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ListView - Sorting by Number or Date

Posted by Pete Cozens on October 13th, 2003

ListView - Sorting by Number or Date

The ListView control that comes with MSCOMCTL.OCX isn't too bad. It supplies us with most of the things that we need, and makes them incredibly easy to code. As a VC++ developer I can tell you that most of the features that we all take for granted can be a real pig to implement using the MFC and API calls.

One thing that this control is sadly lacking in, however, is the ability to sort by number or date. It would also appear to be something that a lot of people are asking for.

My first attempt at implementing this involved using APIs to talk directly to the ListView window. It was fast and did just the job that I wanted. It did, however, have one major drawback - Microsoft, in their infinite wisdom, have given VB developers a wrapper for the ListView window which stores its own internal collection of listitem data, rather than referencing the window's own data. The result of this is not only that two copies of the data are stored in memory (Bloatware? It gets my vote...), but if you try to manipulate the listview directly, then all the VB collections go out of synch with what's displayed on-screen. BIG problem!

For my second attempt, I decided to take a step back, and try something simpler. I decided to make use of the alphabetical sort that has been implemented with the control. It involves locking the window so that no changes in the data are reflected on-screen, re-formatting the list items so that they may be sorted alphabetically, sorting them, and then restoring the original data before unlocking and refreshing the ListView. I know that this is a pig of a way to do things, but it works!

The good news it that the sort is surprisingly fast. On my machine (a PII 350 with 64Mb RAM running NT4), sorting by number takes about 0.4 milliseconds per listitem (when running in the IDE), and by date takes around 0.35ms.

This certainly isn't THE way to sort ListItems by number or date, but it'll me do until Microsoft supply a custom sort for the ListView control.

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  • JonasK

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    ten points

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  • Let ListView sort dates and numbers itself

    Posted by UnderMan on 04/29/2007 02:50pm 

    Just add two more columns with zero lengths to retain extra data.  Pad numbers with leading zeros: Format(a, "000000"), store dates without slashes or commas: Format(d, "mmddyy"), and store them in the hidden columns.  When displayed date or amount columns are chosen, reference the sort to the hidden columns instead.  Voila, sorted without a sort routine.  It's inherently sorted from the get go.  Save all the column information, including the hidden ones, in a file for retrieval on start up.

Private Sub Form_Load()
    'Randomly add dates, amounts, and text to listview
    'lvMain is the name of the listview box
    'Using two extra columns for the date and amount sort data
    Randomize
    For x = 1 To 365
        Set lx = lvMain.ListItems.Add
        l = Date + Int(Rnd * 90) + 1                '90 days from today
        m = Rnd * 250 + 1                           'Up to $250.00 spent
        lx.Text = Format(l, "MMM dd/yy")            'Displayed date
        lx.SubItems(1) = Format(m, "##0.00")        'Displayed amount
        lx.SubItems(2) = Format(l, "mmddyy")        'for date sorting, hidden
        lx.SubItems(3) = Format(m * 100, "0000000") 'for amount sorting, hidden
        d = ""
        For m = 1 To 4
            d = d + Chr(Int(Rnd * 26) + 65)
        Next
        lx.SubItems(4) = d
    Next
    'Don't want any item to be selected when form first opens
    'user selects it himself/herself
    If Not lvMain.SelectedItem Is Nothing Then
        lvMain.SelectedItem.Selected = False
        Set lvMain.SelectedItem = Nothing
    End If
    Sum_It
End Sub 'Form_Load

Private Sub lvMain_ColumnClick(ByVal ColumnHeader As MSComctlLib.ColumnHeader)
    If ColumnHeader = "Amount" Then
        'If column is clicked once, sort in ascending order,
        'clicked a 2nd time sort in descending order
        'same goes for date and text columns
        If lvMain.Tag <> "Amount" Then
            lvMain.Tag = "Amount"
            lvMain.SortOrder = 1
        End If
        lvMain.Sorted = True
        lvMain.SortKey = 4 - 1
        lvMain.SortOrder = 1 Xor lvMain.SortOrder
    ElseIf ColumnHeader = "Date" Then
        If lvMain.Tag <> "Date" Then
            lvMain.Tag = "Date"
            lvMain.SortOrder = 1
        End If
        lvMain.Sorted = True
        lvMain.SortKey = 3 - 1
        lvMain.SortOrder = 1 Xor lvMain.SortOrder
    Else
        If lvMain.Tag <> ColumnHeader Then
            lvMain.Tag = ColumnHeader
            lvMain.SortOrder = 1
        End If
        lvMain.Sorted = True
        lvMain.SortKey = ColumnHeader.Index - 1
        lvMain.SortOrder = 1 Xor lvMain.SortOrder
    End If
End Sub 'lvMain_ColumnClick

Private Sub Sum_It()
    'Sum "Amount" column
    For x = 1 To lvMain.ListItems.Count
        c = c + Val(lvMain.ListItems(x).SubItems(1))
    Next
    lblTotal = c
End Sub 'Sum_It

    Reply

  • Better version of: ListView - Sorting by Number or Date

    Posted by thomasholme on 07/28/2004 04:21am

    I had to use this is a database application with more than 20 listviews, thus I have moved the sort part into it'w own function and I have added the option to sort mixed strings (e.g. 2940.65 $) wich are stored in the DB I have to interface. Please email me if you would like to get my new version of the project. thomas@openmpeg4.org Again, Thanks Pete for a great contribution

    Reply

  • What a great solution, so much better than callbacks!!

    Posted by o2simple on 07/23/2004 01:51pm 

    There are tons of examples using callbacks
and they all suffer from the collecitons getting out of sync.  Do they really expect that no one will use SelectedItem after a sort?  We are using .NET now but we still have a ton of legacy code, and users are tired of double clicking a listitem and having it open the wrong one! Thanx for this great solution.  Its even way faster than my old way using callbacks.

    Reply

  • very nice

    Posted by Legacy on 10/02/2003 12:00am

    Originally posted by: Willem Laarman

    Thank you very much..

    I have been looking for a function like this for a long time. It works great!

    Reply

  • Thank yous

    Posted by Legacy on 07/23/2003 12:00am

    Originally posted by: Au

    Help me much...

    Reply

  • A Solution At Last

    Posted by Legacy on 05/29/2003 12:00am

    Originally posted by: Terry 

    Finally, a workable solution for my app!  I've been struggling with figuring out how to allow my users to sort some reports that range from a few records up to 50000+. My alternatives thusfar were unsatisfactory:


    - Text sort on every column regardless of the column data type.

    - Use the Win API sort method, but screw up the tag information.

    - Export the data to an multi dimensional array, sort it and re-populate the control, which gave me two results:

         - Use a quicksort algorithm, which was fairly fast 

           but would give a stack space error when sorting

           more than 3000 records.

         - Use a slower non-recursive sort method 

           (i.e. shell sort) which didn't crash but would take

           up to an hour to sort on the huge lists.


    Now I can give users good data-aware sorting without the crashing and in a reasonable amount of time (+-10 seconds for numeric sort on 50000 records.)


    It is depressing that the ListView control isn't smart enough to do this for us, but at least now we have an adequate work around. Hokey or not, it works!


    Thanks again!

    Reply

  • Work great

    Posted by Legacy on 05/16/2003 12:00am

    Originally posted by: Gary

    After missing around for a few days with Microsoft solution (Article 170884) 'Sort a ListView Control by Date', I was glad to find your solution. It works great!!!.

    Reply

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