Watch for destruction of widget during callback

fpdfsdk/include/fsdk_baseform.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 FPDFSDK_INCLUDE_FSDK_BASEFORM_H_
 #define FPDFSDK_INCLUDE_FSDK_BASEFORM_H_
 
 #include <map>
+#include <set>
 #include <vector>
 
 #include "core/fpdfdoc/include/fpdf_doc.h"
 #include "core/fxcrt/include/fx_basic.h"
 #include "core/fxge/include/fx_dib.h"
 #include "fpdfsdk/include/fsdk_baseannot.h"
 
 #if _FX_OS_ == _FX_ANDROID_
 #include "time.h"
 #else
@@ skipping 32 matching lines @@
   int nSelEnd;               // in[out]
   int nSelStart;             // in[out]
   CFX_WideString sValue;     // in[out]
   FX_BOOL bWillCommit;       // in
   FX_BOOL bFieldFull;        // in
   FX_BOOL bRC;               // in[out]
 };
 
 class CPDFSDK_Widget : public CPDFSDK_BAAnnot {
  public:
+  class Observer {
+   public:
+    explicit Observer(CPDFSDK_Widget** pWatchedPtr);
+    ~Observer();
+
+    void OnWidgetDestroyed();
+
+   private:
+    CPDFSDK_Widget** m_pWatchedPtr;
+  };
+
 #ifdef PDF_ENABLE_XFA
   CXFA_FFWidget* GetMixXFAWidget() const;
   CXFA_FFWidget* GetGroupMixXFAWidget();
   CXFA_FFWidgetHandler* GetXFAWidgetHandler() const;
 
   FX_BOOL HasXFAAAction(PDFSDK_XFAAActionType eXFAAAT);
   FX_BOOL OnXFAAAction(PDFSDK_XFAAActionType eXFAAAT,
                        PDFSDK_FieldAction& data,
                        CPDFSDK_PageView* pPageView);
 
   void Synchronize(FX_BOOL bSynchronizeElse);
   void SynchronizeXFAValue();
   void SynchronizeXFAItems();
 
   static void SynchronizeXFAValue(CXFA_FFDocView* pXFADocView,
                                   CXFA_FFWidget* hWidget,
                                   CPDF_FormField* pFormField,
                                   CPDF_FormControl* pFormControl);
   static void SynchronizeXFAItems(CXFA_FFDocView* pXFADocView,
                                   CXFA_FFWidget* hWidget,
                                   CPDF_FormField* pFormField,
                                   CPDF_FormControl* pFormControl);
 #endif  // PDF_ENABLE_XFA
 
   CPDFSDK_Widget(CPDF_Annot* pAnnot,
                  CPDFSDK_PageView* pPageView,
                  CPDFSDK_InterForm* pInterForm);
   ~CPDFSDK_Widget() override;
 
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
   // CPDFSDK_Annot
   CFX_ByteString GetSubType() const override;
   CPDF_Action GetAAction(CPDF_AAction::AActionType eAAT) override;
   FX_BOOL IsAppearanceValid() override;
 
   int GetLayoutOrder() const override;
 
   int GetFieldType() const;
 
   // Possible values from PDF 32000-1:2008, table 221.
@@ skipping 61 matching lines @@
 
   void DrawShadow(CFX_RenderDevice* pDevice, CPDFSDK_PageView* pPageView);
 
   void SetAppModified();
   void ClearAppModified();
   FX_BOOL IsAppModified() const;
 
   int32_t GetAppearanceAge() const;
   int32_t GetValueAge() const;
 
+  FX_BOOL IsWidgetAppearanceValid(CPDF_Annot::AppearanceMode mode);
+  void DrawAppearance(CFX_RenderDevice* pDevice,
+                      const CFX_Matrix* pUser2Device,
+                      CPDF_Annot::AppearanceMode mode,
+                      const CPDF_RenderOptions* pOptions) override;
+
+  FX_BOOL HitTest(FX_FLOAT pageX, FX_FLOAT pageY);
+
  private:
   void ResetAppearance_PushButton();
   void ResetAppearance_CheckBox();
   void ResetAppearance_RadioButton();
   void ResetAppearance_ComboBox(const FX_WCHAR* sValue);
   void ResetAppearance_ListBox();
   void ResetAppearance_TextField(const FX_WCHAR* sValue);
 
   CFX_FloatRect GetClientRect() const;
   CFX_FloatRect GetRotatedRect() const;
 
   CFX_ByteString GetBackgroundAppStream() const;
   CFX_ByteString GetBorderAppStream() const;
   CFX_Matrix GetMatrix() const;
 
   CPWL_Color GetTextPWLColor() const;
   CPWL_Color GetBorderPWLColor() const;
   CPWL_Color GetFillPWLColor() const;
 
   void AddImageToAppearance(const CFX_ByteString& sAPType, CPDF_Stream* pImage);
   void RemoveAppearance(const CFX_ByteString& sAPType);
 
- public:
-  FX_BOOL IsWidgetAppearanceValid(CPDF_Annot::AppearanceMode mode);
-  void DrawAppearance(CFX_RenderDevice* pDevice,
-                      const CFX_Matrix* pUser2Device,
-                      CPDF_Annot::AppearanceMode mode,
-                      const CPDF_RenderOptions* pOptions) override;
-
-  FX_BOOL HitTest(FX_FLOAT pageX, FX_FLOAT pageY);
-
- private:
   CPDFSDK_InterForm* const m_pInterForm;
   FX_BOOL m_bAppModified;
   int32_t m_nAppAge;
   int32_t m_nValueAge;
+  std::set<Observer*> m_Observers;
 
 #ifdef PDF_ENABLE_XFA
   mutable CXFA_FFWidget* m_hMixXFAWidget;
   mutable CXFA_FFWidgetHandler* m_pWidgetHandler;
 #endif  // PDF_ENABLE_XFA
 };
 
 #ifdef PDF_ENABLE_XFA
 class CPDFSDK_XFAWidget : public CPDFSDK_Annot {
  public:
@@ skipping 161 matching lines @@
                                      const CPDFSDK_Annot* p2);
 
   TabOrder m_eTabOrder;
   CPDFSDK_PageView* m_pPageView;
   CFX_ByteString m_sType;
   CFX_ByteString m_sSubType;
   std::vector<CPDFSDK_Annot*> m_Annots;
 };
 
 #endif  // FPDFSDK_INCLUDE_FSDK_BASEFORM_H_