• Undo/Redo


    步骤1

    首先识别出你希望哪些操作能支持Undo/Redo。然后,识别出你将在哪个容器下支持Undo/Redo以及你希望哪些对象支持Undo/Redo。

    步骤2

    为了进一步处理每个Undo/Redo操作,识别出需要被保存的属性。

    步骤3

    然后创建一个类(ChangeRepresentationObject),它包含支持全部操作Undo/Redo的所有属性。同样,准备一个动作类型enum,它将代表全部操作。这个动作类型enum是ChangeRepresentationObject类的一部分。

    步骤4

    然后创建一个名为UndoRedo的类,它包含两个类型的ChangeRepresentationObject栈。一个用于撤销操作,一个用于重做操作。

    步骤5

    然后实现具体方法:Undo、 Redo、InsertObjectforUndoRedo。
    在每个Undo操作中:

    •首先检查Undo栈是否为空。
    •如果不是,则弹出一个ChangeRepresentationObject并将其压入重做栈。
    •检查动作类型。
    •然后基于动作类型,利用ChangeRepresentationObject的属性完成撤销操作。
    在每个Redo操作中,你几乎做与Undo同样的事。
    •首先检查Redo栈是否为空。
    •如果不是,弹出一个ChangeRepresentationObject,然后将其压入撤销栈。
    •检查动作类型。
    •然后基于动作的类型,利用ChangeRepresentationObject属性完成重做操作。
    在InsertObjectforUndoRedo操作中,你只要把数据对象插入Undo栈并清空Redo栈中。

    步骤6

    然后,在完成每次操作前,调用InsertObjectforUndoRedo方法以对所有操作提供Undo/Redo支持。在用户界面上点击Undo时,只需调用UndoRedo类的Undo方法,而在用户界面上点击Redo时,只需调用UndoRedo类的redo方法。

    public enum ActionType
         {
             Delete
    = 0,
             Move
    = 1,
             Resize
    = 2,
             Insert
    = 3
         } 
        
    public class ChangeRepresentationObject
         {
            
    public ActionType Action;
            
    public Point Margin;
            
    public double Width;
            
    public double height;
            
    public FrameworkElement UiElement;
         }

    interface IUndoRedo
         {
            
    void Undo(int level);
            
    void Redo(int level);
            
    void InsertObjectforUndoRedo(ChangeRepresentationObject dataobject);
         }

    public partial class UnDoRedo : IUndoRedo
         {
            
    private Stack<ChangeRepresentationObject> _UndoActionsCollection =
        
    new Stack<ChangeRepresentationObject>();
            
    private Stack<ChangeRepresentationObject> _RedoActionsCollection =
        
    new Stack<ChangeRepresentationObject>();
            
            
    #region IUndoRedo Members

            
    public void Undo(int level)
             {
                
    for (int i = 1; i <= level; i++)
                 {
                    
    if (_UndoActionsCollection.Count == 0) return;

                     ChangeRepresentationObject Undostruct
    = _UndoActionsCollection.Pop();
                    
    if (Undostruct.Action == ActionType.Delete)
                     {
                         Container.Children.Add(Undostruct.UiElement);
                        
    this.RedoPushInUnDoForDelete(Undostruct.UiElement);
                     }
                    
    else if (Undostruct.Action == ActionType.Insert)
                     {
                         Container.Children.Remove(Undostruct.UiElement);
                        
    this.RedoPushInUnDoForInsert(Undostruct.UiElement);
                     }
                    
    else if (Undostruct.Action == ActionType.Resize)
                     {
                        
    if (_UndoActionsCollection.Count != 0)
                         {
                             Point previousMarginOfSelectedObject
    = new Point
       (((FrameworkElement)Undostruct.UiElement).Margin.Left,
                                 ((FrameworkElement)Undostruct.UiElement).Margin.Top);
                            
    this.RedoPushInUnDoForResize(previousMarginOfSelectedObject,
       Undostruct.UiElement.Width,
                                 Undostruct.UiElement.Height, Undostruct.UiElement);
                             Undostruct.UiElement.Margin
    = new Thickness
       (Undostruct.Margin.X, Undostruct.Margin.Y,
    0, 0);
                             Undostruct.UiElement.Height
    = Undostruct.height;
                             Undostruct.UiElement.Width
    = Undostruct.Width;
                         }
                     }
                    
    else if (Undostruct.Action == ActionType.Move)
                     {
                         Point previousMarginOfSelectedObject
    = new Point
       (((FrameworkElement)Undostruct.UiElement).Margin.Left,
                             ((FrameworkElement)Undostruct.UiElement).Margin.Top);
                        
    this.RedoPushInUnDoForMove(previousMarginOfSelectedObject,
           Undostruct.UiElement);
                         Undostruct.UiElement.Margin
    = new Thickness
       (Undostruct.Margin.X, Undostruct.Margin.Y,
    0, 0);
                     }
                 }
             }

            
    public void Redo(int level)
             {
                
    for (int i = 1; i <= level; i++)
                 {
                    
    if (_RedoActionsCollection.Count == 0) return;

                     ChangeRepresentationObject Undostruct
    = _RedoActionsCollection.Pop();
                    
    if (Undostruct.Action == ActionType.Delete)
                     {
                         Container.Children.Remove(Undostruct.UiElement);
                        
    this.PushInUnDoForDelete(Undostruct.UiElement);
                     }
                    
    else if (Undostruct.Action == ActionType.Insert)
                     {
                         Container.Children.Add(Undostruct.UiElement);
                        
    this.PushInUnDoForInsert(Undostruct.UiElement);
                     }
                    
    else if (Undostruct.Action == ActionType.Resize)
                     {
                         Point previousMarginOfSelectedObject
    = new Point
       (((FrameworkElement)Undostruct.UiElement).Margin.Left,
                             ((FrameworkElement)Undostruct.UiElement).Margin.Top);
                        
    this.PushInUnDoForResize(previousMarginOfSelectedObject,
           Undostruct.UiElement.Width,
                             Undostruct.UiElement.Height, Undostruct.UiElement);
                         Undostruct.UiElement.Margin
    = new Thickness
       (Undostruct.Margin.X, Undostruct.Margin.Y,
    0, 0);
                         Undostruct.UiElement.Height
    = Undostruct.height;
                         Undostruct.UiElement.Width
    = Undostruct.Width;
                     }
                    
    else if (Undostruct.Action == ActionType.Move)
                     {
                         Point previousMarginOfSelectedObject
    = new Point
       (((FrameworkElement)Undostruct.UiElement).Margin.Left,
                             ((FrameworkElement)Undostruct.UiElement).Margin.Top);
                        
    this.PushInUnDoForMove(previousMarginOfSelectedObject,
           Undostruct.UiElement);
                         Undostruct.UiElement.Margin
    = new Thickness
         (Undostruct.Margin.X, Undostruct.Margin.Y,
    0, 0);
                     }
                 }
             }
            
    public void InsertObjectforUndoRedo(ChangeRepresentationObject dataobject)
             {
                 _UndoActionsCollection.Push(dataobject);_RedoActionsCollection.Clear();
             }
          
    #endregion


    http://hi.baidu.com/light_black/blog/item/79325d232f416046925807e0.html

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  • 原文地址:https://www.cnblogs.com/chenj/p/1558095.html
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