How to: Maximize window from the Main function?

  • Thread starter Thread starter MJB
  • Start date Start date
M

MJB

In the main function of my form I check to see if the application is already
running. If it is, I throw up a message box telling the user. What I would
like to do is also maximize the application, but I am unable to do so. Does
anyone have any experience with this.

TIA,
Matt
 
try this:
this.WindowState = FormWindowState.Maximiz
but you cant do it from Main - use the constructor or or the OnLoad event or
whatever
 
Hi,

I assume that you will kill the second instance and activate the first one,
if so all you have to do is call SetActiveWindow API:

[DllImport("user32.dll")]
IntPtr SetActiveWindow( IntPtr hWnd);

This will do the trick.

You need the hWnd of the first app, if you need code to get it let me know.

Hope this help,
 
Hello,

Ignacio Machin said:
I assume that you will kill the second instance and activate the first one,
if so all you have to do is call SetActiveWindow API:
Click to expand...

You will have to attach the window to the thread's message queue
('AttachThreadInput'):

<msdn>
The window must be attached to the calling thread's message queue.
</msdn>
 
Hi Matt,

Have my application class. :-)

You can call it from Sub Main, Sub MainForm_Load or sometime later.

Regards,
Fergus

<code>
Imports System.Diagnostics.Process

Public Class clsApp

'===================================================================
Public Shared Function tThereIsAnInstanceOfThisProgramAlreadyRunning _
(Optional tToActivateThePrevInstance As Boolean = False, _
Optional ProgramTitle As String = "?") As Boolean
Dim sProcessName As String
Dim aoProcList() As System.Diagnostics.Process

sProcessName = GetCurrentProcess.ProcessName
aoProcList = GetProcessesByName (sProcessName) 'At least 1.

If aoProcList.Length = 1 Then
'There's just me.
Return False
End If

If tToActivateThePrevInstance Then
ActivateMyBetterHalf (ProgramTitle)
End If

'Another me beat me to it.
Return True
End Function

'===================================================================
Public Shared Sub ActivateMyBetterHalf _
(Optional ProgramTitle As String = "?", _
Optional tToCallAppExit As Boolean = False)
Dim MainForm As Form = Nothing

If ProgramTitle = "?" Then
MainForm = Form.ActiveForm 'Assumes that it's the main Form.
If MainForm Is Nothing Then
Throw New Exception ("No ProgramTitle and no Main Form??")
End If
ProgramTitle = MainForm.Text
MainForm.Text = "About to die" 'So AppActivate avoids self.
End If

MsgBox ("This is " & ProgramTitle & "(2) saying ""Bye, bye"" :-(")
AppActivate (ProgramTitle)

If MainForm Is Nothing = False Then
MainForm.Close
End If

If tToCallAppExit Then
Application.Exit
End If

'Or leave it to the caller to close down further as necessary.
End Sub

End Class

'===================================================================
Public Module MainMod
Public Sub Main
MsgBox ("Point 1")
If clsApp.tThereIsAnInstanceOfThisProgramAlreadyRunning (True,
"Form1") Then
Return
End If

MsgBox ("Point 2")
If clsApp.tThereIsAnInstanceOfThisProgramAlreadyRunning Then
clsApp.ActivateMyBetterHalf ("Form1")
Return
End If

Dim F As New Form1
F.Show
Application.Run()
End Sub
End Module

'===================================================================
Private Sub Form1_Load(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles MyBase.Load

MsgBox ("Point 3")
If clsApp.tThereIsAnInstanceOfThisProgramAlreadyRunning Then
'Form.ActiveForm is not yet valid. So give the name.
clsApp.ActivateMyBetterHalf (Me.Text)
Me.Close
Return
End If
End Sub

'===================================================================
Private Sub btnTest_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles btnTest.Click
MsgBox ("Point 4")
If clsApp.tThereIsAnInstanceOfThisProgramAlreadyRunning Then
clsApp.ActivateMyBetterHalf (,True)
End If
End Sub
</code>
 
Hi Herfried,

Mutex looks good. Simple too. :-)

Now, how do you activate the other instance? Is it possible to associate a
value with a mutex?

Regards,
Fergus
 
Hello,

Fergus Cooney said:
Mutex looks good. Simple too. :-)

Now, how do you activate the other instance? Is it possible
to associate a value with a mutex?
Click to expand...

I think that's not easy. You can use 'AppActivate' with the other
instance's process ID (see documentation for 'AppActivate'). I recently
posted a 'PrevInstance' function which returned the 'Process' object for the
other instance by looping through the process list and comparing process
name and file name.
 
Hi,

A mutex is a good idea, now the tricky part is set the focus to that other
process , I proposed using SetActiveWindow API call but as you mentioned you
need to be attached to the calling thread's message queue.

I'm using SetForegroundWindow to do this in a pocketPC application and it
works great:
[DllImport("user32dll",EntryPoint="SetForegroundWindow")]

public static extern bool SetForegroundWindow(IntPtr hWnd);


Hope this help,

--
Ignacio Machin,
ignacio.machin AT dot.state.fl.us
Florida Department Of Transportation
 
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