tablelayoutpanel not raising cellpaint event

Question

I am trying to paint the rows of my tablelayoutpanel object. I added a handler for the cellpaint event but I can't even get the debugger to catch this event. Is there something else that I need to configure on the tablelayoutpanel so that I can custom paint my cells?

I have tried a forced call to invalidate on usercontrol load but that didn't help.

Here's my code:

 Private Sub TableLayoutPanel3_CellPaint(sender As Object, e As TableLayoutCellPaintEventArgs) Handles TableLayoutPanel3.CellPaint
    Select Case e.Row
        Case 1
            e.Graphics.FillRectangle(Brushes.Orange, e.CellBounds)
        Case 2
            e.Graphics.FillRectangle(Brushes.Green, e.CellBounds)
        Case 3
            e.Graphics.FillRectangle(Brushes.Yellow, e.CellBounds)
    End Select
End Sub

I used this other thread as a reference.

Edit: The objects within my tablelayoutpanel cells were not set to autosize. When I enabled autosize I found the cellpaint event would raise and my object visually displayed as I had expected. I suppose this behavior is by design.

Answer 1

In order to load the UserControl on runtime, I will create a button to trigger this. I could do it on Form_Load but for this example, I'll make it on the Button_Click.

I have the following files:

• Form1.vb
• UserControl1.vb

---

Form1.vb

In my Form1.vb I have a TableLayoutPanel (used for resizing the controls). In the first row of my TableLayoutPanel I have a button which notifies the user to "Load User Control". The second row is a place holder for my UserControl.

The following code simply adds in the UserControl1 that I created into my TableLayoutPanel

Public Class Form1
    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        Dim ucColors As New UserControl1 'Create a new instance of the UserControl
        ucColors.Dock = DockStyle.Fill 'Make it dock to it's parent container (this tablelayoutpanel)
        TableLayoutPanel1.Controls.Add(ucColors, 0, 1) 'Add the control to the tablelayoutpanel
    End Sub
End Class

---

UserControl1.vb

This is my UserControl1.vb. I created a TableLayoutPanel in this UserControl and docked it (fill). This makes the TableLayoutPanel resize to the size of the UserControl. I created three rows because you had three rows in your example.

This is the only code I need to paint the UserControl>TableLayoutPanels>Rows.

Public Class UserControl1
    Private Sub TableLayoutPanel1_CellPaint(sender As Object, e As TableLayoutCellPaintEventArgs) Handles TableLayoutPanel1.CellPaint
        Select Case e.Row
            Case 0 'Row 1
                e.Graphics.FillRectangle(Brushes.Orange, e.CellBounds)
            Case 1 'Row 2
                e.Graphics.FillRectangle(Brushes.Green, e.CellBounds)
            Case 2 'Row 3
                e.Graphics.FillRectangle(Brushes.Yellow, e.CellBounds)
            End Select
    End Sub
End Class

---

RunTime

When I execute my program, the Form1 pops up:

And then when I press the Load button, this occurs:

---

So, when I clicked on my button, a new instance of the user control was created which made it execute the Cell_Paint in the UserControl.

Hopefully this clears things up!