Toggle Style off for a TreeView control

[Jules Marchildon]

Hi All!

I have used this method in the past to turn off certain window styles and
it has worked great for me. But for some reason I can't seem to
turn off the Horizontal and Vertical ScrollBars on a TreeView window.

Here is how I created the a very simple TreeView, note I did not specifiy
that %WS_HSCROLL or %WS_VSCROLL styles when I created it.

FUNCTION CreateNewTreeView(ByVal hWnd AS LONG, rc AS RECT) AS LONG
  
    LOCAL hWndNew AS LONG
  
    '---TreeView
    LOCAL tvs          AS TV_INSERTSTRUCT
    LOCAL tvi          AS TV_ITEM
    LOCAL hTreeWnd()   AS LONG
    LOCAL sText        AS STRING
    '---
                                          
 
        'Create the TreeView control
        hWndNew = CreateWindowEx(%WS_EX_CLIENTEDGE ,"SysTreeView32","", _
                                 %WS_CHILD OR %WS_VISIBLE OR %WS_CLIPSIBLINGS _
                                 OR %TVS_HASBUTTONS OR %TVS_HASLINES _
                                 OR %TVS_LINESATROOT OR %TVS_SHOWSELALWAYS, _
                                 rc.nLeft, _
                                 rc.nTop,  _
                                 rc.nRight  - rc.nLeft, _
                                 rc.nBottom - rc.nTop,  _
                                 hWnd,ByVal %NULL,ghInst,ByVal %Null)
 

        'Initialize the tree List
        tvs.hInsertAfter = %TVI_LAST
        tvi.mask         = %TVIF_TEXT
 
        REDIM hTreeWnd(0 To 4)
 
        sText = "One"
        tvi.pszText      = StrPtr(sText)
        tvs.hParent      = %TVI_ROOT
        tvs.item         = tvi
        hTreeWnd(0)      = TreeView_InsertItem(hWndNew,tvs)
 
        sText = "Two"
        tvi.pszText      = StrPtr(sText)
        tvs.hParent      = hTreeWnd(0)
        tvs.item         = tvi
        hTreeWnd(1)      = TreeView_InsertItem(hWndNew,tvs)
 
        sText = "Buckle"
        tvi.pszText      = StrPtr(sText)
        tvs.hParent      = hTreeWnd(1)
        tvs.item         = tvi
        hTreeWnd(2)      = TreeView_InsertItem(hWndNew,tvs)
 
        sText = "My"
        tvi.pszText      = StrPtr(sText)
        tvs.hParent      = hTreeWnd(2)
        tvs.item         = tvi
        hTreeWnd(3)      = TreeView_InsertItem(hWndNew,tvs)
 
        sText = "Shoe"
        tvi.pszText      = StrPtr(sText)
        tvs.hParent      = hTreeWnd(2)
        tvs.item         = tvi
        hTreeWnd(4)      = TreeView_InsertItem(hWndNew,tvs)
 
        'Expand All
        For i& = 0 to 4
            Call TreeView_Expand( hWndNew, hTreeWnd(i&), %TVE_EXPAND )
        Next
 
        'SubClass the control 
        Call SetWindowLong(hWndNew,%GWL_WNDPROC,ByVal CodePtr(ControlSubClassProc))

  
        'Get rid of the scroll bars temporarly
        Oldstyle& = GetWindowLong( hWndNew,%GWL_STYLE )
        Newstyle& = Oldstyle& XOR %WS_VSCROLL XOR %WS_HSCROLL
        Call SetWindowLong( hWndNew, %GWL_STYLE , Newstyle&)
 
  
    FUNCTION = hWndNew
  
END FUNCTION

When the control is created with the tree fully expanded but not in view, the
scroll bars automatically come on. I would like to temporarly turn
this off. Is there a TVS_AUTOHSCROLL/TVS_AUTOVSCROLL style not documented?

How would I do this?


Thanks for any suggestions/help!

Regards, Jules

[Dominic Mitchell]

If this code is for your visual designer then let me offer a suggestion.
Do not use SetWindowLong to set and remove the styles of controls. SetWindowLong is
very limited in what it can change on the fly. The knowledge base article
"Value Returned by GetWindowLong(hWnd, GWL_STYLE)" (ID: Q83366) sheds some light on this.

Destroy and recreate the control using the current styles.

The treeview control is a case in point(on my system).
Depending on the version of insanity(comctl32.dll or internet explorer) that is install
on your system you can use the TVS_NOSCROLL(0x2000) style to disable scrolling.
However, if the treeview control has the scroll bars visible SetWindowLong with TVS_NOSCROLL
disables scrolling but the scrollbars remain visible. If the control is created with
TVS_NOSCROLL set initially then SetWinowLong with TVS_NOSCROLL cleared enables scrolling and
the scrollbars become visible when needed. You do not encounter such madness when you destroy
and recreate the control.

I am curious as to why you would want to hide the scroll bars?

------------------
Dominic Mitchell

[This message has been edited by Dominic Mitchell (edited September 09, 2000).]

[Jules Marchildon]

Dominic,

Thank you for this information. This very useful stuff. I am not at liberty
to discuss the reason online at this time. I can however, email you my code
(~50kbytes snippet) to show you exactly the reason. I have found a fix for
my problem to the scroll bar issue rather then changing the sytle on the fly.

My email is [email protected] if you are interested.

Thanks again!
Regards, Jules