- modificata EgwDataGrid per funzionare correttamente (header) anche quando non e' visibile dall'inizio

EgwWPFBaseLib/EgwDataGrid/EgwDataGrid.vb

@@ -122,6 +122,46 @@ Public Class EgwDataGrid
 
    Private ReadOnly _columnToLayout As New Dictionary(Of DataGridColumn, ColumnLayout)
 
+   Private _headersCaptured As Boolean = False
+
+   Sub New()
+      AddHandler Me.Loaded, AddressOf OnDataGridLoaded
+      AddHandler Columns.CollectionChanged, AddressOf OnColumnsChanged
+   End Sub
+
+   Private Sub OnDataGridLoaded(ByVal sender As Object, ByVal e As RoutedEventArgs)
+      TryHookPresenter()
+   End Sub
+
+   Private Sub TryHookPresenter()
+      Dim presenter = FindVisualChild(Of DataGridColumnHeadersPresenter)(Me)
+      If presenter Is Nothing Then Return
+      AddHandler presenter.ItemContainerGenerator.StatusChanged, AddressOf OnHeadersGenerated
+   End Sub
+
+   Private Sub OnHeadersGenerated(ByVal sender As Object, ByVal e As EventArgs)
+      If _headersCaptured Then Return
+      Dim presenter = FindVisualChild(Of DataGridColumnHeadersPresenter)(Me)
+      If presenter Is Nothing Then Return
+
+      If presenter.ItemContainerGenerator.Status = GeneratorStatus.ContainersGenerated Then
+         _headersCaptured = True
+         RemoveHandler presenter.ItemContainerGenerator.StatusChanged, AddressOf OnHeadersGenerated
+
+         For i As Integer = 0 To Columns.Count - 1
+            Dim header = TryCast(presenter.ItemContainerGenerator.ContainerFromIndex(i), DataGridColumnHeader)
+
+            If header IsNot Nothing Then
+               OnColumnHeaderCreated(header)
+            End If
+         Next
+      End If
+   End Sub
+
+   Protected Overridable Sub OnColumnHeaderCreated(ByVal header As DataGridColumnHeader)
+      GenerateHeaderEvents(header.Column, _columnToLayout(header.Column))
+   End Sub
+
    Private Sub Layouts_CollectionChanged(sender As Object, e As NotifyCollectionChangedEventArgs)
       Select Case e.Action
          Case NotifyCollectionChangedAction.Add
@@ -154,6 +194,11 @@ Public Class EgwDataGrid
       End Select
    End Sub
 
+   Private Sub OnColumnsChanged(ByVal sender As Object, ByVal e As NotifyCollectionChangedEventArgs)
+      _headersCaptured = False
+      TryHookPresenter()
+   End Sub
+
    Private Sub AddColumnFromLayout(layout As ColumnLayout)
       If Resources.Contains(layout.Key) Then
          Dim baseColumn As DataGridColumn = TryCast(Resources(layout.Key), DataGridColumn)
@@ -189,9 +234,11 @@ Public Class EgwDataGrid
                                       If _columnToLayout.TryGetValue(args.Column, l) Then l.SortDirection = args.Column.SortDirection
                                    End Sub
 
-            GenerateHeaderEvents(column, layout)
             UpdateDisplayIndexes()
          End If
+      Else
+         ColumnLayouts.Remove(layout)
+         MessageBox.Show("Errore! Tentativo di caricare una colonna non definita!" & Environment.NewLine & " Column Key: " & layout.Key, "Errore!", MessageBoxButton.OK, MessageBoxImage.Error)
       End If
    End Sub