memdc.h

Visual C++下的界面设计

#ifndef _MEMDC__H
#define _MEMDC__H

//////////////////////////////////////////////////
// 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.
//
// This class implements a memory Device Context

class CMemDC : public CDC 
{
private:
        CBitmap*        m_bitmap;
        CBitmap*        m_oldBitmap;
        CDC*            m_pDC;
        CRect           m_rcBounds;
public:
        CMemDC(CDC* pDC, const CRect& rcBounds) : CDC()
        {
                CreateCompatibleDC(pDC);
                m_bitmap = new CBitmap;
                m_bitmap->CreateCompatibleBitmap(pDC, rcBounds.Width(), rcBounds.Height());
                m_oldBitmap = SelectObject(m_bitmap);
                m_pDC = pDC;
                m_rcBounds = rcBounds;
        }

        ~CMemDC() 
        {
                m_pDC->BitBlt(m_rcBounds.left, m_rcBounds.top, m_rcBounds.Width(), m_rcBounds.Height(), 
                                        this, m_rcBounds.left, m_rcBounds.top, SRCCOPY);
                SelectObject(m_oldBitmap);

                if (m_bitmap != NULL)
					delete m_bitmap;
        }

        CMemDC* operator->() 
		{
                return this;
        }
};


#endif