Animation of graph algorithms with WPF 3D

using System;
using System.Diagnostics;
using System.Windows.Input;

namespace Palmmedia.WpfGraph.Common
{
    /// <summary>
    /// A command whose sole purpose is to relay its functionality to other
    /// objects by invoking delegates. The default return value for the CanExecute
    /// method is 'true'.
    /// </summary>
    public class RelayCommand : ICommand
    {
        /// <summary>
        /// The action which is executed when command is executed.
        /// </summary>
        private readonly Action<object> execute;

        /// <summary>
        /// Determines whether the command can be executed.
        /// </summary>
        private readonly Predicate<object> canExecute;        

        /// <summary>
        /// Initializes a new instance of the <see cref="RelayCommand"/> class.
        /// This instance can always execute.
        /// </summary>
        /// <param name="execute">The action which is executed when command is executed.</param>
        public RelayCommand(Action<object> execute)
            : this(execute, null)
        {
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="RelayCommand"/> class.
        /// This instance can always execute.
        /// </summary>
        /// <param name="execute">The action which is executed when command is executed.</param>
        /// <param name="canExecute">Determinates whether the command can be executed.</param>
        public RelayCommand(Action<object> execute, Predicate<object> canExecute)
        {
            if (execute == null)
            {
                throw new ArgumentNullException("execute");
            }

            this.execute = execute;
            this.canExecute = canExecute;           
        }

        #region ICommand Members
        /// <summary>
        /// Occurs when changes occur that affect whether or not the command should execute.
        /// </summary>
        public event EventHandler CanExecuteChanged
        {
            add { CommandManager.RequerySuggested += value; }
            remove { CommandManager.RequerySuggested -= value; }
        }

        /// <summary>
        /// Defines the method that determines whether the command can execute in its current state.
        /// </summary>
        /// <param name="parameter">Data used by the command.  If the command does not require data to be passed, this object can be set to null.</param>
        /// <returns>
        /// true if this command can be executed; otherwise, false.
        /// </returns>
        public bool CanExecute(object parameter)
        {
            return this.canExecute == null ? true : this.canExecute(parameter);
        }

        /// <summary>
        /// Defines the method to be called when the command is invoked.
        /// </summary>
        /// <param name="parameter">Data used by the command.  If the command does not require data to be passed, this object can be set to null.</param>
        public void Execute(object parameter)
        {
            this.execute(parameter);
        }
        #endregion
    }
}