Adding Controls to a Table Layout Panel in code

Article
2008-06-08

Question

_{Sunday, June 8, 2008 5:54 AM | 1 vote}

I want to add controls to a form in code. I was hoping I could set up the Table Layout Panel with three columns. The hope would be to have a form that looks like this below. I know I can set my GrowthStyle to "AddRows" so that my controls are added to new rows. How do my controls know what columns to be added to when using the Add Method? The idea being that I would add controls to column1 first then columns2, and then finally column 3.

Column1 Column2 Column3
Label #1 Combobox#1 Button

Label #2 Combobox#1

Label #3 Combobox#1 TextBox

Label #4 Combobox#1

Label #5 Combobox#1

Thanks

All replies (5)

_{Sunday, June 8, 2008 11:04 AM ✅Answered | 2 votes}

Dim tlp As New TableLayoutPanel

tlp.ColumnCount = 3

tlp.RowCount = 5

tlp.AutoSize = True

Dim labels(4) As Label

For i As Byte = 0 To 4

labels(i) = New Label

labels(i).Text = "Label number " & i

tlp.Controls.Add(labels(i), 0, i)

Next i

Dim comboboxes(4) As ComboBox

For i As Byte = 0 To 4

comboboxes(i) = New ComboBox

comboboxes(i).Items.AddRange _

(New String() {"first item", "second item", "item number 3"})

tlp.Controls.Add(comboboxes(i), 1, i)

Next i

Dim firstRowButton As New Button

firstRowButton.Text = "New button!"

tlp.Controls.Add(firstRowButton, 2, 0)

Dim thirdRowTextBox As New TextBox

tlp.Controls.Add(thirdRowTextBox, 2, 2)

Me.Controls.Add(tlp)

_{Saturday, June 14, 2008 3:26 AM}

So just out of curiosity if I wanted to add these controls to a control collection I am assuming that I can do the following:

Public CntrlCollection As Collection

Dim labels(4) As Label
        For i As Byte = 0 To 4
            labels(i) = New Label
            labels(i).Text = "Label number " & i
            tlp.Controls.Add(labels(i), 0, i)
            CntrlCollection.Add(labels(i))
        Next i

However when I try this I get an Null Reference Exception ("Object reference not set to an instance of an object.") on the line of code tha says "CntrlCollection.Add(labels(i))"

Lastly my goal is to use the .Show method on the collection so that I can show all the controls. However I the intellisense does not automatically pull up a .Show Method after CntrlCollection.

Do I have to dimension my collection differently?

Thanks

_{Saturday, June 14, 2008 3:34 AM}

The Null Reference is referring to CntrlCollection. You probably need to declare it
*Public CntrlCollection As New Collection

*What isn't clear to me is the purpose of CntrlCollection. When you add the labels to the TLP, they are already becoming members of the collection TLP.Controls.

Adding them to the TLP also displays them, so you don't need to call .Show on anything.

_{Saturday, June 14, 2008 1:56 PM}

Yes I see your point. What I want to do is create a group of controls which I can turn on and off in a Row Enter event in a DataGridView. The code above would be an example of one group of controls. The way the code was originally written, the controls all show. But I want to be able to add mutitple groups of controls to the same table layout panel and turn them on and off. I was hoping to add them to the control collection and the use a Show Method on the collection. The controls currently show when the form loads. But I cannot get the controls to show again when I choose a different row and then come back to the row in question in the DataGridView (i.e. DataGridView1_RowEnter event).

Public CntrlCollection As New Collection

Private Sub DataGridView1_RowEnter(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DataGridView1.RowEnter
Dim SelectedRow As DataGridViewRow
Dim cntrlcounter As Double

        SelectedRow = GetGridRow(e.RowIndex, DataGridView1)

       'Clear existing controls on tablelayoutpanel
        TableLayoutPanel1.Controls.Clear()

        Select Case SelectedRow.Index
            Case Is = 0
                For cntrlcounter = 1 To CntrlCollection.Count
                    Audit1CntrlCollection(cntrlcounter).Show()

           Next

            Case Is = 1
             'Do nothing
          End Select

Thanks

_{Monday, September 15, 2008 3:37 PM}

ExcelMonkey said:

Yes I see your point. What I want to do is create a group of controls which I can turn on and off in a Row Enter event in a DataGridView. The code above would be an example of one group of controls. The way the code was originally written, the controls all show. But I want to be able to add mutitple groups of controls to the same table layout panel and turn them on and off. I was hoping to add them to the control collection and the use a Show Method on the collection. The controls currently show when the form loads. But I cannot get the controls to show again when I choose a different row and then come back to the row in question in the DataGridView (i.e. DataGridView1_RowEnter event).

To add multiple groups of controls, I suggest that you create a userControl and add it to the row/column you want your group of control to be in.

Just in case, you don't know what's a userControl, it will allow you to create an object (or group if you prefer) with more than one control in it. Then, after you build your project, you should see the userControl appears in your toolbox. Pick it from there and add it in the tableLayoutPanel row/column you want your "group of controls" to be in.

Hope it will helps you.

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Adding Controls to a Table Layout Panel in code

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