src/libs/glut/glutBlocker.h

   1 /***********************************************************
   2  *      Copyright (C) 1997, Be Inc.  Copyright (C) 1999, Jake Hamby.
   3  *
   4  * This program is freely distributable without licensing fees
   5  * and is provided without guarantee or warrantee expressed or
   6  * implied. This program is -not- in the public domain.
   7  *
   8  *  FILE:       glutBlocker.h
   9  *
  10  *      DESCRIPTION:    helper class for GLUT event loop.
  11  *              if a window receives an event, wake up the event loop.
  12  ***********************************************************/
  13
  14 /***********************************************************
  15  *      Headers
  16  ***********************************************************/
  17 #include <kernel/OS.h>
  18
  19 /***********************************************************
  20  *      CLASS:  GlutBlocker
  21  *
  22  *      DESCRIPTION:  Fairly naive, but safe implementation.
  23  *              global semaphore controls access to state
  24  *              event semaphore blocks WaitEvent() call if necessary
  25  *              (this is basically a condition variable class)
  26  ***********************************************************/
  27 class GlutBlocker {
  28 public:
  29         GlutBlocker();
  30         ~GlutBlocker();
  31         void WaitEvent();               // wait for new event
  32         void WaitEvent(bigtime_t usecs);        // wait with timeout
  33         void NewEvent();                // new event from a window (may need to wakeup main thread)
  34         void QuickNewEvent() { events = true; } // new event from main thread
  35         void ClearEvents() { events = false; }          // clear counter at beginning of event loop
  36         bool PendingEvent() { return events; }          // XPending() equivalent
  37 private:
  38         sem_id gSem;
  39         sem_id eSem;
  40         bool events;    // are there any new events?
  41         bool sleeping;  // is someone sleeping on eSem?
  42 };
  43
  44 /***********************************************************
  45  *      Global variable
  46  ***********************************************************/
  47 extern GlutBlocker gBlock;