Question

我一直在寻找stackoverflow一段时间来回答这个问题。

我有一个Listview，他的项目是Listviews，其子项实际上是一个列表（字符串），它是父listviewitem的成员。

拖放功能是目标。然而，由于各种原因，这种情况很难证明，其中一个原因是铸造。我需要在我做直接演员才能使它工作之前获得类型 - 至少我认为这会让我遇到一个问题。

但是我甚至无法开始使用这种语法，所以我将从这里开始：

   Dim itemType = listView.ItemContainerGenerator.ItemFromContainer(listViewItem)
   Dim g As Type = GetType(itemtype)

这是我正在尝试的整个拖放实现：

Dim startpoint As Point

Public Sub List_PreviewMouseLeftButtonDown(sender As Object, e As MouseEventArgs)
    ' Store the mouse position
    startpoint = e.GetPosition(Nothing)
End Sub

Private Sub List_MouseMove(sender As Object, e As MouseEventArgs)
    Dim mousePos As Point = e.GetPosition(Nothing)
    Dim diff As Vector = startpoint - mousePos
    If e.LeftButton = MouseButtonState.Pressed And Math.Abs(diff.X) > SystemParameters.MinimumHorizontalDragDistance Or Math.Abs(diff.Y) > SystemParameters.MinimumVerticalDragDistance Then
        Dim listView As ListView = DirectCast(sender, ListView)
        Dim listViewItem As ListViewItem = FindAncestor(Of ListViewItem)(DirectCast(e.OriginalSource, DependencyObject))
        Dim itemType = listView.ItemContainerGenerator.ItemFromContainer(listViewItem)
        Dim g As Type = GetType(itemtype)
        Dim item As String = DirectCast(listView.ItemContainerGenerator.ItemFromContainer(listViewItem), String)
        Dim dragData As New DataObject("myFormat", item)
        DragDrop.DoDragDrop(listViewItem, dragData, DragDropEffects.Move)
    End If

End Sub


Private Shared Function FindAncestor(Of T As DependencyObject)(current As DependencyObject) As T
    Do
        If TypeOf current Is T Then
            Return DirectCast(current, T)
        End If
        current = VisualTreeHelper.GetParent(current)
    Loop While current IsNot Nothing
    Return Nothing
End Function

Private Sub DropList_DragEnter(sender As Object, e As DragEventArgs)
    If Not e.Data.GetDataPresent("myFormat") OrElse sender = e.Source Then
        e.Effects = DragDropEffects.None
    End If
End Sub

Private Sub DropList_Drop(sender As Object, e As DragEventArgs)
    If e.Data.GetDataPresent("myFormat") Then
        Dim contact As String = TryCast(e.Data.GetData("myFormat"), String)
        Dim listView As ListView = TryCast(sender, ListView)
        listView.Items.Add(contact)
    End If
End Sub

这是嵌套的listView：

 <!--DataContext="{StaticResource RcpdInsertViewSource}" This is a collectionviewsource. 
                        RCPDInsert has a list(of string) member that is created from a single string property 
                        and whose order needs to be alterable. 
                        Eg rcpdInsert.template="[stuff] [more stuff]" so rcpdInsert.templateList = list(of String) from template.split("] [") -->
                        <ListView Grid.Column="1" Grid.Row="1" ItemsSource="{Binding}"  
                                  PreviewMouseLeftButtonDown="List_PreviewMouseLeftButtonDown" 
                                  PreviewMouseMove="List_MouseMove"
                                  Drop="DropList_Drop" 
                                  DragEnter="DropList_DragEnter" 
                                  AllowDrop="True">

                                <ListView.ItemTemplate>
                                  <DataTemplate>
                                    <DockPanel>
                                        <TextBox Text="{Binding Path=cpID}"></TextBox>
                                        <TextBox Text="{Binding Path=fieldRef}"></TextBox>
                                        <ListView ItemsSource="{Binding Path=InsertsList}" >
                                            <ListView.ItemTemplate>
                                                <DataTemplate DataType="DataClasses1:RcpdInsert.template" >
                                                    <StackPanel Orientation="Horizontal" Grid.Row="0">
                                                        <TextBlock Text="{Binding}" Margin="5" />
                                                    </StackPanel>
                                                </DataTemplate>
                                            </ListView.ItemTemplate>
                                        </ListView>
                                    </DockPanel>
                                </DataTemplate>
                            </ListView.ItemTemplate>

                        </ListView>

目标：拖放子列表视图的重新排序，理想情况下能够将单个项目从一个子列表视图拉到另一个子列表视图。保存后，后面的代码实际上会将字符串重新连接在一起并更新模板成员。

对于上下文，这里是RcpdInsert的相关成员：

Sub SetupInsertList()
        _insertsList = template.Split(" ").ToList()
        For Each item In InsertsList
            Dim t = item
            RcpdList.Add(RcpdSet.RpcdListShared.Where(Function(x) x.insertID = t).ToList())
        Next
    End Sub

    Public Property RcpdList As New List(Of List(Of Rcpd))

    Private Property _insertsList As New List(Of String)

    Public Property InsertsList As List(Of String)
        Get
            If _insertsList.Count = 0 Then setupInsertList()
            Return _insertsList
        End Get
        Set(value As List(Of String))
            Dim combine As String = value.Aggregate("", Function(current, i) current + (i & " "))
            template = combine
        End Set
    End Property

演员是一个问题，我希望能够做到这一点意味着其他人将更容易解决。

提前感谢任何可以提供帮助的人：）

在VB中动态转换为类型

0 个答案: