The Makings Of An OCX Container

Our experiments with OLE 2.0 and patience (With apologies to Mahatma Gandhi)

 main()
 {
  printf("Oye, C World!");
 }
 

 void file(char* s)
 {
  FILE *fp = fopen("d:\\a.txt","a+");
  fprintf(fp,"%s\n",s);
  fclose(fp);
 }
 

• People can make a comfortable living documenting the erring ways of the OLE documentation. A typical example of this is when the documentation talks about the difference between the loaded state and the running state of an OLE server. We are not too sure when we are in which state. May be this is so fuzzy because the writer was loaded with a few pegs of the right stuff.
  
• One line of code is worth a thousand words. But with the OLE documentation, the code fragments blur the issue further. Even a thousand words wouldn't suffice to explain the code fragments.
  
• Marshalling, one of the most important concepts  of OLE is also one that is dealt with most cursorily. Most of the information on marshalling can be had from a separate MS-Word file and not the help. This file too stops short of giving full details. One good joke is it's redeeming feature.
  
• The documentation starts with the concepts of OLE. These are so finely explained that they are the best way to confuse a person; friend and foe alike.
  
• The OLE Automation help addresses one of our grouses: the help never states specifically the steps involved in writing an application. In doing this, however, it leaves out the explanations. Take care of the dimes and the dollars will take care of themselves? Why does Microsoft always do one or the other and never both?

• Whoever wrote it sat with a Thesaurus next to him. Each and every word was looked up and replaced with an obscure equivalent.
  
• There  was  a meeting of  the  core  committee  at Microsoft where they decided that anybody who commits to anything will be lined up and shot dead. Thus, the OLE documentation is extremely evasive. There are several things that should happen but will they happen? Not even Microsoft knows.
  
• There were two guys, Tweedle-dee & Tweedle-dum, involved in the writing process: Tweedle-dee's was a comprehensive work which explained the details. Tweedle-dum specialized in incomprehensible precis-writing. With Tweedle-dum editing the documentation, the results are there for all to see.
  
• Or is it possible that Microsoft in beta-testing OLE 2.0 found that the Russians were the fastest to learn OLE? So they gave them the task of writing the documentation? or was it the Germans? or the Japanese?

Virtual reality

 class zzz
 {
    public:
     virtual void abc(){}
     virtual void pqr(){}
     virtual void xyz(){}
 };
 
 main()
 {
   zzz *b = new zzz;
 } 

`new  zzz'  creates the object  at  memory  locationn 100.  So,  b is equal to 100.  Beginning  at 100 is a pointer, say 200. 200 is where  the V-table begins. From 200 to 203 is a  pointer, 1000, to the function abc(). From 204 to 207  is  the  pointer,  2000,    to  the   function pqr() and 208 to 211 is occupied by a pointer, 3000, to xyz().
If we have a line of code `b-> pqr()' then the compiler  + linker  combination will replace it with a call to  the  function that starts at the address given by `*(*b+4)'. In our case this    address   evaluates   to   2000.    In    general, `*(*b+4*n)'  is the address of the function to  be  called where  `n'  is the index of the virtual  function  in  the class definition. What if we had a line `b-> xyz()'? Then the compiler + linker combination will replace it with a call  to the function starting at the address given by `*(*b+8)'.

 
 class yyy: public zzz
 {
   public: 
     virtual void lmn(){}
     virtual void efg(){}
     void xyz(){}
     void pqr(){}
 };

Face to face with an interface

Imitation is the best form of flattery

A taste of things to come

Program 1

 #include < afxwin.h> 
 #include < afxext.h> 
 #include < ole2.h> 
 #include < ole2ui.h> 
 #include < dispatch.h> 
 #include < initguid.h> 
 #include < olectl.h> 
 #include "resource.h"
 
 //  Structure used to store details about the properties  of  an OCX
 
 struct PData{
   char *z_sPropName;
   DISPID z_lDispID;
   VARTYPE z_nPropType;
   BOOL z_nPtr;
   PData *z_pNext;
 };
 
 // Structure used to store details about the properties/  events of an OCX
 
 struct FData{
   char *z_sFName;
   char **z_sPName;
   DISPID z_lDispID;
   int z_nNumParams;
   VARTYPE *z_pPTypes;
   VARTYPE z_nRType;
   BOOL z_nPtr;
   FData *z_pNext;
 };
 
 // Structure to store code for an event
 
 struct CData{
   long z_lDispID;
   char **z_sFunction;
   int z_nCount;  
   CData *z_pNext;
 };
 
 // Array used for display and comparison for the data types
 
 char  *z_VarType[] = {"VT_EMPTY","VT_NULL","VT_I2","VT_I4","VT_R4","VT_R8",
 "VT_CY","VT_DATE","VT_BSTR","VT_DISPATCH","VT_ERROR","VT_BOOL",
 "VT_VARIANT","VT_UNKNOWN","VT_I1","VT_UI1","VT_UI2","VT_UI4","VT_I8",
 "VT_UI8","VT_INT","VT_UINT","VT_VOID","VT_HRESULT","VT_PTR", "VT_SAFEARRAY",
"VT_CARRAY","VT_USERDEFINED","VT_LPSTR", "VT_LPWSTR","VT_FILETIME",
"VT_BLOB","VT_STREAM","VT_STORAGE","VT_STREAMED_OBJECT",
"VT_STORED_OBJECT","VT_BLOB_OBJECT","VT_CF","VT_CLSID"
 };                             
 
 // OLE Interfaces
 
 class MOleClientSite 
 {
   public:
     virtual  void* _export _cdecl  QueryInterface(REFIID,void**) {return 0;}
     virtual unsigned long  _export _cdecl A1() {return 0;}
     virtual unsigned long  _export _cdecl A2() {return 0;}
     virtual void* _export _cdecl A3() {return 0;}
     virtual void* _export _cdecl A4() {return 0;}
     virtual void* _export _cdecl A5() {return 0;}   
     virtual void* _export _cdecl A6() {return 0;}  
     virtual void* _export _cdecl A7() {return 0;}    
 };     
 
 class MOleInPlaceFrame
 { 
   public:
     virtual void* _export _cdecl B1() {return 0;}
     virtual unsigned long  _export _cdecl B2() {return 0;}
     virtual unsigned long  _export _cdecl B3() {return 0;}
     virtual void* _export _cdecl B4() {return 0;}
     virtual void* _export _cdecl B5() {return 0;}
     virtual void* _export _cdecl B6() {return 0;}
     virtual void* _export _cdecl B7() {return 0;}
     virtual void* _export _cdecl B8() {return 0;}
     virtual void* _export _cdecl B9() {return 0;} 
     virtual void* _export _cdecl B10() {return 0;}
     virtual void* _export _cdecl B11() {return 0;}
     virtual void* _export _cdecl B12() {return 0;}
     virtual void* _export _cdecl B13() {return 0;}    
     virtual void* _export _cdecl B14() {return 0;}
 };
  
 class MOleInPlaceSite
 {
   public:
     virtual void* _export _cdecl C1() {return 0;}
     virtual unsigned long  _export _cdecl C2() {return 0;}
     virtual unsigned long  _export _cdecl C3() {return 0;}
     virtual void* _export _cdecl GetWindow (HWND *) {return 0;}
     virtual void* _export _cdecl C4() {return 0;}
     virtual void* _export _cdecl C5() {return 0;}
     virtual void* _export _cdecl C6() {return 0;}
     virtual void* _export _cdecl C7() {return 0;}    
     virtual void* _export _cdecl GetWindowContext(IOleInPlaceFrame**,IOleInPlaceUIWindow**,
       RECT*,RECT*,OLEINPLACEFRAMEINFO*) {return 0;}
     virtual void* _export _cdecl C8() {return 0;}       
     virtual void* _export _cdecl C9() {return 0;}      
     virtual void* _export _cdecl C10() {return 0;}                     
     virtual void* _export _cdecl C11() {return 0;}
     virtual void* _export _cdecl C12() {return 0;}
     virtual void* _export _cdecl C13() {return 0;} 
 };
 
 class MDispatch
 {  
   public:
     virtual void* _export _cdecl QueryInterface(REFIID,void  **) {return 0;}
     virtual unsigned long  _export _cdecl  D1() {return 0;}
     virtual unsigned long  _export _cdecl  D2() {return 0;}
     virtual void* _export _cdecl D3() {return 0;}
     virtual void* _export _cdecl D4() {return 0;}
     virtual void* _export _cdecl D5() {return 0;}
     virtual void* _export _cdecl Invoke(DISPID,REFIID,LCID,unsigned short, 
       DISPPARAMS *,VARIANT *,EXCEPINFO *,UINT *);
 };
 
 // MFC classes
 
 class MDialog:public CDialog
 { 
   public:
     MDialog(int) {}
     BOOL OnInitDialog()
     {
       return TRUE;
     }
     void OnOK() {}                                            
     void Select() {}
     void Single() {}          
     void Many() {}                   
     void Save() {}
     void Test1() {}
     void Test(BOOL z_nFlag = 0,CData *z_pCDSearch = 0) {}
     void PropValue() {}                                                        
     void MulProp() {}
     void DispPropPage() {}
     void Accept() {}
     void UIDead() {}
     void AmbBackColor() {}
     void FuncExec(char*) {}
     void Initialize(VARIANT*,char*,int);
     void RetVal(VARIANT *);
     DECLARE_MESSAGE_MAP()
 };                     
 BEGIN_MESSAGE_MAP(MDialog,CDialog)
   ON_LBN_SELCHANGE(IDC_LIST1,Select)
   ON_LBN_SELCHANGE(IDC_LIST2,PropValue)
   ON_BN_CLICKED(IDC_BUTTON1,Single)
   ON_BN_CLICKED(IDC_BUTTON2,Many)
   ON_BN_CLICKED(IDC_BUTTON3,MulProp)
   ON_BN_CLICKED(IDC_TEST,Test1)
   ON_BN_CLICKED(IDC_SAVE,Save)
   ON_BN_CLICKED(IDC_PROPPAGE,DispPropPage)
   ON_BN_CLICKED(IDC_RADIO1,UIDead)
   ON_BN_CLICKED(IDC_RADIO2,UIDead) 
   ON_BN_CLICKED(IDC_BACKCOLOR,AmbBackColor)
   ON_BN_CLICKED(IDC_ACCEPT,Accept)
 END_MESSAGE_MAP()
 
 class MFrameWnd:public CFrameWnd
 {
   public:
     MFrameWnd();                                                        
     void OnPaint() {}
     void OnLButtonDown(UINT,CPoint) {}
     void OnLButtonDblClk(UINT,CPoint) {}
     void OnMouseMove(UINT,CPoint) {}
     void InsertControl();
     void ObjCreate(CLSID);
     void InitArray() {}
     void UserDefined(ITypeInfo*,TYPEDESC*,VARTYPE*) {}
     void Ptr(ITypeInfo*,TYPEDESC*,VARTYPE*) {}
     void SaveToStorage() {}   
     void LoadFromStorage() {}
     void Properties() {}                                      
     void Methods() {}
     void Events() {}
     void Single() {}                                     
     void Multiple() {}                                                                                       
     void Execute() {}
     void PrimaryVerb() {}
     void ShowVerb() {}          
     void OpenVerb() {}
     void HideVerb() {}
     void UIActivateVerb() {}
     void PropertiesVerb() {}                            
     void ChangeProperty() {}
     void AmbientProperties() {}                 
     DECLARE_MESSAGE_MAP()
 };
 BEGIN_MESSAGE_MAP(MFrameWnd,CFrameWnd)
   ON_WM_PAINT()
   ON_WM_LBUTTONDOWN()
   ON_WM_LBUTTONDBLCLK()
   ON_WM_MOUSEMOVE()
   ON_COMMAND(ID_FILE_SAVETOSTORAGE,SaveToStorage)
   ON_COMMAND(ID_FILE_LOADFROMSTORAGE,LoadFromStorage)
   ON_COMMAND(ID_EDIT_INSERTOBJECT,InsertControl)
   ON_COMMAND(ID_EDIT_INVOKESINGLEMETHOD,Single)
   ON_COMMAND(ID_EDIT_INVOKEMULTIPLEMETHODS,Multiple)
   ON_COMMAND(ID_EDIT_EXECUTINGEVENTS,Execute)
   ON_COMMAND(ID_EDIT_CHANGEPROPERTIES,ChangeProperty)
   ON_COMMAND(ID_EDIT_AMBIENTPROPERTIES,AmbientProperties)
   ON_COMMAND(ID_CONTROL_PRIMARY,PrimaryVerb)
   ON_COMMAND(ID_DISPLAY_PROPERTIES,Properties)
   ON_COMMAND(ID_DISPLAY_METHODS,Methods)
   ON_COMMAND(ID_DISPLAY_EVENTS,Events)
   ON_COMMAND(ID_CONTROL_SHOW,ShowVerb)
   ON_COMMAND(ID_CONTROL_OPEN,OpenVerb)
   ON_COMMAND(ID_CONTROL_HIDE,HideVerb)
   ON_COMMAND(ID_CONTROL_UIACTIVE,UIActivateVerb)
   ON_COMMAND(ID_CONTROL_PROPERTIES,PropertiesVerb)
 END_MESSAGE_MAP()
 
 class MWinApp:public CWinApp
 { 
   public:                       
     BOOL InitInstance();
     int ExitInstance();
 };
 
 // Global Variables
 
 int z_nID;                    
 FData *z_pFDSearch;
 CLSID z_PropClsid;
 CMapStringToString  z_sPrgID;
 MFrameWnd *z_pFrameWnd;
 MDialog *z_pDialog; 
 MOleClientSite *z_pOleClientSite;
 MOleInPlaceFrame *z_pInPlaceFrame;
 MOleInPlaceSite *z_pOleInPlaceSite;
 MDispatch *z_pDispatch;
 CRectTracker *z_pTracker;
 COLORREF z_lSelColor;
 BOOL z_nActive,z_nUIDead;
 CLSID z_Clsid,z_ClsidEvents;
 IOleObject *z_pOleObject;
 HWND z_hFWnd;
 CRect z_Rect(50,50,150,200);
 CMenu *z_pMenu;
 CData *z_pCDPrev;
 
 //  starting  pointer  to the link - list that  will  store  the method details
 
 FData *z_pFDFirst;                                                                         
 
 // starting pointer to the link - list that will store the event details
 
 FData *z_pEDFirst;  
 
 // starting pointer to the link - list that will store the event - code 
 
 CData *z_pCDFirst; 
 
 //  starting  pointer  to the link - list that  will  store  the property details
 
 PData *z_pPDFirst; 
 // The Start
 
 MWinApp z_App;
 
 // MFrameWnd Functions
 
 MFrameWnd::MFrameWnd()
 {
   Create(0,"OCX Container");
   z_pMenu = new CMenu;
   z_pMenu-> LoadMenu(IDR_MENU1);
   SetMenu(z_pMenu);             
 }
 
 void MFrameWnd::InsertControl()
 {
   CLSIDFromString("Button.ButtonCtrl.1",&z_Clsid);
   ObjCreate(z_Clsid);
 }
 
 void MFrameWnd::ObjCreate(CLSID z_TempClsid)
 {
   IClassFactory *z_pClassFactory;
 
   CoGetClassObject(z_TempClsid,1,0,IID_IClassFactory,(void**)&z_pClassFactory);
   z_pClassFactory-> CreateInstance(0,IID_IOleObject,(void**)&z_pOleObject);
   z_pOleObject-> DoVerb(OLEIVERB_OPEN ,0,0,-1,m_hWnd,(RECT*)0);
 }    
 
 void MDialog::Initialize(VARIANT *, char *,int)
 {}
 
 void MDialog::RetVal(VARIANT *)
 {}

 // MWinApp Functions
 
 BOOL MWinApp::InitInstance()
 {
   OleInitialize(0);
   z_pFrameWnd = new MFrameWnd;
   m_pMainWnd = z_pFrameWnd;
   z_hFWnd = z_pFrameWnd-> m_hWnd;
   z_pFrameWnd-> ShowWindow(SW_SHOWNORMAL);
   return TRUE;  
 }                       
 
 int MWinApp::ExitInstance()
 {                                     
   OleUninitialize();                     
   CWinApp::ExitInstance();
   return 0;
 }
 
 // MDispatch Functions
 
 void*  _export  _cdecl  MDispatch::Invoke(DISPID,REFIID,LCID,unsigned short,
 DISPPARAMS *,VARIANT *,EXCEPINFO *,UINT *)
 {
   return 0;
 }

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