我在尝试在 ListView 控件中实现撤消/重做操作时遇到太多问题，只是为了添加/删除项目。
我不久前意识到这里有一个相关问题扩展此类以在列表视图中撤消/重做我开始获得 50、100、200 和 300 点的多重赏金，总共 650 点……但没有人能真正帮助我在几周和几个月内完成这个问题。
但是在这个问题之后，终于有一个用户（@ThorstenC）向我展示了一个可能的解决方案和一个好主意，他的代码不完整，所以他的代码就是我想要实现/完成的。
问题是简单的“撤消”工作正常，但是当我尝试重做超过 1 次时，它会抛出一个异常，关于它无法在列表视图中再次添加相同的项目，而且代码还有更多问题，例如目前我无法重做撤消操作，或撤消重做操作。
只是我需要帮助来为 Listview 项目添加/删除创建一个工作撤消/重做管理器，仅此而已，我已经编写了一半的代码，我需要帮助来完成它，我对此一团糟。
这是 VS2012 中的一个简单的 WinForms 源项目，我已上传该项目来测试撤消管理器失败：
http://elektrostudios.tk/UndoManager.zip
这是一个视频，向您展示我尝试撤消/重做的错误：http://www.youtube.com/watch?v=MAzChURATpM
这是 @ThorstenC 的 UndoManager 类，经过一些修改：
Class ListView_UndoManager
Public Property Undostack As New Stack(Of ListView_Action)
Public Property Redostack As New Stack(Of ListView_Action)
Public Property IsDoingUndo As Boolean ' = False
Public Property IsDoingRedo As Boolean ' = False
Private action As ListView_Action = Nothing
''' <summary>
''' Undo the last action.
''' </summary>
''' <remarks></remarks>
Sub UndoLastAction()
If Undostack.Count = 0 Then Exit Sub ' Nothing to Undo.
action = Undostack.Pop ' Get the Action from Stack and remove it.
action.Operation.DynamicInvoke(action.data) ' Invoke the undo Action.
'Redostack = New Stack(Of ListView_Action)(Redostack)
'Redostack.Pop()
'Redostack = New Stack(Of ListView_Action)(Redostack)
End Sub
''' <summary>
''' Redo the last action.
''' </summary>
''' <remarks></remarks>
Sub RedoLastAction()
' If Redostack.Count = Undostack.Count Then Exit Sub
If Redostack.Count = 0 Then Exit Sub ' Nothing to Redo.
'Redostack = New Stack(Of ListView_Action)(Redostack) ' Reverse the Stack contents.
action = Redostack.Pop() ' Get the Action from Stack and remove it.
' action = Redostack.Peek()
action.Operation.DynamicInvoke(action.data) ' Invoke the redo Action.
'Redostack = New Stack(Of ListView_Action)(Redostack) ' Re-Reverse the Stack contents.
End Sub
End Class
Class ListView_Action
''' <summary>
''' Name the Undo / Redo Action
''' </summary>
''' <value></value>
''' <returns></returns>
''' <remarks></remarks>
Property name As String
''' <summary>
''' Points to a method to excecute
''' </summary>
''' <value></value>
''' <returns></returns>
''' <remarks></remarks>
Property Operation As [Delegate]
''' <summary>
''' Data Array for the method to excecute
''' </summary>
''' <value></value>
''' <returns></returns>
''' <remarks></remarks>
Property data As Object()
End Class
这是我尝试撤消/重做添加/删除列表视图项目的其余代码：
Public Class Form1
Dim _undoManager As New ListView_UndoManager
Delegate Sub RemoveDelegate(item As ListViewItem)
Delegate Sub AddDelegate(item As ListViewItem)
Dim newItem As ListViewItem = Nothing
Sub AddItem(ByVal item As ListViewItem)
' // Crate an Undo Action
Dim u As New ListView_Action() With {.name = "Remove Item",
.Operation = New RemoveDelegate(AddressOf RemoveItem),
.data = New Object() {newItem}}
_undoManager.Undostack.Push(u)
ListView_Elektro1.AddItem(item)
End Sub
Sub RemoveItem(item As ListViewItem)
' // Create a Redo Action
Dim r As New ListView_Action() With {.name = "Add Item",
.Operation = New AddDelegate(AddressOf AddItem),
.data = New Object() {item}}
_undoManager.Redostack.Push(r)
' Remove the ListViewItem from ListView
ListView_Elektro1.RemoveItem(item)
End Sub
Private Sub Button_AddItem_Click(sender As Object, e As EventArgs) _
Handles Button_AddItem.Click
Dim index As String = CStr(ListView_Elektro1.Items.Count + 1)
newItem = New ListViewItem _
With {.Text = index}
newItem.SubItems.AddRange({"Hello " & index, "World " & index})
AddItem(newItem)
End Sub
Private Sub Button_RemoveItem_Click(sender As Object, e As EventArgs) _
Handles Button_RemoveItem.Click
newItem = ListView_Elektro1.Items.Cast(Of ListViewItem).Last
RemoveItem(newItem)
End Sub
Private Sub Button_Undo_Click(sender As Object, e As EventArgs) _
Handles Button_Undo.Click
' _undoManager.IsDoingUndo = True
_undoManager.UndoLastAction()
' _undoManager.IsDoingUndo = False
End Sub
Private Sub Button_Redo_Click(sender As Object, e As EventArgs) _
Handles Button_Redo.Click
'_undoManager.IsDoingRedo = True
_undoManager.RedoLastAction()
'_undoManager.IsDoingRedo = False
End Sub
Private Sub ListView_Elektro1_ItemAdded() _
Handles ListView_Elektro1.ItemAdded, _
ListView_Elektro1.ItemRemoved
Label_UndoCount_Value.Text = CStr(_undoManager.Undostack.Count)
Label_RedoCount_Value.Text = CStr(_undoManager.Redostack.Count)
End Sub
End Class
“El URL requerido no fue encontrado en este servidor。”所以我很确定就是这样：
action = Redostack.Peek() ' Get the Action from Stack and remove it.
不，你正在看它without从堆栈中获取它。我确实使用了原始版本和快速修改版：
action = Redostack.Pop()
由于您将实际的 LV 项目存储在堆栈中以回传到 LV，因此当您第二次按下它时，您将查看并尝试恢复 LV 中已有的项目。
由于大多数原始“命令”将撤消/重做数据保存为对象，为什么您不直接公开一个AddLVUndoItem(item)在 UnDoReDoManager 上使用现有代码将 LV 操作与其他控件集成？它的问题是没有 LVItemAdded 事件来自动抓取这些东西。将此功能与另一个功能一起用作用户控制功能的一个问题是，您现在有 2 个堆栈，其中一个跳过 LV，另一个仅跳过 LV。用户可以清空另一个堆栈来尝试进行 LV 撤消操作。
此外，添加项目会落入 UnDo 存储桶中，但不会落入 RemoveItem 中，反之亦然（无法 Undo RemoveItem）。原来Undo中自动将命令添加到ReDo堆栈中。它位于标题和旧请求中，但不在代码中。
Edit这是错误的：
Sub RemoveItem(item As ListViewItem)
' // Create a Redo Action
Dim r As New ListView_Action() With {.name = "Add Item",
.Operation = New AddDelegate(AddressOf AddItem),
.data = New Object() {item}} ' wrong!
_undoManager.Redostack.Push(r)
' Remove the ListViewItem from ListView
ListView_Elektro1.RemoveItem(item)
End Sub
您不必为 undoStack 创建新的 LVI，而是使用传递的 LVI 和删除的 LVI（回想一下，我必须更改 VS 版本的语法）：
Sub RemoveItem(ByVal item As ListViewItem)
' // Create a Redo Action
Dim r As New ListView_Action()
With r
.name = "Add Item"
.Operation = New AddDelegate(AddressOf AddItem)
.data = item ' use the one passed!!!
End With
_undoManager.Redostack.Push(r)
' Remove the ListViewItem from ListView
LVE.RemoveItem(item)
_undoManager.ShowStacks()
End Sub
因此，您的重做不会缓存任何撤消操作。看起来只是由于人工测试数据造成的。