form close reason

Hi!

I would like my form to be hidden when the use clicks on the window close button (the X button on the top-right corner). The e.CloseReason does not provide a value to determine that this particular button is the reason that is closing the form. This was very simple in VB6:

Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)
    If UnloadMode = vbFormControlMenu Then
        Cancel = True
    End If
End Sub

How is this possible in .NET Forms

Answer this question

form close reason

haran14
Please read this thread:
http://forums.microsoft.com/msdn/ShowPost.aspx PostID=64638#64638
flatch
Thanks both!
I tried to use your code David in VB.
Is the equivelant of the two constants declaration the following

Private Const WM_SYSCOMMAND As Integer = &H112
Private Const SC_CLOSE As Integer = &HF060

If so, your code works only if I make the following modification:
(int)m.WParam == SC_CLOSE)
instead of
((int)m.WParam & 65520) == SC_CLOSE)
Joeouts
Yes, I know the cancel property. What I'm asking is how my code will know if the form is closing because the end-user pressed the close button and not for any other reason.
Scott Coffey
Hi,

On .NET winforms, you can try something like this:

protected override void OnClosing(CancelEventArgs e)
{
if ( <insert your condition here> ) e.Cancel = true;
else base.OnClosing (e);
}

The e.Cancel parameter from the received event data is a boolean value where you can set to true to cancel the event.

-chris
DotNetNinja

Replace the '&' with an 'And'.
Johan Levin
Hi,

Take a look at the following code sample:
http://dotnet.mvps.org/dotnet/samples/windowsandforms/CloseWindow.zip

A simpler option using Form1_Closing Event would be to use the following: I am not sure how to detect the other options but you can find out by trial and error with this approach: * Not sure if this works - still verifying*

Private Sub Form1_Closing(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles MyBase.Closing

        Dim objStackFrame As StackFrame = New StackTrace(True).GetFrame(7)
        If objStackFrame.GetMethod().Name = "CallWindowProc" Then
            e.Cancel = True
        End If

End Sub

Regards,
Vikram
vim m.
thanks David. That was it!

Roger Willcocks

Try the following:

using System;
using System.ComponentModel;
using System.Security.Permissions;
using System.Windows.Forms;

namespace MyApplication
{
    public class Form1 : Form
    {
        private const int WM_SYSCOMMAND = 0x0112;
        private const int SC_CLOSE = 0xF060;

private bool _UserClose;

        public Form1()
        {
        }

        protected override void OnClosing(CancelEventArgs e)
        {
            if (_UserClose)
            {
                MessageBox.Show("The user clicked the X button.");
            }

base.OnClosing(e);
}

        [SecurityPermission(SecurityAction.LinkDemand, UnmanagedCode = true)]
        protected override void WndProc(ref Message m)
        {
            if (m.Msg == WM_SYSCOMMAND && ((int)m.WParam & 65520) == SC_CLOSE)
            {
                _UserClose = true;
            }

base.WndProc(ref m);

            _UserClose = false;
        }
    }
}

form close reason

Answer this question