Smooth scrolling rich text box with timer

[Letsgetcoding]

Hey,

I'm wondering how to scroll smoothly down a RTB using a timer. By smooth im not meaning one line at a time, but more a few pixels.

How do I do this?

Thanks,
Jessee

[.paul.]

resize your rtb so it shows all of the text, set scrollbars = none, then paste it onto a panel. set the panel autoscroll property to true, then:

''' <summary>
''' timer
''' </summary>
''' <param name="sender"></param>
''' <param name="e"></param>
''' <remarks>interval = 100ms</remarks>
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
    Panel1.AutoScrollPosition = New Point(Panel1.AutoScrollPosition.X, Math.Abs(Panel1.AutoScrollPosition.Y) + 1)
End Sub

[Letsgetcoding]

Hey,

That works but since the text in the rich text box changes length, I cant have a fixed size textbox.

Which means I have a huge textbox, and the scroll bar on the panel is huge.

Is there an easier way?

Thanks!
Jessee

[.paul.]

ok here's an alternative method without the panel. it uses the windows API function sendmessage:

Public Class Form1
 
    Declare Function SendMessage Lib "user32.dll" Alias "SendMessageA" (ByVal hWnd As IntPtr, ByVal msg As Integer, ByVal wParam As Integer, ByRef lParam As POINT) As Integer
 
    Const EM_GETSCROLLPOS As Integer = 1245
    Const EM_SETSCROLLPOS As Integer = 1246
 
    Structure POINT
        Dim x As Integer
        Dim y As Integer
    End Structure
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Timer1.Enabled = True
    End Sub
 
    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        Dim p As New POINT
        SendMessage(RichTextBox1.Handle, EM_GETSCROLLPOS, 0, p)
        p.y += 1
        SendMessage(RichTextBox1.Handle, EM_SETSCROLLPOS, 0, p)
    End Sub
 
End Class