如何挂接到 WPF 窗口句柄以侦听 USB 事件

Question

我在工作中需要挂钩 WPF 应用程序的 Windows 事件。我需要监听 USB 事件。我发现了分散且不完整的答案，因此我想在一个统一的位置记录我的方法。

我最初的问题发生在尝试复制此处的代码示例时：
/sf/answers/1360502111/

我能够挂钩 Windows 事件并接收设备通知，但它们非常通用，没有为我提供太多可用于我的应用程序的信息。

对该页面的进一步阅读使我在同一页面上得到了不同的答案，该答案直接挂接到窗口句柄中以监视事件：
https ://stackoverflow.com/a/620179/1683999

这个答案提供了链接： https:
//www.codeproject.com/Articles/3946/Trapping-windows-messages

通过按照 codeproject 教程进行一些修改以挂钩 WPF 的窗口句柄，我能够获取 WM_DEVICECHANGE 消息，但在解码 wParam 时，我只收到 DBT_DEVNODES_CHANGED，因为我没有注册监听 USB 事件。通过 Google 快速搜索，我找到了一篇旧的 MSDN 论坛帖子： https:
//social.msdn.microsoft.com/Forums/vstudio/en-US/983dc1ee-6208-4036-903f-3fd5674a1efb/registerdevicenotification-in-wpf ?forum =wpf

在这个帖子中，我找到了我正在寻找的答案。我没有注册 Window 来专门查找 USB 事件，因此我从 Windows 获取了通用事件代码。进一步的研究让我回到了 StackOverflow：
/sf/answers/1137213101/

最后的答案为我解决了这个难题。我提供了一些代码片段，概述了通过挂钩到 WPF 窗口然后创建一个注册该窗口以侦听 USB 事件的侦听器来侦听 Windows 事件所需的内容。

Answer 1

要访问 USB 事件，我们需要做一些事情。

首先我们需要链接到 user32.dll 中的一些方法。

namespace Example
{
    // https://www.pinvoke.net/default.aspx/Structures.DEV_BROADCAST_DEVICEINTERFACE
    [StructLayout(LayoutKind.Sequential)]
    public struct DEV_BROADCAST_DEVICE_INTERFACE
    {
        public int Size;
        public int DeviceType;
        public int Reserved;
        public Guid ClassGuid;
        public short Name;
    }

    public class Win32Native
    {
        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        public static extern IntPtr RegisterDeviceNotification(
            IntPtr hRecipient,
            IntPtr notificationFilter,
            uint flags);

        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        public static extern uint UnregisterDeviceNotification(IntPtr hHandle);
    }
}

我们需要它来注册我们的 WPF 窗口来监听 USB 事件。

namespace Example
{
    public class UsbEventRegistration : IDisposable
    {
        private const int DBT_DEVTYP_DEVICEINTERFACE = 5;

        private static readonly s_guidDevInterfaceUsbDevice =
            new Guid("A5DCBF10-6530-11D2-901F-00C04FB951ED");

        private readonly IntPtr _windowHandle;
        private IntPtr _notificationHandle = IntPtr.Zero;

        public bool IsRegistered => _notificationHandle != IntPtr.Zero;

        public UsbEventRegistration(IntPtr windowHandle)
        {
            _windowHandle = windowHandle;
        }

        public void Register()
        {
            var dbdi = new DEV_BROADCAST_DEVICE_INTERFACE
            {
                DeviceType = DBT_DEVTYP_DEVICEINTERFACE,
                Reserved = 0,
                ClassGuid = s_guidDevInterfaceUsbDevice,
                Name = 0,
            };
            dbdi.Size = Marshal.SizeOf(dbdi);

            IntPtr buffer = Marshal.AllocHGlobal(dbdi.Size);
            Marshal.StructureToPtr(dbdi, buffer, true);
            _notificationHandle = Win32Native.RegisterDeviceNotification(
                _windowHandle, 
                buffer, 
                0);
        }

        // Call on window unload.
        public void Dispose()
        {
            Win32Native.UnregisterDeviceNotification(_notificationHandle);
        }
    }
}

最后，准备好 WPF 窗口代码隐藏。

namespace Example
{
    public partial class WPFWindow : Window
    {

        private UsbEventRegistration _usbEventRegistration;

        public WPFWindow()
        {
            InitializeComponent();
        }

        protected override void OnSourceInitialized(EventArgs e)
        {
            base.OnSourceInitialized(e);

            // IMO this should be abstracted away from the code-behind.
            var windowSource = (HwndSource)PresentationSource.FromVisual(this);
            _usbEventRegistration = new UsbEventRegistration(windowSource.Handle);
           // This will allow your window to receive USB events.
           _usbEventRegistration.Register();
           // This hook is what we were aiming for. All Windows events are listened to here. We can inject our own listeners.
           windowSource.AddHook(WndProc);
        }

        private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
        {
            // Here's where the help ends. Do what you need here.
            // Get additional info from http://www.pinvoke.net/
            // USB event message is msg == 0x0219 (WM_DEVICECHANGE).
            // USB event plugin is wParam == 0x8000 (DBT_DEVICEARRIVAL).
            // USB event unplug is wParam == 0x8004 (DBT_DEVICEREMOVECOMPLETE).
            // Your device info is in lParam. Filter that.
            // You need to convert wParam/lParam to Int32 using Marshal.
            return IntPtr.Zero;
        }
    }
}