Question

我正在开发一个应用程序，它需要获取在应用程序运行时已经处于活动状态的Windows名称，目前我每隔半秒执行一次对GetForegroundwindow（）的调用，但这几乎不准确，我不知道我想把它放到100毫秒间隔，我认为它只是坏的而且不准确，是否有任何系统事件可以为我做到这一点？

感谢。

Answer 1

- 更新 -

您可以使用SetWindowsHookEx来监控当前桌面，但这在托管代码中不起作用。相反，您必须使用SetWinEventHook。

您曾询问如何使用SetWinEventHook p / Invoke方法。这是你的答案：

首先确保此行位于代码文件的顶部：

Imports System.Runtime.InteropServices

接下来，声明调用呼叫所需的所有内容：

Public Const WINEVENT_OUTOFCONTEXT = &H0  
'' Events are ASYNC

Public Const WINEVENT_SKIPOWNTHREAD = &H1  
'' Don't call back for events on installer's thread

Public Const WINEVENT_SKIPOWNPROCESS = &H2  
'' Don't call back for events on installer's process

Public Const WINEVENT_INCONTEXT = &H4  
'' Events are SYNC, this causes your dll to be injected into every process

    Public Declare Function SetWinEventHook Lib "user32.dll" _
       (eventMin As UInteger, _
        eventMax As UInteger, _
        hmodWinEventProc As IntPtr, _
        lpfnWinEventProc As IntPtr, _
        idProcess As UInteger, _
        idThread As UInteger, _
        dwflags As UInteger) As IntPtr

    Public Declare Function UnhookWinEvent Lib "user32.dll" _
        (hWinEventHook As IntPtr) As <MarshalAs(UnmanagedType.Bool)> Boolean

    Public Delegate Sub WinEventProc( _
          hWinEventHook As IntPtr, _
          [event] As UInteger, _
          hwnd As IntPtr, _
          idObject As Integer, _
          idChild As Integer, _
          dwEventThread As UInteger, _
          dwmsEventTime As UInteger)

接下来，将函数和新变量声明为具有该函数地址的函数：

    Public Sub EventCallBack( _
      hWinEventHook As IntPtr, _
      [event] As UInteger, _
      hwnd As IntPtr, _
      idObject As Integer, _
      idChild As Integer, _
      dwEventThread As UInteger, _
      dwmsEventTime As UInteger)

' Some code goes here
    End Sub

    Private eventProc As New WinEventProc(AddressOf EventCallBack)
    Private hEventHook As IntPtr

最后，你将它们绑在一起，然后传递以下代码行来创建你的钩子（0和255是任意数字，用你想要观察的最小和最大消息代码替换它们）：

hEventHook = SetWinEventHook(0, _
                             255, _
                             IntPtr.Zero, _
                             Marshal.GetFunctionPointerForDelegate(eventProc), _
                             0, _
                             0, _
                             WINEVENT_OUTOFCONTEXT)

当您的程序完成后，将以下行添加到Application终止事件或表单的Dispose或Finalize方法：

        UnhookWinEvent(hEventHook)

这在我的测试应用程序中按预期运行。

GetForegroundWindow（）更改时是否会触发任何系统事件？

1 个答案: