src/common/time.cpp

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // Name:        src/common/time.cpp
   3 // Purpose:     Implementation of time-related functions.
   4 // Author:      Vadim Zeitlin
   5 // Created:     2011-11-26
   6 // RCS-ID:      $Id: wxhead.cpp,v 1.11 2010-04-22 12:44:51 zeitlin Exp $
   7 // Copyright:   (c) 2011 Vadim Zeitlin <vadim@wxwidgets.org>
   8 // Licence:     wxWindows licence
   9 ///////////////////////////////////////////////////////////////////////////////
  10
  11 // ============================================================================
  12 // declarations
  13 // ============================================================================
  14
  15 // ----------------------------------------------------------------------------
  16 // headers
  17 // ----------------------------------------------------------------------------
  18
  19 // for compilers that support precompilation, includes "wx.h".
  20 #include "wx/wxprec.h"
  21
  22 #ifdef __BORLANDC__
  23     #pragma hdrstop
  24 #endif
  25
  26 #include "wx/time.h"
  27
  28 #ifndef WX_GMTOFF_IN_TM
  29     // Define it for some systems which don't (always) use configure but are
  30     // known to have tm_gmtoff field.
  31     #if defined(__WXPALMOS__) || defined(__DARWIN__)
  32         #define WX_GMTOFF_IN_TM
  33     #endif
  34 #endif
  35
  36 // ============================================================================
  37 // implementation
  38 // ============================================================================
  39
  40 // returns the time zone in the C sense, i.e. the difference UTC - local
  41 // (in seconds)
  42 int wxGetTimeZone()
  43 {
  44 #ifdef WX_GMTOFF_IN_TM
  45     // set to true when the timezone is set
  46     static bool s_timezoneSet = false;
  47     static long gmtoffset = LONG_MAX; // invalid timezone
  48
  49     // ensure that the timezone variable is set by calling wxLocaltime_r
  50     if ( !s_timezoneSet )
  51     {
  52         // just call wxLocaltime_r() instead of figuring out whether this
  53         // system supports tzset(), _tzset() or something else
  54         time_t t = time(NULL);
  55         struct tm tm;
  56
  57         wxLocaltime_r(&t, &tm);
  58         s_timezoneSet = true;
  59
  60         // note that GMT offset is the opposite of time zone and so to return
  61         // consistent results in both WX_GMTOFF_IN_TM and !WX_GMTOFF_IN_TM
  62         // cases we have to negate it
  63         gmtoffset = -tm.tm_gmtoff;
  64
  65         // this function is supposed to return the same value whether DST is
  66         // enabled or not, so we need to use an additional offset if DST is on
  67         // as tm_gmtoff already does include it
  68         if ( tm.tm_isdst )
  69             gmtoffset += 3600;
  70     }
  71     return (int)gmtoffset;
  72 #elif defined(__DJGPP__) || defined(__WINE__)
  73     struct timeb tb;
  74     ftime(&tb);
  75     return tb.timezone*60;
  76 #elif defined(__VISUALC__)
  77     // We must initialize the time zone information before using it (this will
  78     // be done only once internally).
  79     _tzset();
  80
  81     // Starting with VC++ 8 timezone variable is deprecated and is not even
  82     // available in some standard library version so use the new function for
  83     // accessing it instead.
  84     #if wxCHECK_VISUALC_VERSION(8)
  85         long t;
  86         _get_timezone(&t);
  87         return t;
  88     #else // VC++ < 8
  89         return timezone;
  90     #endif
  91 #elif defined(WX_TIMEZONE) // If WX_TIMEZONE was defined by configure, use it.
  92     return WX_TIMEZONE;
  93 #elif defined(__BORLANDC__) || defined(__MINGW32__) || defined(__VISAGECPP__)
  94     return _timezone;
  95 #elif defined(__MWERKS__)
  96     return 28800;
  97 #else // unknown platform -- assume it has timezone
  98     return timezone;
  99 #endif // WX_GMTOFF_IN_TM/!WX_GMTOFF_IN_TM
 100 }