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Combobox Column Clearselection

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GridView

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answered on 12 Nov 2009, 09:07 PM

I have created a custom combo column to handle the clear selection, virtualized items and custom itemtemplates. This is working great except for one problem which is that with the VirtualizingStackPanel when I go to the cell it does not automatically browse to the selected item.

                    Imports Telerik.Windows.Controls         
            Imports System.Windows.Data         
            Imports System.Windows         
            Imports System.Collections         
            Imports System.Windows.Markup         
                     
            Public Class GridViewCustomComboBoxColumn         
                Inherits GridViewComboBoxColumn         
                     
                Private _ItemTemplate As DataTemplate         
                     
                Public Property ItemTemplate() As DataTemplate         
                    Get         
                        Return _ItemTemplate         
                    End Get         
                    Set(ByVal Value As DataTemplate)         
                        _ItemTemplate = Value         
                    End Set         
                End Property         
                     
                Public Overrides Function CreateCellElement(ByVal cell As Telerik.Windows.Controls.GridView.GridViewCell, ByVal dataItem As Object) As System.Windows.FrameworkElement         
                     
                    If ItemTemplate Is Nothing Then         
                     
                        Return Nothing         
                     
                    Else         
                     
                        Dim value As Object = dataItem.GetType.GetProperty(Me.DataMemberBinding.Path.Path).GetValue(dataItem, Nothing)         
                     
                        Dim cellTemplate As FrameworkElement = CType(ItemTemplate.LoadContent, FrameworkElement)         
                        cellTemplate.DataContext = (From i In ItemsSource _         
                                                    Where i.GetType.GetProperty(SelectedValueMemberPath).GetValue(i, Nothing).Equals(value) _         
                                                    Select i).FirstOrDefault         
                        Return cellTemplate         
                     
                    End If         
                     
                End Function         
                     
                Public Overrides Function CreateCellEditElement(ByVal cell As Telerik.Windows.Controls.GridView.GridViewCell, ByVal dataItem As Object) As System.Windows.FrameworkElement         
                     
                    Dim cellEditElement As RadComboBox = CType(MyBase.CreateCellEditElement(cell, dataItem), RadComboBox)         
                     
                    cellEditElement.ClearSelectionButtonVisibility = Windows.Visibility.Visible         
                    cellEditElement.ClearSelectionButtonContent = "Clear Selection"         
                     
                    If Not ItemTemplate Is Nothing Then         
                        cellEditElement.DisplayMemberPath = Nothing         
                        cellEditElement.ItemTemplate = ItemTemplate         
                    End If         
                     
                    If CType(ItemsSource, IList).Count > 100 Then         
                        Dim itemsPanelTemplate As New ItemsPanelTemplate         
                        itemsPanelTemplate = CType(XamlReader.Load("<ItemsPanelTemplate xmlns=""http://schemas.microsoft.com/winfx/2006/xaml/presentation""><VirtualizingStackPanel /></ItemsPanelTemplate>"), ItemsPanelTemplate)         
                        cellEditElement.ItemsPanel = itemsPanelTemplate         
                    End If         
                     
                    Return cellEditElement         
                     
                End Function         
                     
            End Class         
                     

answered on 20 Nov 2009, 03:21 PM

inheritedcomboboxcolumn-vb.zip

Hi Scott ,
I have prepared a small project to try reproduce the problem ( please find it attached) .

However I was not able to find any disturbing behavior of the combo with the virtualizing panel. Am I missing something ?

Regards,
Pavel

answered on 20 Nov 2009, 04:44 PM

The sample isn't using the virtualizing panel because it has < 100 records. Make the following change.

                        Private Function GetCountries() As List(Of Country)         
                    Dim countries As New List(Of Country)()         
                    For x As Integer = 1 To 1000         
                        countries.Add(New Country(x, InlineAssignHelper(Name, "Test " + x.ToString)))         
                    Next                 
                    Return countries         
                End Function         

Select a record in the list then leave that cell and go back to it. The value will still be correct but it will not autoscoll to that selected item in the list and will just show the first few items.

answered on 25 Nov 2009, 04:03 PM

inheritedcomboboxcolumn.zip

Hello Scott Rakestraw,

This issue is fixed with the latest internal build assemblies. I'm attaching the same test application for a reference.

Best wishes,
Nedyalko Nikolov
the Telerik team

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