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RelayCommand.cs (2970B)

      1 using System;
      2 using System.Collections.Generic;
      3 using System.Linq;
      4 using System.Text;
      5 using System.Threading.Tasks;
      6 using System.Windows.Input;
      7 
      8 namespace File360.Common
      9 {
     10     /// <summary>
     11     /// A command whose sole purpose is to relay its functionality 
     12     /// to other objects by invoking delegates. 
     13     /// The default return value for the CanExecute method is 'true'.
     14     /// <see cref="RaiseCanExecuteChanged"/> needs to be called whenever
     15     /// <see cref="CanExecute"/> is expected to return a different value.
     16     /// </summary>
     17     public class RelayCommand : ICommand
     18     {
     19         private readonly Action _execute;
     20         private readonly Func<bool> _canExecute;
     21 
     22         /// <summary>
     23         /// Raised when RaiseCanExecuteChanged is called.
     24         /// </summary>
     25         public event EventHandler CanExecuteChanged;
     26 
     27         /// <summary>
     28         /// Creates a new command that can always execute.
     29         /// </summary>
     30         /// <param name="execute">The execution logic.</param>
     31         public RelayCommand(Action execute)
     32             : this(execute, null)
     33         {
     34         }
     35 
     36         /// <summary>
     37         /// Creates a new command.
     38         /// </summary>
     39         /// <param name="execute">The execution logic.</param>
     40         /// <param name="canExecute">The execution status logic.</param>
     41         public RelayCommand(Action execute, Func<bool> canExecute)
     42         {
     43             if (execute == null)
     44                 throw new ArgumentNullException("execute");
     45             _execute = execute;
     46             _canExecute = canExecute;
     47         }
     48 
     49         /// <summary>
     50         /// Determines whether this <see cref="RelayCommand"/> can execute in its current state.
     51         /// </summary>
     52         /// <param name="parameter">
     53         /// Data used by the command. If the command does not require data to be passed, this object can be set to null.
     54         /// </param>
     55         /// <returns>true if this command can be executed; otherwise, false.</returns>
     56         public bool CanExecute(object parameter)
     57         {
     58             return _canExecute == null ? true : _canExecute();
     59         }
     60 
     61         /// <summary>
     62         /// Executes the <see cref="RelayCommand"/> on the current command target.
     63         /// </summary>
     64         /// <param name="parameter">
     65         /// Data used by the command. If the command does not require data to be passed, this object can be set to null.
     66         /// </param>
     67         public void Execute(object parameter)
     68         {
     69             _execute();
     70         }
     71 
     72         /// <summary>
     73         /// Method used to raise the <see cref="CanExecuteChanged"/> event
     74         /// to indicate that the return value of the <see cref="CanExecute"/>
     75         /// method has changed.
     76         /// </summary>
     77         public void RaiseCanExecuteChanged()
     78         {
     79             var handler = CanExecuteChanged;
     80             if (handler != null)
     81             {
     82                 handler(this, EventArgs.Empty);
     83             }
     84         }
     85     }
     86 }