Listview prevent Column Resizing
Michael Fritz
is it possible to prevent resizing certain columns of a listview control? If
so, how can a manage it?
Michael
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Michael Fritz
fri...@degnet.baynet.de
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galen nickerson
similar to yours that was posted in vb.controls. That question wanted to
prevent the first two ColumnHeaders from being resized when their width was
set to 0. I'm sure you can modify the code to meet your needs. The code
assumes you've already added the ColumnHeaders. Let me know if you have any
problems with the code.
'==========================
You can prevent resizing of your ColumnHeaders by
subclassing and intercepting the HDN_BEGINTRACK header notification message.
This message is sent to the header control's parent window when the user
begins dragging a divider. However, the columns can still be resized if the
user double clicks on a column separator. You can prevent this by
intercepting the HDN_DIVIDERDBLCLICK header notification message. The code
is as follows:
'Tested on a ListView with 3 ColumnHeaders
'ColumnHeader1 = FirstName
'ColumnHeader2 = LastName
'ColumnHeader3 = FullName
'===============
'Begin Module Code
Option Explicit
Public Const WM_NOTIFY = &H4E
Public Const GWL_WNDPROC = -4
Global lpPrevWndProc As Long
Global gHW As Long
Public Declare Function CallWindowProc Lib "user32" Alias _
"CallWindowProcA" (ByVal lpPrevWndFunc As Long, _
ByVal hwnd As Long, ByVal Msg As Long, _
ByVal wParam As Long, ByVal lParam As Long) As Long
Public Declare Function SetWindowLong Lib _
"user32" Alias "SetWindowLongA" _
(ByVal hwnd As Long, ByVal nIndex As Long, _
ByVal dwNewLong As Long) As Long
Public Declare Sub MoveMemory Lib _
"kernel32" Alias "RtlMoveMemory" _
(pDest As Any, pSource As Any, _
ByVal dwLength As Long)
'The NMHDR structure contains information
'about a notification message.
'The pointer to this structure is specified as
'the lParam member of the WM_NOTIFY message.
Public Type NMHDR
hwndFrom As Long ' Window handle of control sending message
idFrom As Long ' Identifier of control sending message
code As Long ' Specifies the notification code
End Type
Private Type NMHEADER
hdr As NMHDR
iItem As Long
iButton As Long
lPtrHDItem As Long ' HDITEM FAR* pItem
End Type
'Header Notifications
'HDN_BEGINDRAG Drag operation has begun
'HDN_BEGINTRACK User began dragging a divider
'HDN_DIVIDERDBLCLICK User double clicked the divider area
'HDN_ENDDRAG Drag operation has ended
'HDN_ENDTRACK User finished dragging a divider
'HDN_GETDISPINFO Item information request
'HDN_ITEMCHANGED An item has changed
'HDN_ITEMCHANGING An item is changing
'HDN_ITEMCLICK User clicked the control
'HDN_ITEMDBLCLICK User double-clicked the control
'HDN_TRACK User is dragging a divider
'NM_CUSTOMDRAW Custom draw request notification
'NM_RCLICK User clicked right mouse button in control
'NM_RELEASEDCAPTURE Control is releasing mouse capture
Public Enum HD_Notifications
HDN_FIRST = -300&
HDN_LAST = -399&
HDN_GETDISPINFO = (HDN_FIRST - 9)
HDN_BEGINDRAG = (HDN_FIRST - 10)
HDN_ENDDRAG = (HDN_FIRST - 11)
HDN_ITEMCLICK = (HDN_FIRST - 2)
HDN_ITEMDBLCLICK = (HDN_FIRST - 3)
HDN_DIVIDERDBLCLICK = (HDN_FIRST - 5)
HDN_ITEMCHANGING = (HDN_FIRST - 0)
HDN_ITEMCHANGED = (HDN_FIRST - 1)
HDN_BEGINTRACK = (HDN_FIRST - 6)
HDN_ENDTRACK = (HDN_FIRST - 7)
HDN_TRACK = (HDN_FIRST - 8)
NM_FIRST = -0& ' (0U- 0U)
NM_CUSTOMDRAW = (NM_FIRST - 12)
NM_RCLICK = (NM_FIRST - 5)
NM_RELEASEDCAPTURE = (NM_FIRST - 16)
End Enum
Public Sub Hook()
'Establish a hook to capture messages to this window
lpPrevWndProc = SetWindowLong(gHW, _
GWL_WNDPROC, _
AddressOf WindowProc)
End Sub
Public Sub Unhook()
Dim temp As Long
'Reset the message handler for this window
temp = SetWindowLong(gHW, _
GWL_WNDPROC, lpPrevWndProc)
End Sub
Function WindowProc(ByVal hwnd As Long, ByVal uMsg As Long, _
ByVal wParam As Long, ByVal lParam As Long) As Long
Dim nmh As NMHDR
Dim nmhd As NMHEADER
Select Case uMsg
Case WM_NOTIFY
' Fill the NMHDR struct from the lParam pointer.
' (for any WM_NOTIFY msg, lParam always points to a struct which is
' either the NMHDR struct, or whose 1st member is the NMHDR struct)
Call MoveMemory(nmh, ByVal lParam, Len(nmh))
'You could combine HDN_BEGINTRACK
'and HDN_DIVIDERDBLCLICK into one
'(i.e., Case HDN_BEGINTRACK, HDN_DIVIDERDBLCLICK:)
Select Case nmh.code
Case HDN_BEGINTRACK
'User began dragging a divider
Call MoveMemory(nmhd, ByVal lParam, Len(nmhd))
Debug.Print "HDN_BEGINTRACK: " & nmhd.iItem
Select Case nmhd.iItem
'Select Case ListView ColumnHeader Index
'You want to Prevent Tracking
'Note API is 0 based unlike
'ColumnHeaders Collection
'which is 1 based
Case 0
'ListView ColumnHeader Index 1
'First Name Column
'Prevent Tracking
Debug.Print "ListViewColumnHeader: " & _
(nmhd.iItem + 1) & " - Tracking Disabled"
WindowProc = 1
Exit Function
Case 1
'ListView ColumnHeader Index 2
'Last Name Column
'Prevent Tracking
Debug.Print "ListViewColumnHeader: " & _
(nmhd.iItem + 1) & " - Tracking Disabled"
WindowProc = 1
Exit Function
Case Else
'Other ColumnHeaders
'Full Name Column
'Allow Resizing
Debug.Print "ListViewColumnHeader: " & _
(nmhd.iItem + 1) & " - Tracking Enabled"
End Select
Case HDN_DIVIDERDBLCLICK
'User double clicked the divider area
Call MoveMemory(nmhd, ByVal lParam, Len(nmhd))
Debug.Print "HDN_DIVIDERDBLCLICK: " & nmhd.iItem
Select Case nmhd.iItem
'Select Case ListView ColumnHeader Index
'You want to Prevent Resizing if the User
'double clicks on a Column separator
'Note API is 0 based unlike
'ColumnHeaders Collection
'which is 1 based
Case 0
'ListView Column Index 1
'First Name Column
'Prevent Resizing if the User
'double clicks on a Column separator
Debug.Print "ListViewColumnHeader: " & _
(nmhd.iItem + 1) & " - Resizing Disabled"
WindowProc = 1
Exit Function
Case 1
'ListView ColumnHeader Index 2
'Last Name Column
'Prevent Resizing if the User
'double clicks on a Column separator
Debug.Print "ListViewColumnHeader: " & _
(nmhd.iItem + 1) & " - Resizing Disabled"
WindowProc = 1
Exit Function
Case Else
'ListView Column Index 3
'Full Name Column
'nothing
'Allow resize if user double clicks
Debug.Print "ListViewColumnHeader: " & _
(nmhd.iItem + 1) & " - Resizing Enabled"
End Select
End Select
End Select
'Pass message on to the original window message handler
WindowProc = CallWindowProc(lpPrevWndProc, hwnd, _
uMsg, wParam, lParam)
End Function
'End Module Code
'===============
'Begin Form Code
Private Sub Form_Load()
'Store handle
gHW = ListView1.hwnd
Hook
End Sub
Private Sub Form_Unload(Cancel As Integer)
'Pressing the End button or selecting End from _
the Run menu without unhooking causes _
an Invalid Page Fault and closes Microsoft Visual Basic.
'Call procedure to stop intercepting
'the messages for this window
Unhook
End Sub
'End Form Code
'===============
See the following for more info:
Header Control Notification Messages
http://msdn.microsoft.com/library/sdkdoc/shellcc/commctls/header/notificatio
ns/notifications.htm
'--------
galen
Michael Fritz <fri...@degnet.baynet.de> wrote in message
news:OL123RBh#GA.264@cppssbbsa03...
Michael Fritz
thank you for your reply
galen nickerson <g_nickerson...@email.msn.com> schrieb in im
Newsbeitrag: OSMdJECh#GA....@cppssbbsa02.microsoft.com...