Re: list view question

From: Sameh Ahmed (essoplus_at_hotmail.com)
Date: 03/16/04 

Date: Tue, 16 Mar 2004 15:30:27 +0200

Thanks a lot
will test and update you
thanks for your time
Sameh
"Dino Buljubasic" <dino@noplacelikehome.com> wrote in message
news:04gc50t2j5ok4vq2uoosuf41h190g04i40@4ax.com...
>
> Hi Ahmed,
>
> sorting columns in .net is not as simple as in VB. .net sorts column
> as strings (by default only first colum) so you must provide a way to
> sort data other than strings and columns other than first column.
>
> To do that, you need a new class that implements Icomparer that
> exposes compare method to compare two objects.
>
> Inside the Compare function of your class, you need to check which
> column to perform sorting on and then to do the sorting on that column
> by the type of values it contains.
>
> To do this you need to:
> 1) Inside the form that holds the list view - add inside construcotr
> of the form line:
> AddHandler lvwMyList.ColumnClick, AddressOf Me.lvwMyList_ColumnClick
>
> , then add event lvwMyList_ColumnClick()
>
> Now you can build your class clsSorter as :
>
> --------- CLASS CODE -------------------------------------------------
> ' class : classSortER
> ' purpose : This class is providing functionality to sort list view
> items in
> ' A form depending on which column of the list view has
> been
> ' clicked. This is necessary because vb.net will
> otherwise do
> ' sorting on first column only and the default sort is on
> strings.
> ' sorting : ascending by default
> '
> ' requirements
> ' - in form's constructor, add following line of code
> ' AddHandler lvwMyList.ColumnClick, AddressOf
> Me.lvwMyList_ColumnClick
> ' to connect the event handler with the list view
> column click
> ' event.
> ' - add lvwMyList_ColumnClick event in your form
>
> Public Class classSorter
> Implements IComparer ' exposes method (compare) to compare two
> objects
>
> Private col As Integer ' column to sort
> Private order As SortOrder ' asc or desc
>
> 'Dim blnSortingIn As Boolean ' true, sort ascending; false, sort
> descending
>
> Public Sub New()
> col = 0 ' sort first col by default in ascending order
> order = SortOrder.Ascending
> End Sub
>
> ' c-tor that receives column to sort and in which order
> Public Sub New(ByVal aColumn As Integer, ByVal order As SortOrder,
> ByVal aForm As Form)
> col = aColumn
> Me.order = order
> End Sub
>
> ' method to compare two objects (list view items)
> Public Function Compare(ByVal x As Object, ByVal y As Object) _
> As Integer Implements
> System.Collections.IComparer.Compare
>
> Dim returnVal As Integer = -1
>
> Dim xItem As System.Windows.Forms.ListViewItem = x
> Dim yItem As System.Windows.Forms.ListViewItem = y
>
> If TypeOf CallerForm Is Demeter25.frmViewEditInactiveDocuments
> Then
> ' if the caller form is frmViewEditInactiveDocuments then
> sort according the
> ' columns in select case statement below
> Select Case col
> Case 0 ' in this case 0th column holds numerics
> ' sort numeric values
> Dim blnCompare As Boolean
>
> blnCompare = Val(xItem.SubItems(col).Text) >
> Val(yItem.SubItems(col).Text)
>
> If blnCompare Then
> returnVal = 1
> Else
> returnVal = -1
> End If
>
> Case 1 ' in this case 1th column holds strings
> ' sort strings
> returnVal = [String].Compare(CType(x,
> ListViewItem).SubItems(col).Text, CType(y,
> ListViewItem).SubItems(col).Text)
>
> Case 2 '' in this case 2nd column holds datetime vals
> ' sort date time values
> returnVal =
> DateTime.Compare(CDate(xItem.SubItems(col).Text),
> CDate(yItem.SubItems(col).Text))
>
> Case 3 '' in this case 3rd column holds datetime
> vals, too
> ' sort date time values
> returnVal =
> DateTime.Compare(CDate(xItem.SubItems(col).Text),
> CDate(yItem.SubItems(col).Text))
>
> Case 4 '' in this case 0th column holds numerics
> ' sort numeric values
> Dim blnCompare As Boolean
>
> blnCompare = Val(xItem.SubItems(col).Text) >
> Val(yItem.SubItems(col).Text)
>
> If blnCompare Then
> returnVal = 1
> Else
> returnVal = -1
> End If
>
> Case Else
>
> End Select
>
>
> ' is sort order descending
> If order = SortOrder.Descending Then
> ' ivert the value returned by string.compare.
> returnVal *= -1
> End If
>
> Return returnVal
> End Function
>
> End Class
> ---------END OF CLASS CODE----------------------------------------
>
> Now, in variable declaration part of your form add:
> dim sortColumn as integer = -1 ' no sorting yet
>
> inside the lvwMyList_ColumnClick event add:
> If e.Column <> sortColumn then
> sortColumn = e.column
> lvwMyList.Sorting = Sorting.Ascending ' asc by default
>
> if lvwMyList.Sorting = sortOrder.Ascending then
> lvwMyList.Sorging = SortOrder.Descending
> else
> lvwMyList.Sorging = SortOrder.Ascending
> end if
>
> lvwMyList.Sort()
> lvwMyList.ListViewItemSorter = New clsSorter(e.Column,
> lvwMyList.Sorting)
>
> end if
>
>
> hope this helps,
>
> Dino
>
> On Mon, 15 Mar 2004 22:48:34 +0200, "Sameh Ahmed"
> <essoplus@hotmail.com> wrote:
>
> >Excellent
> >both worked fine:)
> >now a another quick question if possible
> >I set the tree view Sorting to Ascending
> >what if I want it to be sorting depending on the column that the user
clicks
> >it's header
> >Example:
> >when he click the header column header of emplid it will be sorted by
that
> >column and so on?
> >Thanks for your time
> >Regards
> >Sameh
> >
> >"Herfried K. Wagner [MVP]" <hirf-spam-me-here@gmx.at> wrote in message
> >news:c352l9$22kfb0$2@ID-208219.news.uni-berlin.de...
> >> * "Sameh Ahmed" <essoplus@hotmail.com> scripsit:
> >> > Hello there
> >> > I have a listview with 3 header columns, I can populate the first and
> >second
> >> > one with the following code, but cannot figure out how to populate
the
> >third
> >> > and the following header columns?
> >> > listview.Items.Add(empname)
> >> > listview.Items(i).SubItems.Add(empid)
> >>
> >> The same as the line above. Add a 2nd 'SubItem' to 'Items(i)'.
> >>
> >> --
> >> Herfried K. Wagner [MVP]
> >> <http://dotnet.mvps.org/>
> >
>

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