浅谈 MFC 的子类化机制和该机制的一个应用

 

class CDumpMsgBox : public CWnd 

{

       DECLARE_DYNAMIC(CDumpMsgBox)

 

// Constructors

public:

       CDumpMsgBox();

 

// Attributes

public:

       CEdit m_editDump;         // Dumping edit control added to the message box.

 

       CMemFile m_fileDump;   // Dumping context's target file.

       CDumpContext m_dumpContext;          // The dump context object.

 

// Operations

public:

       int DoMessageBox(UINT nIDPrompt, UINT nType = MB_OK, UINT nIDHelp = (UINT)-1);

 

       AFX_INLINE CDumpContext& GetDumpContext()     {     return m_dumpContext; };

       AFX_INLINE void RemoveAll()                                 {     m_fileDump.SetLength(0);    };

 

// Implementations

public:

       virtual ~CDumpMsgBox();

       virtual void DoDumpObject(CObject* pDumpObject);

       virtual int DoMessageBox(LPCTSTR lpszText, UINT nType = MB_OK, UINT nIDHelp = 0);

 

#ifdef _DEBUG

       virtual void AssertValid() const;

       virtual void Dump(CDumpContext& dc) const;

#endif

 

protected:

       virtual BOOL OnDumpOut(LPSTR pszDumpBuffer, UINT nBufferSize);

 

// Overrides

       // ClassWizard generated virtual function overrides

       //{{AFX_VIRTUAL(CChildFrame)

       //}}AFX_VIRTUAL

 

// Generated message map functions

protected:

       //{{AFX_MSG(CMainFrame)

       afx_msg int OnCreate(LPCREATESTRUCT lpCreateStruct);

        // NOTE - the ClassWizard will add and remove member functions here.

        //    DO NOT EDIT what you see in these blocks of generated code!

       //}}AFX_MSG

       DECLARE_MESSAGE_MAP()

};

 

// Identify of the edit control CDumpMsgBox::m_editDump.

#define IDC_DUMPMSGBOX_EDITBOX           1047

 

//////////////////////////////////////////////////////////////////////

// CDumpMsgBox

 

IMPLEMENT_DYNAMIC(CDumpMsgBox, CWnd)

 

BEGIN_MESSAGE_MAP(CDumpMsgBox, CWnd)

       //{{AFX_MSG_MAP(CWnd)

        // NOTE - the ClassWizard will add and remove mapping macros here.

        //    DO NOT EDIT what you see in these blocks of generated code !

       ON_WM_CREATE()

       //}}AFX_MSG_MAP

END_MESSAGE_MAP()

 

////////////////////////////////////////////////////////////////////////////

// CDumpMsgBox construction/destruction

 

CDumpMsgBox::CDumpMsgBox() : m_fileDump(512),

                                            m_dumpContext(&m_fileDump)

{

       m_fileDump.AssertValid();

 

       m_dumpContext.SetDepth(1);

       m_dumpContext << "Dump From Objects: \r\n========================================\r\n";

}

 

CDumpMsgBox::~CDumpMsgBox()

{

       BYTE* pszDumpBuffer = (BYTE*)m_fileDump.Detach();

 

       if (pszDumpBuffer)

        free(pszDumpBuffer);

 

       m_dumpContext.m_pFile = NULL;

}

 

////////////////////////////////////////////////////////////////////////////

// CDumpMsgBox Implementations

 

int CDumpMsgBox::OnCreate(LPCREATESTRUCT lpcs)

{

       if (CWnd::OnCreate(lpcs) == -1)

       {

        TRACE0("CDumpMsgBox::OnCreate error: call CWnd::OnCreate return FALSE.\n");

        return -1;

       }

      

       CRect rectBox;

       GetWindowRect(&rectBox);

 

       // adjust message box sizes to fill a dump edit control.

       if (rectBox.Width() < 350)

        rectBox.right = rectBox.left + 350;

       rectBox.bottom += 130;

       MoveWindow(&rectBox, FALSE);

 

       // create edit control to display dump texts

       ScreenToClient(&rectBox);

       CRect rectEdit(rectBox.left + 8, rectBox.bottom - 132,

        rectBox.right - 8, rectBox.bottom - 8);

       if (!m_editDump.Create(WS_CHILD | WS_VISIBLE | WS_VSCROLL | WS_TABSTOP |

        ES_MULTILINE | ES_READONLY | ES_AUTOVSCROLL,

        rectEdit, this, IDC_DUMPMSGBOX_EDITBOX))

       {

        TRACE0("CDumpMsgBox::OnCreate error: m_editDump.Create return FALSE.\n");

        return -1;

       }

 

       // set WS_EX_CLIENTEDGE style to edit control (let it has a drop edge)

       m_editDump.ModifyStyleEx(0L, WS_EX_CLIENTEDGE,

        SWP_NOSIZE | SWP_NOMOVE | SWP_NOZORDER | SWP_NOACTIVATE | SWP_FRAMECHANGED);

 

       // set edit control's font to DEFAULT_GUI_FONT.

       CFont Font;

       Font.Attach((HFONT)GetStockObject(DEFAULT_GUI_FONT));

       m_editDump.SetFont(&Font);

 

       // write end-dump text and flush all data to file

       m_dumpContext << "\r\n========================================\r\nDump End";

       m_dumpContext.Flush();

 

       m_fileDump.Write("\0", sizeof(CHAR));

 

       UINT nBufferSize = m_fileDump.GetLength();

       LPSTR pszDumpBuffer = (LPSTR)m_fileDump.Detach();

 

       if (!OnDumpOut(pszDumpBuffer, nBufferSize))

       {

        TRACE0("CDumpMsgBox::OnCreate error: OnDumpOut return FALSE.\n");

 

        m_fileDump.Attach((BYTE*)pszDumpBuffer, nBufferSize, 512);

        return -1;

       }

 

       // attach used dump buffer for next dump.

       m_fileDump.Attach((BYTE*)pszDumpBuffer, nBufferSize, 512);

 

       return 0;

}

 

未完，剩余部分请参考 浅谈 MFC 的子类化机制和该机制的一个应用（2）。