Lots of examples of how to invoke methods, but how does one change a simple property?
For demonstration-sake, here's a very simple set of code that should help. Let's say I need to set the visible property from a child form, and thus, it needs to be invoked:
Friend Sub activateItem(ByVal myItem As PictureBox)
If myItem.InvokeRequired = True Then
????
Else
myItem.Visible = True
End If
End Sub
Thanks
If you're using VB.Net 2010, you can use a lambda expression:
If myItem.InvokeRequired Then
myItem.Invoke(Sub() myItem.Visible = True)
In your particular case, you can also call myItem.Invoke(myItem.Show).
Related
I have a Userform that has a Checkbox. I am able to check the value of it, but it is always False whether it is checked or not.
Update
This is how the UserForm is being called (This is in another UserForm ):
Private Sub AddOutgoingbtn_Click()
With New AddIncomingForm
.TopBottom.Value = False
.Show
.Repaint
End With
End Sub
End Update
I created a sub to look for a change in the value like:
Sub TopBottom2_Change()
With AddOutgoingForm
If .TopBottom2.Value = True Then TopBottom = True
If .TopBottom2.Value = False Then TopBottom = False
End With
End Sub
But no matter what I do the .TopBottom2.Value is always False.
I've put a breakpoint on the With line so that I know it is hitting this Sub, then I step through it each time. I open the UserForm and check the box, step through and the value is False, then I uncheck the box and step through. The value is still False.
I am not setting the value in any other way with VBA. I am checking the value in the UserForms code, not in any other place.
I have an If in a Calculation Module that is looking at this value for when it is true or falses, but it is always false.
Here are all the Properties of the Checkbox:
With AddOutgoingForm
That's referring to the form's default instance, which may or may not be the instance that's currently being displayed.
You have two options:
At the call site, instead of doing this (or something similar):
With New AddOutgoingForm
.Show
'...
End With
Do this:
AddOutgoingForm.Show
'...
That way you'll be working with the default instance and the checkbox value-check should work.
...but IMO that's a very very bad idea, because then your form contains code that will only ever work when you're showing the default instance.
Leave the call site alone, and NEVER refer to the default instance of a UserForm inside that form's code-behind. In other words change With AddOutgoingForm for With Me.
The Me keyword refers to the current instance - and that is what you want. Doing this will make the form work regardless of what the call site does.
Alternatively, just drop the With block altogether: With Me wouldn't be doing anything useful here.
I will assume the checkbox is indeed on your user form so just use me or you could use
AddOutgoingForm.TopBottom2.Value
But let me ask you, where is TopBottom and what is it a Boolean variable or another Checkbox? Also on the same form? The Subs are also all in the form? You have to be calling the form from somewhere so be careful between the worksheet, workbook, module variables. Is TopBottom a Global variable to the whole project (in a module called Global_Variables with Public in front of it perhaps?) You may not have access to TopBottom from inside of your form if you are not passing anything in or out.
Private Sub TopBottom2_Change()
If (Me.TopBottom2.Value) = True Then
Me.TopBottom.Value = True
Else
Me.TopBottom.Value = False
End If
End Sub
Cheers,
-WWC
I am learning vb.net and I'm having issues searching for what I need. I want to create a button that is "re-usable" throughout my application without needing to write code for each instance. So, what I would like to start with is take a variable in a form, example, public integer value and when this value changes I want to write to the text of a button. I know I can easily do this by writing code in the form btn_xxx.text = variable, but what if I have several buttons and each button looks at the same variable? Currently what I do is create a component which inherits a button and have a timer that on tick will look at the variable and write to the text. I'm sure there is a better way. Can anyone point me in the right direction? I know part of my problem is I don't know the nomenclature on what things are called, so hopefully I asked my question without too much confusion.
I saw this, https://www.daniweb.com/programming/software-development/threads/124842/detect-variable-change, but I don't see how to adapt that to my situation.
Here is what I have:
Private WithEvents Active_Alarm As New Nav_Active_Alarm
Then inside of a sub that calculates the count:
Active_Alarm.Count = CInt(dt_Active_Alarms.Rows.Count)
The user control:
Public Class Nav_Active_Alarm
Private mActive_Alarm_Count As Integer
Public Event Active_Alarm_Count_Changed(ByVal mvalue As Integer)
Public Property Count() As Integer
Get
Count = mActive_Alarm_Count
End Get
Set(ByVal value As Integer)
mActive_Alarm_Count = value
If Not Me.DesignMode Then
RaiseEvent Active_Alarm_Count_Changed(mActive_Alarm_Count)
test()
End If
End Set
End Property
Private Sub test()
If Not Me.DesignMode Then
If mActive_Alarm_Count = 0 Then
Me.btn_Goto_Active_Alarm.Image = My.Resources.Alarm_Clock_Static
'console or msgbox will work but updating the image will not
Else
Me.btn_Goto_Active_Alarm.Image = My.Resources.Alarm_Clock_Animation
'console or msgbox will work but updating the image will not
End If
End If
End Sub
End Class
If I write to console or add a msgbox I will see the event working. But, the image will not change. If I call the test sub from a timer it will work. Why won't the button update (by the way, I did try refresh and update in the code)?
Observer pattern is what you probably looking for.
This is quick and dirty.
Create a class to hold the variable value. Add a method that adds a button instance to a list.
Then a button that needs to know about the variable calls the register method.
When the value of the variable changes, it iterates through the list of buttons and sets the Text property of each one.
You might have jumped in a bit too deep too quick here. Google Custom data binding in .net, there's loads of built in stuff you can use. Though do it yourself is a good exercise.
A simple method to do this might be:
Create a form level list to hold the buttons you are interested in
Add the buttons you are interested in, into the list (maybe in form load or some other place where you have initialization code)
Create a private property in your form with a backing variable to hold the value you want to have applied to the buttons. In the setter portion spin through the list and set each buttons text.
Dim lstButtons As New List(Of Button)
Sub SetupButtons()
'call from form load or other init code
lstButtons.Add(btnPopulate)
lstButtons.Add(btnPopulate)
End Sub
Private _buttonText As String
Private Property ButtonText As String
Get
Return _buttonText
End Get
Set(value As String)
_buttonText = value
For Each b As Button In lstButtons
b.Text = value
Next
End Set
End Property
When you set the property - which now acts as your variable - it will update all of your textboxes for you.
I realize you mentioned without having to write code - but something has to tie things together. Even if you used the observer pattern (which is an elegant solution for this - so props to those who suggested it) you'd probably end up creating a class to hold the property and have that class implement the INotifyPropertyChanged from System.ComponentModel, and then you'd also have to have each button have a databinding for its text property to the property in the object of your class. There isn't really a way (that I can think of) to get around having to write some code for each form you do this in (though the class part you'd only have to write once of course).
I'm new to VB6, and trying to write some macro in use for CorelDraw.
I have a variable that need to be passed from Class module to Standard module, in my Class Module "SaveOptClass" I have a public variable called IsSaved and it's set on the class module:
Public IsSaved As Boolean
Public Sub SaveFile()
If <some triggers> Then
IsSaved = True
End If
In Standard module:
Sub DoSave()
Dim SaveClass As SaveOptClass
Set SaveClass = New SaveOptClass
If SaveClass.IsSaved = True Then
ActiveDocument.Save
Else
Form1.Show
End If
End Sub
Basically I'm trying to pass "IsSaved" boolean value from class module to standard. (If IsSaved is true, save the document or else display a form.)
I have tested that the boolean is True when I executed the code, but I can't get the state to pass to the other module.
Is there something I miss here? Thanks in advance.
As already answered by #shahkalpesh the problem is that you're not using a meaningful instance of SaveOptClass.
In my opinion the best way to design this kind of dependency is by mean of a parameter in the routine is using it and avoid as much as possible the use of global variables.
In your case this brings to this rewriting:
' in someOtherModule
Public Sub DoSave(saveOptObj as SaveOptClass)
If saveOptObj.IsSaved Then ' = True is unnecessary
ActiveDocument.Save
Else
Form1.Show
End If
End Sub
The client code could be:
private saveOptObj as SaveOptClass
Public Sub SaveFile()
If <some triggers> Then
saveOptObj.IsSaved = True
End If
' ....
someOtherModule.DoSave(saveOptObj)
' ...
Consider also, at this point, a renaming of DoSave, given that the actions taken suggest different semantics. In similar cases is preferable moving the If Else logic in the caller. Anyway, if you prefer to group actions with different semantics in the same routine you'd better use namings like DoSaveOr<SomethingElse>.
I have a userform which contains a TextBox object named myTextBox.
The text inside the object can be changed either by the user or by the code. There's a "onChange" procedures attached to the textbox:
Private Sub myTextBox_Change()
'do some stuffs
End Sub
I would like the event to be processed only when is the user changing the text, but not the code. I had thought about adding an Optional parameter like the following:
Private Sub myTextBox_Change(Optional isCode As Boolean)
If isCode = False Then
'do some stuffs
End If
End Sub
but this is not really helpful because I cannot pass the isCode = True when changing the name programmatically, like this:
myForm.myTextBox = "new text"
Does anyone have an idea on how I can fix this?
One way (perhaps not the right way?) would be to declare a global variable to use in the same way as your IsCode Boolean. Set it to true during your code block so the textbox_change event knows code is processing in the background, and then set back to false when that code has finished.
Put this at the top of a normal module (won't work in a form module)
Option Compare Database
Option Explicit
Global IsCode As Boolean
and then in the code you're running just set IsCode=true as required.
I've created the instance "Lassie" of the class "Dog" within a particular sub in my program. I have also given it some useful properties, such as Lassie.Age = 7 and Lassie.HeelCapability = False.
Now I would like to access another sub and change the Lassie.HeelCapability to True.
How do I go about defining the instance "Lassie" within this new sub so it can be worked with?
All the code I have come accross goes like this:
Dim Lassie As classDog
Set Lassie = New classDog
Essentially what I am looking for is a way to import the existing instance "Lassie" into another sub, without using the keyword "New" and thereby creating a new "Lassie" (without all the properties previously given).
The errormessages I have been receiving tell me either "object required" or "object variable or with block variable not set".
Surely there is a way to do this.
Thanks in advance.
You will need to pass 'Lassie' as a parameter to your other sub.
public sub DeclareSub()
Dim Lassie as classDog
Lassie = new classDog
OtherSub Lassie
end sub
public sub OtherSub(ByRef dog as classDog)
end sub
The variable 'dog' in the subroutine 'OtherSub' refers to the same object instance as the variable 'Lassie' from 'DeclareSub'.
Pass the object in ByRef to your new Subroutine.
Sub ChangeHeel(ByRef olassie As classDog)
'change the object here, and it will be changed in the calling sub
olassie.HeelCapability = True
End Sub