設置DataContext時發生異常

Question

我創建了一個自定義UserControl，它公開了一些DependencyProperties，例如HeaderTitle和HeaderTitleForeground

public partial class PageHeaderControl : UserControl
{
    public string HeaderTitle 
    {
        get { return (string)GetValue(HeaderTitleProperty); }
        set { SetValue(HeaderTitleProperty, value); }
    }

    public static readonly DependencyProperty HeaderTitleProperty = DependencyProperty.Register("HeaderTitle", typeof(string), typeof(PageHeaderControl), new PropertyMetadata(""));

    public string HeaderTitleForeground
    {
        get { return (string)GetValue(HeaderTitleForegroundProperty); }
        set { SetValue(HeaderTitleForegroundProperty, value); }
    }

    public static readonly DependencyProperty HeaderTitleForegroundProperty = DependencyProperty.Register("HeaderTitleForeground", typeof(string), typeof(PageHeaderControl), new PropertyMetadata(""));

    public PageHeaderControl()
    {
        InitializeComponent();
        (this.Content as FrameworkElement).DataContext = this;
    }
}

但是，當我調試我的應用程序時，它會拋出一個異常，如下所示：

  System.Exception occurred
   _HResult=-2146233088
   _message=Error HRESULT E_FAIL has been returned from a call to a COM component.
   HResult=-2146233088
   Message=Error HRESULT E_FAIL has been returned from a call to a COM component.
   Source=System.Windows
   StackTrace:
      at MS.Internal.XcpImports.CheckHResult(UInt32 hr)
   InnerException: 

但是，正確繪制了自定義控件。 那么，我該如何解決呢？ 這是關鍵問題嗎？

Answer 1

您的班級是PageHeaderControl但您的依賴項道具PageHeaderControl其ElevationPageHeaderControl注冊為所有者。

Answer 2

我發現了我的錯誤。 這是HeaderTitleForeground的類型，因此我只是從字符串更改為SolidColorBrush，然后將SolidColorBrush（Colors.Black）添加到了PropertyMetadata。 這是UserControl的固定版本：

public partial class PageHeaderControl : UserControl
{
public string HeaderTitle 
{
    get { return (string)GetValue(HeaderTitleProperty); }
    set { SetValue(HeaderTitleProperty, value); }
}

public static readonly DependencyProperty HeaderTitleProperty = DependencyProperty.Register("HeaderTitle", typeof(string), typeof(PageHeaderControl), new PropertyMetadata(""));

public SolidColorBrush HeaderTitleForeground
{
    get { return (SolidColorBrush)GetValue(HeaderTitleForegroundProperty); }
    set { SetValue(HeaderTitleForegroundProperty, value); }
}

public static readonly DependencyProperty HeaderTitleForegroundProperty = DependencyProperty.Register("HeaderTitleForeground", typeof(SolidColorBrush), typeof(PageHeaderControl), new PropertyMetadata(new SolidColorBrush(Colors.Black)));

public PageHeaderControl()
{
    InitializeComponent();
    (this.Content as FrameworkElement).DataContext = this;
}
}