Question

当我从源列表框中拖动一个项目时，我有两个列表框我希望目标列表框根据列表框上的鼠标位置选择项目。我实现了这个，但MouseOver事件仅在您不拖动时触发。如何根据列表框的dragOver发明选择项目。

这是代码

 Private Sub CasesBox2_DragEnter(sender As Object, e As System.Windows.DragEventArgs) Handles CasesBox2.DragEnter
    CasesBox2.CaptureMouse()
    If Not e.Data.GetDataPresent("contact") OrElse sender = e.Source Then
        e.Effects = DragDropEffects.None


    Else
        e.Effects = DragDropEffects.All
    End If


End Sub

Private Sub CasesBox2_DragOver(sender As Object, e As System.Windows.DragEventArgs) Handles CasesBox2.DragOver

    Dim MousePoint As Windows.Point = e.GetPosition(Nothing)

End Sub

Private Sub CasesBox2_Drop(sender As Object, e As System.Windows.DragEventArgs) Handles CasesBox2.Drop

    If e.Data.GetDataPresent("myFormat") Then
        Dim contact As Details = TryCast(e.Data.GetData("myFormat"), Details)
        Dim cse As Cases = CasesBox2.SelectedItem
        If cse IsNot Nothing Then
            Dim cs2 As ObservableCollection(Of Details) = DtlBox3.ItemsSource
            cs2.Remove(contact)
            cse.AddDetailsToCase(contact)
            IsDragInitiated = False
        End If
        IsDragInitiated = False
    End If
    IsDragInitiated = False

End Sub


Private Sub CasesBox2_SelectionChanged(sender As Object, e As System.Windows.Controls.SelectionChangedEventArgs) Handles CasesBox2.SelectionChanged
    Try
        If IsDragInitiated Then

        Else
            Dim SelectedItem As Cases = CasesBox2.SelectedItem
            DtlBox3.ItemsSource = SelectedItem.CaseDetails
        End If



    Catch ex As Exception

    End Try

End Sub

Private Sub DtlBox3_MouseMove(sender As Object, e As System.Windows.Input.MouseEventArgs) Handles DtlBox3.MouseMove
    Try
        ' Get the current mouse position
        Dim mousePos As Windows.Point = e.GetPosition(Nothing)
        Dim diff As Vector = StartPoint - mousePos

        If e.LeftButton = MouseButtonState.Pressed AndAlso Math.Abs(diff.X) > SystemParameters.MinimumHorizontalDragDistance OrElse Math.Abs(diff.Y) > SystemParameters.MinimumVerticalDragDistance Then
            ' Get the dragged ListViewItem
            Dim listView As ListBox = TryCast(sender, ListBox)
            Dim listViewItem As ListBoxItem = FindAnchestor(Of ListBoxItem)(DirectCast(e.OriginalSource, DependencyObject))

            ' Find the data behind the ListViewItem
            Dim contact As Details = DirectCast(listView.ItemContainerGenerator.ItemFromContainer(listViewItem), Details)

            ' Initialize the drag & drop operation
            Dim dragData As New DataObject("myFormat", contact)
            IsDragInitiated = True
            DragDrop.DoDragDrop(listViewItem, dragData, DragDropEffects.Move)


        End If
    Catch ex As Exception

    End Try


End Sub

' Helper to search up the VisualTree
Private Shared Function FindAnchestor(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 DtlBox3_PreviewMouseLeftButtonDown(sender As Object, e As System.Windows.Input.MouseButtonEventArgs) Handles DtlBox3.PreviewMouseLeftButtonDown
    StartPoint = e.GetPosition(Nothing)
End Sub

Private Sub Border_MouseEnter(sender As System.Object, e As System.Windows.Input.MouseEventArgs)
    CasesBox2.SelectedItem = CType(sender, Border).DataContext
    If CasesBox2.IsFocused Then
    Else
        CasesBox2.Focus()
    End If
End Sub

Answer 1

听起来你正在尝试使用DragOver对单个列表项进行热跟踪。

如果你正在使用WPF，你可能会为ListBoxItems制作一个自定义模板，它有一个触发器。

如果不是：您可以在列表项本身而不仅仅是ListBox控件上实现DragOver，并且您需要维护对当前热跟踪项目的引用，以便您可以取消突出显示它。这意味着您的ListBox必须填充一些自定义对象。

如何在DragOver事件中获取列表框选定项

1 个答案: