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Prevent smooth scrolling of richtextbox control

Posted on 2003-04-01
Medium Priority
Last Modified: 2013-12-25
Looking for a way to make the richtextbox control scroll a line at a time.  I have a custom control that implements line numbers by pairing a picture box and the richtextbox as constituent controls.  A timer checks the current line (via SendMessage) of the richtextbox and prints a range of line numbers to the picturebox.

The problem is that the user sees the smooth scrolling of the richtextbox, while the picturebox with the line numbers appears to jump to the next line.  So I need to either disable the smooth scrolling of the richtextbox or figure out how to make the printing of line numbers work on pixel boundaries.  I'm not opposed to subclassing if that's the only way to do it.
Question by:Nomlas
  • 3
  • 2
LVL 11

Expert Comment

ID: 8249934
this is probably not the best way.

Private Sub Timer1_Timer()
    With Me.RichTextBox1
        SendKeys "{Down}"
    End With
End Sub

' Good Luck!

Author Comment

ID: 8252931
Thanks, but I need a way that still lets the user work the scroll bar in the normal manner.  

Author Comment

ID: 8253169
Thanks, but I need a way that still lets the user work the scroll bar in the normal manner.  
LVL 11

Accepted Solution

supunr earned 750 total points
ID: 8257987
Private Declare Function SendMessage Lib "user32" Alias _
        "SendMessageA" (ByVal hwnd As Long, _
        ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long

Dim m_iScrollDir As Integer

Private Sub Timer1_Timer()

    If (m_iScrollDir = 1) Then
         ' Send a WM_VSCROLL message 0 is up and 1 is down
           SendMessage Me.RichTextBox1.hwnd, 277&, 0&, vbNull
         Else 'Scroll Down
           SendMessage RichTextBox1.hwnd, 277&, 1&, vbNull
         End If
End Sub

Author Comment

ID: 8261461
Looking back at my question, I see that it could have been stated better.  

I'm looking for a way to override the default behavior of the richtextbox so that when the USER scrolls the box (by the vertical scroll bar or the up/down arrow)it will scroll only in complete line increments.  My scheme for keeping another control with line numbers in it synchronized to the RTB depends on line-incremental scrolling.

Right now, I'm subclassing the WM_VSCROLL and sending it to another RTB containing the line numbers.  This is OK when the user only uses the scroll bar but gets complicated when the user uses the keyboard arrows.  I don't see a message for up/down arrows and I don't want to go to the extra complexity of hooking the keyboard events.  If I knew the RTB would scroll in line increments, I could go to a simpler method of printing line numbers to a picturebox.  Plus I just don't like smooth scrolling for this particular application use.


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