Just doing some light reading on WPF where I need to bind the selectedItems from a DataGrid but I am unable to come up with anything tangible. I just need the selected objects.
DataGrid:
<DataGrid Grid.Row="5"
Grid.Column="0"
Grid.ColumnSpan="4"
Name="ui_dtgAgreementDocuments"
ItemsSource="{Binding Path=Documents, Mode=TwoWay}"
SelectedItem="{Binding Path=DocumentSelection, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
HorizontalAlignment="Stretch"
VerticalAlignment="Stretch"
Background="White"
SelectionMode="Extended" Margin="2,5"
IsReadOnly="True"
CanUserAddRows="False"
CanUserReorderColumns="False"
CanUserResizeRows="False"
GridLinesVisibility="None"
HorizontalScrollBarVisibility="Hidden"
columnHeaderStyle="{StaticResource GreenTea}"
HeadersVisibility="Column"
BorderThickness="2"
BorderBrush="LightGray"
CellStyle="{StaticResource NonSelectableDataGridCellStyle}"
SelectionUnit="FullRow"
HorizontalContentAlignment="Stretch" AutoGenerateColumns="False">
This will work:
MultiSelectorBehaviours.vb
Imports System.Collections
Imports System.Windows
Imports System.Windows.Controls.Primitives
Imports System.Windows.Controls
Imports System
Public NotInheritable Class MultiSelectorBehaviours
Private Sub New()
End Sub
Public Shared ReadOnly SynchronizedSelectedItems As DependencyProperty = _
DependencyProperty.RegisterAttached("SynchronizedSelectedItems", GetType(IList), GetType(MultiSelectorBehaviours), New PropertyMetadata(Nothing, New PropertyChangedCallback(AddressOf OnSynchronizedSelectedItemsChanged)))
Private Shared ReadOnly SynchronizationManagerProperty As DependencyProperty = DependencyProperty.RegisterAttached("SynchronizationManager", GetType(SynchronizationManager), GetType(MultiSelectorBehaviours), New PropertyMetadata(Nothing))
''' <summary>
''' Gets the synchronized selected items.
''' </summary>
''' <param name="dependencyObject">The dependency object.</param>
''' <returns>The list that is acting as the sync list.</returns>
Public Shared Function GetSynchronizedSelectedItems(ByVal dependencyObject As DependencyObject) As IList
Return DirectCast(dependencyObject.GetValue(SynchronizedSelectedItems), IList)
End Function
''' <summary>
''' Sets the synchronized selected items.
''' </summary>
''' <param name="dependencyObject">The dependency object.</param>
''' <param name="value">The value to be set as synchronized items.</param>
Public Shared Sub SetSynchronizedSelectedItems(ByVal dependencyObject As DependencyObject, ByVal value As IList)
dependencyObject.SetValue(SynchronizedSelectedItems, value)
End Sub
Private Shared Function GetSynchronizationManager(ByVal dependencyObject As DependencyObject) As SynchronizationManager
Return DirectCast(dependencyObject.GetValue(SynchronizationManagerProperty), SynchronizationManager)
End Function
Private Shared Sub SetSynchronizationManager(ByVal dependencyObject As DependencyObject, ByVal value As SynchronizationManager)
dependencyObject.SetValue(SynchronizationManagerProperty, value)
End Sub
Private Shared Sub OnSynchronizedSelectedItemsChanged(ByVal dependencyObject As DependencyObject, ByVal e As DependencyPropertyChangedEventArgs)
If e.OldValue IsNot Nothing Then
Dim synchronizer As SynchronizationManager = GetSynchronizationManager(dependencyObject)
synchronizer.StopSynchronizing()
SetSynchronizationManager(dependencyObject, Nothing)
End If
Dim list As IList = TryCast(e.NewValue, IList)
Dim selector As Selector = TryCast(dependencyObject, Selector)
' check that this property is an IList, and that it is being set on a ListBox
If list IsNot Nothing AndAlso selector IsNot Nothing Then
Dim synchronizer As SynchronizationManager = GetSynchronizationManager(dependencyObject)
If synchronizer Is Nothing Then
synchronizer = New SynchronizationManager(selector)
SetSynchronizationManager(dependencyObject, synchronizer)
End If
synchronizer.StartSynchronizingList()
End If
End Sub
''' <summary>
''' A synchronization manager.
''' </summary>
Private Class SynchronizationManager
Private ReadOnly _multiSelector As Selector
Private _synchronizer As TwoListSynchronizer
''' <summary>
''' Initializes a new instance of the <see cref="SynchronizationManager"/> class.
''' </summary>
''' <param name="selector">The selector.</param>
Friend Sub New(ByVal selector As Selector)
_multiSelector = selector
End Sub
''' <summary>
''' Starts synchronizing the list.
''' </summary>
Public Sub StartSynchronizingList()
Dim list As IList = GetSynchronizedSelectedItems(_multiSelector)
If list IsNot Nothing Then
_synchronizer = New TwoListSynchronizer(GetSelectedItemsCollection(_multiSelector), list)
_synchronizer.StartSynchronizing()
End If
End Sub
''' <summary>
''' Stops synchronizing the list.
''' </summary>
Public Sub StopSynchronizing()
_synchronizer.StopSynchronizing()
End Sub
Public Shared Function GetSelectedItemsCollection(ByVal selector As Selector) As IList
If TypeOf selector Is MultiSelector Then
Return TryCast(selector, MultiSelector).SelectedItems
ElseIf TypeOf selector Is ListBox Then
Return TryCast(selector, ListBox).SelectedItems
Else
Throw New InvalidOperationException("Target object has no SelectedItems property to bind.")
End If
End Function
End Class
End Class
IListItemConverter.vb
''' <summary>
''' Converts items in the Master list to Items in the target list, and back again.
''' </summary>
Public Interface IListItemConverter
''' <summary>
''' Converts the specified master list item.
''' </summary>
''' <param name="masterListItem">The master list item.</param>
''' <returns>The result of the conversion.</returns>
Function Convert(ByVal masterListItem As Object) As Object
''' <summary>
''' Converts the specified target list item.
''' </summary>
''' <param name="targetListItem">The target list item.</param>
''' <returns>The result of the conversion.</returns>
Function ConvertBack(ByVal targetListItem As Object) As Object
End Interface
TwoListSynchronizer.vb
Imports System.Collections
Imports System.Collections.Specialized
Imports System.Linq
Imports System.Windows
''' <summary>
''' Keeps two lists synchronized.
''' </summary>
Public Class TwoListSynchronizer
Implements IWeakEventListener
Private Shared ReadOnly DefaultConverter As IListItemConverter = New DoNothingListItemConverter()
Private ReadOnly _masterList As IList
Private ReadOnly _masterTargetConverter As IListItemConverter
Private ReadOnly _targetList As IList
''' <summary>
''' Initializes a new instance of the <see cref="TwoListSynchronizer"/> class.
''' </summary>
''' <param name="masterList">The master list.</param>
''' <param name="targetList">The target list.</param>
''' <param name="masterTargetConverter">The master-target converter.</param>
Public Sub New(ByVal masterList As IList, ByVal targetList As IList, ByVal masterTargetConverter As IListItemConverter)
_masterList = masterList
_targetList = targetList
_masterTargetConverter = masterTargetConverter
End Sub
''' <summary>
''' Initializes a new instance of the <see cref="TwoListSynchronizer"/> class.
''' </summary>
''' <param name="masterList">The master list.</param>
''' <param name="targetList">The target list.</param>
Public Sub New(ByVal masterList As IList, ByVal targetList As IList)
Me.New(masterList, targetList, DefaultConverter)
End Sub
Private Delegate Sub ChangeListAction(ByVal list As IList, ByVal e As NotifyCollectionChangedEventArgs, ByVal converter As Converter(Of Object, Object))
''' <summary>
''' Starts synchronizing the lists.
''' </summary>
Public Sub StartSynchronizing()
ListenForChangeEvents(_masterList)
ListenForChangeEvents(_targetList)
' Update the Target list from the Master list
SetListValuesFromSource(_masterList, _targetList, AddressOf ConvertFromMasterToTarget)
' In some cases the target list might have its own view on which items should included:
' so update the master list from the target list
' (This is the case with a ListBox SelectedItems collection: only items from the ItemsSource can be included in SelectedItems)
If Not TargetAndMasterCollectionsAreEqual() Then
SetListValuesFromSource(_targetList, _masterList, AddressOf ConvertFromTargetToMaster)
End If
End Sub
''' <summary>
''' Stop synchronizing the lists.
''' </summary>
Public Sub StopSynchronizing()
StopListeningForChangeEvents(_masterList)
StopListeningForChangeEvents(_targetList)
End Sub
''' <summary>
''' Receives events from the centralized event manager.
''' </summary>
''' <param name="managerType">The type of the <see cref="T:System.Windows.WeakEventManager"/> calling this method.</param>
''' <param name="sender">Object that originated the event.</param>
''' <param name="e">Event data.</param>
''' <returns>
''' true if the listener handled the event. It is considered an error by the <see cref="T:System.Windows.WeakEventManager"/> handling in WPF to register a listener for an event that the listener does not handle. Regardless, the method should return false if it receives an event that it does not recognize or handle.
''' </returns>
Public Function ReceiveWeakEvent(ByVal managerType As Type, ByVal sender As Object, ByVal e As EventArgs) As Boolean Implements System.Windows.IWeakEventListener.ReceiveWeakEvent
HandleCollectionChanged(TryCast(sender, IList), TryCast(e, NotifyCollectionChangedEventArgs))
Return True
End Function
''' <summary>
''' Listens for change events on a list.
''' </summary>
''' <param name="list">The list to listen to.</param>
Protected Sub ListenForChangeEvents(ByVal list As IList)
If TypeOf list Is INotifyCollectionChanged Then
CollectionChangedEventManager.AddListener(TryCast(list, INotifyCollectionChanged), Me)
End If
End Sub
''' <summary>
''' Stops listening for change events.
''' </summary>
''' <param name="list">The list to stop listening to.</param>
Protected Sub StopListeningForChangeEvents(ByVal list As IList)
If TypeOf list Is INotifyCollectionChanged Then
CollectionChangedEventManager.RemoveListener(TryCast(list, INotifyCollectionChanged), Me)
End If
End Sub
Private Sub AddItems(ByVal list As IList, ByVal e As NotifyCollectionChangedEventArgs, ByVal converter As Converter(Of Object, Object))
Dim itemCount As Integer = e.NewItems.Count
For i As Integer = 0 To itemCount - 1
Dim insertionPoint As Integer = e.NewStartingIndex + i
If insertionPoint > list.Count Then
list.Add(converter(e.NewItems(i)))
Else
list.Insert(insertionPoint, converter(e.NewItems(i)))
End If
Next
End Sub
Private Function ConvertFromMasterToTarget(ByVal masterListItem As Object) As Object
Return If(_masterTargetConverter Is Nothing, masterListItem, _masterTargetConverter.Convert(masterListItem))
End Function
Private Function ConvertFromTargetToMaster(ByVal targetListItem As Object) As Object
Return If(_masterTargetConverter Is Nothing, targetListItem, _masterTargetConverter.ConvertBack(targetListItem))
End Function
Private Sub HandleCollectionChanged(ByVal sender As Object, ByVal e As NotifyCollectionChangedEventArgs)
Dim sourceList As IList = TryCast(sender, IList)
Select Case e.Action
Case NotifyCollectionChangedAction.Add
PerformActionOnAllLists(AddressOf AddItems, sourceList, e)
Exit Select
Case NotifyCollectionChangedAction.Move
PerformActionOnAllLists(AddressOf MoveItems, sourceList, e)
Exit Select
Case NotifyCollectionChangedAction.Remove
PerformActionOnAllLists(AddressOf RemoveItems, sourceList, e)
Exit Select
Case NotifyCollectionChangedAction.Replace
PerformActionOnAllLists(AddressOf ReplaceItems, sourceList, e)
Exit Select
Case NotifyCollectionChangedAction.Reset
UpdateListsFromSource(TryCast(sender, IList))
Exit Select
Case Else
Exit Select
End Select
End Sub
Private Sub MoveItems(ByVal list As IList, ByVal e As NotifyCollectionChangedEventArgs, ByVal converter As Converter(Of Object, Object))
RemoveItems(list, e, converter)
AddItems(list, e, converter)
End Sub
Private Sub PerformActionOnAllLists(ByVal action As ChangeListAction, ByVal sourceList As IList, ByVal collectionChangedArgs As NotifyCollectionChangedEventArgs)
If sourceList Is _masterList Then
PerformActionOnList(_targetList, action, collectionChangedArgs, AddressOf ConvertFromMasterToTarget)
Else
PerformActionOnList(_masterList, action, collectionChangedArgs, AddressOf ConvertFromTargetToMaster)
End If
End Sub
Private Sub PerformActionOnList(ByVal list As IList, ByVal action As ChangeListAction, ByVal collectionChangedArgs As NotifyCollectionChangedEventArgs, ByVal converter As Converter(Of Object, Object))
StopListeningForChangeEvents(list)
action(list, collectionChangedArgs, converter)
ListenForChangeEvents(list)
End Sub
Private Sub RemoveItems(ByVal list As IList, ByVal e As NotifyCollectionChangedEventArgs, ByVal converter As Converter(Of Object, Object))
Dim itemCount As Integer = e.OldItems.Count
' for the number of items being removed, remove the item from the Old Starting Index
' (this will cause following items to be shifted down to fill the hole).
For i As Integer = 0 To itemCount - 1
list.RemoveAt(e.OldStartingIndex)
Next
End Sub
Private Sub ReplaceItems(ByVal list As IList, ByVal e As NotifyCollectionChangedEventArgs, ByVal converter As Converter(Of Object, Object))
RemoveItems(list, e, converter)
AddItems(list, e, converter)
End Sub
Private Sub SetListValuesFromSource(ByVal sourceList As IList, ByVal targetList As IList, ByVal converter As Converter(Of Object, Object))
StopListeningForChangeEvents(targetList)
targetList.Clear()
For Each o As Object In sourceList
targetList.Add(converter(o))
Next
ListenForChangeEvents(targetList)
End Sub
Private Function TargetAndMasterCollectionsAreEqual() As Boolean
Return _masterList.Cast(Of Object)().SequenceEqual(_targetList.Cast(Of Object)().[Select](Function(item) ConvertFromTargetToMaster(item)))
End Function
''' <summary>
''' Makes sure that all synchronized lists have the same values as the source list.
''' </summary>
''' <param name="sourceList">The source list.</param>
Private Sub UpdateListsFromSource(ByVal sourceList As IList)
If sourceList Is _masterList Then
SetListValuesFromSource(_masterList, _targetList, AddressOf ConvertFromMasterToTarget)
Else
SetListValuesFromSource(_targetList, _masterList, AddressOf ConvertFromTargetToMaster)
End If
End Sub
''' <summary>
''' An implementation that does nothing in the conversions.
''' </summary>
Friend Class DoNothingListItemConverter
Implements IListItemConverter
''' <summary>
''' Converts the specified master list item.
''' </summary>
''' <param name="masterListItem">The master list item.</param>
''' <returns>The result of the conversion.</returns>
Public Function Convert(ByVal masterListItem As Object) As Object Implements IListItemConverter.Convert
Return masterListItem
End Function
''' <summary>
''' Converts the specified target list item.
''' </summary>
''' <param name="targetListItem">The target list item.</param>
''' <returns>The result of the conversion.</returns>
Public Function ConvertBack(ByVal targetListItem As Object) As Object Implements IListItemConverter.ConvertBack
Return targetListItem
End Function
End Class
End Class
Then for the XAML:
<DataGrid ..... local:MultiSelectorBehaviours.SynchronizedSelectedItems="{Binding SelectedResults}" />
And finally the VM:
Public ReadOnly Property SelectedResults As ObservableCollection(Of StatisticsResultModel)
Get
Return _objSelectedResults
End Get
End Property
Credit Goes to: http://blog.functionalfun.net/2009/02/how-to-databind-to-selecteditems.html