wpf - 前一个元素 MouseLeave 事件之前的 wpf HwndHost MouseMove 事件

Question

我们有一个带有 Hwndhost 元素的 Wpf 应用程序，用于通过 DirectX 呈现 3d 内容。我们向包含 MouseEnter 和 MouseLeave 事件的客户端公开一个“Panel”接口。对于 Hwndhost“面板”，我们在第一次收到 HwndHost.WndProc 的 WM_MOUSEMOVE 事件时模拟 MouseEnter 事件，因为 win32 没有 WM_MOUSEENTER 事件。此外，对于 HwndHost，我们通过 TrackMouseEvent() 请求 WM_MOUSELEAVE 事件，该事件在我们的“面板”界面上模拟 MouseLeave 事件。

问题在于，当用户将鼠标快速移动到 HwndHost 面板或从 HwndHost 面板移动时，我们会从鼠标移动到的面板接收到 enter 事件，然后才会收到鼠标移动到的面板的离开事件。 当源面板和目标面板都是 wpf 元素时，这不会发生，只有在涉及 hwndhost 元素时才会发生。此外，如果这些 HwndHost 元素中有两个彼此相邻，则会发生相同的行为，因此看起来 win32 没有按照它们发生的顺序发送消息。

有谁知道解决这个问题的方法？ 如果有办法让 Win32 按事件发生的顺序发送事件，那就太好了。

这是一个示例应用程序，它向调试器输出窗口展示了打印消息的问题：

// App.xaml.cs
using System;
using System.Windows;
using System.Runtime.InteropServices;

namespace WpfHostingWin32Control
{
    public partial class App : Application
    {
        [DllImport("comctl32.dll", EntryPoint = "InitCommonControls", CharSet =         CharSet.Auto)]
        public static extern void InitCommonControls();
        private void ApplicationStartup(object sender, StartupEventArgs args)
        {
            InitCommonControls();
            HostWindow host = new HostWindow();
            host.InitializeComponent();
        }
    }
}

// App.xaml
<Application x:Class="WpfHostingWin32Control.App"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    StartupUri="MainWindow.xaml"
    Startup="ApplicationStartup">
</Application>

// HostWindow.xaml.cs
using System;
using System.Windows;
using System.Windows.Input;  

namespace WpfHostingWin32Control
{
    public partial class HostWindow : Window
    {
        WpfHostingWin32Control.ControlHost ctrlHost;

        public HostWindow()
        {
            InitializeComponent();
            txtbox1.MouseEnter += MouseEnterHandler;
            txtbox1.MouseLeave += MouseLeaveHandler;
        }

        void MouseEnterHandler(object sender, MouseEventArgs e)
        {
            System.Diagnostics.Debug.WriteLine("Wpf MouseEnter");
        }

        void MouseLeaveHandler(object sender, MouseEventArgs e)
        {
            System.Diagnostics.Debug.WriteLine("Wpf MouseLeave");
        }

        private void On_UIReady(object sender, EventArgs e)
        {
            ctrlHost = new ControlHost(600, 600);
            ControlHostElement.Child = ctrlHost;
        }
    }
}

// HostWindow.xaml
<Window x:Class="WpfHostingWin32Control.HostWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Name="mainWindow"
    Width="1250"
    Height="700"
    Background="LightGreen" 
    Loaded="On_UIReady">
    <StackPanel Margin="20" Orientation="Horizontal">
        <Border Name="ControlHostElement" Width="600" Height="600"/>
        <TextBox Margin="5,0,0,0" x:Name="txtbox1" Width="600" Height="600"/>
    </StackPanel>
</Window>  

// ControlHost.cs
using System;
using System.Windows;
using System.Windows.Interop;
using System.Runtime.InteropServices;

namespace WpfHostingWin32Control
{
    public class ControlHost : HwndHost
    {
        IntPtr hwndHost;
        int hostHeight, hostWidth;
        bool m_MouseHasEntered;

        public ControlHost(double height, double width)
        {
            hostHeight = (int)height;
            hostWidth = (int)width;
        }

        protected override HandleRef BuildWindowCore(HandleRef hwndParent)
        {
            hwndHost = IntPtr.Zero;
            hwndHost = CreateWindowEx(0, "listbox", "",WS_CHILD | WS_VISIBLE | WS_BORDER, 0, 0, 
                hostWidth, hostHeight, hwndParent.Handle, IntPtr.Zero, IntPtr.Zero, 0);

            return new HandleRef(this, hwndHost);
        }

        protected override IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
        {
            switch (msg)
            {
                case WM_MOUSEMOVE:
                    {
                        if (m_MouseHasEntered == false)
                        {
                            RequestMouesLeaveNotification();
                            m_MouseHasEntered = true;
                            System.Diagnostics.Debug.WriteLine("WM_MOUSEMOVE/ENTER");
                        }
                    }
                    break;

                case WM_MOUSELEAVE:
                    {
                        m_MouseHasEntered = false;
                        System.Diagnostics.Debug.WriteLine("WM_MOUSELEAVE");
                    }
                    break;
            }

            handled = false;
            return IntPtr.Zero;
        }

        private void RequestMouesLeaveNotification()
        {
            var tme = new TRACKMOUSEEVENT()
            {
                cbSize = (uint)Marshal.SizeOf(typeof(TRACKMOUSEEVENT)),
                dwFlags = TME_LEAVE,
                hwndTrack = hwndHost,
                dwHoverTime = 0
            };

            if (!TrackMouseEvent(out tme))
                System.Diagnostics.Debug.WriteLine("TrackMouseEvent failed!");
        }

        protected override void DestroyWindowCore(HandleRef hwnd)
        {
            DestroyWindow(hwnd.Handle);
        }

        //PInvoke declarations
        [DllImport("user32.dll", EntryPoint = "CreateWindowEx", CharSet = CharSet.Unicode)]
        internal static extern IntPtr CreateWindowEx(int dwExStyle,
                                                      string lpszClassName,
                                                      string lpszWindowName,
                                                      int style,
                                                      int x, int y,
                                                      int width, int height,
                                                      IntPtr hwndParent,
                                                      IntPtr hMenu,
                                                      IntPtr hInst,
                                                      [MarshalAs(UnmanagedType.AsAny)] object pvParam);

        [DllImport("user32.dll", EntryPoint = "DestroyWindow", CharSet = CharSet.Unicode)]
        internal static extern bool DestroyWindow(IntPtr hwnd);

        private const int WM_MOUSEMOVE = 0x0200;
        private const int WM_MOUSELEAVE = 0x02A3;
        private const int TME_LEAVE = 0x00000002;
        private const int WS_CHILD = 0x40000000;
        private const int WS_VISIBLE = 0x10000000;
        private const int WS_BORDER = 0x00800000;

        [StructLayout(LayoutKind.Sequential)]
        private struct TRACKMOUSEEVENT
        {
            public uint cbSize;
            public uint dwFlags;
            public IntPtr hwndTrack;
            public uint dwHoverTime;
        }

        [DllImport("user32.dll")]
        private static extern bool TrackMouseEvent(out TRACKMOUSEEVENT tme);
    }
}