@TOC
一、场景
1、WPF控件
众所周知，由于WPF的底层绘制原理不同，WPF的大多数控件都不具备句柄，具备句柄的也就只有那么几种：Window、Popup、ContextMenu等。
2、集成ActiViz或者VTK
在集成VTK时： 一般选择WindowsFormsHost作为载体，将WinForm具备句柄的控件：如Panel，嵌入WPF布局中。然后将Panel的句柄传给C++。
在集成ActiViz时： 需要以RenderWindowControl来承接三维渲染内容，同样一般选择WindowsFormsHost作为载体，将RenderWindowControl放入其中，然后渲染三维内容。
二、问题
1、需求
如果需求是在三维布局界面，悬浮一些控件，且控件的背景色可以设置成透明。
2、空域问题
你会发现悬浮的WPF控件，始终在WindowsFormsHost之下，也就是说WindowsFormsHost所承载的内容始终置顶。这就是WPF由来已久的空域问题。
三、解决方案
1、用WindowsFormsHost包裹住ElementHost，然后将WPF的控件放在ElementHost职中：
<wf:WindowsFormsHost>
<wf:ElementHost>
<Grid>
</Grid>
</wf:ElementHost>
</wf:WindowsFormsHost>
如此，WPF的控件可置顶。但是会产生一下问题： ①WPF的控件绑定需要重新指定数据源 ②较多的WindowsFormsHost会增加界面刷新的负担 ③较多的WindowsFormsHost处理不慎的话，会出现严重的内存泄漏问题 ④WindowsFormsHost所包裹的WPF控件无法透明背景，影响界面美观
2、用Window或者Popup去悬浮
优点：可悬浮于WindowsFormsHost之上、可透明背景 缺点： ①会产生其他显示问题，处理复杂：Popup永远置顶，在锁屏或者弹窗时，Popup始终在最上方。当然用Windows的API重写Popup，可取消置顶，但任然在不同环境可能有取消置顶失败的情况出现。 ②Popup和Window作为单独的窗口，已经不再和主页面为一个整体，在页面切换和页面移动时，需要手动更新Popup，Window的显隐和位置，处理较为麻烦。 ③Popup的使用在窗口关闭时，存在内存泄漏问题。
3、使用第三方库Microsoft.DwayneNeed（这也是网上出现较多的答案）
<xmlns:interop=clr-namespace:Microsoft.DwayneNeed.Interop;assembly=Microsoft.DwayneNeed></xmlns>
<airspace:AirspaceDecorator AirspaceMode="Redirect" IsInputRedirectionEnabled="True" IsOutputRedirectionEnabled="True">
<WindowsFormsHost Name="FormsHost">
<winform:WebBrowser>
</WindowsFormsHost></airspace:AirspaceDecorator>
以上方式，的确可以实现控件悬浮置顶，且控件背景透明。但经过本人实测，会出现以下不可控问题： ①在切换界面布局，或者刷新界面时会产生不可控的BUG，难以解决 ②刷新界面时，存在严重的性能问题 ③占用资源过多，三维界面的鼠标交互异常卡顿
四、最新解决方案
基于最新的ActiViz 9.3的版本，可以自己实现一个RenderWindowControl来解决空域问题。
1、步骤
①将D3D11Image控件封装到控件，通过DirectX 纹理映射来绘制图像 ②将D3D11Image控件DirectN获取到系统能支持的控件句柄 ③将该句柄设置上下文方式，设置到vtkWin32OpenGLDXRenderWindow中： RenderWindow.SetD3DDeviceContext(p); ④重写鼠标交互
2、需要用到的库
DirectNCore Kitware.mummy.Runtime Kitware.VTK Microsoft.Wpf.Interop.DirectX
3、关键代码如下：
using System;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Interop;
using System.Windows.Media;
using DirectN;
using Kitware.VTK;
using Microsoft.Wpf.Interop.DirectX;
namespace WpfD3D11Interop_Net6._0
{
internal class MyRenderWindowControl : Image
{
public vtkWin32OpenGLDXRenderWindow RenderWindow;
public vtkRenderWindowInteractor Interactor;
private bool _readyForRendering;
private IComObject<ID3D11Device> _device;
private IComObject<ID3D11Texture2D>? _d3d11Texture;
private D3D11Image _d3d11ImageSource;
public MyRenderWindowControl()
{
_d3d11ImageSource = new D3D11Image();
base.Source = (ImageSource)(object)_d3d11ImageSource;
_d3d11ImageSource.OnRender = new Action<nint, bool>(Render);
D3D11_CREATE_DEVICE_FLAG val = (D3D11_CREATE_DEVICE_FLAG)32;
RenderWindow = vtkWin32OpenGLDXRenderWindow.New();
RenderWindow.ShowWindowOff();
RenderWindow.SetColorTextureFormat(87u);
Extensions.WithComPointer<ID3D11DeviceContext>(ID3D11DeviceExtensions.GetImmediateContext(_device), (Action<IntPtr>)delegate (nint p)
{
RenderWindow.SetD3DDeviceContext(p);
});
RenderWindow.Initialize();
RenderWindow.Render();
RenderWindow.RegisterSharedTexture();
Interactor = vtkRenderWindowInteractor.New();
Interactor.EnableRenderOff();
RenderWindow.SetInteractor(Interactor);
Interactor.RenderEvt += Interactor_RenderEvt;
vtkInteractorStyleTrackballCamera interactorStyle = vtkInteractorStyleTrackballCamera.New();
Interactor.SetInteractorStyle(interactorStyle);
base.MouseMove += RenderWindowControl_MouseMove;
base.MouseDown += RenderWindowControl_MouseDown;
base.MouseUp += RenderWindowControl_MouseUp;
base.MouseWheel += RenderWindowControl_MouseWheel;
base.KeyDown += RenderWindowControl_KeyDown;
base.KeyUp += RenderWindowControl_KeyUp;
base.Focusable = true;
base.IsHitTestVisible = true;
base.Loaded += RenderWindowControl_Loaded;
base.SizeChanged += RenderWindowControl_SizeChanged;
CompositionTarget.Rendering += CompositionTarget_Rendering;
}
private void RenderWindowControl_MouseWheel(object sender, MouseWheelEventArgs e)
{
if (!base.IsFocused)
{
Focus();
}
if (e.Delta < 0)
{
Interactor.MouseWheelBackwardEvent();
}
else if (e.Delta > 0)
{
Interactor.MouseWheelForwardEvent();
}
}
private void RenderWindowControl_MouseDown(object sender, MouseButtonEventArgs e)
{
Point position = e.GetPosition(this);
Interactor.SetEventPosition((int)position.X, (int)position.Y);
CaptureMouse();
if (!base.IsFocused)
{
Focus();
}
if (e.ChangedButton == MouseButton.Left)
{
Interactor.LeftButtonPressEvent();
}
if (e.ChangedButton == MouseButton.Right)
{
Interactor.RightButtonPressEvent();
}
if (e.ChangedButton == MouseButton.Middle)
{
Interactor.MiddleButtonPressEvent();
}
}
private void RenderWindowControl_MouseUp(object sender, MouseButtonEventArgs e)
{
Point position = e.GetPosition(this);
Interactor.SetEventPosition((int)position.X, (int)position.Y);
ReleaseMouseCapture();
if (e.ChangedButton == MouseButton.Left)
{
Interactor.LeftButtonReleaseEvent();
}
if (e.ChangedButton == MouseButton.Right)
{
Interactor.RightButtonReleaseEvent();
}
if (e.ChangedButton == MouseButton.Middle)
{
Interactor.MiddleButtonReleaseEvent();
}
}
private void RenderWindowControl_MouseMove(object sender, MouseEventArgs e)
{
Point position = e.GetPosition(this);
Interactor.SetEventPosition((int)position.X, (int)position.Y);
Interactor.MouseMoveEvent();
}
private void RenderWindowControl_KeyUp(object sender, KeyEventArgs e)
{
SetInteractorKeyEventInformation(e);
Interactor.KeyReleaseEvent();
e.Handled = true;
}
private void RenderWindowControl_KeyDown(object sender, KeyEventArgs e)
{
SetInteractorKeyEventInformation(e);
Interactor.KeyPressEvent();
string text = e.Key.ToString();
if (text.Length == 1 && text.All(char.IsLetter))
{
Interactor.CharEvent();
}
e.Handled = true;
}
protected void SetInteractorKeyEventInformation(KeyEventArgs e)
{
bool flag = (Keyboard.GetKeyStates(Key.Capital) & KeyStates.Toggled) == KeyStates.Toggled;
int ctrl = (((Keyboard.Modifiers & ModifierKeys.Control) == ModifierKeys.Control) ? 1 : 0);
int num = (((Keyboard.Modifiers & ModifierKeys.Shift) == ModifierKeys.Shift) ? 1 : 0);
int altKey = (((Keyboard.Modifiers & ModifierKeys.Alt) == ModifierKeys.Alt) ? 1 : 0);
int repeatcount = (e.IsRepeat ? 1 : 0);
string text = e.Key.ToString();
sbyte keycode = 0;
if (text.Length == 1)
{
if (text.All(char.IsLetter) && num == 0 && !flag)
{
text = text.ToLower();
}
keycode = (sbyte)text[0];
}
Interactor.SetKeyEventInformation(ctrl, num, keycode, repeatcount, text);
Interactor.SetAltKey(altKey);
}
private void Interactor_RenderEvt(vtkObject sender, vtkObjectEventArgs e)
{
_readyForRendering = true;
}
private void Render(nint surface, bool isNewSurface)
{
//IL_001d: Unknown result type (might be due to invalid IL or missing references)
//IL_0040: Unknown result type (might be due to invalid IL or missing references)
if (isNewSurface)
{
nint num = default(nint);
ComObject.From<IDXGIResource>(ComObject.QueryObjectInterface<ID3D11Texture2D>((object)ComObject.From<ID3D11Texture2D>((IntPtr)surface, true), true), true).Object.GetSharedHandle(out num);
object obj = default(object);
_device.Object.OpenSharedResource((IntPtr)num, typeof(ID3D11Resource).GUID, out obj);
nint num2 = ComObject.QueryObjectInterface(obj, typeof(ID3D11Texture2D).GUID, true);
_d3d11Texture = (IComObject<ID3D11Texture2D>?)(object)ComObject.From<ID3D11Texture2D>((IntPtr)num2, true);
_readyForRendering = true;
}
if (_readyForRendering)
{
RenderWindow.Lock();
RenderWindow.Render();
RenderWindow.Unlock();
Extensions.WithComPointer<ID3D11Texture2D>(_d3d11Texture, (Action<IntPtr>)delegate (nint p)
{
RenderWindow.BlitToTexture(p, IntPtr.Zero);
});
}
}
private void CompositionTarget_Rendering(object? sender, EventArgs e)
{
_d3d11ImageSource.RequestRender();
_readyForRendering = false;
}
private void RenderWindowControl_SizeChanged(object sender, SizeChangedEventArgs e)
{
_readyForRendering = true;
RenderWindow.SetSize((int)base.ActualWidth, (int)base.ActualHeight);
_d3d11ImageSource.SetPixelSize((int)base.ActualWidth, (int)base.ActualHeight);
}
private void RenderWindowControl_Loaded(object sender, RoutedEventArgs e)
{
if (PresentationSource.FromVisual(this) is HwndSource hwndSource)
{
_d3d11ImageSource.WindowOwner = hwndSource.Handle;
}
RenderWindow.SetSize((int)base.DesiredSize.Width, (int)base.DesiredSize.Height);
_d3d11ImageSource.SetPixelSize((int)base.DesiredSize.Width, (int)base.DesiredSize.Height);
}
}
}
4、运行结果预览：
5、源码链接
踩坑创作不易，白嫖党勿扰：源码
五、总结
困扰了C#集成VTK很久的空域问题，终于在ActiViz9.3推出了vtkWin32OpenGLDXRenderWindow类之后，得到解决。其解决原理与QT集成VTK的原理一致，都用到了DirectX绘制，并重写交互。本人亲测，目前无任何负面影响。
