Triple State Checkbox (VB6)

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I know you can have triple state check boxes in Access but I don’t see a way to have this in VB. I want to have a ‘true’, ‘false’ or ‘not selected’ (greyed out) status.

Anyone know how to do this? Do I need to get a 3rd party control?

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In VBA you set the set the TripleState property to true, and whilst I do not have VB6 available to me just know, I woul de surprised it was any different.

Try CheckBox1.TripleState = True, in your FormLoad event.

Andrew C

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VB does not act at all like Access. If you have a CheckBox, it can have a value of vbChecked or vbUnchecked (corresponding to checked or not), plus it has an Enabled property which is either True or False (corresponding to grayed-out or not), so it it like a QuadState! See this thread for some more info on transition from Access to VB.

Try this example: put an array of four checkboxes on a new form along with a single command button and enter this code:

Option Explicit
Dim InCheckEvent

Private Sub Check1_Click(Index As Integer)
    If InCheckEvent Then Exit Sub
    InCheckEvent = True
    Check1((Index +1) Mod 4).Enabled = True
    Check1((Index+1) Mod 4).Value = vbUnchecked
    Check1((Index +2) Mod 4).Enabled = False
    Check1((Index+2) Mod 4).Value = vbChecked
    Check1((Index +3) Mod 4).Enabled = False
    Check1((Index+3) Mod 4).Value = vbUnchecked
    DoEvents
    InCheckEvent = False
End Sub

Private Sub Command1_Click()
Dim cb As CheckBox
    InCheckEvent = True
    For Each cb in Check1
        cb.Enabled = True
        cb.Value = vbUnchecked
    Next cb
    InCheckEvent = False
End Sub

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Sam,
I recall reading somewhere (no idea where though!) that checkboxes in VB could have values of 0 (unchecked), 1 (checked) or 2 (dimmed). Is my memory failing me? (I hope not – I’m too young for that to be kicking in already! )

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You are absolutely correct, Rory! I never knew it, but there is a vbGrayed. If you set the Value of a checkbox to vbGrayed, it is checked and dimmed and the Enabled property is unchanged, so a checkbox can have six different states.

Now I have a question, what use is a dimmed checkbox and what does a user do to dim a checkbox?

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Never having used VB proper, only VBA, I couldn’t say for sure but I assume it’s the same as an Access triplestate checkbox – you have Yes/No/Unspecified(Null in Access). If you don’t want a default value for a checkbox, you’d set its triplestate property to true and then you know whether it was specifically UNchecked rather than ignored. I may, of course, be entirely wrong!
I don’t think there is actually a way for a user to dim it other than not touching it at all.

**Edit**
Not sure what I was thinking of – in Access at any rate, clicking on a triplestate checkbox cycles through all three possible states. Perfect for Yes/No/Don’t know questionnaires!

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Having had a chance to check out the VB Checkbox, it can have one of 3 possible value initially, but once clicked can then only alternate between True and False.

It seems it cannot be given any value other tan 0 or 1 from code, and 2 (Grayed) has to set at design time.

So I would suggest the best use for it is to accept a global default if left in grayed state, otherwise True or False to apply a specific value.

VBA Checkboxes do cycle through 3 possible values if set to TripleState, Null, 0 and 1

Andrew C

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But you could easily use the click event to cycle thru the three states, just make sure you use a global varable to “disable” the click event when you click it in code like I did in the example above.

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Yes, VB checkboxes can have three states.
Look at the Value property.

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There’s been a lot of discussion on how to do this and not a single question as to why. The null state of a checkbox normally indicates that it hasn’t been touched, which is why you can’t cycle through the states easily. True or False indicate that a value has been set. What are you trying to achieve with a triple-state checkbox anyhow?

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The reason I wanted a triple state check box is for when users set options to download data from a datasource – e.g. if there is a boolean field ‘sold’ , I want to be able to select items that are set to TRUE (check box TRUE), FALSE (check box FALSE), or both (check box unselected).

So basically I want to be able to select true, false or either – like you can do in Access.

Thanks

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But if you don’t set a default stste for the control or you set the default to Null, wouldn’t that serve the same purpose without requiring any “cycling”? You wouldn’t ordinarily include a criteria condition in a query for a field where you wanted all records, regardless of value.

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I am creating an ‘advanced search criteria’ form and I would like users to be able to cycle through the three states on one of the check boxes.

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Here is the click event that you need to cycle:

Option Explicit
Dim InCheckEvent As Boolean
Dim Check2Value As CheckBoxConstants
Private Sub Check2_Click()
    If InCheckEvent Then Exit Sub
    InCheckEvent = True
    Check2Value = (Check2Value + 1) Mod 3
    Check2.Value = Check2Value
    DoEvents
    InCheckEvent = False
End Sub

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I came up with this:

‘//cycle through True, False & vbGrayed
If chkIncDel(Index) = vbTrue Then
i = i + 1
Else
If chkIncDel(Index) = vbFalse Then
i = i + 1
End If
End If

If i = 2 Then
chkIncDel(Index) = vbGrayed
i = 0
End If

i is an integer set to 0 on form load.

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