C# 在WPF中加载vtk的RenderWindowControl时出现NullReferenceException

我正在尝试使用ActiViz.NET和Visual Studio 2013从WPF项目上的vtk库加载RenderWindowControl。这个库工作得很好，因为我做了一个新项目只是为了练习它，但是当我试图将它集成到我的工作中时，这次我得到了一个空的RenderWindowControl。这是我的代码：

MainWindow.xaml：

<Window x:Class="myProject.Views.MainWindow"
    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:VtkTab="clr-namespace:myProject.Views.UITabs.VtkTab"
    x:Name="Mainwindow"
    MinHeight="600"
    MinWidth="800"
    Title="{Binding Title}"
    Height="720"
    Width="1280"
    Icon="{StaticResource ApplicationIcon}"
    Loaded="OnLoaded"
    DataContext="{Binding Main, Source={StaticResource ViewModelLocator}}"
    Style="{StaticResource WindowStyle}"
    mc:Ignorable="d">

    <DockPanel>
        <TabControl>
        ....
        ....
        <VtkTab:VtkTabView />
        ....
        .... 
        </TabControl>
    </DockPanel>
</Window>

---

RenderControl.RenderWindow在WindowLoaded（VtkTabView.xaml.cs）上为空，我不知道为什么。可能是因为我从第二个xamp加载UITabView，而我丢失了RenderControl？的内容，这是我看到的与我所做的示例的唯一区别

访问RenderWindow控件的RenderWindow加载事件

e、 g

---

很好，它解决了NullReferenceException的问题。谢谢你，伙计@Benjaminidele：“他问他为什么会得到它”--是的，这是“什么是NullReferenceException以及如何修复它？”的第二部分，处理NRE相对来说是微不足道的，一篇帖子包含了99.94%的案例所需的所有信息。一篇询问如何修复NRE的帖子，而不描述实际采取了哪些步骤来调试问题，实际上是解释如何修复NRE的帖子的重复（因为我们必须假设OP没有对其进行调试）。

<UserControl x:Class="myProject.Views.UITabs.VtkTab.VtkTabView"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:vtk="clr-namespace:Kitware.VTK;assembly=Kitware.VTK"
        Loaded="WindowLoaded"
        Height="480" Width="640">
        <WindowsFormsHost Name="Wfh">
            <vtk:RenderWindowControl x:Name="RenderControl" />
        </WindowsFormsHost>
</UserControl>

public partial class UITabView
{

    protected static Random _random = new Random();
    vtkActor actor = vtkActor.New();

    public VtkTabView()
    {
        InitializeComponent();

        var sphere = vtkSphereSource.New();
        sphere.SetThetaResolution(8);
        sphere.SetPhiResolution(16);

        var shrink = vtkShrinkPolyData.New();
        shrink.SetInputConnection(sphere.GetOutputPort());
        shrink.SetShrinkFactor(0.9);

        var move = vtkTransform.New();
        move.Translate(_random.NextDouble(), _random.NextDouble(), _random.NextDouble());
        var moveFilter = vtkTransformPolyDataFilter.New();
        moveFilter.SetTransform(move);

        moveFilter.SetInputConnection(shrink.GetOutputPort());

        var mapper = vtkPolyDataMapper.New();
        mapper.SetInputConnection(moveFilter.GetOutputPort());

        // The actor links the data pipeline to the rendering subsystem 
        actor.SetMapper(mapper);
        actor.GetProperty().SetColor(1, 0, 0);
    }

    private void WindowLoaded(object sender, RoutedEventArgs e)
    {
        var renderer = RenderControl.RenderWindow.GetRenderers().GetFirstRenderer();
        renderer.AddActor(actor);
    }
}

public VtkTabView()
{
    InitializeComponent();
    // initialize your sphrere and actor

    RenderControl.Load += MyRenderWindowControlOnLoad;
}

private void MyRenderWindowControlOnLoad(object sender_in, EventArgs eventArgs_in){

//access the RenderWindow here

}