Question

在myUserControl.xaml.cs中我有一个名为＆＃39; IsExtensionValid＆＃39;的bool DependencyProperty。其值由以下行分配：

    bool a = TargetFile.Extension.MatchFileMask(FileFilters, true);
    bool b = (FileValidator is null) ? true : FileValidator(TargetFile).Item1;
    IsExtensionValid = (a && b);

其中FileFilters和FileValidator分别是字符串和委托类型DependencyProperty＆FileValidator的委托类型定义为：

    public delegate Tuple<bool, string> ExtraValidation(FileInfo fileInfo);
    public delegate Tuple<bool, string> StaticExtraValidation(FileInfo fileInfo, object o);
    // I also tried this static version with corresponding modifications to the function definition and usages (see below) but still couldn't bind

在mainwindow.xaml.cs 中，我定义了一个函数：

    public Tuple<bool, string> ValidateMinFile(FileInfo f) // ExtraValidation delegate
    { return new Tuple<bool, string>(true, "File is invalid"); }
    // meaningful test logic removed but principle stands

在mainwindow.xaml 我试图通过xaml绑定myUserControlInstance.FileValidator = ValidateMinFile。我尝试了多种方法组合，包括make ValidateMinFile静态与否，包含或不作为资源，是否引用为RelativeSource，以及其他一些我不记得的方法。我当前的迭代（翻译成人工实例 - 土地）是：

<local:myUserControl x:Name="MinFileControl"
                       FileFilters="Min Files|*.min"
                       FileValidator="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:}}, Path=ValidateMinFile}"/>

实线看起来像这样：

<local:FileSelectGroup x:Name="fsgMinFile" DockPanel.Dock="Top" Margin="2"
                       Title="Min file:"
                       FileFilters="Min Files|*.min"
                       PropertyChanged="fsgMinFile_PropertyChanged"
                       FileValidator="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:mainwindow}}, Path=ValidateMinFile}"/>

编辑：我尝试过的另一件事是创建委托类型作为主窗口的属性，并将其设置为引用静态版本ValidateMinFile

FileSelectGroup.ExtraValidation ValidateMinFileDelegate = ValidateMinFile;`

ValidateMinFile静态但当我在myUserControl中访问FileValidator（bool b = FileValidator...的那一行）的断点时，FileValidator为空。

如何将窗口本地的函数绑定到该窗口中包含的UserControl的DependencyProperty？或在这种特殊情况下：如何设置myUserControlInstance.FileValidator = ValidateMinFile XAML？

Answer 1

UserControl1.xaml.cs

public delegate Tuple<bool, string> ExtraValidation(FileInfo fi);

public partial class UserControl1 : UserControl
{
    public UserControl1()
    {
        InitializeComponent();
    }

    #region FileValidator Property
    public ExtraValidation FileValidator
    {
        get { return (ExtraValidation)GetValue(FileValidatorProperty); }
        set { SetValue(FileValidatorProperty, value); }
    }

    public static readonly DependencyProperty FileValidatorProperty =
        DependencyProperty.Register(nameof(FileValidator), typeof(ExtraValidation), typeof(UserControl1),
            new PropertyMetadata(null, FileValidator_PropertyChanged));
    #endregion FileValidator Property

    protected static void FileValidator_PropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        //  I just put this here for testing: If it's non-null, it'll be called. 
        //  I set a breakpoint in the MainWindow method to detect the call. 
        (d as UserControl1).FileValidator?.Invoke(null);
    }
}

MainWindow.xaml.cs

    public MainWindow()
    {
        InitializeComponent();

        FileValidator = ValidateMinFile;
    }

    #region FileValidator Property
    public ExtraValidation FileValidator
    {
        get { return (ExtraValidation)GetValue(FileValidatorProperty); }
        set { SetValue(FileValidatorProperty, value); }
    }

    public static readonly DependencyProperty FileValidatorProperty =
        DependencyProperty.Register(nameof(FileValidator), typeof(ExtraValidation), typeof(MainWindow),
            new PropertyMetadata(null));
    #endregion FileValidator Property

    public Tuple<bool, string> ValidateMinFile(FileInfo f) // ExtraValidation delegate
    {
        //  Breakpoint here
        return new Tuple<bool, string>(false, "blah");
    }

MainWindow.xaml

    <local:UserControl1
        FileValidator="{Binding FileValidator, RelativeSource={RelativeSource AncestorType=Window}}"
        />

工作正常。

将方法绑定到委托类型DependencyProperty

1 个答案: