using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Text;
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using System.Windows.Input;
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namespace XHandler.Class
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{
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public class RelayCommand : ICommand
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{
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#region Fields
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/// <summary>
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/// Encapsulated the execute action
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/// </summary>
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private Action<object> execute;
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/// <summary>
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/// Encapsulated the representation for the validation of the execute method
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/// </summary>
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private Predicate<object> canExecute;
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#endregion // Fields
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#region Constructors
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/// <summary>
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/// Initializes a new instance of the RelayCommand class
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/// Creates a new command that can always execute.
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/// </summary>
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/// <param name="execute">The execution logic.</param>
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public RelayCommand(Action<object> execute)
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: this(execute, DefaultCanExecute)
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{
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}
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/// <summary>
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/// Initializes a new instance of the RelayCommand class
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/// Creates a new command.
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/// </summary>
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/// <param name="execute">The execution logic.</param>
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/// <param name="canExecute">The execution status logic.</param>
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public RelayCommand(Action<object> execute, Predicate<object> canExecute)
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{
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if (execute == null)
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{
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throw new ArgumentNullException("execute");
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}
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if (canExecute == null)
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{
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throw new ArgumentNullException("canExecute");
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}
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this.execute = execute;
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this.canExecute = canExecute;
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}
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#endregion // Constructors
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#region ICommand Members
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/// <summary>
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/// An event to raise when the CanExecute value is changed
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/// </summary>
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/// <remarks>
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/// Any subscription to this event will automatically subscribe to both
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/// the local OnCanExecuteChanged method AND
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/// the CommandManager RequerySuggested event
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/// </remarks>
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public event EventHandler CanExecuteChanged
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{
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add
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{
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CommandManager.RequerySuggested += value;
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this.CanExecuteChangedInternal += value;
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}
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remove
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{
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CommandManager.RequerySuggested -= value;
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this.CanExecuteChangedInternal -= value;
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}
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}
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/// <summary>
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/// An event to allow the CanExecuteChanged event to be raised manually
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/// </summary>
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private event EventHandler CanExecuteChangedInternal;
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/// <summary>
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/// Defines if command can be executed
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/// </summary>
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/// <param name="parameter">the parameter that represents the validation method</param>
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/// <returns>true if the command can be executed</returns>
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public bool CanExecute(object parameter)
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{
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return this.canExecute != null && this.canExecute(parameter);
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}
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/// <summary>
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/// Execute the encapsulated command
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/// </summary>
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/// <param name="parameter">the parameter that represents the execution method</param>
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public void Execute(object parameter)
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{
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this.execute(parameter);
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}
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#endregion // ICommand Members
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/// <summary>
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/// Raises the can execute changed.
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/// </summary>
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public void OnCanExecuteChanged()
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{
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EventHandler handler = this.CanExecuteChangedInternal;
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if (handler != null)
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{
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//DispatcherHelper.BeginInvokeOnUIThread(() => handler.Invoke(this, EventArgs.Empty));
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handler.Invoke(this, EventArgs.Empty);
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}
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}
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/// <summary>
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/// Destroys this instance.
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/// </summary>
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public void Destroy()
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{
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this.canExecute = _ => false;
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this.execute = _ => { return; };
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}
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/// <summary>
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/// Defines if command can be executed (default behaviour)
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/// </summary>
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/// <param name="parameter">The parameter.</param>
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/// <returns>Always true</returns>
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private static bool DefaultCanExecute(object parameter)
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{
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return true;
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}
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}
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}
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