Question

I have a form (Form1) and it has 30 controls.
When I hit a button, I want to remove those 30 buttons and put other controls on the form.
Now, my problem is that this is to slow.

I have this list with controls I want to delete and I run through them with a For Each.

Private Sub ClearControls()
    'removing the controls from Me.Controls
    For Each Control As Control In ListToDelete
        Me.Controls.Remove(Control)
    Next
    ListToDelete = New List(Of Control)
End Sub

Now, if you watch the form, you see the controls getting deleted 1 by 1. This action takes about 0.4 seconds (timed with the build-in stopwatch) and that’s too long.

Are there any solutions to delete the controls in a faster way or is it only possible to delete the controls 1 by 1?

Maybe an important fact is that everything is connected with a database.
The controls are created by a class I defined myself (TableDrawer) and it creates a rectangle or circle (depends on info from the database).
I add the selfmade controls to the form and when I want to delete them, it takes 0.4 seconds to get other controls on the form – also with information out of my database.

Hopefully this clears some things up and I hope you can help me out… It really has to go a bit faster (I hope to get 0.1s or lower)

Answer 1

Hiding the Panel first seems to make the controls disappear quicker than just clearing the Panel. See this code:

Option Strict On

Public Class Form1

    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        Panel1.Visible = False

        If Not Panel1.Controls.OfType(Of Button).Any() Then
            For x As Integer = 1 To 10
                For y As Integer = 1 To 10
                    Dim btn As New Button()
                    btn.Size = New Size(45, 45)
                    btn.Location = New Point((x - 1) * 45, (y - 1) * 45)
                    btn.Text = (x * y).ToString()
                    Panel1.Controls.Add(btn)
                    btn.Visible = True
                Next
            Next
        End If

        Panel1.Visible = True
    End Sub

    Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
        Panel1.Visible = False
        Panel1.Controls.Clear()
        Panel1.Visible = True
    End Sub
End Class

This code has 2 buttons, and a Panel. Button1 generates 100 buttons, places them on a Panel. Button2 hides the panel before removing them. Perhaps you can experiment with this idea.