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Posted 31 Mar 2001

Hooks and DLLs

, 31 Mar 2001
There is a lot of confusion about how to set up and use global hook functions. This essay attempts to clear up some of these issues.
HOTT
hook
hook.dsp
hook.dsw
MouseHook
MouseHook.dsp
res
captured.cur
fleeing.cur
hook.ico
// hookDlg.cpp : implementation file
//

#include "stdafx.h"
#include "hook.h"
#include "MouseHook.h"
#include "HookHelp.h"
#include "Cat.h"
#include "hookDlg.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

static UINT UWM_MOUSEMOVE = ::RegisterWindowMessage(UWM_MOUSEMOVE_MSG);
static UINT UWM_GIVE_HINT = ::RegisterWindowMessage(UWM_GIVE_HINT_MSG);

/////////////////////////////////////////////////////////////////////////////
// CAboutDlg dialog used for App About

class CAboutDlg : public CDialog
{
public:
	CAboutDlg();

// Dialog Data
	//{{AFX_DATA(CAboutDlg)
	enum { IDD = IDD_ABOUTBOX };
	//}}AFX_DATA

	// ClassWizard generated virtual function overrides
	//{{AFX_VIRTUAL(CAboutDlg)
	protected:
	virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support
	//}}AFX_VIRTUAL

// Implementation
protected:
	//{{AFX_MSG(CAboutDlg)
	//}}AFX_MSG
	DECLARE_MESSAGE_MAP()
};

CAboutDlg::CAboutDlg() : CDialog(CAboutDlg::IDD)
{
	//{{AFX_DATA_INIT(CAboutDlg)
	//}}AFX_DATA_INIT
}

void CAboutDlg::DoDataExchange(CDataExchange* pDX)
{
	CDialog::DoDataExchange(pDX);
	//{{AFX_DATA_MAP(CAboutDlg)
	//}}AFX_DATA_MAP
}

BEGIN_MESSAGE_MAP(CAboutDlg, CDialog)
	//{{AFX_MSG_MAP(CAboutDlg)
		// No message handlers
	//}}AFX_MSG_MAP
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CHookDlg dialog

CHookDlg::CHookDlg(CWnd* pParent /*=NULL*/)
	: CDialog(CHookDlg::IDD, pParent)
{
	//{{AFX_DATA_INIT(CHookDlg)
		// NOTE: the ClassWizard will add member initialization here
	//}}AFX_DATA_INIT
	// Note that LoadIcon does not require a subsequent DestroyIcon in Win32
	m_hIcon = AfxGetApp()->LoadIcon(IDR_MAINFRAME);
}

void CHookDlg::DoDataExchange(CDataExchange* pDX)
{
	CDialog::DoDataExchange(pDX);
	//{{AFX_DATA_MAP(CHookDlg)
	DDX_Control(pDX, IDC_HINT, c_Hint);
	DDX_Control(pDX, IDC_CAT, c_Cat);
	DDX_Control(pDX, IDC_XY, c_XY);
	DDX_Control(pDX, IDC_ENABLE, c_Enable);
	//}}AFX_DATA_MAP
}

BEGIN_MESSAGE_MAP(CHookDlg, CDialog)
        ON_REGISTERED_MESSAGE(UWM_MOUSEMOVE, OnMyMouseMove)
	ON_REGISTERED_MESSAGE(UWM_GIVE_HINT, OnGiveHint)
	//{{AFX_MSG_MAP(CHookDlg)
	ON_WM_SYSCOMMAND()
	ON_WM_PAINT()
	ON_WM_QUERYDRAGICON()
	ON_WM_CLOSE()
	ON_BN_CLICKED(IDC_ENABLE, OnEnable)
	ON_BN_CLICKED(IDC_HELPME, OnHelp)
	//}}AFX_MSG_MAP
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CHookDlg message handlers

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

	// Add "About..." menu item to system menu.

	// IDM_ABOUTBOX must be in the system command range.
	ASSERT((IDM_ABOUTBOX & 0xFFF0) == IDM_ABOUTBOX);
	ASSERT(IDM_ABOUTBOX < 0xF000);

	CMenu* pSysMenu = GetSystemMenu(FALSE);
	if (pSysMenu != NULL)
	{
		CString strAboutMenu;
		strAboutMenu.LoadString(IDS_ABOUTBOX);
		if (!strAboutMenu.IsEmpty())
		{
			pSysMenu->AppendMenu(MF_SEPARATOR);
			pSysMenu->AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);
		}
	}

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

void CHookDlg::OnSysCommand(UINT nID, LPARAM lParam)
{
	if ((nID & 0xFFF0) == IDM_ABOUTBOX)
	{
		CAboutDlg dlgAbout;
		dlgAbout.DoModal();
	}
	else
	{
		CDialog::OnSysCommand(nID, lParam);
	}
}

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

		SendMessage(WM_ICONERASEBKGND, (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 to obtain the cursor to display while the user drags
//  the minimized window.
HCURSOR CHookDlg::OnQueryDragIcon()
{
	return (HCURSOR) m_hIcon;
}

void CHookDlg::OnCancel() 
{
}

void CHookDlg::OnOK() 
{
}

void CHookDlg::OnClose() 
   {
    CDialog::OnOK();
   }

void CHookDlg::OnEnable() 
   {
    if(c_Enable.GetCheck() == BST_CHECKED)
       { /* enable it */
	BOOL result = setMyHook(m_hWnd);
	c_Cat.SetActive(result);
	if(!result)
	    { /* error */
	     DWORD err = ::GetLastError();
	     c_Enable.SetCheck(BST_UNCHECKED);
             CString s;
	     s.Format(_T("%d"), err);
	     c_XY.SetWindowText(s);
	    } /* error */
	else
	   { /* set hook */
	    SetWindowPos(&wndTopMost, 0, 0, 0, 0,
			 SWP_NOMOVE | SWP_NOSIZE);
	   } /* set hook */
       } /* enable it */
    else
       { /* disable it */
	clearMyHook(m_hWnd);
	c_XY.SetWindowText(_T(""));
	c_Cat.SetActive(FALSE);
	SetWindowPos(&wndNoTopMost, 0, 0, 0, 0,
		     SWP_NOMOVE | SWP_NOSIZE);
       } /* disable it */
	
   }

/****************************************************************************
*                           CHookDlg::OnMyMouseMove
* Inputs:
*       WPARAM: unused
*	LPARAM: (x,y) coordinates of mouse
* Result: LRESULT
*       Logically void, 0, always
* Effect: 
*       Handles the mouse move event notification
****************************************************************************/

LRESULT CHookDlg::OnMyMouseMove(WPARAM, LPARAM lParam)
    {
     CPoint pt;
     GetCursorPos(&pt);
     CString s;
     s.Format(_T("%d, %d"), pt.x, pt.y);
     c_XY.SetWindowText(s);
     c_Cat.Redraw();
     return 0;
    } // CHookDlg::OnMyMouseMove


/****************************************************************************
*                            CHookDlg::OnGiveHint
* Inputs:
*       WPARAM: (WPARAM)(BOOL)TRUE to show hint, FALSE to remove it if visible
*	LPARAM: ignored
* Result: LRESULT
*       Logically void, 0, always
* Effect: 
*       Displays the hint
****************************************************************************/

LRESULT CHookDlg::OnGiveHint(WPARAM wParam, LPARAM)
    {
     if(wParam)
	{ /* show hint */
	 c_Hint.ShowWindow(SW_SHOW);
	} /* show hint */
     else
	{ /* remove hint */
	 c_Hint.ShowWindow(SW_HIDE);
	} /* remove hint */
     return 0;
    } // CHookDlg::OnGiveHint

void CHookDlg::OnHelp() 
{
 CHookHelp dlg;
 dlg.DoModal();
}

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About the Author

Joseph M. Newcomer
Retired
United States United States
PhD, Computer Science, Carnegie Mellon University, 1975
Certificate in Forensic Science and the Law, Duquesne University, 2008

Co-Author, [i]Win32 Programming[/i]

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