Firing an Event for a control

  • Thread starter Thread starter One Handed Man
  • Start date Start date
O

One Handed Man

How can one fire an event programatically for a given control. In another
post someone wanted to cause an event in order to make a RichTextBox scroll
down.

However, the onVscroll method is a protected method for this control. How
can this be acheived. ?

Your help is appreciated. - Many Thanks

--
Regards - One Handed Man

Author : Fish .NET & Keep .NET
=========================================
This posting is provided "AS IS" with no warranties,
and confers no rights.
 
One Handed Man,
Having a protected OnVscroll Sub to raise the VScroll Event is the Standard
..NET Event Pattern. Its recommended that you use it in classes that you
create that raise events. Especially when those classes are inheritable.

http://msdn.microsoft.com/library/d...s/cpgenref/html/cpconeventusageguidelines.asp

Unless the control has an explicit public method to raise event MyEvent,
such as Button.PerformClick, the way to raise the event is to derive from
the class, then call the protected OnMyEvent method. This allows derived
controls a chance to change the behavior when the event is raised. It also
allows derived controls a chance to raise an event of the base class.

The On*event* subs are normally hidden, to see them use "Tools - Options -
Text Editor - Basic - General - Hide advanced members".

Remember only derived classes can call Protected Members.

Public Class MyRichTextBox
Inherits RichTextBox

Public Sub PerformVScroll()
MyBase.OnVScroll(EventArgs.Empty)
End Sub

End Class

Hope this helps
Jay
 
Your post has been most helpful.

Thank You Very Much

--
Regards - One Handed Man

Author : Fish .NET & Keep .NET
=========================================
This posting is provided "AS IS" with no warranties,
and confers no rights.
 
I created the sub class asyour directed and added a handler for the event. I
can see that the event fires uding debug. But what happens is this.

When the RTB appears with all the text ( exceeding the height of the
control ) the scroll bars do not appear even when forced using properties.
Once the event is fired the cursor disapears due to lost focus but the text
does not scroll in the box.


Any ideas ? sorry if this sounds vague. I'm sure Im doing something wrong
but here is the code.

Public Class Form1

Inherits System.Windows.Forms.Form

Public WithEvents RTB As New MyRichTextBox



#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

SetUpRTB()







End Sub

'Form overrides dispose to clean up the component list.

Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)

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.

Friend WithEvents Button2 As System.Windows.Forms.Button

<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()

Me.Button2 = New System.Windows.Forms.Button

Me.SuspendLayout()

'

'Button2

'

Me.Button2.Location = New System.Drawing.Point(112, 40)

Me.Button2.Name = "Button2"

Me.Button2.TabIndex = 2

Me.Button2.Text = "Button2"

'

'Form1

'

Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)

Me.ClientSize = New System.Drawing.Size(376, 349)

Me.Controls.Add(Me.Button2)

Me.Name = "Form1"

Me.Text = "Form1"

Me.ResumeLayout(False)

End Sub

#End Region

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs)

Dim ea As New EventArgs

End Sub

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load

rtb.ScrollBars = RichTextBoxScrollBars.None

rtb.Text +=
"RichTextBox1jkhkhgjkhgkjjkhkjhgjghjgjkhkhgjkhgkjjkhkjhgjghjgjkhkhgjkhgkjjkh
kjhgjghjgjkhkhgjkhgkjjkhkjhgjghjgjkhkhgjkhgkjjkhkjhgjghjgjkhkhgjkhgkjjkhkjhg
jghjgjkhkhgjkhgkjjkhkjhgjghjgjkhkhgjkhgkjjkhkjhgjghjgjkhkhgjkhgkjjkhkjhgjghj
gjkhkhgjkhgkjjkhkjhgjghjgjkhkhgjkhgkjjkhkjhgjghjgjkhkhgjkhgkjjkhkjhgjghjgjkh
khgjkhgkjjkhkjhgjghjgjkhkhgjkhgkjjkhkjhgjghjgjkhkhgjkhgkjjkhkjhgjghjgjkhkhgj
khgkjjkhkjhgjghJJJJJkjjkhkjhgjghjgjkhkhgjkhgkjjkhkjhgjghjgjkhkhgjkhgkjjkhkjh
gjghjgjkhkhgjkhgkjjkhkjhgjghjgjkhkhgjkhgkjjkhkjhgjghjgjkhkhgjkhgkjjkhkjhgjgh
jgjkhkhgjkhgkjjkhkjhgjghjgjkhkhCCCCCC*******CCCCCC"

End Sub



Sub SetUpRTB()

Me.Controls.Add(Me.RTB)

Me.RTB.Location = New System.Drawing.Point(112, 144)

Me.RTB.Name = "rtb"

Me.RTB.ScrollBars = RichTextBoxScrollBars.Both

Me.RTB.Enabled = True

Me.RTB.Size = New System.Drawing.Size(208, 96)

Me.RTB.TabIndex = 0

Me.RTB.Text = ""

Me.RTB.Visible = True

End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button2.Click

RTB.PerformVScroll()

End Sub

Private Sub handleScroll(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles RTB.VScroll

Console.WriteLine("Handling scroll")

End Sub

End Class


--
Regards - One Handed Man

Author : Fish .NET & Keep .NET
=========================================
This posting is provided "AS IS" with no warranties,
and confers no rights.
 
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