Introduction
This article describes a simple solution for automatically closing a message box. I have looked at many similar articles in the Inetrnet which are quite complex, so I thought I would make this one a little more simple.
Understanding the CMsgBox class
CMsgBox
is a class which implements auto-close functionality. This class is derived from the CWnd
class. It exposes a method called "MessageBox()
", which in turn would call CWnd::MessageBox()
to display a message box.
Getting the auto-close functionality implemented is very simple. In the CMsgBox::MessageBox()
method, we start a timer (SetTimer()
method) just before we call the CWnd::MessageBox
API. In the OnTimer
method, we try to find the message box window by using its window name (caption). Once found, we post a WM_CLOSE
message to close the message box. That's it !
void CMsgBox::MessageBox(CString sMsg, CString sCaption, UINT nSleep,
UINT nFlags, bool bAutoClose)
{
m_Caption = sCaption;
if(bAutoClose)
SetTimer(100, nSleep, NULL);
CWnd::MessageBox(sMsg, sCaption, nFlags);
}
void CMsgBox::OnTimer(UINT nIDEvent)
{
BOOL bRetVal = false;
CWnd* pWnd = FindWindow(NULL, m_Caption);
if(pWnd != NULL)
{
::PostMessage(pWnd->m_hWnd, WM_CLOSE, 0, 0);
}
KillTimer(100);
CWnd::OnTimer(nIDEvent);
}
Using the code
Add these two files to your project: "MsgBox.cpp" and "MsgBox.h". #include "MsgBox.h"
wherever appropriate. Create the CMsgBox
object as:
CMsgBox obj(this);
Or like this:
CMsgBox obj;
obj.SetParent(this);
Use the MessageBox()
method for displaying the message box. Set the bAutoClose
parameter to false if you don't need the auto-close functionality.
obj.MessageBox("This message box will auto close in 2 seconds.",
"Auto Close Msg Box", 2000, MB_OK | MB_ICONINFORMATION);
Conclusion
Wasn't that simple? Also, this being my first post, please forgive me for any mistakes.
References
Sandeep completed his masters in Computer Applications in 2003 and has been hooked onto programming since then. His first project involved communicating with hardware devices which actually got him more interested in device programming.