src/Tizen.NUI/src/public/XamlBinding/Command.cs

   1 using System;
   2 using System.Reflection;
   3 using System.Windows.Input;
   4
   5 namespace Tizen.NUI.Binding
   6 {
   7         internal sealed class Command<T> : Command
   8         {
   9                 public Command(Action<T> execute)
  10                         : base(o =>
  11                         {
  12                                 if (IsValidParameter(o))
  13                                 {
  14                                         execute((T)o);
  15                                 }
  16                         })
  17                 {
  18                         if (execute == null)
  19                         {
  20                                 throw new ArgumentNullException(nameof(execute));
  21                         }
  22                 }
  23
  24                 public Command(Action<T> execute, Func<T, bool> canExecute)
  25                         : base(o =>
  26                         {
  27                                 if (IsValidParameter(o))
  28                                 {
  29                                         execute((T)o);
  30                                 }
  31                         }, o => IsValidParameter(o) && canExecute((T)o))
  32                 {
  33                         if (execute == null)
  34                                 throw new ArgumentNullException(nameof(execute));
  35                         if (canExecute == null)
  36                                 throw new ArgumentNullException(nameof(canExecute));
  37                 }
  38
  39                 static bool IsValidParameter(object o)
  40                 {
  41                         if (o != null)
  42                         {
  43                                 // The parameter isn't null, so we don't have to worry whether null is a valid option
  44                                 return o is T;
  45                         }
  46
  47                         var t = typeof(T);
  48
  49                         // The parameter is null. Is T Nullable?
  50                         if (Nullable.GetUnderlyingType(t) != null)
  51                         {
  52                                 return true;
  53                         }
  54
  55                         // Not a Nullable, if it's a value type then null is not valid
  56                         return !t.GetTypeInfo().IsValueType;
  57                 }
  58         }
  59
  60     /// <summary>
  61     /// Defines an ICommand implementation that wraps a Action.
  62     /// </summary>
  63         public class Command : ICommand
  64         {
  65                 readonly Func<object, bool> _canExecute;
  66                 readonly Action<object> _execute;
  67
  68         /// <summary>
  69         /// Initializes a new instance of the Command class.
  70         /// </summary>
  71         /// <param name="execute">An instance to execute when the Command is executed.</param>
  72                 public Command(Action<object> execute)
  73                 {
  74                         if (execute == null)
  75                                 throw new ArgumentNullException(nameof(execute));
  76
  77                         _execute = execute;
  78                 }
  79
  80         /// <summary>
  81         /// Initializes a new instance of the Command class.
  82         /// </summary>
  83         /// <param name="execute">An Action to execute when the Command is executed.</param>
  84                 public Command(Action execute) : this(o => execute())
  85                 {
  86                         if (execute == null)
  87                                 throw new ArgumentNullException(nameof(execute));
  88                 }
  89
  90         /// <summary>
  91         /// Initializes a new instance of the Command class.
  92         /// </summary>
  93         /// <param name="execute">An Action to execute when the Command is executed.</param>
  94         /// <param name="canExecute">A instance indicating if the Command can be executed.</param>
  95                 public Command(Action<object> execute, Func<object, bool> canExecute) : this(execute)
  96                 {
  97                         if (canExecute == null)
  98                                 throw new ArgumentNullException(nameof(canExecute));
  99
 100                         _canExecute = canExecute;
 101                 }
 102
 103         /// <summary>
 104         /// Initializes a new instance of the Command class.
 105         /// </summary>
 106         /// <param name="execute">An Action to execute when the Command is executed.</param>
 107         /// <param name="canExecute">A instance indicating if the Command can be executed.</param>
 108                 public Command(Action execute, Func<bool> canExecute) : this(o => execute(), o => canExecute())
 109                 {
 110                         if (execute == null)
 111                                 throw new ArgumentNullException(nameof(execute));
 112                         if (canExecute == null)
 113                                 throw new ArgumentNullException(nameof(canExecute));
 114                 }
 115
 116         /// <summary>
 117         /// Returns a Boolean indicating if the Command can be exectued with the given parameter.
 118         /// </summary>
 119         /// <param name="parameter">An Object used as parameter to determine if the Command can be executed.</param>
 120         /// <returns>true if the Command can be executed, false otherwise.</returns>
 121                 public bool CanExecute(object parameter)
 122                 {
 123                         if (_canExecute != null)
 124                                 return _canExecute(parameter);
 125
 126                         return true;
 127                 }
 128
 129         /// <summary>
 130         /// Occurs when the target of the Command should reevaluate whether or not the Command can be executed.
 131         /// </summary>
 132                 public event EventHandler CanExecuteChanged;
 133
 134         /// <summary>
 135         /// Invokes the execute Action.
 136         /// </summary>
 137         /// <param name="parameter">An Object used as parameter for the execute Action.</param>
 138         public void Execute(object parameter)
 139                 {
 140                         _execute(parameter);
 141                 }
 142
 143         /// <summary>
 144         /// Send a CanExecuteChanged.
 145         /// </summary>
 146                 public void ChangeCanExecute()
 147                 {
 148                         EventHandler changed = CanExecuteChanged;
 149                         changed?.Invoke(this, EventArgs.Empty);
 150                 }
 151         }
 152 }