src/libs/glut/glutBlocker.cpp

   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.cpp
   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 "glutBlocker.h"
  18
  19 /***********************************************************
  20  *      Global variable
  21  ***********************************************************/
  22 GlutBlocker gBlock;
  23
  24 /***********************************************************
  25  *      Member functions
  26  ***********************************************************/
  27 GlutBlocker::GlutBlocker() {
  28         gSem = create_sem(1, "gSem");
  29         eSem = create_sem(0, "eSem");
  30         events = false;
  31         sleeping = false;
  32 }
  33
  34 GlutBlocker::~GlutBlocker() {
  35         delete_sem(eSem);
  36         delete_sem(gSem);
  37 }
  38
  39 void GlutBlocker::WaitEvent() {
  40         acquire_sem(gSem);
  41         if(!events) {                   // wait for new event
  42                 sleeping = true;
  43                 release_sem(gSem);
  44                 acquire_sem(eSem);      // next event will release eSem
  45         } else {
  46                 release_sem(gSem);
  47         }
  48 }
  49
  50 void GlutBlocker::WaitEvent(bigtime_t usecs) {
  51         acquire_sem(gSem);
  52         if(!events) {                   // wait for new event
  53                 sleeping = true;
  54                 release_sem(gSem);
  55                 acquire_sem_etc(eSem, 1, B_TIMEOUT, usecs);     // wait for next event or timeout
  56         } else {
  57                 release_sem(gSem);
  58         }
  59 }
  60
  61 void GlutBlocker::NewEvent() {
  62         acquire_sem(gSem);
  63         events = true;          // next call to WaitEvent returns immediately
  64         if(sleeping) {
  65                 sleeping = false;
  66                 release_sem(eSem);      // if event loop is blocking, wake it up
  67         }
  68         release_sem(gSem);
  69 }