Is the form hidden VB.Net 2005

Posted on 2009-05-10
Last Modified: 2012-05-06

How do you determine if a form is hidden or closed.  

I've tried using the "created" property but I'm getting mixed results.  If the form is closed and I try an "if formname.visible = false" type query then I get True where the form is hidden or closed.  I can put in a workaround but I'm ideally looking for an answer to this.

NB. A modification to the IsLoaded function below is required to capture hidden forms.
Function IsLoaded(ByVal Loadedfrm As Form) As Boolean
        Dim frm As Form
        For Each frm In My.Application.OpenForms
            If frm.Name Is Loadedfrm.Name Then
                IsLoaded = True
                IsLoaded = False
            End If
    End Function

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Question by:geraintcollins
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LVL 15

Expert Comment

ID: 24348411
What do you mean by a closed form, when you close a form, then the is no longer available unless code within the form is still running.  In VB6 you could close a form and still be able to access the form, you can't do that in .net.

Author Comment

ID: 24350225
The difference is explained below.  Now how do you tell, say from another form or module in the application, whether form1 is closed or hidden?
Public Class Form1
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    End Sub
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
    End Sub
End Class

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LVL 86

Accepted Solution

Mike Tomlinson earned 50 total points
ID: 24350336
Try something like this:

        If Not Form1.IsHandleCreated Then
            Label1.Text = "Form1 Closed"
        ElseIf Form1.Visible Then
            Label1.Text = "Form1 Open"
            Label1.Text = "Form1 Hidden"
        End If

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LVL 15

Expert Comment

ID: 24350375
You can do me.close, but then you can't do, as me has been closed, you would have to create a new copy of the form to be able to use it again
LVL 86

Expert Comment

by:Mike Tomlinson
ID: 24350379
*Unless you are working with the DEFAULT INSTANCE of the form...    ;)

LVL 15

Expert Comment

ID: 24352073
True, I had overlooked that as a possibility as its lazy programming, and if any of my staff do that I make them change it so that you only work with objects that you have created. I was surprised that they put that back in after omitting it from .net 2003, but thats another discussion....

Author Closing Comment

ID: 31579899
Excellent, answered the question without getting stuck on the reason why, I appreciate that.

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