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// MemDC.cpp: implementation of the CMemDC class. 
// 
////////////////////////////////////////////////////////////////////// 
 
#include "stdafx.h" 
#include "MemDC.h" 
 
#ifdef _DEBUG 
#undef THIS_FILE 
static char THIS_FILE[]=__FILE__; 
#define new DEBUG_NEW 
#endif 
 
////////////////////////////////////////////////////////////////////// 
// Construction/Destruction 
////////////////////////////////////////////////////////////////////// 
 
CMemDC::CMemDC(CDC* pDC):CDC() 
{ 
 
	ASSERT(pDC!=NULL); 
 
	m_pDC=pDC; 
	m_pOldBitmap=NULL; 
	m_bMemDC=!pDC->IsPrinting(); 
	// 
	if(m_bMemDC) 
	{ 
		pDC->GetClipBox(&m_rect); 
		CreateCompatibleDC(pDC); 
		m_bitmap.CreateCompatibleBitmap(pDC,m_rect.Width(),m_rect.Height()); 
		m_pOldBitmap=SelectObject(&m_bitmap); 
		SetWindowOrg(m_rect.left,m_rect.top); 
	} 
	else		//为相关的现有设备准备打印 
	{ 
		m_bPrinting=pDC->m_bPrinting; 
		m_hDC=pDC->m_hDC; 
		m_hAttribDC=pDC->m_hAttribDC; 
	} 
 
} 
 
CMemDC::~CMemDC() 
{ 
	if(m_bMemDC) 
	{ 
		m_pDC->BitBlt(m_rect.left,m_rect.top,m_rect.Width(),m_rect.Height(), 
			this,m_rect.left,m_rect.top,SRCCOPY); 
		SelectObject(m_pOldBitmap); 
	} 
	else 
	{ 
		m_hDC=m_hAttribDC=NULL; 
	} 
 
} 
//	CMemDC* operator->(){return this;} 
//	operator CMemDC*(){return this;}