HOWTO: Sort a ListView Control by Date

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Article ID: 170884 - View products that this article applies to.
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SUMMARY

When using a Listview control, you can set the Sorted property for the control to sort the list alphabetically. However, the Listview control does not expose a property or method for sorting a list by date. This article presents a method that you can use to sort a Listview control by date.

MORE INFORMATION

WARNING: One or more of the following functions are discussed in this article; VarPtr, VarPtrArray, VarPtrStringArray, StrPtr, ObjPtr. These functions are not supported by Microsoft Technical Support. They are not documented in the Visual Basic documentation and are provided in this Knowledge Base article "as is." Microsoft does not guarantee that they will be available in future releases of Visual Basic.

To sort data in a ListView control by date, it is necessary to provide a comparison function to the control via AddressOf.

NOTE: Using this approach, you will sort the data in the control but not the ListItems collection. Therefore, if you must read the data from the list in sorted order, it is necessary to step through the actual list rather than the ListItems collection.

Step-by-Step Example

  1. Start a new Visual Basic project. Form1 is created by default.
  2. On the Project menu, click Components, select the Microsoft Windows Common Controls 5.0 check box, and then click OK.

    NOTE: You can also use Visual Basic 6.0 and select the Microsoft Windows Common Controls 6.0 check box with only one minor change, as noted below.
  3. Add a Module to the project.
  4. Draw a ListView control on Form1.
  5. Add the following code to Form1:
          Option Explicit
    
          Private Sub Form_Load()
    
            Dim clmAdd As ColumnHeader
            Dim itmAdd As ListItem
    
            'Add two Column Headers to the ListView control
            Set clmAdd = ListView1.ColumnHeaders.Add(Text:="Name")
            Set clmAdd = ListView1.ColumnHeaders.Add(Text:="Date")
    
            'Set the view property of the Listview control to Report view
            ListView1.View = lvwReport
    
            'Add data to the ListView control
            Set itmAdd = ListView1.ListItems.Add(Text:="Joe")
            itmAdd.SubItems(1) = "05/07/97"
    
            Set itmAdd = ListView1.ListItems.Add(Text:="Sally")
            itmAdd.SubItems(1) = "04/08/97"
    
            Set itmAdd = ListView1.ListItems.Add(Text:="Bill")
            itmAdd.SubItems(1) = "05/29/97"
    
            Set itmAdd = ListView1.ListItems.Add(Text:="Fred")
            itmAdd.SubItems(1) = "05/17/97"
    
            Set itmAdd = ListView1.ListItems.Add(Text:="Anne")
            itmAdd.SubItems(1) = "04/01/97"
    
          End Sub
    
          ' Use this line of code for Common Controls 5.0:
          Private Sub ListView1_ColumnClick(ByVal ColumnHeader As _
                  ComctlLib.ColumnHeader)
          ' For Common Controls 6.0, uncomment the line below and comment the line above.
          'Private Sub ListView1_ColumnClick(ByVal ColumnHeader As _
                  MSComctlLib.ColumnHeader)
    
            Dim strName As String
            Dim dDate As Date
            Dim lngItem As Long
    
            'Handle User click on column header
            If ColumnHeader.Text = "Name" Then  'User clicked on Name header
              ListView1.Sorted = True        'Use default sorting to sort the
              ListView1.SortKey = 0          'items in the list
            Else
              ListView1.Sorted = False       'User clicked on the Date header
                                             'Use our sort routine to sort
                                             'by date
              SendMessage ListView1.hWnd, _
                          LVM_SORTITEMS, _
                          ListView1.hWnd, _
                          AddressOf CompareDates
            End If
    
            'Refresh the ListView before writing the data
            ListView1.Refresh
    
            'Loop through the items in the List to print them out in
            'sorted order.
            'NOTE: You are looping through the ListView control because when _
            'sorting by date the ListItems collection won't be sorted.
    
            For lngItem = 0 To ListView1.ListItems.Count - 1
              ListView_GetListItem lngItem, ListView1.hWnd, strName, dDate
            Next
    
          End Sub
    					
  6. Add the following code to Module1:
          Option Explicit
    
          'Structures
    
          Public Type POINT
            x As Long
            y As Long
          End Type
    
          Public Type LV_FINDINFO
            flags As Long
            psz As String
            lParam As Long
            pt As POINT
            vkDirection As Long
          End Type
    
          Public Type LV_ITEM
            mask As Long
            iItem As Long
            iSubItem As Long
            State As Long
            stateMask As Long
            pszText As Long
            cchTextMax As Long
            iImage As Long
            lParam As Long
            iIndent As Long
          End Type
    
          'Constants
          Private Const LVFI_PARAM = 1
          Private Const LVIF_TEXT = &H1
    
          Private Const LVM_FIRST = &H1000
          Private Const LVM_FINDITEM = LVM_FIRST + 13
          Private Const LVM_GETITEMTEXT = LVM_FIRST + 45
          Public Const LVM_SORTITEMS = LVM_FIRST + 48
    
          'API declarations
    
          Declare Function SendMessage Lib "user32" Alias "SendMessageA" ( _
            ByVal hWnd As Long, _
            ByVal wMsg As Long, _
            ByVal wParam As Long, _
            ByVal lParam As Long) As Long
    
          'Module Functions and Procedures
    
          'CompareDates: This is the sorting routine that gets passed to the
          'ListView control to provide the comparison test for date values.
    
          Public Function CompareDates(ByVal lngParam1 As Long, _
                                       ByVal lngParam2 As Long, _
                                       ByVal hWnd As Long) As Long
    
            Dim strName1 As String
            Dim strName2 As String 
            Dim dDate1 As Date
            Dim dDate2 As Date
    
            'Obtain the item names and dates corresponding to the
            'input parameters
    
            ListView_GetItemData lngParam1, hWnd, strName1, dDate1
            ListView_GetItemData lngParam2, hWnd, strName2, dDate2
    
            'Compare the dates
            'Return 0 ==> Less Than
            '       1 ==> Equal
            '       2 ==> Greater Than
    
            If dDate1 < dDate2 Then
              CompareDates = 0
            ElseIf dDate1 = dDate2 Then
              CompareDates = 1
            Else
              CompareDates = 2
            End If
    
          End Function
    
          'GetItemData - Given Retrieves
    
          Public Sub ListView_GetItemData(lngParam As Long, _
                                          hWnd As Long, _
                                          strName As String, _
                                          dDate As Date)
            Dim objFind As LV_FINDINFO
            Dim lngIndex As Long
            Dim objItem As LV_ITEM
            Dim baBuffer(32) As Byte
            Dim lngLength As Long
    
            '
            ' Convert the input parameter to an index in the list view
            '
            objFind.flags = LVFI_PARAM
            objFind.lParam = lngParam
            lngIndex = SendMessage(hWnd, LVM_FINDITEM, -1, VarPtr(objFind))
    
            '
            ' Obtain the name of the specified list view item
            '
            objItem.mask = LVIF_TEXT
            objItem.iSubItem = 0
            objItem.pszText = VarPtr(baBuffer(0))
            objItem.cchTextMax = UBound(baBuffer)
            lngLength = SendMessage(hWnd, LVM_GETITEMTEXT, lngIndex, _
                                    VarPtr(objItem))
            strName = Left$(StrConv(baBuffer, vbUnicode), lngLength)
    
            '
            ' Obtain the modification date of the specified list view item
            '
            objItem.mask = LVIF_TEXT
            objItem.iSubItem = 1
            objItem.pszText = VarPtr(baBuffer(0))
            objItem.cchTextMax = UBound(baBuffer)
            lngLength = SendMessage(hWnd, LVM_GETITEMTEXT, lngIndex, _
                                    VarPtr(objItem))
            If lngLength > 0 Then
              dDate = CDate(Left$(StrConv(baBuffer, vbUnicode), lngLength))
            End If
    
          End Sub
    
          'GetListItem - This is a modified version of ListView_GetItemData
          ' It takes an index into the list as a parameter and returns
          ' the appropriate values in the strName and dDate parameters.
    
          Public Sub ListView_GetListItem(lngIndex As Long, _
                                          hWnd As Long, _
                                          strName As String, _
                                          dDate As Date)
            Dim objItem As LV_ITEM
            Dim baBuffer(32) As Byte
            Dim lngLength As Long
    
            '
            ' Obtain the name of the specified list view item
            '
            objItem.mask = LVIF_TEXT
            objItem.iSubItem = 0
            objItem.pszText = VarPtr(baBuffer(0))
            objItem.cchTextMax = UBound(baBuffer)
            lngLength = SendMessage(hWnd, LVM_GETITEMTEXT, lngIndex, _
                                    VarPtr(objItem))
            strName = Left$(StrConv(baBuffer, vbUnicode), lngLength)
    
            '
            ' Obtain the modification date of the specified list view item
            '
            objItem.mask = LVIF_TEXT
            objItem.iSubItem = 1
            objItem.pszText = VarPtr(baBuffer(0))
            objItem.cchTextMax = UBound(baBuffer)
            lngLength = SendMessage(hWnd, LVM_GETITEMTEXT, lngIndex, _
                                    VarPtr(objItem))
            If lngLength > 0 Then
              dDate = CDate(Left$(StrConv(baBuffer, vbUnicode), lngLength))
            End If
    
          End Sub
    					
  7. Save your project.
  8. Press the F5 key to run the application. Click the Date column header to sort the items in the list by date.

Properties

Article ID: 170884 - Last Review: February 24, 2005 - Revision: 2.2
APPLIES TO
  • Microsoft Visual Basic 6.0 Learning Edition
  • Microsoft Visual Basic 5.0 Learning Edition
  • Microsoft Visual Basic 6.0 Professional Edition
  • Microsoft Visual Basic 5.0 Professional Edition
  • Microsoft Visual Basic 6.0 Enterprise Edition
  • Microsoft Visual Basic 5.0 Enterprise Edition
  • Microsoft Visual Basic 5.0 Control Creation Edition
Keywords: 
kbhowto kbapi KB170884

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