Very Simple Print Preview without the Doc/View Architecture

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Introduction

The Doc/View architecture in MFC is not the fastest way to create a simple print preview. This article will explain how to create your own print preview.

MFC Doc/View is designed to make the MSVC programmers get their work done in minutes, including print preview. Sometimes, we do not need to use Doc/View framework but we really do need its print-preview power.

The key to Print Preview is in the following functions:

• CreateCompatibleBitmap
• CreateCompatibleDC
• GetDeviceCaps
• GetTextExtent

Besides those four functions, Print Preview needs a function that will work for scaling and painting on the screen DC.

Luckily, we have StretchBlt and BitBlt ready to do the dirty work, but sometimes StretchBlt might need to be replaced by your favourite routine (for dithering, filtering, antialiasing, etc.).

The function to perform print preview in a window is as follows:

// pWnd is the window you wish to show the preview
// Design and implementation cinoban@yahoo.com 13 Jan 2000 15:14
//	Danang Suharno
//	Ngadinegaran MJ 3/156
//	Yogyakarta 55143
//	Indonesia
//
void PrintPreview(CWnd *pWnd) 
{
	CString strWords;
	CWnd* pWnd = GetDlgItem(IDC_STATIC_PREVIEW); // This is a rectangle control
	CDC* dc;
	CDC memoriDC;
	CBitmap memBMP;
	CBitmap* pOldBMP;
	CFont fnt;
	CFont* pOldFnt;
	CRect rect;
	CRect rectMemory;
	CSize zMetrix;

	//
	//
	//
	CPrintDialog pdlg(FALSE);
	DOCINFO di;
	CDC prnDC;

	di.cbSize = sizeof(DOCINFO);
	di.lpszDocName = "This string will appear in Printer Queue";
	di.lpszOutput = NULL;     
	di.lpszDatatype = NULL;
	di.fwType = 0;

	//
	// Get current printer setting
	//
	pdlg.GetDefaults();
	
	//
	dc = pWnd->GetDC();
	pWnd->GetClientRect(&rect);

	// DC printer???
	if( !prnDC.Attach(pdlg.GetPrinterDC()) )
		AfxMessageBox("Invalid Printer DC");

	memoriDC.CreateCompatibleDC(&prnDC); // Create DC for Preview

	//
	// Get the resolution of Screen and Current Default Printer
	//
	int iPrnX = prnDC.GetDeviceCaps(HORZRES);
	int iPrnY = prnDC.GetDeviceCaps(VERTRES);
	int iMonX = dc->GetDeviceCaps(HORZRES); // Device Target is Monitor
	int iMonY = dc->GetDeviceCaps(VERTRES);

	rectMemory.top = 0;
	rectMemory.left = 0;
	rectMemory.bottom = iPrnY;
	rectMemory.right = iPrnX;

	//
	// Create a Memory Bitmap that is compatible with the Printer DC
	// then select or make the bitmap as current GDI active object
	//
	memBMP.CreateCompatibleBitmap(&prnDC, rectMemory.Width(), rectMemory.Height());
	pOldBMP = memoriDC.SelectObject(&memBMP);

	//
	// Clear memory DC or in other words
	// paint the bitmap with white colour and transparent text
	//
	memoriDC.SetBkMode(TRANSPARENT);
	memoriDC.SetTextColor(RGB(0, 0, 0));
	memoriDC.PatBlt(0, 0, rectMemory.Width(), rectMemory.Height(), WHITENESS);

	//
	// Prepare the font
	//
	int iPointz = 100;
	fnt.CreatePointFont(iPointz, "OCR A", &memoriDC);
	strWords.Format("This is line number    ");        // Test string
	pOldFnt = memoriDC.SelectObject(&fnt);
	zMetrix = memoriDC.GetTextExtent(strWords);
	int iPos = 0;

	//
	// Write string or Paint something
	//
	int iMaksimal = 0;
	int iLineHeight = 1;
	int iLoop;
	CString strPuncak;

	//
	// Calculate how many lines we could fit
	//
	for(iLoop = 1; iLoop < 100; iLoop++)
	{
		if( ((zMetrix.cy+iLineHeight)*iLoop) < iPrnY ) 
			iMaksimal++;
	}

	strPuncak.Format("Maximum Amount of line(s) for %d points are %d lines", 
		iPointz, iMaksimal);
	
	//
	//
	//
	for(iLoop = 0; iLoop < iMaksimal; iLoop++)
	{
		strWords.Format("This is line %d", iLoop);
		memoriDC.TextOut(0, iLoop*(zMetrix.cy+iLineHeight), strWords);
	}
	
	//
	// Reseting font
	//
	memoriDC.SelectObject(pOldFnt);

	//
	// Calculate ratio
	//
	float fXRatio = (float) iMonX/iPrnX;
	float fYRatio = (float) iMonY/iPrnY;	
	
	//  iLebar = Width
	//  iTinggi = Height
	//  iXPosisiPreview = horizontal location of preview
	//  iYPosisiPreview = vertical location of preview
	//
	int iLebar = rect.Width()*fXRatio;
	int iTinggi = rect.Height()*fYRatio;
	int iXPosisiPreview = (rect.Width() - iLebar)/2;
	int iYPosisiPreview = (rect.Height() - iTinggi)/2;
	CPen pen(PS_SOLID, 2, RGB(255, 0, 0));
	CPen* pOldPen;

	//
	// Create an outline
	//	
	pOldPen = dc->SelectObject(&pen);
	dc->Rectangle(iXPosisiPreview, iYPosisiPreview,iXPosisiPreview + iLebar + 2,
		iYPosisiPreview + iTinggi + 2);
	dc->SelectObject(pOldPen);

	//
	// Put in the box
	//
	dc->StretchBlt(iXPosisiPreview , iYPosisiPreview, iLebar, iTinggi,
		&memoriDC, 0, 0, rectMemory.Width(), rectMemory.Height(), SRCCOPY);
	
	//
	// Cleaning Up
	//
	fnt.DeleteObject();
	memoriDC.SelectObject(pOldBMP);
	memoriDC.DeleteDC();
	memBMP.DeleteObject();
	prnDC.Detach();

	//
	pWnd->ReleaseDC(dc);
}

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