Question

I have a ListView with the columns ‘Name’, ‘Expected’, ‘Total’, and I want to add another column saying ‘Recount’ at the end. The ‘Recount’ column will ideally have a checkbox only if the ‘Expected’ value is larger than the ‘Total’ value.

So far I have got the ListView with columns and can add a check box on the left hand side, but that check box is not under a column heading (though I can probably put another column with no values in there to work around that) and it is on all of the records.

Anyone have any ideas what else I can do?

Answer 1

This is actually relatively simple to implement, provided that you’re willing to endure the drudgery of P/Invoke to access functionality built into the native Windows control, but not exposed by the .NET FW.

I demonstrate in my answer here how this exact same thing can be done with a TreeView control, and considering how similar a ListView is to a TreeView, it should not be particularly surprising that this can be done in very much the same way with a ListView.

Here’s all the code that is required (make sure that you’ve added an Imports declaration for the System.Runtime.InteropServices namespace):

' P/Invoke declarations
Private Const LVIF_STATE As Integer = &H8
Private Const LVIS_STATEIMAGEMASK As Integer = &HF000
Private Const LVM_FIRST As Integer = &H1000
Private Const LVM_SETITEM As Integer = LVM_FIRST + 76

<StructLayout(LayoutKind.Sequential, Pack:=8, CharSet:=CharSet.Auto)> _
Private Structure LVITEM
   Public mask As Integer
   Public iItem As Integer
   Public iSubItem As Integer
   Public state As Integer
   Public stateMask As Integer
   <MarshalAs(UnmanagedType.LPTStr)> _
   Public lpszText As String
   Public cchTextMax As Integer
   Public iImage As Integer
   Public lParam As IntPtr
End Structure

<DllImport("user32.dll", CharSet:=CharSet.Auto)> _
Private Shared Function SendMessage(ByVal hWnd As IntPtr, ByVal Msg As Integer, ByVal wParam As IntPtr, ByRef lParam As LVITEM) As IntPtr
End Function

''' <summary>
''' Hides the checkbox for the specified item in a ListView control.
''' </summary>
Private Sub HideCheckBox(ByVal lvw As ListView, ByVal item As ListViewItem)
   Dim lvi As LVITEM = New LVITEM()
   lvi.iItem = item.Index
   lvi.mask = LVIF_STATE
   lvi.stateMask = LVIS_STATEIMAGEMASK
   lvi.state = 0
   SendMessage(lvw.Handle, LVM_SETITEM, IntPtr.Zero, lvi)
End Sub

And then you can simply call the above method like this:

Private Sub btnHideCheckForSelected_Click(ByVal sender As Object, ByVal e As EventArgs)
   ' Hide the checkbox next to the currently selected ListViewItem
   HideCheckBox(myListView, myListView.SelectedItems(0))
End Sub

Producing something that looks a bit like this (after clicking the “Hide Check” button for both the tomato and the cucumber items):