I have declared a form as
Private _fUpdate As frmUpdate
There are all kinds of solutions to check if a form is open and visible.
However, if a form is Minimized and not shown in the taskbar, it doesn't show up in Application.OpenForms.
Also Form.IsHandleCreated returns false with the above window state.
If Not uForm Is Nothing returns True even if the form has not yet been instanciated, so it isn't usuable as well.
Is there another way to check whether a form is loaded then a variable storing the window existance and hidden/shown state?
What I usually do if I need to get the instance of a form from somewhere else within my application, is create a Shared property in your form called Instance or something similar and set it in the form's Load event.
With this instance property, you can call it from anywhere else in your application, and use the WindowState property of your form to check its state.
Example of the form:
Public Class frmUpdate
Public Shared Property Instance As frmUpdate
Private Sub OnLoad(sender As Object, e As EventArgs) Handles MyBase.Load
Instance = Me
End Sub
End Class
Example usage in some other method:
Private Sub DoSomething()
If (frmUpdate.Instance.WindowState = FormWindowState.Minimized)
'Do something
End If
End Sub
Related
I have a form called "partmanager". On it is a button to show another form "parteditor" to allow editing details of a part. Clicking that button will show the form and pass in a variable to the parteditors "new" routine.
My problem is that when the calling form (partmanager) starts, it immediately calls new routine in the parteditor form before it (partmanager) is even initialized so the parteditor form does not get the string that is supposed to be passed in. Later, when the calling form is visible and I click the button to show the parteditor form, new has already been prematurely called and so is not called again and the form does not get the string passed in.
I hope this makes sense!
I can implement a property in the parteditor form and pass in my variable that way prior to showing the form and that will work, thereby not even requiring a "new" routine in the parteditor forms code.
So my question is, is implementing the property the proper way to pass this variable to the form being called, or am I not properly coding my forms? (I also have an intermediary module called "commands" where I have been defining command procedures, in this case just showing a form.)
any pointers would be appreciated, thanks!
here is the code for the button in the calling form:
Private Sub EditButton_Click(sender As Object, e As EventArgs) Handles EditButton.Click
Commands.EditPart(_PartNumber) 'call the editpart command
Me.Close()
Me.Dispose()
End Sub
here is the code for the form being called:
Public Class PartEditForm
Private _partNumber As String = String.Empty
Public Sub New(partNumber As String)
' This call is required by the designer.
InitializeComponent()
' Add any initialization after the InitializeComponent() call.
_partNumber = partNumber
End Sub
Private Sub PartEditForm_Load(sender As Object, e As EventArgs) Handles Me.Load
Label1.Text = _partNumber
End Sub
End Class
and here is the code in my "commands" module for loading/showing the form:
Public PartEditForm As New PartEditForm(_partNumber)
Public Sub EditPart(partnumber As String)
If PartEditForm.IsDisposed Then
PartEditForm = New PartEditForm(partnumber)
End If
PartEditForm.Show()
End Sub
you can save the routine in a dim variable and get this on the other form and close the first form or hide but you need get in new var and contine where stop before.
So I am building a form based application, and I am running into an issue with passing data between forms. I have a combo box that, based on selection, triggers a new form to open with several buttons to pick from. Once you select a button, the form closes, but I can't get the selection to be carried over to the original form.
basic idea of the code is like this
Public Class frmMain
Public intStore As integer
Private Sub cboSample_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cboSample.SelectedIndexChanged
Dim selection as Integer
selection = cboSample.SelectedIndex
If selection = -1 Then
Else
Select Case selection
Case 0
frmOne.Show()
Case 1
frmTwo.Show()
End Select
End If
End Sub
End Class
Here is a sample of the second form code
Public Class frmOne
Public storage As varStorage
Private Sub btn_Clicked(sender As Object, e As EventArgs) Handles btn.Clicked
storage = New varStorage With {.datastore = 1}
Me.Close()
End Sub
End Class
frmTwo is pretty much the same but handles more options
The Class I created looks like this
Public Class varStorage
Public _dataStore As Integer
Public Property dataStore() As Integer
Get
Return _dataStore
End Get
Set (value As Integer)
_dataStore = value
End Set
End Property
End Class
as I said, the issue comes from the point of the form being called, and the form closing, the variable data is not being saved. I am almost certain I am missing some code somewhere, but not sure where. any help would be greatly appreciated.
Rather than using Show() to open another form, using ShowDialog() will open the form modally. The form will behave like a MessageBox. It will wait for you to respond to, and close, this form before returning to your main form. We can obtain a value from this modal-form, safe in the knowledge that the form has been closed (and so the value we have obtained will not be changed).
The other way is to make a Public Property of the form. then you can create Get and Set methods to have access to your form objects
Public Class yourFormClass
Public Property Note As String
Get
Return txtNote.Text
End Get
Set(value As String)
End Set
End Property
End Class
and Then you can use it like
dialog = New yourFormClass()
someOtherTextbox.Text = dialog.Note
I currently have 2 forms. 1 holds user data and is modifiable. The other is a display/read only form.
I am trying to pull data (tbUSI.text) from ReportSettings and pass it to Form1 and display it on my UserData.text control.
I have tried using public properties but to no avail. I would rather use public properties, since its cleaner. Here is the code im using to set the property:
Public Property UserSignedInto As String
Get
Return tbUSI.Text
End Get
Set(value As String)
End Set
End Property
Here is my code attempting to call that property on the main form (form1)
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
UserData.text = UserSignedInto
End Sub
It doesn't pull anything, the textbox on my main form is blank.
Take a look here:
SCCMReports = New ReportSettings
UserData.text = SCCMReports.UserSignedInto
When was the SCCMReports form ever displayed to the user? Since it was never displayed, its tbUSI.Text value will of course be empty because the user never had an opportunity to enter text.
It sounds like you need a reference to an existing instance of ReportSettings, rather than creating a new instance. Where do you have that existing instance?
If Form1 created the instance in another block of code, store it in a class-level member on Form1 (perhaps called SCCMReportsInstance or something of that nature). When the instance is created, set it to the value of that property and reference that property in your code:
UserData.text = Me.SCCMReportsInstance.UserSignedInto
If the ReportSettings form is instead creating the instance of Form1 then it can pass a reference to itself. You'd still have a property on Form1, it would just be set in the constructor. Something like this:
Sub New(ByVal sccmReportsInstance As ReportSettings)
Me.SCCMReportsInstance = sccmReportsInstance
End Sub
So when initializing the Form1 instance, you'd pass the reference:
Dim form1 As Form1
form1 = New Form1(Me)
form1.Show()
Any way you go about it, you need to access the existing instance of the displayed form in order to access its properties. A new instance would have new versions of those properties and wouldn't have the same values.
I need some help getting my head wrapped about instances and classes. In the code below I have a main_form, and I am also loading a user_control into the main_form. I have a property that resides inside main_form that I will be setting data called obj. My question is when I am doing work inside of the user_control, how can I reach in and set the obj property of main_form. I tried main_form.obj but I keep getting the error "object reference not set to an instance of an object". So, I'm not sure how to do it. Here's the dumbed down code
Public Class FormControlClass
Private _obj As New objCollection
Public Property obj As objCollection
Get
Return _obj
End Get
Set(ByVal value As objCollection)
_obj = value
End Set
End Property
'Load User Control Into Form from here.
me.controls.add('UserControl')
End Class
Public Class UserControlClass
'Access the obj property in the form control class from here.
FormControlClass.obj = 1
End Class
Even if you could do what you are trying to do, it would be a bad idea, because you would be coupling your user control to this particular form, making it useless outside of this form.
Instead you need to have your user control generate an event that the form can subscribe to and handle itself. In other words, you want to make the user control create a message that can be delivered to the form, like this:
Public Class UserControlClass
' Define event that will be raised by user control to anyone interested in handling the event
Public Event UC_Button1Click()
' Mechanism to allow event to be raised by user control
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
RaiseEvent UC_Button1Click()
End Sub
End Class
Now in your form class, you need to add a handler for the event raised by the user control, like this:
AddHandler userControl1.UC_Button1Click, AddressOf Button1_Click
Finally, you would create the method that is referenced in the AddressOf syntax, like this:
Public Sub Button1_Click(ByVal sender As Object, ByVal args As EventArgs)
' Do something here
End Sub
I have a mdicontainer form that summons forms. My problem is when the a user clicks again the menu for that form, it also make another instance of it.
What I did is declare a public class with a public variable on it ex: Boolean isFormOneOpen = false. Then every time formOne opens, it checks first the global variable I declared a while ago if it's false, if it is, instantiate an object of a formOne and then show it. Otherwise, do nothing. Very static, imagine if I have many forms, I have to declare a variable for each form to check if it's already open. Can you provide me a solution for this? Maybe a method that accepts a Form? Or any more clever way to do this.
You don't need a variable, you could iterate the MdiChildren collection to see if the form is already opened. For example:
Private Sub btnViewChild_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnViewChild.Click
For Each child In Me.MdiChildren
If TypeOf child Is Form2 Then
child.WindowState = FormWindowState.Normal
child.Focus()
Exit sub
End If
Next
Dim frm As New Form2
frm.MdiParent = Me
frm.Show()
End Sub
The VB.NET-centric solution:
Private Sub btnViewChild_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnViewChild.Click
Form2.MdiParent = Me
Form2.WindowState = FormWindowState.Normal
Form2.Show
End Sub
Rather than a boolean, declare a variable of the form's type. Then just make sure the variable isn't Nothing and call it's .Open() method. This has the nice side effect of also bringing your existing form instance to the front if it's already open.
Even better, in VB.Net 2.0 and later all forms have a default instance with the same name as their type, so you can just say FormName.Open() and be done with it. However, I haven't tried this in an mdi situation before.