couple of simple questions

Got two questions.

1. How can I prevent the user from starting two instances of the same program?

2. I am executing a SHELL command from within my program. Is there a way to have my program wait until the SHELL command has completed?

1. In Form_Load do

VB Code:

If App.PrevInst Then Unload Me

Added

VB Code:

If App.PrevInstance then
   Unload me
   End
End If

I get an error when I try and execute a second copy.

RunTime Error 91
Object Variable or with Variable not set

Please post the Form_Load sub.

i'd recommend using Sub Main instead:

VB Code:

' In a module
Private Sub Main()
    If Not App.PrevInstance Then frmMain.Show
End Sub

VB Code:

Private Sub Form_Load
 
   If App.PrevInstance then
      Unload Me
      End
   End If

Rest of Form_Load code runs OK. It is only when I add the code at the top of Form_Load that I get the error.

Quote:

---

Originally Posted by bushmobile

i'd recommend using Sub Main instead:

VB Code:

' In a module
Private Sub Main()
    If Not App.PrevInstance Then frmMain.Show
End Sub

---

As long as the App.PrevInstance is the first thing in Form_Load the effect is the same.

Quote:

---

Originally Posted by JohnDonaldson

VB Code:

Private Sub Form_Load
 
   If App.PrevInstance then
      Unload Me
      End
   End If

Rest of Form_Load code runs OK. It is only when I add the code at the top of Form_Load that I get the error.

---

Is this being done in VB6?

Quote:

---

Originally Posted by MartinLiss

As long as the App.PrevInstance is the first thing in Form_Load the effect is the same.

---

I know, but controling the manner in which your app loads is easier in Sub Main and you don't have to think about unloading stuff etc.

2. Try this ShellWait function (need one CommandButton):

VB Code:

Option Explicit
 
Private Declare Function WaitForSingleObject Lib "kernel32" (ByVal hHandle As Long, ByVal dwMilliseconds As Long) As Long
Private Declare Function OpenProcess Lib "kernel32" (ByVal dwDesiredAccess As Long, ByVal bInheritHandle As Long, ByVal dwProcessID As Long) As Long
Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long
 
Private Const INFINITE = &HFFFF
Private Const SYNCHRONIZE = &H100000
Private Const WAIT_TIMEOUT = &H102
 
Public Sub ShellWait(PathName, Optional WindowStyle As VbAppWinStyle = vbMinimizedFocus, Optional bDoEvents As Boolean = False)
    Dim dwProcessID As Long
    Dim hProcess As Long
    
    dwProcessID = Shell(PathName, WindowStyle)
    
    If dwProcessID = 0 Then
        Exit Sub
    End If
    
    hProcess = OpenProcess(SYNCHRONIZE, False, dwProcessID)
    
    If hProcess = 0 Then
        Exit Sub
    End If
    
    If bDoEvents Then
        Do While WaitForSingleObject(hProcess, 100) = WAIT_TIMEOUT
            DoEvents
        Loop
    Else
        WaitForSingleObject hProcess, INFINITE
    End If
    
        CloseHandle hProcess
End Sub
 
Private Sub Command1_Click()
    ShellWait "notepad.exe", vbNormalFocus
        MsgBox "Finished !"
            'continue code...
End Sub

Once again I ask please post your complete code for the Sub. I'm also curious as to why "then" isn't capitalized.

Quote:

---

Originally Posted by bushmobile

...and you don't have to think about unloading stuff etc.

---

But you don't the other way either.

you need to set the start up object to Sub Main.

Project Menu | Project Properties

change the Startup Object combobox to Sub Main

Now I'm confused. The code I posted should be the first line in the Form_Load Sub of your main (first) form. Is it?

I already have a module1.bas , so I added the code to it. Now I get multi-instances.

The code I posted should be the first line in the Form_Load Sub of your main FORM.

I first added the code to the top of my Main form Form_Load. it generates a RunTime Error 91. The first instance runs OK, it is only when I try and execute the program the second time that it pops the RunTime Error 91.


If there is a way to LOCK my program on the screen, so that the user can not move it, the problem becomes mute.

Quote:

---

Originally Posted by JohnDonaldson

I first added the code to the top of my Main form Form_Load. it generates a RunTime Error 91....

---

Sorry, but that's not possible. Make an exe from the attached form and you'll only be able to get one instance.

both the methods suggest (Form_Load or Sub Main) will work - we'd need to see code to see why they're not working for you.

To stop the form being moved: You can set Moveable = False at design time. Or check out Karl E. Peterson's FormBdr example to change it a runtime.

I tried adding at the top of Form_Load

VB Code:

Private Sub Form_Load
 
     Me.Movable = False

It generates this message error

"Function or interface marked as restricted, or function uses an automation type not supported by Visual Basic."

Attach your form.

Quote:

---

Originally Posted by bushmobile

To stop the form being moved: You can set Moveable = False at design time. Or check out Karl E. Peterson's FormBdr example to change it a runtime.

---

....

Hack.....Just the Form_Load or the entire Form. The entire Form is too big to post here.

Quote:

---

Originally Posted by JohnDonaldson

Hack.....Just the Form_Load or the entire Form. The entire Form is too big to post here.

---

Attach the form. If it's too big then put it in a zip file.

I am allowed to post the Form_Load but not the entire Form. IP reasons.

VB Code:

Private Sub Form_Load()
    Dim conPath As String
        
    'conPath = "Data Source=" & App.Path & "\PatientFiles2.mdb;"
    'conPath = "Data Source=" & "D:" & "\PatientFiles2.mdb;"
    conPath = "Data Source=" & "C:" & "\PatientFiles2.mdb;"
    
    Set objAccessConnection = New ADODB.Connection
    Set rsAccess = New ADODB.Recordset
              
    'open connection to server
    objAccessConnection.Open "PROVIDER=Microsoft.Jet.OLEDB.3.51;" & _
    conPath & "Jet OLEDB:Database Password="
    
    'check connection status
    If objAccessConnection.State = adStateOpen Then
        'MsgBox "Connection open!", 64, "Connection status."
        connectionopen = True
    Else
        MsgBox "Connection not possible.", 64, "Connection status."
        connectionopen = False
    End If
    
    txtDate.Text = Date
    txtTime.Text = Time()
    
    
    'Connect and setup JoyStick
    Dim rt As Long
    Dim JoyTestInfo As JOYINFO
    Dim JoyTestInfo1 As JOYINFO
    Dim JoyStickCaps As JOYCAPS
    Dim JoyStickCaps1 As JOYCAPS
 
    'Get the max and min position on the joystick
   
    joyGetDevCaps JOYSTICK1, JoyStickCaps, Len(JoyStickCaps)
    With JoyStickCaps
        MaxX = .wXmax
        MinX = .wXmin
        MaxY = .wYmax
        MinY = .wYmin
    End With
    
    joyGetDevCaps JOYSTICK2, JoyStickCaps1, Len(JoyStickCaps1)
    With JoyStickCaps1
        MaxX = .wXmax
        MinX = .wXmin
        MaxY = .wYmax
        MinY = .wYmin
    End With
    
    StopButton1 = True
    'RootPathName = "D:\"
    RootPathName = "C:\"
    'get the drive's disk parameters
    Call GetDiskFreeSpaceEx(RootPathName, _
                            BytesFreeToCaller, _
                            TotalBytes, _
                            TotalFreeBytes)
    
    
    'Read INI file
   sIniFile = App.Path & "\perkins.ini"
   
   sSection = "PlaySnd"
   Call LoadIniFile
   sSection = "FootSwitch"
   Call LoadIniFile
   
   frmIntializing.lblNew.Caption = " "
    ShowPatients
    
   VideoCapture = False
   
    'Blank out Icons if no Patients in Database
    If rsAccess.BOF Or rsAccess.EOF Then
        'No more records
        Image_Delete.Visible = False
        Image_Update.Visible = False
        Image_Capture.Visible = False
        Image_Play.Visible = False
        Image_DVD.Visible = False
    End If
    
    Disk80P = -1
    Disk85P = -1
    Me.FrameMenu.BackColor = &HFFECCC
    Me.lblDate.BackColor = &HFFECCC
    Me.lblTime.BackColor = &HFFECCC
    Me.lblDiskSpace.BackColor = &HFFECCC
    Me.lblPercent.BackColor = &HFFECCC
    Me.Timer2.Enabled = False
    
    'set Datagrid to highligt row and disable row moving
    With DataGrid1
        .MarqueeStyle = dbgHighlightRow
        .AllowRowSizing = False
    End With
    
End Sub

John if you put the PrevInstance code at the top of that and you get an error then something very strange is going on. Did you try the form I attached? If so, what happened when you did?

MartinLess........Your form run OK.

Then if you did the same thing in your project and it's still a problem I'm sorry but there is nothing else I can do for you without your project. If you can get permission you could PM me and I'll give you my email address so you could send it to me.

Thanks anyway.

Quote:

---

Originally Posted by JohnDonaldson

I tried adding at the top of Form_Load

VB Code:

Private Sub Form_Load
 
     Me.Movable = False

---

me.MOVEABLE...notice the E there after the V and before the A? Anyway, set it at design time rather than in form_load...look up "moveable" and set it to false on the form...that should work (did for me)

Found a lot easier method. I just removed the title bar by setting "BorderSytle = 0". Then adding to Form_Load

VB Code:

With Me
    .Top = 0
    .Left = 0
End With

Now the user can not move the window and it is locked to 0,0.

Now to disable the Windows Key and ALT+Esc so that the user can not get to the desktop and I'll all set.