The Practical Guide to Multithreading - Part 2

// LargeFileReading_MFCDlg.cpp : implementation file
//

#include "stdafx.h"
#include "LargeFileReading_MFC.h"
#include "LargeFileReadingNoSpell.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#endif



CLargeFileReadingDlg::CLargeFileReadingDlg(CWnd* pParent /*=NULL*/)
	: CDialog(CLargeFileReadingDlg::IDD, pParent)
{
	m_hIcon = AfxGetApp()->LoadIcon(IDR_MAINFRAME);
}

void CLargeFileReadingDlg::DoDataExchange(CDataExchange* pDX)
{
	CDialog::DoDataExchange(pDX);
	
	DDX_Control(pDX, IDC_WHOLE_TEXT, m_cWholeFile);
	DDX_Control(pDX, IDC_READ_PROGRESS, m_cReadProgress);
}

BEGIN_MESSAGE_MAP(CLargeFileReadingDlg, CDialog)
	ON_WM_PAINT()
	ON_WM_QUERYDRAGICON()
	//}}AFX_MSG_MAP
	ON_BN_CLICKED(IDC_OPEN_FILE, &CLargeFileReadingDlg::OnBnClickedOpenFile)
	ON_MESSAGE(WM_TEXT_READ_MESSAGE, OnTextReadMessage)
END_MESSAGE_MAP()


// CLargeFileDlg message handlers

BOOL CLargeFileReadingDlg::OnInitDialog()
{
	CDialog::OnInitDialog();

	// Set the icon for this dialog.  The framework does this automatically
	//  when the application's main window is not a dialog
	SetIcon(m_hIcon, TRUE);			// Set big icon
	SetIcon(m_hIcon, FALSE);		// Set small icon


	m_cWholeFile.SetTextMode( TM_PLAINTEXT | TM_SINGLELEVELUNDO);


	return TRUE;  // return TRUE  unless you set the focus to a control
}

// If you add a minimize button to your dialog, you will need the code below
//  to draw the icon.  For MFC applications using the document/view model,
//  this is automatically done for you by the framework.

void CLargeFileReadingDlg::OnPaint()
{
	if (IsIconic())
	{
		CPaintDC dc(this); // device context for painting

		SendMessage(WM_ICONERASEBKGND, reinterpret_cast<WPARAM>(dc.GetSafeHdc()), 0);

		// Center icon in client rectangle
		int cxIcon = GetSystemMetrics(SM_CXICON);
		int cyIcon = GetSystemMetrics(SM_CYICON);
		CRect rect;
		GetClientRect(&rect);
		int x = (rect.Width() - cxIcon + 1) / 2;
		int y = (rect.Height() - cyIcon + 1) / 2;

		// Draw the icon
		dc.DrawIcon(x, y, m_hIcon);
	}
	else
	{
		CDialog::OnPaint();
	}
}

// The system calls this function to obtain the cursor to display while the user drags
//  the minimized window.
HCURSOR CLargeFileReadingDlg::OnQueryDragIcon()
{
	return static_cast<HCURSOR>(m_hIcon);
}

UINT LargeFileReaderThread(void* pArg)
{
	CLargeFileReadingDlg* pDialog = static_cast<CLargeFileReadingDlg*> ( pArg );

	pDialog->LargeFileReaderProc();

	return 0;
}

void CLargeFileReadingDlg::LargeFileReaderProc()
{
	// Though file pointer be at beginning, we set it anyway.
	m_cTextFile.SeekToBegin();

	CString strOneLine;

	// Though using TCHAR* would be more efficeint than using CString object.
	// But I am using CString for easiness.
	
	
	//pBuffer->SetLength(	)

	CString* pBuffer = new CString();
	int nLines=0;

	while (m_cTextFile.ReadString(strOneLine))
	{
		(*pBuffer) += strOneLine + _T("\n");	

		if(++nLines>10000)
		{
			PostMessage(WM_TEXT_READ_MESSAGE, (WPARAM)pBuffer, FALSE);
			pBuffer = new CString();
			nLines=0;
		}
	}
	// Send the last set, specifying TRUE that thread finished work.
	PostMessage(WM_TEXT_READ_MESSAGE, (WPARAM)pBuffer, TRUE);

	// AfxMessageBox(_T("done"));
}

LRESULT CLargeFileReadingDlg::OnTextReadMessage(WPARAM wLineInfo, LPARAM lParam)
{

	// Updating the (Rich) text box doesnt work well as I expected
	// Some solution might exist for better approach for 'appending'
	// text to the text/richtext control, than the one I used here.
	// But I found out that textbox uses ARRAY of characters, but
	// richtext doesnt. That's why rich text is somewhat faster.
	// Few smart editors in market implement their own 'text' controls.

	CString* pString = (CString*)wLineInfo;

	int nTextLen = m_cWholeFile.GetWindowTextLength();
	m_cWholeFile.SetSel(nTextLen, nTextLen);

	m_cWholeFile.ReplaceSel(*pString);

	nTextLen = m_cWholeFile.GetTextLength();
	m_cReadProgress.SetPos(nTextLen/1024);

	// LPARAM would be set to TRUE, if thread has finished reading
	// Thus we can enable controls
	if(lParam == TRUE)
	{
		GetDlgItem(IDC_OPEN_FILE)->EnableWindow();
		m_cReadProgress.ShowWindow(SW_HIDE);
	}



//	m_cWholeFileR.SetSel(0,0);

	delete pString;

	return 0;
}

void CLargeFileReadingDlg::OnBnClickedOpenFile()
{
	CFileDialog fdOpen(TRUE, _T(".TXT"), NULL, 6, 
		_T("Text Files|*.txt;*.log||") );

	if( fdOpen.DoModal() != IDOK )
		return;

	if (m_cTextFile.m_pStream)
	{
		m_cTextFile.Close();
		m_cTextFile ;
	}
	
	
	m_cTextFile.Open(fdOpen.GetPathName(), CFile::typeText | CFile::modeRead | CFile::shareDenyNone);

//	m_cWholeFileR.set;
	m_nFileSize = m_cTextFile.GetLength();


	m_cWholeFile.SetWindowText( _T(""));

	// Update progress on every 1KB
	m_cReadProgress.SetRange32(1,static_cast<int> (m_nFileSize/1024) );
	m_cReadProgress.ShowWindow(SW_SHOW);

	GetDlgItem(IDC_OPEN_FILE)->EnableWindow(false);

	AfxBeginThread(LargeFileReaderThread, this);
}