Metis_xctg/Annotation/Command/Command.cs

namespace PaintDotNet.Annotation.Command
{
    public abstract class Command
    {
        // This function is used to make Undo operation.
        // It makes action opposite to the original command.
        public abstract void Undo(GraphicsList list);

        // This command is used to make Redo operation.
        // It makes original command again.
        public abstract void Redo(GraphicsList list);

        // Derived classes have members which contain enough information
        // to make Undo and Redo operations for every specific command.
    }
}