51 lines
2.1 KiB
C#
51 lines
2.1 KiB
C#
using System.Windows.Input;
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namespace Melskin.Utilities;
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/// <summary>
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/// 一个简单的ICommand实现，用于传递动作。
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/// </summary>
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internal class RelayCommand : ICommand
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{
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private readonly Action<object?> execute;
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private readonly Predicate<object?>? canExecute;
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/// <summary>
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/// 当命令的可执行状态更改时发生的事件。
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/// 广播此事件通知UI，当命令的CanExecute方法返回值发生变化时，需要重新查询命令的状态。
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/// </summary>
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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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/// <summary>
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/// 初始化 RelayCommand 的新实例。
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/// </summary>
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/// <param name="execute">命令执行的逻辑。</param>
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/// <param name="canExecute">判断命令是否可以执行的逻辑（可选）。如果为 null，则命令始终可执行。</param>
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/// <exception cref="ArgumentNullException">execute 为 null 时抛出。</exception>
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public RelayCommand(Action<object?> execute, Predicate<object?>? canExecute = null)
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{
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this.execute = execute ?? throw new ArgumentNullException(nameof(execute));
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this.canExecute = canExecute;
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}
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/// <summary>
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/// 判断命令是否可以执行。
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/// </summary>
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/// <param name="parameter">传递给命令的参数。</param>
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/// <returns>返回一个布尔值，指示命令是否能够执行。对于此实现，总是返回true。</returns>
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public bool CanExecute(object? parameter) => canExecute == null || canExecute(parameter);
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/// <summary>
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/// 执行命令。
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/// </summary>
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/// <param name="parameter">传递给命令的参数。</param>
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public void Execute(object? parameter) => execute(parameter);
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/// <summary>
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/// 通知命令管理器重新查询此命令的 CanExecute 状态，手动更新，应对一些特殊场景，如倒计时功能结束，手动调用刷新按钮状态。
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/// </summary>
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public void RaiseCanExecuteChanged() => CommandManager.InvalidateRequerySuggested();
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}
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