c# - WPF 在运行期间禁用命令

Question

我需要在它运行时禁用按钮。我有这段代码:

RelayCommand.cs 这是我的命令类。

class RelayCommand : ICommand
{
    readonly Action<object> _execute;
    readonly Predicate<object> _canExecute;

    public RelayCommand(Action<object> execute)
        : this(execute, null)
    {
    }

    public RelayCommand(Action<object> execute, Predicate<object> canExecute)
    {
        if (execute == null)
        {
            throw new ArgumentNullException("execute");
        }

        _execute = execute;
        _canExecute = canExecute;
    }

    public bool CanExecute(object parameter)
    {
        return _canExecute == null ? true : _canExecute(parameter);
    }

    public event EventHandler CanExecuteChanged
    {
        add { CommandManager.RequerySuggested += value; }
        remove { CommandManager.RequerySuggested -= value; }
    }

    public void Execute(object parameter)
    {
        _execute(parameter);
    }
}

MainWindowViewModel.cs 这是我的绑定(bind)命令。

private RelayCommand _getTextCommand;
public ICommand GetTextCommand
{
    get
    {
        if (_getTextCommand == null)
        {
            _getTextCommand = new RelayCommand(
                param => this.GetText(param),
                param => true
                );
        }

        return _getTextCommand;
    }
}

MainWindow.xaml 这是我绑定(bind)命令的 XAML 代码。

<Button x:Name="getTextButton" Command="{Binding GetTextCommand}" CommandParameter="{Binding ElementName=textTypeSelector, Path=SelectedIndex}"/>

这是我在命令中启动的代码:

public async void GetText(object o)
{
    await Task.Factory.StartNew(() =>
    {
        // code
    });
}

Answer 1

试试这个:在 View 模型中添加一个 bool 属性并在 View 模型中实现 INotifyPropertyChanged

    private bool isEnable = true;

    public bool IsEnable 
    {
        get { return isEnable; }
        set
        {
            isEnable = value; 
            NotifyPropertyChanged();
        } 
    }

    public async void GetText(object o)
    {
        await Task.Factory.StartNew(() =>
        {

            IsEnable = false;
        });
        IsEnable = true;
    }

    public event PropertyChangedEventHandler PropertyChanged;

    private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

将其绑定(bind)到按钮的 IsEnable 属性上

<Button x:Name="abc"
                Command="{Binding GetTextCommand}"
                IsEnabled="{Binding IsEnable}" />

根据需要设置 IsEnable。