget* pWidget) const {
+  CFWL_WidgetMgrItem* pItem = GetWidgetMgrItem(pWidget);
+  return pItem && pItem->pChild ? pItem->pChild->pWidget : nullptr;
+}
+
+IFWL_Widget* CFWL_WidgetMgr::GetLastChildWidget(IFWL_Widget* pWidget) const {
+  CFWL_WidgetMgrItem* pItem = GetWidgetMgrItem(pWidget);
+  pItem = pItem ? pItem->pChild : nullptr;
+  while (pItem && pItem->pNext)
+    pItem = pItem->pNext;
+
+  return pItem ? pItem->pWidget : nullptr;
+}
+
+IFWL_Widget* CFWL_WidgetMgr::GetSystemFormWidget(IFWL_Widget* pWidget) const {
+  CFWL_WidgetMgrItem* pItem = GetWidgetMgrItem(pWidget);
+  while (pItem) {
+    if (IsAbleNative(pItem->pWidget))
+      return pItem->pWidget;
+    pItem = pItem->pParent;
+  }
+  return nullptr;
+}
+
 FX_BOOL CFWL_WidgetMgr::SetWidgetIndex(IFWL_Widget* pWidget, int32_t nIndex) {
   CFWL_WidgetMgrItem* pItem = GetWidgetMgrItem(pWidget);
   if (!pItem)
@@ -225,7 +204,7 @@ FWL_Error CFWL_WidgetMgr::RepaintWidget(IFWL_Widget* pWidget,
       pOuter = pOuter->GetOuter();
     }
   } else if (!IsAbleNative(pWidget)) {
-    pNative = GetWidget(pWidget, FWL_WGTRELATION_SystemForm);
+    pNative = GetSystemFormWidget(pWidget);
     if (!pNative)
       return FWL_Error::Indefinite;
     pWidget->TransformTo(pNative, rect.left, rect.top);
@@ -345,10 +324,9 @@ void CFWL_WidgetMgr::SetParent(IFWL_Widget* pParent, IFWL_Widget* pChild) {
 FX_BOOL CFWL_WidgetMgr::IsChild(IFWL_Widget* pChild, IFWL_Widget* pParent) {
   IFWL_Widget* pTemp = pChild;
   do {
-    if (pTemp == pParent) {
+    if (pTemp == pParent)
       return TRUE;
-    }
-    pTemp = GetWidget(pTemp, FWL_WGTRELATION_Parent);
+    pTemp = GetParentWidget(pTemp);
   } while (pTemp);
   return FALSE;
 }
@@ -382,7 +360,7 @@ IFWL_Widget* CFWL_WidgetMgr::GetWidgetAtPoint(IFWL_Widget* parent,
     return NULL;
   FX_FLOAT x1;
   FX_FLOAT y1;
-  IFWL_Widget* child = GetWidget(parent, FWL_WGTRELATION_LastChild);
+  IFWL_Widget* child = GetLastChildWidget(parent);
   while (child) {
     if ((child->GetStates() & FWL_WGTSTATE_Invisible) == 0) {
       x1 = x;
@@ -401,7 +379,7 @@ IFWL_Widget* CFWL_WidgetMgr::GetWidgetAtPoint(IFWL_Widget* parent,
         return GetWidgetAtPoint(child, x1, y1);
       }
     }
-    child = GetWidget(child, FWL_WGTRELATION_PriorSibling);
+    child = GetPriorSiblingWidget(child);
   }
   return parent;
 }
@@ -416,29 +394,32 @@ void CFWL_WidgetMgr::NotifySizeChanged(IFWL_Widget* pForm,
 IFWL_Widget* CFWL_WidgetMgr::nextTab(IFWL_Widget* parent,
                                      IFWL_Widget* focus,
                                      FX_BOOL& bFind) {
-  IFWL_Widget* child =
-      FWL_GetWidgetMgr()->GetWidget(parent, FWL_WGTRELATION_FirstChild);
+  CFWL_WidgetMgr* pMgr = CFWL_WidgetMgr::GetInstance();
+  IFWL_Widget* child = pMgr->GetFirstChildWidget(parent);
   while (child) {
-    if (focus == child) {
+    if (focus == child)
       bFind = TRUE;
-    }
+
     if ((child->GetStyles() & FWL_WGTSTYLE_TabStop) &&
         (!focus || (focus != child && bFind))) {
       return child;
     }
     IFWL_Widget* bRet = nextTab(child, focus, bFind);
-    if (bRet) {
+    if (bRet)
       return bRet;
-    }
-    child = FWL_GetWidgetMgr()->GetWidget(child, FWL_WGTRELATION_NextSibling);
+
+    child = pMgr->GetNextSiblingWidget(child);
   }
-  return NULL;
+  return nullptr;
 }
+
 int32_t CFWL_WidgetMgr::CountRadioButtonGroup(IFWL_Widget* pFirst) {
   int32_t iRet = 0;
   IFWL_Widget* pChild = pFirst;
-  while (pChild)
-    pChild = GetWidget(pChild, FWL_WGTRELATION_NextSibling);
+  while (pChild) {
+    pChild = GetNextSiblingWidget(pChild);
+    ++iRet;
+  }
   return iRet;
 }
 IFWL_Widget* CFWL_WidgetMgr::GetSiblingRadioButton(IFWL_Widget* pWidget,
@@ -453,19 +434,19 @@ IFWL_Widget* CFWL_WidgetMgr::GetRadioButtonGroupHeader(
       return pNext;
     pNext = GetSiblingRadioButton(pNext, FALSE);
   }
-  pNext = GetWidget(pRadioButton, FWL_WGTRELATION_LastSibling);
+  pNext = GetLastSiblingWidget(pRadioButton);
   while ((pNext = GetSiblingRadioButton(pNext, FALSE)) != nullptr &&
          pNext != pRadioButton) {
     if (pNext->GetStyles() & FWL_WGTSTYLE_Group)
       return pNext;
   }
-  pNext = GetWidget(pRadioButton, FWL_WGTRELATION_FirstSibling);
+  pNext = GetFirstSiblingWidget(pRadioButton);
   return GetSiblingRadioButton(pNext, TRUE);
 }
 void CFWL_WidgetMgr::GetSameGroupRadioButton(
     IFWL_Widget* pRadioButton,
     CFX_ArrayTemplate<IFWL_Widget*>& group) {
-  IFWL_Widget* pFirst = GetWidget(pRadioButton, FWL_WGTRELATION_FirstSibling);
+  IFWL_Widget* pFirst = GetFirstSiblingWidget(pRadioButton);
   if (!pFirst) {
     pFirst = pRadioButton;
   }
@@ -491,7 +472,7 @@ IFWL_Widget* CFWL_WidgetMgr::GetDefaultButton(IFWL_Widget* pParent) {
     return pParent;
   }
   IFWL_Widget* child =
-      FWL_GetWidgetMgr()->GetWidget(pParent, FWL_WGTRELATION_FirstChild);
+      CFWL_WidgetMgr::GetInstance()->GetFirstChildWidget(pParent);
   while (child) {
     if ((child->GetClassID() == FWL_Type::PushButton) &&
         (child->GetStates() & (1 << (FWL_WGTSTATE_MAX + 2)))) {
@@ -501,7 +482,7 @@ IFWL_Widget* CFWL_WidgetMgr::GetDefaultButton(IFWL_Widget* pParent) {
     if (find) {
       return find;
     }
-    child = FWL_GetWidgetMgr()->GetWidget(child, FWL_WGTRELATION_NextSibling);
+    child = CFWL_WidgetMgr::GetInstance()->GetNextSiblingWidget(child);
   }
   return NULL;
 }
@@ -550,7 +531,8 @@ int32_t CFWL_WidgetMgr::TravelWidgetMgr(CFWL_WidgetMgrItem* pParent,
   }
   return iCount - 1;
 }
-FX_BOOL CFWL_WidgetMgr::IsAbleNative(IFWL_Widget* pWidget) {
+
+FX_BOOL CFWL_WidgetMgr::IsAbleNative(IFWL_Widget* pWidget) const {
   if (!pWidget)
     return FALSE;
   if (!pWidget->IsInstance(FX_WSTRC(FWL_CLASS_Form))) {
@@ -677,11 +659,10 @@ void CFWL_WidgetMgrDelegate::DrawChild(IFWL_Widget* parent,
     return;
 
   FX_BOOL bFormDisable = m_pWidgetMgr->IsFormDisabled();
-  IFWL_Widget* pNextChild =
-      m_pWidgetMgr->GetWidget(parent, FWL_WGTRELATION_FirstChild);
+  IFWL_Widget* pNextChild = m_pWidgetMgr->GetFirstChildWidget(parent);
   while (pNextChild) {
     IFWL_Widget* child = pNextChild;
-    pNextChild = m_pWidgetMgr->GetWidget(child, FWL_WGTRELATION_NextSibling);
+    pNextChild = m_pWidgetMgr->GetNextSiblingWidget(child);
     if (child->GetStates() & FWL_WGTSTATE_Invisible)
       continue;
 
@@ -719,7 +700,7 @@ void CFWL_WidgetMgrDelegate::DrawChild(IFWL_Widget* parent,
 
     DrawChild(child, clipBounds, pGraphics,
               bFormDisable ? &widgetMatrix : pMatrix);
-    child = m_pWidgetMgr->GetWidget(child, FWL_WGTRELATION_NextSibling);
+    child = m_pWidgetMgr->GetNextSiblingWidget(child);
   }
 }
 
@@ -776,7 +757,7 @@ FX_BOOL CFWL_WidgetMgrDelegate::IsNeedRepaint(IFWL_Widget* pWidget,
     return FALSE;
 
   IFWL_Widget* pChild =
-      FWL_GetWidgetMgr()->GetWidget(pWidget, FWL_WGTRELATION_FirstChild);
+      CFWL_WidgetMgr::GetInstance()->GetFirstChildWidget(pWidget);
   if (!pChild)
     return TRUE;
 
@@ -835,8 +816,8 @@ FX_BOOL CFWL_WidgetMgrDelegate::IsNeedRepaint(IFWL_Widget* pWidget,
       if (r.Contains(hitPoint[i].hitPoint))
         hitPoint[i].bNotNeedRepaint = true;
     }
-  } while ((pChild = FWL_GetWidgetMgr()->GetWidget(
-                pChild, FWL_WGTRELATION_NextSibling)) != NULL);
+  } while (
+      (pChild = CFWL_WidgetMgr::GetInstance()->GetNextSiblingWidget(pChild)));
 
   if (!bChildIntersectWithDirty)
     return TRUE;
diff --git a/xfa/fwl/core/fwl_widgetmgrimp.h b/xfa/fwl/core/fwl_widgetmgrimp.h
index 6e4fffeca1..64fda0724e 100644
--- a/xfa/fwl/core/fwl_widgetmgrimp.h
+++ b/xfa/fwl/core/fwl_widgetmgrimp.h
@@ -12,7 +12,6 @@
 
 #include "core/fxcrt/include/fx_system.h"
 #include "xfa/fwl/core/fwl_error.h"
-#include "xfa/fwl/core/ifwl_widgetmgr.h"
 #include "xfa/fxgraphics/include/cfx_graphics.h"
 
 #define FWL_WGTMGR_DisableThread 0x00000001
@@ -58,21 +57,25 @@ class CFWL_WidgetMgrItem {
 #endif
 };
 
-class CFWL_WidgetMgr : public IFWL_WidgetMgr {
+class CFWL_WidgetMgr {
  public:
-  CFWL_WidgetMgr(CXFA_FFApp* pAdapterNative);
-  ~CFWL_WidgetMgr() override;
-
-  // IFWL_WidgetMgr:
-  int32_t CountWidgets(IFWL_Widget* pParent = NULL) override;
-  IFWL_Widget* GetWidget(int32_t nIndex, IFWL_Widget* pParent = NULL) override;
-  IFWL_Widget* GetWidget(IFWL_Widget* pWidget,
-                         FWL_WGTRELATION eRelation) override;
-  int32_t GetWidgetIndex(IFWL_Widget* pWidget) override;
-  FX_BOOL SetWidgetIndex(IFWL_Widget* pWidget, int32_t nIndex) override;
-  FWL_Error RepaintWidget(IFWL_Widget* pWidget,
-                          const CFX_RectF* pRect = NULL) override;
-  uint32_t GetCapability() override { return m_dwCapability; }
+  static CFWL_WidgetMgr* GetInstance();
+
+  explicit CFWL_WidgetMgr(CXFA_FFApp* pAdapterNative);
+  ~CFWL_WidgetMgr();
+
+  IFWL_Widget* GetParentWidget(IFWL_Widget* pWidget) const;
+  IFWL_Widget* GetOwnerWidget(IFWL_Widget* pWidget) const;
+  IFWL_Widget* GetFirstSiblingWidget(IFWL_Widget* pWidget) const;
+  IFWL_Widget* GetPriorSiblingWidget(IFWL_Widget* pWidget) const;
+  IFWL_Widget* GetNextSiblingWidget(IFWL_Widget* pWidget) const;
+  IFWL_Widget* GetLastSiblingWidget(IFWL_Widget* pWidget) const;
+  IFWL_Widget* GetFirstChildWidget(IFWL_Widget* pWidget) const;
+  IFWL_Widget* GetLastChildWidget(IFWL_Widget* pWidget) const;
+  IFWL_Widget* GetSystemFormWidget(IFWL_Widget* pWidget) const;
+
+  FX_BOOL SetWidgetIndex(IFWL_Widget* pWidget, int32_t nIndex);
+  FWL_Error RepaintWidget(IFWL_Widget* pWidget, const CFX_RectF* pRect = NULL);
 
   void AddWidget(IFWL_Widget* pWidget);
   void InsertWidget(IFWL_Widget* pParent,
@@ -110,7 +113,7 @@ class CFWL_WidgetMgr : public IFWL_WidgetMgr {
                           int32_t* pIndex,
                           CFWL_WidgetMgrItem* pItem,
                           IFWL_Widget** pWidget = NULL);
-  FX_BOOL IsAbleNative(IFWL_Widget* pWidget);
+  FX_BOOL IsAbleNative(IFWL_Widget* pWidget) const;
 
   uint32_t m_dwCapability;
   std::unique_ptr<CFWL_WidgetMgrDelegate> m_pDelegate;
diff --git a/xfa/fwl/core/ifwl_app.h b/xfa/fwl/core/ifwl_app.h
index 41983ef8f5..5fbac6644f 100644
--- a/xfa/fwl/core/ifwl_app.h
+++ b/xfa/fwl/core/ifwl_app.h
@@ -22,11 +22,11 @@
 #include "xfa/fwl/core/fwl_error.h"
 
 class CFWL_NoteDriver;
+class CFWL_WidgetMgr;
 class CXFA_FFApp;
 class CXFA_FWLAdapterWidgetMgr;
 class IFWL_ThemeProvider;
 class IFWL_Widget;
-class IFWL_WidgetMgr;
 
 class IFWL_App {
  public:
@@ -37,7 +37,7 @@ class IFWL_App {
   FWL_Error Initialize();
   FWL_Error Finalize();
   CXFA_FFApp* GetAdapterNative();
-  IFWL_WidgetMgr* GetWidgetMgr();
+  CFWL_WidgetMgr* GetWidgetMgr();
   IFWL_ThemeProvider* GetThemeProvider();
   void SetThemeProvider(IFWL_ThemeProvider* pThemeProvider);
   void Exit(int32_t iExitCode);
diff --git a/xfa/fwl/core/ifwl_widgetmgr.h b/xfa/fwl/core/ifwl_widgetmgr.h
deleted file mode 100644
index 6e25b72290..0000000000
--- a/xfa/fwl/core/ifwl_widgetmgr.h
+++ /dev/null
@@ -1,47 +0,0 @@
-// 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
-
-#ifndef XFA_FWL_CORE_IFWL_WIDGETMGR_H_
-#define XFA_FWL_CORE_IFWL_WIDGETMGR_H_
-
-#include "core/fxcrt/include/fx_system.h"
-#include "xfa/fwl/core/fwl_error.h"
-#include "core/fxcrt/include/fx_coordinates.h"
-
-class CFX_WideString;
-class CFX_Matrix;
-class IFWL_Widget;
-
-enum FWL_WGTRELATION {
-  FWL_WGTRELATION_Parent = 0,
-  FWL_WGTRELATION_Owner,
-  FWL_WGTRELATION_FirstSibling,
-  FWL_WGTRELATION_PriorSibling,
-  FWL_WGTRELATION_NextSibling,
-  FWL_WGTRELATION_LastSibling,
-  FWL_WGTRELATION_FirstChild,
-  FWL_WGTRELATION_LastChild,
-  FWL_WGTRELATION_SystemForm
-};
-
-class IFWL_WidgetMgr {
- public:
-  virtual ~IFWL_WidgetMgr() {}
-  virtual int32_t CountWidgets(IFWL_Widget* pParent = NULL) = 0;
-  virtual IFWL_Widget* GetWidget(int32_t nIndex,
-                                 IFWL_Widget* pParent = NULL) = 0;
-  virtual IFWL_Widget* GetWidget(IFWL_Widget* pWidget,
-                                 FWL_WGTRELATION eRelation) = 0;
-  virtual int32_t GetWidgetIndex(IFWL_Widget* pWidget) = 0;
-  virtual FX_BOOL SetWidgetIndex(IFWL_Widget* pWidget, int32_t nIndex) = 0;
-  virtual FWL_Error RepaintWidget(IFWL_Widget* pWidget,
-                                  const CFX_RectF* pRect = NULL) = 0;
-  virtual uint32_t GetCapability() = 0;
-};
-
-IFWL_WidgetMgr* FWL_GetWidgetMgr();
-
-#endif  // XFA_FWL_CORE_IFWL_WIDGETMGR_H_
diff --git a/xfa/fwl/lightwidget/cfwl_widget.cpp b/xfa/fwl/lightwidget/cfwl_widget.cpp
index 8d3237605f..20c9a3b92f 100644
--- a/xfa/fwl/lightwidget/cfwl_widget.cpp
+++ b/xfa/fwl/lightwidget/cfwl_widget.cpp
@@ -217,7 +217,7 @@ IFWL_WidgetDelegate* CFWL_Widget::SetDelegate(IFWL_WidgetDelegate* pDelegate) {
 CFWL_Widget::CFWL_Widget()
     : m_pIface(nullptr), m_pDelegate(nullptr), m_pProperties(nullptr) {
   m_pProperties = new CFWL_WidgetProperties;
-  m_pWidgetMgr = static_cast<CFWL_WidgetMgr*>(FWL_GetWidgetMgr());
+  m_pWidgetMgr = CFWL_WidgetMgr::GetInstance();
   ASSERT(m_pWidgetMgr);
 }
 
diff --git a/xfa/fwl/theme/cfwl_widgettp.cpp b/xfa/fwl/theme/cfwl_widgettp.cpp
index 764c86e314..f4aea4aab6 100644
--- a/xfa/fwl/theme/cfwl_widgettp.cpp
+++ b/xfa/fwl/theme/cfwl_widgettp.cpp
@@ -13,9 +13,9 @@
 #include "xfa/fwl/core/cfwl_themebackground.h"
 #include "xfa/fwl/core/cfwl_themepart.h"
 #include "xfa/fwl/core/cfwl_themetext.h"
+#include "xfa/fwl/core/fwl_widgetmgrimp.h"
 #include "xfa/fwl/core/ifwl_themeprovider.h"
 #include "xfa/fwl/core/ifwl_widget.h"
-#include "xfa/fwl/core/ifwl_widgetmgr.h"
 #include "xfa/fxgraphics/cfx_color.h"
 #include "xfa/fxgraphics/cfx_path.h"
 #include "xfa/fxgraphics/cfx_shading.h"
@@ -35,16 +35,15 @@ const float kCYBorder = 1.0f;
 }  // namespace
 
 static void FWL_SetChildThemeID(IFWL_Widget* pParent, uint32_t dwThemeID) {
-  IFWL_WidgetMgr* pWidgetMgr = FWL_GetWidgetMgr();
-  IFWL_Widget* pChild =
-      pWidgetMgr->GetWidget(pParent, FWL_WGTRELATION_FirstChild);
+  CFWL_WidgetMgr* pWidgetMgr = CFWL_WidgetMgr::GetInstance();
+  IFWL_Widget* pChild = pWidgetMgr->GetFirstChildWidget(pParent);
   while (pChild) {
     IFWL_ThemeProvider* pTheme = pChild->GetThemeProvider();
     if (pTheme) {
       pTheme->SetThemeID(pChild, dwThemeID, FALSE);
     }
     FWL_SetChildThemeID(pChild, dwThemeID);
-    pChild = pWidgetMgr->GetWidget(pChild, FWL_WGTRELATION_NextSibling);
+    pChild = pWidgetMgr->GetNextSiblingWidget(pChild);
   }
 }