How can I make to scroll richtextbox vertically one line up and one line down into my code in VB.NET?

Question

I want to write a code that make scrolls vertically my Richtextbox1 One line up or one line down. How can I make it ? Thanks for all.

Answer 1

Public Const WM_VSCROLL As Integer = &H115
Public Const SB_LINEDOWN As Integer = 1
Public Const SB_PAGEDOWN As Integer = 3
Public Const SB_LINEUP As Integer = 1
Public Const SB_PAGEUP As Integer = 2

Public Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
(ByVal hwnd As IntPtr, ByVal wMsg As Integer, ByVal wParam As Integer, ByVal lParam As Integer) As Integer

Private Sub RichTextBox1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles RichTextBox1.KeyDown

If e.KeyCode = Keys.Down Then
  e.Handled = True

  SendMessage(Me.RichTextBox1.Handle, WM_VSCROLL, SB_PAGEDOWN, 0)
ElseIf e.KeyCode = Keys.Up Then
  e.Handled = True

  SendMessage(Me.RichTextBox1.Handle, WM_VSCROLL, SB_PAGEUP, 0)
End If

 End Sub