Re: Locking columns


"Mo" <Mo@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:EBFB64AE-4C34-469C-899D-968A44D2ACF6@xxxxxxxxxxxxxxxx
> Hi, i am using the ListView control to display data from a database. the
> problem i am having is to restrict users from changing the column sizes
> when
> the program runs. hwo do i do this?
>

The way I would recommend doing this is to subclass the listview's
columnheader and eat the WM_SETCURSOR message. To get the handle of the
header control, you need to send the ListView an LVM_GETHEADER message.

Here's how to do that:

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

Private Const LVM_FIRST As Long = &H1000&
Private Const LVM_GETHEADER As Long = LVM_FIRST + 31

'Get handle to Header control
hHeader = SendMessage(ListView.hwnd, LVM_GETHEADER, 0&, ByVal 0&)

Now that you have the hwnd, you can subclass it. In your winproc function,
you'd have something like this:

Private Function WndProcHeader(ByVal hwnd As Long, ByVal uMsg As Long, ByVal
wParam As Long, ByVal lParam As Long) As Long

Select Case uMsg
Case WM_SETCURSOR
'If not allowing columns to be resized, return 1 for this
message
'and don't call the default window proc. This also prevents
'the mouse pointer from changing to the "resize" cursor
If bAllowColumnResize Then
WndProcHeader = CallWindowProc(lpfnOldWinProc, hwnd,
uMsg, wParam, lParam)
Else
WndProcHeader = 1
End If


There is another way that doesn't involve subclassing. Unfortunately, I
don't recall what it is right now. I do remember why I don't use it: the
mouse pointer still changes to the resize cursor, which could confuse users.


> Another problem is when clicking twice in quick sucession, the first
> column
> (the product code) can be changed by the user - although this change does
> not
> update the database. so when you run the program again, the default values
> are back. how do i stop users from changing this value?
>

Set the ListView's LabelEdit property to 1 - lvwManual. With that setting to
the property, you must call the StartLabelEdit method to edit the column
data.


--
Mike
Microsoft MVP Visual Basic


.

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