绑定WindowsFormsHost子属性

Question

我正在创建一个MVVM应用程序。

在我的模型中，我需要在视图中显示的System.Windows.Forms.Panel的句柄。我的想法是在ViewModel中创建这个面板，然后从一边--绑定视图到它--，将它的句柄传递给模型。

我有一个WindowsFormsHost控件：

<Page x:Class="Test.Views.RenderPage"
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:WinForms="clr-namespace:System.Windows.Forms;assembly=System.Windows.Forms"
      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
      xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
      xmlns:local="clr-namespace:Test.Views"
      mc:Ignorable="d" 
      d:DesignHeight="800" d:DesignWidth="1200"
      Title="Page1">

    <DockPanel>
        <WindowsFormsHost x:Name="winformsHost" Child="{Binding RenderPanel}"/>
    </DockPanel>
</Page>

我想将它的子属性绑定到ViewModel提供的我的ViewModel

public ObservableObject<System.Windows.Forms.Panel> RenderPanel { get; private set; }

public VideoRecorderViewModel ()
{
    RenderPanel = new System.Windows.Forms.Panel (); //Bind it here
    var model = new Model (RenderPanel.Handle); pass it to the model
}

但是，我收到一个错误，它说：

System.Windows.Markup.XamlParseException: 
A 'Binding' cannot be set on the 'Child' property of type 'WindowsFormsHost'. 
A 'Binding' can only be set on a DependencyProperty of a DependencyObject.

怎么解决这个问题？

Answer 1

错误是不言自明的。不能绑定到属于WPF WindowsFormsHost控件的子对象的属性。

您可以创建一个具有附加属性的类以实现以下目标：Workaround for inability to bind to a property that belongs to a WindowsFormsHost Child object in C#/XAML app?

或者您可以使用类似于以下的ContentControl来包装它：Created Bindable WindowsFormsHost, but child update is not being reflected to control

Answer 2

创建类型为WindowsFormHost的依赖项属性和对象，并在属性约束事件处理程序中设置子属性。

using System.Windows.Forms.Integration;

namespace MainStartUp.DependencyObjects
{
  public class FormHostDependencyObject : WindowsFormsHost
   {
       public static readonly DependencyProperty ContentControlProperty =
        DependencyProperty.Register("ContentControl", 
         typeof(System.Windows.Forms.Control), 
            typeof(FormHostDependencyObject),
            new PropertyMetadata(new System.Windows.Forms.Control(), 
            PropertyChaged));       

    public static void SetContentControl(UIElement element, string value)
    {  
        element.SetValue(ContentControlProperty, value);          
    }

    public static string GetContentControl(UIElement element)
    {
        return (string)element.GetValue(ContentControlProperty);
    }

    private static void PropertyChaged(DependencyObject dependencyObject, 
       DependencyPropertyChangedEventArgs e)
    {
        ((FormHostDependencyObject)dependencyObject).Child = 
               (System.Windows.Forms.Control)e.NewValue;
     }
   }
 }

在xaml中使用它，如下所示。

<UserControl x:Class="MainStartUp.Views.WIndowsHostUserControl"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup- 
         compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         xmlns:local="clr-namespace:MainStartUp.Views"
         xmlns:DependecyObjects="clr- 
         namespace:MainStartUp.DependencyObjects"
         xmlns:wf="clr- 
         namespace:System.Windows.Forms;assembly=System.Windows.Forms"  
         mc:Ignorable="d" 
         d:DesignHeight="300" d:DesignWidth="300">
   <Grid>
       <!--<ContentControl Content="{Binding ContentControl}" />-->
       <DependecyObjects:FormHostDependencyObject ContentControl="{Binding 
        ContentControl}"></DependecyObjects:FormHostDependencyObject>
   </Grid>
</UserControl>

在我的视图模型中，我有一个object属性，为此我将托管窗口控制对象：

public object ContentControl
    {
        get
        {
            return _contentControl;
        }
        set
        {
            _contentControl = value;
            RaisePropertyChangedEvent("ContentControl");
    }
}