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Posted 19 Nov 2002

DirectUI Window as in XP system folders

A control to show a list of possible tasks just as in XP.
#ifndef _MEMDC_H_
#define _MEMDC_H_

// CMemDC - memory DC
// Author: Keith Rule
// Email:
// 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 {
	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.
	CMemDC(CDC* pDC, const CRect* pRect = NULL) : CDC()

		// Some initialization
		m_pDC = pDC;
		m_oldBitmap = NULL;
		m_bMemDC = !pDC->IsPrinting();

		// Get the rectangle to draw
		if (pRect == NULL) {
		} else {
			m_rect = *pRect;

		if (m_bMemDC) {
			// Create a Memory DC

			m_bitmap.CreateCompatibleBitmap(pDC, m_rect.Width(), m_rect.Height());
			m_oldBitmap = SelectObject(&m_bitmap);



		} 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());
		if (m_bMemDC) {
			// Copy the offscreen bitmap onto the screen.
			m_pDC->BitBlt(m_rect.left,, m_rect.Width(), m_rect.Height(),
				this, m_rect.left,, SRCCOPY);			
			//Swap back the original bitmap.
		} 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;


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About the Author

Alexander Bischofberger
Web Developer
Germany Germany
Ok, a few words about me:

I started programming on the C64 by the "trial and error" method. Years later my parents got their first PC (Atari PC4, AT 8 MHz) where I started with Turbo Pascal. The next steps led to Turbo Pascal for Windows, Visual C++ 1.52c, and finally Visual C++ 6.

I had several chances to code larger projects, e.g.
* stand-alone disc copy station software (Win 3.1) with automatic reboot, disc encryption, ...
* government-used strategic decision system
* MLM marketing tool (
* maintenance for show planning system and other TV software (

A lot of code, tipps and help came from this site for my later projects. Thanks again to all who helped me, even if they don't know it. I'm trying to share code (which is worth sharing) so others can get the help I got (and still need) for everyday problems.

Well, I think that's enough.

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