Question

我正在尝试收到外部应用程序何时关闭的警报。对于我的测试，我已经检索了记事本的hwnd并将其设置到我的显示器中。奇怪的是，即使记事本尚未关闭，每当我从记事本点击其他应用程序时，我都会收到系统事件。有谁知道为什么？

调用代码的一些快速示例：

uint EVENT_OBJECT_DESTROY = 0x8001;
IntPtr notepadHwnd = <your pointer>
var mon = new WindowMonitor(notepadHwnd, EVENT_OBJECT_DESTROY);
mon.EventOccurred += (sender, args) => Console.WriteLine("closed");

显示器：

  public class WindowMonitor : IDisposable
  {
    //store delegate to prevent GC
    private User32.WinEventDelegate dEvent;

    private IntPtr _hook;
    private readonly IntPtr _window;
    private readonly List<uint> _watchedEvents = new List<uint>();

    public event EventHandler<AccessibleEventTypeEventArgs> EventOccurred;

    public WindowMonitor(IntPtr windowToMonitor, params User32.AccessibleEventType[] eventsToMonitor)
    {
      //prevent junk
      if (eventsToMonitor == null || eventsToMonitor.Length == 0)
        throw new ArgumentNullException("eventsToMonitor", "Must specify events to monitor");
      if (windowToMonitor == IntPtr.Zero)
        throw new ArgumentNullException("windowToMonitor", "Must specify a valid window handle to monitor");

      _window = windowToMonitor;

      //cast them now so we dont have to cast each one when evaluting events
      uint lowest = (uint) User32.AccessibleEventType.EVENT_MAX;
      uint highest = (uint) User32.AccessibleEventType.EVENT_MIN;
      foreach (User32.AccessibleEventType eventType in eventsToMonitor)
      {
        var castType = (uint) eventType;
        _watchedEvents.Add(castType);

        //need the range of events to subscribe to
        if (castType > highest)
          highest = castType;
        if (castType < lowest)
          lowest = castType;
      }

      //sign up for the event
      dEvent = this.winEvent;
      _hook = User32.SetWinEventHook(lowest, highest, IntPtr.Zero, dEvent, 0, 0, User32.WINEVENT_OUTOFCONTEXT);

      //ensure it worked
      if (IntPtr.Zero.Equals(_hook)) throw new Win32Exception();

      //no kill callback
      GC.KeepAlive(dEvent);
    }

    private void winEvent(IntPtr hWinEventHook, uint eventType, IntPtr hWnd, int idObject, int idChild, uint dwEventThread, uint dwmsEventTime)
    {
      //only care about the events for the specified window
      if (hWnd != _window)
        return;

      if (_watchedEvents.Contains(eventType))
      {
        if (EventOccurred != null)
          EventOccurred(this, new AccessibleEventTypeEventArgs((User32.AccessibleEventType) eventType));
      }
    }

    public void Dispose()
    {
      //unhook the listener
      if (!IntPtr.Zero.Equals(_hook))
        User32.UnhookWinEvent(_hook);

      //clear variables
      _hook = IntPtr.Zero;
      dEvent = null;

      //kill any event listeners
      EventOccurred = null;

      GC.SuppressFinalize(this);
    }
  }

和一些winapi（我省略了事件竞争列表）：

public delegate void WinEventDelegate(IntPtr hWinEventHook, uint eventType, IntPtr hwnd,
  int idObject, int idChild, uint dwEventThread, uint dwmsEventTime);

[DllImport("user32.dll")]
public static extern IntPtr SetWinEventHook(uint eventMin, uint eventMax, IntPtr hmodWinEventProc,
  WinEventDelegate lpfnWinEventProc, uint idProcess, uint idThread, uint dwFlags);

[DllImport("user32.dll")]
public static extern bool UnhookWinEvent(IntPtr hWinEventHook);

Answer 1

您可能会看到插入事件的事件。当你获得winevent时，你通常需要检查HWND 和 idObject，以确保它实际上是关于你关心的窗口部分的事件;窗口本身（OBJID_WINDOW）或其他方面，如滚动条，插入符号或其他内容。

要调试winevents，请查看Accessible Event Watcher tool - 将其配置为通过Mode菜单收听WinEvents，然后在Mode / Settings ...中选择您想要的事件 - 例如。 EVENT_OBJECT_DESTROY，然后显示事件信息，通常是hwnd，idObject和idChild。

-

顺便说一下，对你的代码发表一条评论：如果你只是从特定窗口查找事件，那么获取该窗口的线程（GetWindowThreadProcessId）会更有效，然后只使用带有该idThread的SetWinEventHook从该特定线程获取事件而不是传递0来监听所有线程;这允许Win32在事件源处为您进行过滤，这比从整个桌面上的所有线程获取该类型的事件更有效，然后忽略那些您不需要的事件。

从记事本EVENT_OBJECT_DESTROY丢失焦点？

1 个答案: