www.pudn.com > TreePropSheetEx.rar > memdc.h

#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 
// 
// This class implements a memory Device Context which allows 
// flicker free drawing. 
 
class CMemDC : public CDC { 
private:	 
	CBitmap		m_bitmap;		// Offscreen bitmap 
	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: 
	 
	CMemDC(CDC* pDC, const CRect* pRect = NULL) : CDC() 
	{ 
		ASSERT(pDC != NULL);  
 
		// Some initialization 
		m_pDC = pDC; 
		m_oldBitmap = NULL; 
		m_bMemDC = !pDC->IsPrinting(); 
 
		// 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 = SelectObject(&m_bitmap); 
 
			SetMapMode(pDC->GetMapMode()); 
 
			SetWindowExt(pDC->GetWindowExt()); 
			SetViewportExt(pDC->GetViewportExt()); 
 
			pDC->DPtoLP(&m_rect); 
			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; 
		} 
 
		// 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. 
			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; 
		}	 
	} 
	 
	// Allow usage as a pointer	 
	CMemDC* operator->()  
	{ 
		return this; 
	}	 
 
	// Allow usage as a pointer	 
	operator CMemDC*()  
	{ 
		return this; 
	} 
}; 
 
#endif