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#ifndef _MEMDC_H_
#define _MEMDC_H_

//////////////////////////////////////////////////
// CMemDC - memory DC
//
// Author: Keith Rule
// Email:  keithr@europa.com
// Copyright 1996-2002, 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. - KR
//
//           11/3/99 Fixed most common complaint. Added
//                   background color fill. - KR
//
//           11/3/99 Added support for mapping modes other than
//                   MM_TEXT as suggested by Lee Sang Hun. - KR
//
//           02/11/02 Added support for CScrollView as supplied
//                    by Gary Kirkham. - KR
//
//			 06/21/02 Modified to compile with WTL
//					  Rama Krishna			
// This class implements a memory Device Context which allows
// flicker free drawing.

class CMemDC : public CDC {
private:	
	WTL::CBitmap		m_bitmap;		// Offscreen bitmap
	HBITMAP	m_oldBitmap;	// bitmap originally found in CMemDC
	WTL::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.
public:
	
	CMemDC(WTL::CDC* pDC, const CRect* pRect = NULL) : CDC()
	{
		ATLASSERT(pDC != NULL); 

		// Some initialization
		m_pDC = pDC;
		m_oldBitmap = NULL;
		m_bMemDC = TRUE;

		// Get the rectangle to draw
		if (pRect == NULL) {
			pDC->GetClipBox(&m_rect);
		} else {
			m_rect = *pRect;
		}

		if (m_bMemDC) {
			// Create a Memory DC
			CreateCompatibleDC(*pDC);
			pDC->LPtoDP(&m_rect);

			m_bitmap.CreateCompatibleBitmap(*pDC, m_rect.Width(), m_rect.Height());
			m_oldBitmap = SelectBitmap(m_bitmap);

			SetMapMode(pDC->GetMapMode());
			
			CSize size;
			pDC->GetWindowExt(&size);
			SetWindowExt(size.cx, size.cy);
			
			pDC->GetViewportExt(&size);
			SetViewportExt(size.cx, size.cy);

			pDC->DPtoLP(&m_rect);
			SetWindowOrg(m_rect.left, m_rect.top);
		} 

		// Fill background 
		FillSolidRect(m_rect, pDC->GetBkColor());
	}
	
	~CMemDC()	
	{		
		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.
			SelectBitmap(m_oldBitmap);		
		} 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 = NULL;
		}	
	}
	
	// Allow usage as a pointer	
	CMemDC* operator->() 
	{
		return this;
	}	

	// Allow usage as a pointer	
	operator CMemDC*() 
	{
		return this;
	}
};

#endif