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memdc.h

#if !defined(AFX_MEMDC_H__75FED539_1CA2_4C25_920E_ABD04348B248__INCLUDED_)
#define AFX_MEMDC_H__75FED539_1CA2_4C25_920E_ABD04348B248__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000
// MemDC.h : header file
//
//×¢Òâ:±¾Àà±¾²»ÊʺϻæÖƶ¯»­Ê±¶¯Ì¬´´½¨
/////////////////////////////////////////////////////////////////////////////

class CMemDC : public CDC//´ÓCDCÀ๫ÓÐÅÉÉú
{
// Construction
public:
 CMemDC(UINT heigh,UINT width);//¹¹Ô캯Êý,´«Èë¸ßºÍ¿í

// Attributes
public:

// Implementation
public:
 HBITMAP CloseMemDC();//¹«ÓгÉÔ±º¯Êý,
 virtual ~CMemDC();//Îö¹¹º¯Êý,Ð麯Êý

private:
 CBitmap  m_bitmap;      //˽ÓÐÊý¾Ý³ÉÔ±
    CBitmap* m_pOldBitmap;//˽ÓÐÊý¾Ý³ÉÔ±
 UINT m_bmpHeigh;//˽ÓÐÊý¾Ý³ÉÔ±:¸ß
 UINT m_bmpWidth;//˽ÓÐÊý¾Ý³ÉÔ±:¿í
};

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

//{{AFX_INSERT_LOCATION}}
// Microsoft Visual C++ will insert additional declarations immediately before the previous line.

#endif // !defined(AFX_MEMDC_H__75FED539_1CA2_4C25_920E_ABD04348B248__INCLUDED_)

memdc.cpp

// MemDC.cpp : implementation file
//

#include "stdafx.h"
#include "MemDC.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

/////////////////////////////////////////////////////////////////////////////
// CMemDC

CMemDC::CMemDC(UINT width,UINT heigh)
{  
 CDC *pDC = CDC::FromHandle(::GetDC(GetDesktopWindow()));
 ASSERT(pDC != NULL);
    CreateCompatibleDC(pDC);
 m_bmpWidth = width;
 m_bmpHeigh = heigh;
    m_bitmap.CreateCompatibleBitmap(pDC, m_bmpWidth, m_bmpHeigh);
    m_pOldBitmap = SelectObject(&m_bitmap);
 ::ReleaseDC(GetDesktopWindow(), pDC->m_hDC);
}

CMemDC::~CMemDC()
{
 SelectObject(m_pOldBitmap);
 m_bitmap.DeleteObject();
 DeleteDC();
}
/////////////////////////////////////////////////////////////////////////////
// CMemDC message handlers

HBITMAP CMemDC::CloseMemDC()
{
 SelectObject(m_pOldBitmap);
 return (HBITMAP)(m_bitmap.Detach());
}