Creating Buttons In Code

[c0ley]

Apologies if this has been asked many times before, but I'm a fairly new VB.Net programmer, and I'm having a slight problem here with VB.Net

Without elaborating on my reasoning, I am adding controls to my form in code rather in designer mode. For example, buttons are added like this

' *** REST OF CODE IN HERE ***

Dim MyButton as New Button
MyButton.Location = New Point (100, 100)
MyButton.Size = New Size (64, 64)
MyButton.Text = "Click me to say Hello World"
Me.Controls.Add(MyButton)

' *** REST OF CODE IN HERE ***

rather than by the traditional way of "drawing" buttons on the form.

My question is, having done this, how do I write code to (say) display a message box to say "Hello World"?

What I mean is that, if I had drawn the button on using the designer, I would click on the button to generate a function within which I could enter code, e.g.

Private Sub MyButton_Click(etc.etc.) Handles MyButton.Click

MessageBox("Hello World!") ' or similar

End Sub

or similar. However, because I've created the button in code, VB.Net will not allow me to do this.

Anybody have any ideas? Any help would be greatly appreciated!!!!

Thanks again.

[Grunt]

cant you use the event drop downlist in code view?

[c0ley]

Hi Grunt, thanks for replying.

Because I've created the button within the code itself, it does not show up on the event list (which is mildly annoying).

Only controls that I have drawn onto the form show up there.

[Grunt]

declare it withevents:

Friend WithEvents MyButton As System.Windows.Forms.Button

[mpdeglau]

To add attach a button created at runtime to an event when creating the button add this:

AddHandler MyButton.Click , AddressOf MyButton_Click

I believe another issue you will run into is where you are declaring the button. It should be declared at the class level (outside any function) and have withevents.

Private WithEvents MyButton as Button
 
Private Sub TheSubWithTheCode
MyButton = New Button
AddHandler MyButton.Click, AddressOf MyButton_Click
'Then the rest that you have
 
End Sub

[kleinma]

you also need an actual sub called MyButton_Click, that has the same signature as the actual button click event.

[kleinma]

Public Class Form3
    Inherits System.Windows.Forms.Form
    [b]Private WithEvents MyButton As Button[/b]
 
#Region " Windows Form Designer generated code "
 
    Public Sub New()
        MyBase.New()
 
        'This call is required by the Windows Form Designer.
        InitializeComponent()
 
        'Add any initialization after the InitializeComponent() call
 
    End Sub
 
    'Form overrides dispose to clean up the component list.
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        [b]RemoveHandler MyButton.Click, AddressOf SayHelloWorld[/b]
        If disposing Then
            If Not (components Is Nothing) Then
                components.Dispose()
            End If
        End If
        MyBase.Dispose(disposing)
    End Sub
 
    'Required by the Windows Form Designer
    Private components As System.ComponentModel.IContainer
 
    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer.  
    'Do not modify it using the code editor.
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        '
        'Form3
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
        Me.ClientSize = New System.Drawing.Size(456, 302)
        Me.Name = "Form3"
        Me.Text = "Form3"
 
    End Sub
 
#End Region
[b]
    Private Sub Form3_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        MyButton = New Button
        MyButton.Location = New Point(100, 100)
        MyButton.Size = New Size(64, 64)
        MyButton.Text = "Click me to say Hello World"
        AddHandler MyButton.Click, AddressOf SayHelloWorld
        Me.Controls.Add(MyButton)
    End Sub
 
    Private Sub SayHelloWorld(ByVal sender As Object, ByVal e As System.EventArgs)
        MessageBox.Show("Hello World")
    End Sub
End Class
[/b]

Don't forget to remove any handlers you add

[c0ley]

Guys, especially Kleinma, thanks very much! Kleinma - your method worked!

The only problem now is that I've got a whole lot of code to re-work...a late night for me, unfortunately!

Thanks again guys, take care.