www.pudn.com > snatl.rar > MemDC.h

#if !defined(AFX_MEMDC_H__CA1D3541_7235_11D1_ABBA_00A0243D1382__INCLUDED_) 
#define AFX_MEMDC_H__CA1D3541_7235_11D1_ABBA_00A0243D1382__INCLUDED_ 
 
#if _MSC_VER >= 1000 
#pragma once 
#endif // _MSC_VER >= 1000 
// MemDC.h : header file 
// 
 
////////////////////////////////////////////////// 
// CMemDC - memory DC 
// 
// Author: Keith Rule 
// Email:  keithr@europa.com 
// Copyright 1996-1997, Keith Rule 
// 
// You may freely use or modify this code provided this 
// Copyright is included in all derived versions. 
// 
// History - 10/3/97 Fixed scrolling bug. 
//                   Added print support. 
//           25 feb 98 - fixed minor assertion bug 
// 
// This class implements a memory Device Context 
 
class CMemDC1 : public CDC 
{ 
public: 
	 
	// constructor sets up the memory DC 
	CMemDC1(CDC* pDC) : CDC() 
    { 
		ASSERT(pDC != NULL); 
		 
		m_pDC = pDC; 
		m_pOldBitmap = NULL; 
        m_bMemDC = !pDC->IsPrinting(); 
		 
        if (m_bMemDC)	// Create a Memory DC 
		{ 
            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		// Make a copy of the relevent parts of the current DC for printing 
		{ 
            m_bPrinting = pDC->m_bPrinting; 
            m_hDC		= pDC->m_hDC; 
            m_hAttribDC = pDC->m_hAttribDC; 
        } 
	} 
	 
	// Destructor copies the contents of the mem DC to the original DC 
	~CMemDC1() 
    { 
		if (m_bMemDC) {	 
			// Copy the offscreen bitmap onto the screen. 
			m_pDC->BitBlt(m_rect.left, m_rect.top, m_rect.Width(), m_rect.Height(), 
				this, m_rect.left, m_rect.top, SRCCOPY); 
			 
            //Swap back the original bitmap. 
            SelectObject(m_pOldBitmap); 
		} else { 
			// All we need to do is replace the DC with an illegal value, 
			// this keeps us from accidently deleting the handles associated with 
			// the CDC that was passed to the constructor. 
            m_hDC = m_hAttribDC = NULL; 
		} 
	} 
	 
	// Allow usage as a pointer 
    CMemDC1* operator->() {return this;} 
	 
    // Allow usage as a pointer 
    operator CMemDC1*() {return this;} 
 
private: 
	CBitmap  m_bitmap;		// Offscreen bitmap 
    CBitmap* m_pOldBitmap;	// bitmap originally found in CMemDC 
    CDC*     m_pDC;			// Saves CDC passed in constructor 
    CRect    m_rect;		// Rectangle of drawing area. 
    BOOL     m_bMemDC;		// TRUE if CDC really is a Memory DC. 
}; 
 
///////////////////////////////////////////////////////////////////////////// 
 
//{{AFX_INSERT_LOCATION}} 
// Microsoft Developer Studio will insert additional declarations immediately before the previous line. 
 
#endif // !defined(AFX_MEMDC_H__CA1D3541_7235_11D1_ABBA_00A0243D1382__INCLUDED_)