Correctly implement GetPartState() function

xfa/fwl/core/fwl_formimp.h

 // 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_FWL_FORMIMP_H_
 #define XFA_FWL_CORE_FWL_FORMIMP_H_
 
 #include "xfa/fwl/core/fwl_widgetimp.h"
@@ skipping 29 matching lines @@
     m_dwState |= FWL_SYSBUTTONSTATE_Pressed;
   }
   void SetHover() {
     SetNormal();
     m_dwState |= FWL_SYSBUTTONSTATE_Hover;
   }
   void SetDisabled(FX_BOOL bDisabled) {
     bDisabled ? m_dwState |= FWL_SYSBUTTONSTATE_Disabled
               : m_dwState &= ~FWL_SYSBUTTONSTATE_Disabled;
   }
-  int32_t GetPartState() {
-    return (IsDisabled() ? CFWL_PartState_Disabled : (m_dwState + 1));
+  uint32_t GetPartState() {
+    if (IsDisabled())
+      return CFWL_PartState_Disabled;
+    if (m_dwState & FWL_SYSBUTTONSTATE_Pressed)
+      return CFWL_PartState_Pressed;
+    if (m_dwState & FWL_SYSBUTTONSTATE_Hover)
+      return CFWL_PartState_Hovered;
+    return CFWL_PartState_Normal;
   }
 
   CFX_RectF m_rtBtn;
   uint32_t m_dwState;
 };
 
 enum FORM_RESIZETYPE {
   FORM_RESIZETYPE_None = 0,
   FORM_RESIZETYPE_Cap,
 };
@@ skipping 119 matching lines @@
   void OnMouseMove(CFWL_MsgMouse* pMsg);
   void OnMouseHover(CFWL_MsgMouse* pMsg);
   void OnMouseLeave(CFWL_MsgMouse* pMsg);
   void OnLButtonDblClk(CFWL_MsgMouse* pMsg);
   void OnWindowMove(CFWL_MsgWindowMove* pMsg);
   void OnClose(CFWL_MsgClose* pMsg);
   CFWL_FormImp* m_pOwner;
 };
 
 #endif  // XFA_FWL_CORE_FWL_FORMIMP_H_