How to determine if an process is the currently active / foreground application

Question

I\'d like to be able to query some function and give it a processID or processName - It then should return true or false on wether that process is

Answer 1

GetForegroundWindow and GetWindowThreadProcessId should let you get this information.

i.e., if you know the pid just check it against a function like this:

bool IsForegroundProcess(DWORD pid)
{
   HWND hwnd = GetForegroundWindow();
   if (hwnd == NULL) return false;

   DWORD foregroundPid;
   if (GetWindowThreadProcessId(hwnd, &foregroundPid) == 0) return false;

   return (foregroundPid == pid);
}

This will work for any application that uses the core Win32 library at some level - this'll include Windows Forms, WPF, native Win32 applications, etc. Note this'll only work for applications running on the calling desktop and session - you can't use this to determine if another user's application is in the foreground, for instance.