將方法綁定到委托類型DependencyProperty

Question

在myUserControl.xaml.cs中，我有一個名為'IsExtensionValid'的布爾DependencyProperty，其值由以下幾行分配：

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

當FileFilters和FileValidator是字符串，並委托類型的DependencyProperty的分別和委托類型FileValidator被定義為：

    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 ，我定義了一個函數：

    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中，我試圖通過xaml綁定myUserControlInstance.FileValidator = ValidateMinFile 。 我嘗試了多種方法的組合，包括使ValidateMinFile靜態或不靜態，是否作為資源包括，是否作為RelativeSource引用以及更多我不記得的方法。 我當前的迭代（轉換為人為的示例土地）是：

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

實際的行實際上看起來像這樣：

<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}"/>

編輯：我嘗試過的另一件事是創建一個委托類型作為mainwindow的屬性，並將其設置為引用ValidateMinFile的靜態版本

FileSelectGroup.ExtraValidation ValidateMinFileDelegate = ValidateMinFile;`

使用ValidateMinFile靜態，但是當我在myUserControl中訪問FileValidator的行處斷點時（ bool b = FileValidator... ），FileValidator為null。

---

如何將窗口本地的功能綁定到該窗口中包含的UserControl的DependencyProperty？ 或在這種情況下： 如何通過xaml設置myUserControlInstance.FileValidator = ValidateMinFile ？

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。