C# ViewModel属性在'；相应的CustomControl属性已更新

我正在尝试将VideoPreview自定义控件类中的IntPtr VidHandle属性绑定到其视图模型（vm:DebugHiresCamerawindViewModel）中的IntPtr PreviewHandle

在VideoPreview的构造函数中，我调用：

this.VidHandle = picBox.Handle;

更新视频预览的VidHandleProperty DependencyProperty属性。这很好用。但是，未更新ViewModel中的PreviewHandle属性。当我打电话时：

camera.StartVideoStream(PreviewHandle);

在视图模型中，PreviewHandle为0，因为它从未从VideoPreview更新。我感觉我的DependencyProperty VidHandleProperty没有正确实现，但我可能错了

以下是一些代码片段：

主窗口XAML：

<Window 
x:Class="AoiImageLift.Views.DebugHiResCameraWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:vm="clr-namespace:AoiImageLift.Presentation.ViewModels"
xmlns:wf="clr-namespace:System.Windows.Forms;assembly=System.Windows.Forms"
xmlns:com="clr-namespace:AoiImageLift.Components"
xmlns:local="clr-namespace:AoiImageLift"
Title="DebugHiResCameraWindow"
Name="hiResWindow"
Height="300" 
Width="300">
<Window.Resources>
    <vm:DebugHiResCameraWindowViewModel x:Key="viewModel"/>
</Window.Resources>
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition/>
        <RowDefinition/>
    </Grid.RowDefinitions>

    <com:VideoPreview
        DataContext="{StaticResource viewModel}"
        x:Name="videoHost"
        VidHandle="{Binding PreviewHandle, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type com:VideoPreview}}}"/>

    <Button
        DataContext="{StaticResource viewModel}"
        Grid.Row="1"
        Width="100"
        Height="40"
        Command="{Binding StartCaptureCommand}"
        Content="Start"/>
</Grid>

查看模型类：

public class DebugHiResCameraWindowViewModel : ViewModel
{
    private Uri capturedImage;
    private BitmapImage bmp;
    private ISnapImages camera;

    public DebugHiResCameraWindowViewModel() 
    {
        camera = LumeneraCamera.Instance;
        bmp = new BitmapImage();
    }

    public IntPtr PreviewHandle { get; set; }
    public Uri CapturedImage
    {
        get { return capturedImage; }
        set { capturedImage = value; OnPropertyChanged("CapturedImage"); }
    }
    public ICommand StartCaptureCommand
    {
        get
        {
            return new DelegateCommand(() =>
            {
                try
                {
                    camera.StartVideoStream(PreviewHandle);
                }
                catch (CustomException ex)
                {
                    MessageBox.Show(ex.Message, ex.Caption, ex.Button, ex.Image);
                }
            });
        }
    }
}

---

它看起来像

VideoPreview

控件的

VidHandle

绑定到

VideoPreview

控件的

PreviewHandle

（该控件不存在）

当您开始调试时，请检查输出窗口，它应该向您显示绑定错误（例如，当它找不到属性时）

也许这就是你想要的

<Window 
x:Class="AoiImageLift.Views.DebugHiResCameraWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:vm="clr-namespace:AoiImageLift.Presentation.ViewModels"
xmlns:wf="clr-namespace:System.Windows.Forms;assembly=System.Windows.Forms"
xmlns:com="clr-namespace:AoiImageLift.Components"
xmlns:local="clr-namespace:AoiImageLift"
Title="DebugHiResCameraWindow"
Name="hiResWindow"
Height="300" 
Width="300">
<!-- CHANGED HERE: set DataContext of Window -->
<Window.DataContext>
    <vm:DebugHiResCameraWindowViewModel />
</Window.DataContext>
<Grid>
    <Grid.RowDefinitions>
        <RowDefinition/>
        <RowDefinition/>
    </Grid.RowDefinitions>

    <!-- CHANGED HERE: removed DataContext (set at Window) -- updated binding -->
    <com:VideoPreview
        x:Name="videoHost"
        VidHandle="{Binding PreviewHandle}"/>

    <!-- CHANGED HERE: removed DataContext (set at Window) -- binding OK -->
    <Button
        Grid.Row="1"
        Width="100"
        Height="40"
        Command="{Binding StartCaptureCommand}"
        Content="Start"/>
</Grid>

并加上

void VideoPreview_Loaded(object sender, RoutedEventArgs e)
{
    this.VidHandle = picBox.Handle;
}

在视图中，更新绑定：

VidHandle="{Binding PreviewHandle, UpdateSourceTrigger=PropertyChanged}"

---

您可能还需要

Mode=OneWayToSource

，假设句柄应该只来自

VideoPreview

，谢谢您的响应，但是当我进行这些更改时，当我单击按钮时，DebugHiResCameraWindowViewModel的PreviewHandle属性仍然为0，该按钮告诉我VideoPreview类中VidHandle的值没有影响到它在视图模型中的绑定属性。我的VideoPreview自定义控件类是否正确实现？我不需要打电话来更新视图模型？您的更改非常有效！关键是在已加载的事件处理程序中而不是在构造函数中设置VideoPreview类的VidHandle在绑定

VidHandle=“{binding PreviewHandle…}

建立之前执行。因此绑定只会覆盖

VidHandle

的值。您可以在

VidHandle

的属性更改回调中设置

picBox.Handle

。

void VideoPreview_Loaded(object sender, RoutedEventArgs e)
{
    this.VidHandle = picBox.Handle;
}

VidHandle="{Binding PreviewHandle, UpdateSourceTrigger=PropertyChanged}"