#ifndef _MEMDC_H_
#define _MEMDC_H_

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

class CMemDC : public CDC {
private:
	CBitmap* m_oldBitmap; // 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.
public:
	CBitmap m_bitmap; // Offscreen bitmap
	CMemDC(CDC* pDC, const CRect& rcBounds) : CDC(), m_oldBitmap(NULL), m_pDC(pDC)
	{
		ASSERT(m_pDC != NULL); // If you asserted here, you passed in a NULL CDC.
		
		m_bMemDC = !pDC->IsPrinting();
		

		if (m_bMemDC){
			// Create a Memory DC
			CreateCompatibleDC(pDC);
			pDC->GetClipBox(&m_rect);
			m_bitmap.CreateCompatibleBitmap(pDC, m_rect.Width(), m_rect.Height());
			m_oldBitmap = SelectObject(&m_bitmap);
			SetWindowOrg(m_rect.left, m_rect.top);

			//CBrush *bkg = new CBrush(RGB(255,255,255));
			//FillRect(m_rect, bkg);
			PatBlt(m_rect.left, m_rect.top, m_rect.Width(), m_rect.Height(), WHITENESS);

			//delete(bkg);
		} 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;
		}
	}
	
	~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.
			SelectObject(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 = m_hAttribDC = NULL;
		}
	}


	CMemDC(CDC* pDC, CBitmap* pBmp)
	{
		// This	is the device context constructor, used	for	normal device contexts
		// crFill =	color to fill background with
		// pBmp	- bitmap to	be drawn to

		ASSERT_VALID(pDC);
		m_pDC =	pDC;
		m_oldBitmap =	NULL;

		// Memory DC is	we're not printing
		m_bMemDC = !pDC->IsPrinting();

		if (m_bMemDC)
		{
			// Step	1 -	Create a Memory	DC
			CreateCompatibleDC(pDC);

			// Step	2 -	Get	the	clip area 
			pDC->GetClipBox(&m_rect);
			pDC->LPtoDP(&m_rect);

			// BITMAP CASE 1: User passed bitmap, use it
			if (pBmp !=	NULL)
				m_oldBitmap =	SelectObject(pBmp);
			// BITMAP CASE 2: Create our own bitmap
			else
			{
				m_bitmap.CreateCompatibleBitmap(pDC, m_rect.Width(),	m_rect.Height());
				m_oldBitmap =	SelectObject(&m_bitmap);
			}

			SetMapMode(pDC->GetMapMode());
			pDC->DPtoLP(&m_rect);

			SetWindowOrg(m_rect.left,	m_rect.top);

			// Step	3 -	"Erase"	the	background using passed	color

			PatBlt(m_rect.left, m_rect.top,	m_rect.Width(), m_rect.Height(), WHITENESS);
		}
		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;
		}
	}
	
	// Allow usage as a pointer
	CMemDC* operator->() {return this;}
	
	// Allow usage as a pointer
	operator CMemDC*() {return this;}
};

#endif