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MDI Childrens or Singleton

Posted on 2004-08-18
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408 Views
Last Modified: 2006-11-17
Hello,
I have a vb.net application. But I only want to have 1 actife children.....
This is the issue.
I have a search option in my main menu, which works fine. However, if I select search again, it will open a new instance (child) instead of refreshing the previous one....
Please help
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Comment
Question by:Ilianam
  • 6
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  • +1
13 Comments
 
LVL 15

Expert Comment

by:SRigney
ID: 11830935
You should be able to check to see if it already exists, and if it does switch to it instead of creating a new one each time.

In your main you can do something like this

Dim frmSearch As SearchForm

Then in your menu item click event

If frmSearch != null Then
   frmSearch.Show()
Else
   frmSearch = New SearchForm
End If

That should be close enough to give you the idea.
0
 
LVL 85

Expert Comment

by:Mike Tomlinson
ID: 11830976
SRigney is right on track.  Here is a more complete example (assuming Form1 is the MDIParent and Form2 is the MDIChild):

Public Class Form1
    Inherits System.Windows.Forms.Form

    Private WithEvents f2 As Form2

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        If f2 Is Nothing Then
            f2 = New Form2
            f2.MdiParent = Me
            f2.Show()
        End If

        If f2.WindowState = FormWindowState.Minimized Then
            f2.WindowState = FormWindowState.Normal
        End If
        f2.Focus()
    End Sub

    Private Sub f2_Closed(ByVal sender As Object, ByVal e As System.EventArgs) Handles f2.Closed
        f2 = Nothing
    End Sub

End Class
0
 

Author Comment

by:Ilianam
ID: 11831638
Is this for vb.net?
0
 

Author Comment

by:Ilianam
ID: 11831913
SGrigney It doesn't work
0
 
LVL 69

Expert Comment

by:Éric Moreau
ID: 11832314
You can use this method:

    Private Function IsChildInMemory(ByVal pChildName As String) As Boolean
        'A small method that checks to see if a particular form is currently displayed as a child form
        Dim frmChild As Form
        For Each frmChild In Me.MdiChildren
            If TypeName(frmChild).ToUpper = pChildName.ToUpper Then
                frmChild.Activate()
                Return True
            End If
        Next
        Return False
    End Function
0
 

Author Comment

by:Ilianam
ID: 11833270
Emoreau,
It works, however if I "search" again its minimized...The main menu is an mdicontainer at run time....
0
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LVL 69

Expert Comment

by:Éric Moreau
ID: 11835529
>>however if I "search" again its minimized

What is minimizing your child form? You could check the windowstate to see if it is minimize!
0
 
LVL 85

Expert Comment

by:Mike Tomlinson
ID: 11835665
Look at my example...it shows how to check the windowstate and put it back to normal...

Idle_Mind
0
 

Author Comment

by:Ilianam
ID: 11840951
Thank you...But I tried everything and I still cann't see my child.....
0
 
LVL 85

Expert Comment

by:Mike Tomlinson
ID: 11841066
To further troubleshoot your problem we would need to see your code.

Idle_Mind
0
 
LVL 69

Accepted Solution

by:
Éric Moreau earned 500 total points
ID: 11841725
0
 

Author Comment

by:Ilianam
ID: 11841945
Thank you to all the solution was pretty simple
Private Sub MenuItem2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MenuItem2.Click
        If Me.MdiChildren.GetLength(0) < 2 Then
            Dim Look As New Search
            Look.MdiParent = Me
            Look.Text = "Search " & Me.MdiChildren.GetLength(0)
            Look.Show()
       end if
0
 

Author Comment

by:Ilianam
ID: 11841952
However is there a list of mdi properties that you can change at run time?
0

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