Undo/Redo实现

最新推荐文章于 2024-10-12 22:59:08 发布

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最新推荐文章于 2024-10-12 22:59:08 发布

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文章标签： c#

本文介绍了如何在C#中实现Command模式与UndoManager模式。通过定义ICommand接口及其实现类，配合UndoManager类来管理操作的撤销与重做功能。文章详细展示了类的设计与实现代码。

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一使用Command模式如下：

二使用Singleton的UndoManager如下：

三C#的类代码如下：

public interface ICommand
{
   void Execute();
   void Reverse();
}

public class ACommand : ICommand
{
   void Execute(){};
   void Reverse(){};
}

public class BCommand : ICommand
{
   void Execute(){};
   void Reverse(){};
}

public class CCommand : ICommand
{
   void Execute(){};
   void Reverse(){};
}

public class UndoManager
{
    public UndoManager()
    {
      UndoStack = new Stack<ICommand>();
      RedoStack = new Stack<ICommand>();
    }

    public Stack<ICommand> UndoStack { get; protected set; }
    public Stack<ICommand> RedoStack { get; protected set; }

    public bool CanUndo { get { return UndoCommands.Count > 0; } }
    public bool CanRedo { get { return RedoCommands.Count > 0; } }

    public void Execute(ICommand command)
    {
      if (command == null) return;
      // Execute command
      command.Execute();
      UndoStack.Push(command);
      // Clear the redo history upon adding new undo entry.
      // This is a typical logic for most applications
      RedoStack.Clear();
    }

    public void Undo()
    {
      if (CanUndo)
      {
        ICommand command = UndoStack.Pop();
        if(command != null)
        {
            command.Reverse();
            RedoStack.Push(command);
        }
      }
    }

    public void Redo()
    {
      if (CanRedo)
      {
        ICommand command = RedoStack.Pop();
        if (command != null)
        {
          command.Execute();
          UndoStack.Push(command);
        }
      }
    }
}

完！