How to remove the inactive scroll bars till the text is big enough in multiline text box?

[Ravi Kiran]

Well, the subject says it all..

If you set the Multiline property of a textbox to true, and set the scrollbar to say vertical, a vertical scroll bar is displayed all the time. I want it to display the scroll bar only when the text is big enough i.e outside the visible range? is it possible?
API way is ok.
I am doing some searching on my own.. meanwhile.. any ideas pointers...

Thanks in advance

RK

[Ravi Kiran]

I am answering my own post:
Here is info for anybody who want to know about it:

Use ShowScrollbar Api fn.

Declare Function ShowScrollBar Lib "user32" (byval hwnd as Long, byval wBar as Long, byval bshow as Long) as Long
Const SB_HORZ = 0
Const SB_VERT = 1
Const SB_CTL = 2 ' Applicable for a Scroll bar control Only
Const SB_BOTH = 3




RK

[Ravi Kiran]

But there is something funny about it:

IF you dont create a text box with scroll bars initally ( ie set ScrollBars = 0 , in design mode), and then just set the style with
SetWindowLong.hwnd, GWL_STYLE, lstyle Or WS_VHSCROLL, the fn goes thru w/o Error
and even
lrtn = ShowScrollBar(.hwnd, SB_VERT, 1)
also goes thru w/o error, but the scroll bar doesn't show!!

Where as instead of SB_VERT, if you say SB_BOTH, in the above line, both scroll bars appear!!, any body want to investigate this??


private Sub Text3_Change()
Dim nl as Long, ll as Long
Dim lstyle as Long
Dim rect1 as RECT

With Text3
nl = SendMessage(.hwnd, EM_GETLINECOUNT, 0, byval &H0&)

nl = SendMessage(.hwnd, EM_GETFIRSTVISIBLELINE, 0, byval &H0&)
If nl <> 0 then
Debug.print "First visible line:"; nl;
lstyle = GetWindowLong(Text3.hwnd, GWL_STYLE)
Debug.print "Style of text3 = 0x"; Hex$(lstyle);

Debug.Assert (lstyle And &H4&) = &H4&
If (lstyle And &H4&) = &H4& then
' it is a multi line text box.
If (lstyle And WS_VSCROLL) = 0 then
lstyle = lstyle Or WS_VSCROLL

lrtn = SetWindowLong(.hwnd, GWL_STYLE, lstyle)
If lrtn = 0 then
MsgBox "Setwindow long failed with err code=" & Str(Err.LastDllError)
End If

lrtn = ShowScrollBar(.hwnd, SB_VERT, 1)
' apparently there is no way to find out, if the scroll bar
' is already visible. So just make it true always
Debug.print "Show scrollbar returns:"; lrtn
End If
End If
.Refresh
End If
End With

End Sub




However, if you create the window with V-Scrollbar intially, and hide it on the form load with ShowWindow(..,SB_VERT , 0), and just enable it when the size > visible size, then it works fine.

RK

[Chris Eastwood]

I think a text box has to specify that it has scrollbars when it is created (like a multi-line textbox) - ie. When VB does the CreateWindowEx call. As you know, it's nigh-on impossible to change these properties once your program is running so always use scrollbars in the textbox, just don't show them when required.

Unless of course, you want to create your own TextBox control using the API ;-)

(mind you, the guys over at http://vbaccelerator.com have already done this - it destroys and then recreates the window when you change one of 'those' properties).


Chris Eastwood

CodeGuru - the website for developers
http://codeguru.developer.com/vb

[Ravi Kiran]

Hi Chris,

I know that some properties need to be set before window creation and cannot be changed afterwords.
But the question was "Why does it work for the case of SB_BOTH", unless ofcourse, vb is doing internally what guys at vbaccelerator are doing! :-)

RK

[Chris Eastwood]

I'm not sure why it works with SB_BOTH - I discovered the ShowScrollBar stuff quite a while ago and only really used it to determine the client area of a control. I wouldn't imagine that VB is destroying the window then recreating it again (it only does that when you switch from IDE to run-time AFAIK).

I suppose it could be one of those built in 'features' of VB and it's controls that we all learn to love.


Chris Eastwood

CodeGuru - the website for developers
http://codeguru.developer.com/vb