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MSN Messenger Type Task Bar Message Box

Wednesday Nov 28th 2001 by Prateek Kaul

[Update]This article shows you the source code about making a pop up message window like MSN Messenger.

Environment: VC++ 6.0, VC++ .NET Beta 2, Windows 2000

Introduction

There are times when you want to make messages pop up in an unobtrusive way and display messages to the user without interrupting him with dialog boxes.

This article shows you the source code about making a pop up message window like MSN Messenger.

Include the following files in your project.

  1. TaskBarMsgWnd.h
  2. TaskBarMsgWnd.cpp


Following lines show how to create an object of CTaskBarMsgWnd and use it to pop up a window. We use a pseudo constructor called CreateObject() because we want to force heap creation. For making the normal constructor unavailable we make it "private". We want to make the object on the heap because the PopMsg()function will trigger timers and animate the poping up and collapsing of the window even after it has returned. So the message window should remain in memory till all timers subside and the window collapses. This even makes the parent application and the window's thread more responsive than using Sleep()API which was used earlier. Using Sleep() made the thread block till the window got destroyed.

CTaskBarMsgWnd* t_MsgWnd = CTaskBarMsgWnd::CreateObject(
        _T("Some idiot has signed in !!"),// the message to be displayed
        180,  // width of the window
        150,  // height of window
        4000, // time in milliseconds for the message to be displayed
        10,   // delay for animation, how fast the window opens
              // and closes in milliseconds
        CRect(30, 30, 130, 110), // rectangle in the window where the 
                                 // message will be displayed
        RGB(120, 0, 0),          // Color of the background
        RGB(255, 255, 255)	     // Color of the text
        );


t_MsgWndMsg->PopMsg();


Creation of Window in Separate Thread

The earlier version of this article created the message window in the same thread. Hence there were some performance hits because the main window was not much responsive to user inputs like menu selections, window drag, window resize etc.

In this updated version of article we will create the message window in a separate thread. Out of the two threads provided by MFC we chose the user interface thread creation. Create a new class called CPopWndThread derived from CWinThread..Override the InitInstance() of this thread as shown below

BOOL CPopWndThread::InitInstance()
{
    m_pMainWnd = CTaskBarMsgWnd::CreateObject(
                                     _T("Some idiot has signed in !!"), 
                                     180, 
                                     150, 
                                     3000, 
                                     1,
                                     CRect(30, 30, 130, 110),
                                     RGB(120, 0, 0),
                                     RGB(255, 255, 255)
                                    );

    CTaskBarMsgWnd* pMsgWnd = (CTaskBarMsgWnd*)m_pMainWnd;

    pMsgWnd->PopMsg();

    return TRUE;
}

The thread and the associated window are destroyed automatically when the message window collapses in the OnTimer() function of CTaskBarMsgWnd using DestroyWindow() and PostQuitMessage() to exit the thread.



Creation of Thread

The separate user interface thread is created in the CMainFrame::OnMessagePop() using the following code,

void CMainFrame::OnMessagePop() 
{
    ::AfxBeginThread(RUNTIME_CLASS(CPopWndThread));
}


Animation Details

The PopMsg() function first checks where the Task Bar is on the desktop. There are only four cases

  1. Task Bar at the bottom of the screen.
  2. Task Bar at top of the screen.
  3. Task Bar at the left of the screen.
  4. Task Bar at the right of the screen.

The follwing code of PopMsg() function shown



void CTaskBarMsgWnd::PopMsg()
{
    if (CheckIfTaskBarBottom()) // Most frequent case is status
                                  // bar at bottom
    {
        PopWndForBottomTaskBar();
    }
    else
    {
        if (CheckIfTaskBarTop())
        {
            PopWndForTopTaskBar();
        }
        else
        {
            if (CheckIfTaskBarLeft())
            {
                PopWndForLeftTaskBar();
            }
            else
            {
                PopWndForRightTaskBar();
            }
        }
    }
}


The CheckIfTaskBarBottom()(or CheckIfTaskBarTop(), CheckIfTaskBarLeft())functions use GetSystemMetrics() and SystemParatmeterInfo() APIs to calculate the full screen area and the area on the screen minus the status bar. Then with some elementary high school mathematics we calculate where exactly the status bar is(bottom, top, left or right) and appropriately show the message window with some animation.

The real action occurs in the OnTimer() function which gets triggered because of WM_TIMER messages. There are three timers

  1. IDT_POP_WINDOW_TIMER -> Gets triggered for animating popup
  2. IDT_SHOW_WINDOW_TIMER -> Gets triggered for showing and keeping the window in position for some time
  3. IDT_COLLAPSE_WINDOW_TIMER -> Gets triggered for animating window collapse

There are three other constants namely STP_BOTTOM, STP_TOP, STP_RIGHT and STP_LEFT which represent where the status bar position is. These are used in OnTimer() for the appropriate animation calculations.

The window is automatically deleted after collapsing in the OnTimer() function using CWnd::DestroyWindow(). That's the reason we force this window's creation on heap

Class Details

The class CTaskBarMsgWnd is derived from CFrameWnd. The title bar is removed int the follwing code in the OnCreate() member function.

Two CFont objects are created, one underlined font and the other non-underlined. We show the underlined font when mouse is above the window using OnMouseHover() function (for WM_MOUSEHOVER message). Similarly we use the non-underlined font when the mouse leaves the window with OnMouseLeave() function (for WM_MOUSELEAVE message). Initialize a "hand" cursor m_hCursor for showing the mouse when it is over the window.

Rewrite the OnLButtonDown() for the WM_LBUTTONDOWN message to suit any thing you would like to do...!!!!. At this point OnLBottonDown() only shows a message box. You can change and do anything to suit your needs.

int CTaskBarMsgWnd::OnCreate( LPCREATESTRUCT lpCreateStruct )
{
    if (CFrameWnd::OnCreate(lpCreateStruct) == -1)
      return -1;

    ModifyStyle(WS_CAPTION, 0, SWP_FRAMECHANGED); // removes title bar

    // Start creating two fonts, one underlined , other non underlined 
    //
    // LOGFONT structure for font properties
    LOGFONT lf;
    ::ZeroMemory (&lf, sizeof (lf));
    lf.lfHeight = 100;
    lf.lfWeight = FW_BOLD;
    lf.lfUnderline = TRUE;

    ::strcpy (lf.lfFaceName, _T("Arial"));

    // Prepare for an underlined font
    m_fontMessageUnderline.CreatePointFontIndirect(&lf);

    // Prepare  an non undelined font
    lf.lfUnderline = FALSE;
    m_fontMessageNoUnderline.CreatePointFontIndirect(&lf);

    // Initialize the cursor.
    m_hCursor = ::LoadCursor(NULL, IDC_HAND);

    return 0;
}

Downloads

Download demo project - 22 Kb
Download source - 7 Kb
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