c# - 从 IValueConverter 获取对代码隐藏类实例的引用

Question

我有这个代码:

namespace Test
{
    public partial class SearchField : UserControl
    {
        public SearchStrategy Strategy { get; set; }
        public SearchField() { InitializeComponent(); }
    }

    public class TextToTipConverter : IValueConverter
    {
        public object Convert(object value, Type targetType,
            object parameter, CultureInfo culture)
        {
            SearchStrategy Strategy = // How do I get reference to SearchField.Strategy from here?

            return Strategy.parseInput<string> (value.ToString(), (first, inp) => Strategy.tipMap.ContainsKey(first) && inp.Length == 1 ? first + Strategy.tipMap[first] : "", AppResources.GeneralSearchTip);
        }

        public object ConvertBack(object value, Type targetType,
            object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }
}

XAML 代码:

<UserControl.Resources>
        <controls:TextToTipConverter x:Key="TextToTip" />
</UserControl.Resources>
...
<TextBox x:Name="Search" Grid.Column="0" Canvas.ZIndex="1" 
                 Style="{StaticResource SearchBoxStyle}" Foreground="{StaticResource PhoneForegroundBrush}" />

<TextBox x:Name="Tip" Grid.Column="0" Canvas.ZIndex="0" IsReadOnly="True"
                 Style="{StaticResource SearchBoxStyle}" Opacity="0.5" Foreground="{StaticResource PhoneAccentBrush}"
                 Text="{Binding ElementName=Search, Converter={StaticResource TextToTip}, Path=Text}" />

SearchField 的 SearchStrategy Strategy 有一些我需要从 TextToTipConverter 访问的方法和字段。我怎样才能得到它？

Answer 1

SearchField.xaml 是 View ，SearchField.xaml.cs 是背后的代码。您可以在 msdn 上阅读有关 MVVM、数据绑定(bind)和 ViewModel 的信息。您可以创建一个名为 ViewModel 的类，您将在其上绑定(bind)数据。例如，假设有以下类:

public class SearchViewModel : INotifyPropertyChanged
{
    public string Text { get; set; }
    public SearchStrategy Strategy { get; set; }
}

您的 SearchField.xaml.cs 将是:

public partial class SearchField : UserControl
{
    private SearchViewModel viewModel;

    public SearchField() 
    {
        this.viewModel = new SearchViewModel ();
        this.DataContext = this.viewModel;
    }
}

现在在你的 xaml 中，

TextBox x:Name="Search" Text="{Binding Text}"

将 viewModel 中的数据与 TextBox 绑定(bind)你将能够做到:

TextBox x:Name="Tip" Text="{Binding, Converter={StaticResource TextToTip}, Path=Text}"

在转换器中，名为 value 的参数将是您可以在其上获取属性的 View 模型:

SearchViewModel vm = (SearchViewModel) value;
vm.Strategy;
vm.Text

不知道我说的对不对