The 设置WinEventHook http://msdn.microsoft.com/en-us/library/dd373640%28v=vs.85%29.aspxAPI 正是您在这里寻找的。您需要做的就是在您的应用程序以正确的选项启动时调用此函数,并且每当用户从桌面上当前运行的任何进程更改焦点时您应该开始收到通知。
[DllImport("user32.dll", SetLastError = true)]
internal static extern IntPtr SetWinEventHook(uint eventMin, uint eventMax, IntPtr hmodWinEventProc, WinEventProc lpfnWinEventProc, int idProcess, int idThread, uint dwflags);
[DllImport("user32.dll")]
internal static extern int UnhookWinEvent(IntPtr hWinEventHook);
internal delegate void WinEventProc(IntPtr hWinEventHook, uint iEvent, IntPtr hWnd, int idObject, int idChild, int dwEventThread, int dwmsEventTime);
const uint WINEVENT_OUTOFCONTEXT = 0;
const uint EVENT_SYSTEM_FOREGROUND = 3;
private IntPtr winHook;
private WinEventProc listener;
public void StartListeningForWindowChanges()
{
listener = new WinEventProc(EventCallback);
//setting the window hook
winHook = SetWinEventHook(EVENT_SYSTEM_FOREGROUND, EVENT_SYSTEM_FOREGROUND, IntPtr.Zero, listener, 0, 0, WINEVENT_OUTOFCONTEXT);
}
public void StopListeningForWindowChanges()
{
UnhookWinEvent(winHook);
}
private static void EventCallback(IntPtr hWinEventHook, uint iEvent, IntPtr hWnd, int idObject, int idChild, int dwEventThread, int dwmsEventTime)
{
// handle active window changed!
}