magicmanam.UndoRedo

magicmanam.UndoRedo nuget package is easy and lightweight Undo/Redo operations implementation

In order to add it to your solution, run Install-Package magicmanam.UndoRedo from your NuGet Package Manager console in Visual Studio.

Quick start

1. Define class which will represent your application state at any time (for example AppState class)

public class AppState
{
    public int X { get; set; }
    public int Y { get; set; }
}

2. Implement interface IStatefulComponent<AppState> to have possibility to retrieve current application state:

public class AppStateComponent : IStatefulComponent<AppState>
{
    public AppState State { get; set; }

    public AppState UndoableState
    {
        get
        {
            return new AppState
            {
                X = State.X,
                Y = State.Y
            };// Deep copy
        }
        set
        {
            this.State.X = value.X;
            this.State.Y = value.Y;
        }
    }
}

3. Initialize current undoable context for your application state:

var stateComponent = new AppStateComponent();
stateComponent.State = new AppState { X = 0, Y = 0 };

UndoableContext<AppState>.Current = new UndoableContext<AppState>(stateComponent);

4. Wrap any action which changes application state with the following code:

using (var action = UndoableContext<AppState>.Current.StartAction("Sample action name"))
{
    stateComponent.State.X = 23;
    stateComponent.State.Y = 10;
    // action.Cancel(); - you can cancel your application state change and the previous state will be restored
    // nested actions are supported: there is outer action tracked only, any action can be cancelled.
}

5. Now you can undo/redo any your action made in scope of current undoable context:

UndoableContext<AppState>.Current.Undo();
// stateComponent returns the previous state now: X = 0, Y = 0
// or
UndoableContext<AppState>.Current.Redo();
// Rollbacks the previous Undo operation: X = 23, Y = 10

6. You can subscribe on any action in scope of the current undoable context including cancelled actions and Undo/Redo operations:

UndoableContext<AppState>.Current.UndoableAction += (object sender, UndoableActionEventArgs<AppState> e) =>
{
    if (e.Action.IsCancelled)
    {
        // Action was cancelled
    }
    else
    {
        if (e.IsUndo)
        {
             // The latest action was undone
        }
        else if (e.IsRedo)
        {
             // The latest undo operation was restored
        }
        else
        {
             // e.Action.Name == "Sample action name"
             // Ordinary action on application state was performed
        }
    }

    if (e.Action.IsNested)
    {
        // Action is nested
    }
};

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