112 lines
3.5 KiB
C#
112 lines
3.5 KiB
C#
using System;
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using System.Diagnostics;
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using System.Threading.Tasks;
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using System.Windows.Input;
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namespace XLIMS.MVVM.Base
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{
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/// <summary>
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/// Асинхронная команда без параметра.
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/// </summary>
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public class AsyncRelayCommand : ICommand
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{
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private readonly Func<Task> _execute;
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private readonly Func<bool>? _canExecute;
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private bool _isExecuting;
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public AsyncRelayCommand(Func<Task> execute, Func<bool>? canExecute = null)
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{
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_execute = execute ?? throw new ArgumentNullException(nameof(execute));
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_canExecute = canExecute;
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}
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public bool CanExecute(object? parameter)
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{
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if (_isExecuting) return false;
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return _canExecute == null || _canExecute();
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}
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public async void Execute(object? parameter)
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{
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if (!CanExecute(parameter)) return;
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try
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{
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_isExecuting = true;
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CommandManager.InvalidateRequerySuggested();
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await _execute();
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}
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finally
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{
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_isExecuting = false;
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CommandManager.InvalidateRequerySuggested();
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}
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}
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public event EventHandler? CanExecuteChanged
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{
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add { CommandManager.RequerySuggested += value; }
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remove { CommandManager.RequerySuggested -= value; }
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}
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// Удобный статический метод для создания из метода с параметром (если вдруг понадобится)
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public static AsyncRelayCommand FromAsync(Func<object?, Task> execute, Func<object?, bool>? canExecute = null)
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{
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return new AsyncRelayCommand(() => execute(null), canExecute == null ? null : () => canExecute(null));
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}
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}
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/// <summary>
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/// Асинхронная команда с параметром (типизированная).
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/// </summary>
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public class AsyncRelayCommand<T> : ICommand
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{
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private readonly Func<T?, Task> _execute;
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private readonly Predicate<T?>? _canExecute;
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private bool _isExecuting;
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public AsyncRelayCommand(Func<T?, Task> execute, Predicate<T?>? canExecute = null)
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{
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_execute = execute ?? throw new ArgumentNullException(nameof(execute));
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_canExecute = canExecute;
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}
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public bool CanExecute(object? parameter)
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{
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if (_isExecuting) return false;
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if (_canExecute == null) return true;
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// Если параметр неправильного типа — считаем, что нельзя выполнить
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return parameter is T typedParam && _canExecute(typedParam);
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}
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public async void Execute(object? parameter)
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{
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if (!CanExecute(parameter)) return;
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T? typedParam = parameter is T p ? p : default;
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try
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{
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_isExecuting = true;
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CommandManager.InvalidateRequerySuggested();
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await _execute(typedParam);
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}
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finally
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{
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_isExecuting = false;
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CommandManager.InvalidateRequerySuggested();
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}
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}
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public event EventHandler? CanExecuteChanged
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{
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add { CommandManager.RequerySuggested += value; }
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remove { CommandManager.RequerySuggested -= value; }
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}
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}
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} |