how to trap X button in windows form (c#)

  • Thread starter Thread starter RAJ
  • Start date Start date
R

RAJ

hi

plz tell me how to know "how window is going to close"...
i have to right code for X button of forms...

plz telll me
thanks

bye
 
Too lazy? Took me 2 seconds to find the events on MSDN.

ms-help://MS.MSDNQTR.2003APR.1033/cpref/html/frlrfsystemwindowsformsformclas
sclosingtopic.htm
and
ms-help://MS.MSDNQTR.2003APR.1033/cpref/html/frlrfsystemwindowsformsformclas
sclosedtopic.htm


Form.Closing Event
See Also
Form Class | Form Members | System.Windows.Forms Namespace | IsMdiContainer
| OnClosing | Form Members (Visual J# Syntax) | Managed Extensions for C++
Programming

Requirements
Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows
2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003
family

Language
a.. C#

b.. C++

c.. JScript

d.. Visual Basic

e.. Show All
Occurs when the form is closing.

[Visual Basic]
Public Event Closing As CancelEventHandler
[C#]
public event CancelEventHandler Closing;
[C++]
public: __event CancelEventHandler* Closing;
[JScript] In JScript, you can handle the events defined by a class, but you
cannot define your own.

Event Data
The event handler receives an argument of type CancelEventArgs containing
data related to this event. The following CancelEventArgs property provides
information specific to this event.

Property Description
Cancel Gets or sets a value indicating whether the event should be
canceled.

Remarks
The Closing event occurs as the form is being closed. When a form is closed,
all resources created within the object are released and the form is
disposed. If you cancel this event, the form remains opened. To cancel the
closure of a form, set the Cancel property of the CancelEventArgs passed to
your event handler to true.

When a form is displayed as a modal dialog box, clicking the Close button
(the button with an X at the upper-right corner of the form) causes the form
to be hidden and the DialogResult property to be set to DialogResult.Cancel.
You can override the value assigned to the DialogResult property when the
user clicks the Close button by setting the DialogResult property in an
event handler for the Closing event of the form.

Note When the Close method is called on a Form displayed as a modeless
window, you cannot call the Show method to make the form visible, because
the form's resources have already been released. To hide a form and then
make it visible, use the Control.Hide method.
CAUTION The Form.Closed and Form.Closing events are not raised when the
Application.Exit method is called to exit your application. If you have
validation code in either of these events that must be executed, you should
call the Form.Close method for each open form individually before calling
the Exit method.
If the form is an MDI parent form, the Closing events of all MDI child forms
are raised before the MDI parent form's Closing event is raised. In
addition, the Closed events of all MDI child forms are raised before the
Closed event of the MDI parent form is raised. Canceling the Closing event
of an MDI child form does not prevent the Closing event of the MDI parent
form from being raised. However, cancelling the event will set to false the
System.Windows.Forms.ClosingEventArgs.Cancel property of the
System.Windows.Forms.ClosingEventArgs that is passed as a parameter to the
parent form. To force all MDI parent and child forms to close, set the
System.Windows.Forms.ClosingEventArgs.Cancel property to false in the MDI
parent form.

For more information about handling events, see Consuming Events.

Example
Form.Closed Event
See Also
Form Class | Form Members | System.Windows.Forms Namespace | IsMdiContainer
| OnClosed | Load | Form Members (Visual J# Syntax) | Managed Extensions for
C++ Programming

Requirements
Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows
2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003
family

Language
a.. C#

b.. C++

c.. JScript

d.. Visual Basic

e.. Show All
Occurs when the form is closed.

[Visual Basic]
Public Event Closed As EventHandler
[C#]
public event EventHandler Closed;
[C++]
public: __event EventHandler* Closed;
[JScript] In JScript, you can handle the events defined by a class, but you
cannot define your own.

Event Data
The event handler receives an argument of type EventArgs.

Remarks
This event occurs after the form has been closed by the user or by the Close
method of the form. To prevent a form from closing, handle the Closing event
and set the Cancel property of the CancelEventArgs passed to your
event-handling method to true.

You can use this event to perform tasks such as freeing resources used by
the form and to save information entered in the form or to update its parent
form.

CAUTION The Form.Closed and Form.Closing events are not raised when the
Application.Exit method is called to exit your application. If you have
validation code in either of these events that must be executed, you should
call the Form.Close method for each open form individually before calling
the Exit method.
If the form is an MDI parent form, the Closing events of all MDI child forms
are raised before the MDI parent form's Closing event is raised. In
addition, the Closed events of all MDI child forms are raised before the
Closed event of the MDI parent form is raised.

For more information about handling events, see Consuming Events.
 
hi Jack Meyhoff

i had seen these MSDN pages but i m still confused
how i will know this is X button of form or something else...

bye
 
http://beta.experts-exchange.com/Programming/Programming_Languages/C_Sharp/Q
_20407745.html

To quote from that page.

--
To hide the window when the user presses the close button (X) subscribe to
the Form's Closing event...

(C#)
this.Closing += new
System.ComponentModel.CancelEventHandler(this.Form1_Closing);

Then in the event handler hide the form, and cancel the close... Be careful
as this code alone will prevent you from ever closing the application,
somewhere you need to provide a way of closing the form, maybe use a flag
which can be tested in this event handler to determine whether or not the
event should be cancelled.

(C#)
private void Form1_Closing(object sender,
System.ComponentModel.CancelEventArgs e)
{
// Hide the form...
this.Hide();

// Cancel the close...
e.Cancel = true;
}

You might also want to look at the following question/answer which describes
how to put an icon in the system tray
http://www.experts-exchange.com/Programming/Programming_Languages/C_Sharp/Q_
20397858.html

As for the second part of your question...

The Form.Close() method will simply close that form and all resources
created within the object are closed and the form is disposed.

The Application.Exit() method informs all message pumps that they must
terminate, and then closes ALL application windows after the messages have
been processed. It is usually recommended that Form.Close() is called for
each form individually before calling Application.Exit().

If you need to get out of an application quick and don't care about cleaning
up (closing files, etc) then you can use Application.Exit(). The more usual
case would be to do a controlled Form.Close() of the main Form letting the
application come to a natural end.
--

Jack Meyhoff said:
the [X] button is the same as WM_SYSTEM -> SC_CLOSE in win32 messaging.

RAJ T said:
hi Jack Meyhoff

i had seen these MSDN pages but i m still confused
how i will know this is X button of form or something else...

bye
Click to expand...
Click to expand...
 
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