memdc.h

一个小的文件分割器。

#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:  [e-mail]
// 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_)