/**********************************************************************
 *** IdleTime - CEnvi program to start a maximized clock after the  ***
 ***            mouse and keyboard buttons have been idle, and then ***
 ***            terminate the clock when the buttons are active     ***
 ***            again.  This code checks for keyboard or mouse      ***
 ***            activity by periodically checking the global        ***
 ***            keyboard table and checking the mouse position      ***
 **********************************************************************/


#define  DELAY_WHILE_WAITING     5
   // Delay, in seconds, between each check for activity, while waiting
   // for inactivity
#define  INACTIVE_PERIOD         1
   // How many minutes of keyboard inactivity will start the program
#define  DELAY_WHILE_EXECUTING   750
   // Delay, in milliseconds (1000 = 1 second), while waiting for
   // keyboard or mouse activity to start again


main()   // this is where the program begins. This will loop forever
{
   // Uncomment ("remove "//") from following line to hide CEnvi icon
   // HideThisCEnviProgram(); // make CEnvi icon invisible
   while(TRUE) {
      WaitForInactivity();    // wait for period of inactivity
      window = StartProgram();// start program, and get handle
      if ( window ) {
         WaitForActivity();      // wait for a keyboard or mouse press
         EndProgram(window);
      }
   }
}


StartProgram() // Start the clock program, maximize it and return
{              // a handle, or return 0 if cannot start it
   window = spawn(P_NOWAIT,"CLOCK.EXE");
   if ( !window  ||  -1 == window )
      return(0);
   MaximizeWindow(window);
   return(window);
}


EndProgram(handle)   // terminate this program handle by sending
{                    // it a WM_CLOSE message
   #define WM_CLOSE  0x0010
   DynamicLink("USER","POSTMESSAGE",SWORD16,PASCAL,
               handle,WM_CLOSE,0,0,0);
}


WaitForInactivity() // check every once in a while, and return after a
{                   // long period of inactivity
   // check at every interval and set keyboard if it is not already set
   PrevTable = GetGlobalKeyboardTable();
   PrevPos = CursorPosition();
   EndTime = time() + (INACTIVE_PERIOD * 60);
   // stay in this block until period of inactivity has occurred
   do {
      suspend(DELAY_WHILE_WAITING * 1000); // wait a while
      CurrentTable = GetGlobalKeyboardTable();
      CurrentPos = CursorPosition();
      if ( memcmp(CurrentTable,PrevTable,256) || CurrentPos != PrevPos ) {
         // table has changed; reset EndTime and remember table
         EndTime = time() + (INACTIVE_PERIOD * 60);
         PrevTable = CurrentTable;
         PrevPos = CurrentPos;
      }
   } while ( time() < EndTime );
}


WaitForActivity() // check every once in a while, and return after a
{                 // change in the keyboard or mouse
   PreviousTable = GetGlobalKeyboardTable();
   PrevPos = CursorPosition();
   while( !memcmp(PreviousTable,GetGlobalKeyboardTable(),256)
       && PrevPos == CursorPosition() ) {
      suspend(DELAY_WHILE_EXECUTING);
   }
}


GetGlobalKeyboardTable()   // return 256 byte buffer for current
{                          // keyboard state
   keyBuf[255] = '\0'; // initialize a 256-byte array
   DynamicLink("USER","GETKEYBOARDSTATE",SWORD16,PASCAL,keyBuf);
   return(keyBuf);
}


HideThisCEnviProgram()  // hide the CEnvi window icon
{
   #define SW_HIDE   0
   DynamicLink("USER","SHOWWINDOW",SWORD16,PASCAL,ScreenHandle(),SW_HIDE);
}

MaximizeWindow(handle)
{
   #define SW_SHOWMAXIMIZED   3
   DynamicLink("USER","SHOWWINDOW",SWORD16,PASCAL,handle,SW_SHOWMAXIMIZED);
}

CursorPosition()  // return current cursor position in screen coordinates
{                 // structure elements returned are .col and .row
   BLObSize(point,4);
   DynamicLink("USER","GETCURSORPOS",SWORD16,PASCAL,point);
   position.col = BLObGet(point,0,SWORD16);
   position.row = BLObGet(point,2,SWORD16);
   return(position);
}