src/glut/beos/glutBlocker.h

   1 /***********************************************************
   2  *      Copyright (C) 1997, Be Inc.  All rights reserved.
   3  *
   4  *  FILE:       glutBlocker.h
   5  *
   6  *      DESCRIPTION:    helper class for GLUT event loop.
   7  *              if a window receives an event, wake up the event loop.
   8  ***********************************************************/
   9
  10 /***********************************************************
  11  *      Headers
  12  ***********************************************************/
  13 #include <kernel/OS.h>
  14
  15 /***********************************************************
  16  *      CLASS:  GlutBlocker
  17  *
  18  *      DESCRIPTION:  Fairly naive, but safe implementation.
  19  *              global semaphore controls access to state
  20  *              event semaphore blocks WaitEvent() call if necessary
  21  *              (this is basically a condition variable class)
  22  ***********************************************************/
  23 class GlutBlocker {
  24 public:
  25         GlutBlocker();
  26         ~GlutBlocker();
  27         void WaitEvent();               // wait for new event
  28         void WaitEvent(bigtime_t usecs);        // wait with timeout
  29         void NewEvent();                // new event from a window (may need to wakeup main thread)
  30         void QuickNewEvent() { events = true; } // new event from main thread
  31         void ClearEvents() { events = false; }          // clear counter at beginning of event loop
  32         bool PendingEvent() { return events; }          // XPending() equivalent
  33 private:
  34         sem_id gSem;
  35         sem_id eSem;
  36         bool events;    // are there any new events?
  37         bool sleeping;  // is someone sleeping on eSem?
  38 };
  39
  40 /***********************************************************
  41  *      Global variable
  42  ***********************************************************/
  43 extern GlutBlocker gBlock;