Implement new static function wxDateTime::GetFirstWeekDay()

This function tries to determine the preferred first day of week to use in
calendars. The procedure for obtaining this information is highly
platform-dependent, and is not possible on all platforms; in that case
Sunday is used as the fallback value.

Implementations are included for MSW, OSX, and Linux.

configure

@@ -32987,6 +32987,47 @@ $as_echo "$wx_cv_struct_tm_has_gmtoff" >&6; }
 
     fi
 
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking for _NL_TIME_FIRST_WEEKDAY in langinfo.h" >&5
+$as_echo_n "checking for _NL_TIME_FIRST_WEEKDAY in langinfo.h... " >&6; }
+if ${wx_cv_have_nl_time_first_weekday+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+        cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+                     #define _GNU_SOURCE
+                     #include <langinfo.h>
+
+int
+main ()
+{
+
+                     _NL_TIME_FIRST_WEEKDAY;
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+
+                     wx_cv_have_nl_time_first_weekday=yes
+
+else
+  wx_cv_have_nl_time_first_weekday=no
+
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $wx_cv_have_nl_time_first_weekday" >&5
+$as_echo "$wx_cv_have_nl_time_first_weekday" >&6; }
+
+    if test "$wx_cv_have_nl_time_first_weekday" = "yes"; then
+        $as_echo "#define HAVE_NL_TIME_FIRST_WEEKDAY 1" >>confdefs.h
+
+    fi
+
     SAMPLES_SUBDIRS="$SAMPLES_SUBDIRS typetest"
 fi
 

configure.in

@@ -5949,6 +5949,28 @@ if test "$wxUSE_DATETIME" = "yes"; then
         AC_DEFINE(WX_GMTOFF_IN_TM)
     fi
 
+    AC_CACHE_CHECK([for _NL_TIME_FIRST_WEEKDAY in langinfo.h],
+                   wx_cv_have_nl_time_first_weekday,
+    [
+        AC_TRY_COMPILE(
+                [
+                     #define _GNU_SOURCE
+                     #include <langinfo.h>
+                ],
+                [
+                     _NL_TIME_FIRST_WEEKDAY;
+                ],
+                [
+                     wx_cv_have_nl_time_first_weekday=yes
+                ],
+                wx_cv_have_nl_time_first_weekday=no
+        )
+    ])
+
+    if test "$wx_cv_have_nl_time_first_weekday" = "yes"; then
+        AC_DEFINE(HAVE_NL_TIME_FIRST_WEEKDAY)
+    fi
+
     SAMPLES_SUBDIRS="$SAMPLES_SUBDIRS typetest"
 fi
 

include/wx/datetime.h

@@ -392,6 +392,9 @@ public:
         // returns true if the given year is a leap year in the given calendar
     static bool IsLeapYear(int year = Inv_Year, Calendar cal = Gregorian);
 
+        // acquires the first day of week based on locale and/or OS settings
+    static bool GetFirstWeekDay(WeekDay *firstDay);
+
         // get the century (19 for 1999, 20 for 2000 and -5 for 492 BC)
     static int GetCentury(int year);
 

interface/wx/datetime.h

@@ -1483,6 +1483,18 @@ public:
     static bool IsDSTApplicable(int year = Inv_Year,
                                   Country country = Country_Default);
 
+    /**
+         Acquires the first weekday of a week based on locale and/or OS settings.
+         If the information was not available, returns @c Sun.
+         @param firstDay
+             The address of a WeekDay variable to which the first weekday will be
+             assigned to.
+	     @return If the first day could not be determined, returns false,
+		     and firstDay is set to a fallback value.
+         @since 3.1.1
+    */
+    static bool GetFirstWeekDay(WeekDay *firstDay);
+
     /**
         Returns @true if the @a year is a leap one in the specified calendar.
         This functions supports Gregorian and Julian calendars.

setup.h.in

@@ -935,6 +935,9 @@
 /* struct tm doesn't always have the tm_gmtoff field, define this if it does */
 #undef WX_GMTOFF_IN_TM
 
+/* check if nl_langinfo() can be called with argument _NL_TIME_FIRST_WEEKDAY */
+#undef HAVE_NL_TIME_FIRST_WEEKDAY
+
 /* Define if you have poll(2) function */
 #undef HAVE_POLL
 

src/common/datetime.cpp

@@ -541,6 +541,55 @@ bool wxDateTime::IsLeapYear(int year, wxDateTime::Calendar cal)
     }
 }
 
+#ifdef __WINDOWS__
+#include "wx/msw/registry.h"
+
+/* static */
+bool wxDateTime::GetFirstWeekDay(wxDateTime::WeekDay *firstDay)
+{
+    wxCHECK_MSG( firstDay, false, wxS("output parameter must be non-null") );
+    wxRegKey key(wxRegKey::HKCU, "Control Panel\\International");
+    wxString val;
+
+    if ( key.Exists() && key.HasValue("iFirstDayOfWeek") )
+    {
+        key.QueryValue("iFirstDayOfWeek", val);
+        *firstDay = wxDateTime::WeekDay((wxAtoi(val) + 1) % 7);
+        return true;
+    }
+    else
+    {
+        *firstDay = wxDateTime::Sun;
+        return false;
+    }
+}
+
+#elif defined(__APPLE__)
+// implementation in utils_base.mm
+#elif defined(HAVE_NL_TIME_FIRST_WEEKDAY)
+
+#include <langinfo.h>
+
+/* static */
+bool wxDateTime::GetFirstWeekDay(wxDateTime::WeekDay *firstDay)
+{
+    wxCHECK_MSG( firstDay, false, wxS("output parameter must be non-null") );
+    *firstDay = wxDateTime::WeekDay((*nl_langinfo(_NL_TIME_FIRST_WEEKDAY) - 1) % 7);
+    return true;
+}
+
+#else
+
+/* static */
+bool wxDateTime::GetFirstWeekDay(wxDateTime::WeekDay *firstDay)
+{
+    wxCHECK_MSG( firstDay, false, wxS("output parameter must be non-null") );
+    *firstDay = wxDateTime::Sun;
+    return false;
+}
+
+#endif
+
 /* static */
 int wxDateTime::GetCentury(int year)
 {

src/osx/cocoa/utils_base.mm

@@ -16,6 +16,7 @@
 #ifndef WX_PRECOMP
     #include "wx/intl.h"
     #include "wx/app.h"
+    #include "wx/datetime.h"
 #endif
 
 #include "wx/apptrait.h"
@@ -157,3 +158,14 @@ wxString wxGetOsDescription()
     return osDesc;
 }
 
+/* static */
+bool wxDateTime::GetFirstWeekDay(wxDateTime::WeekDay *firstDay)
+{
+    wxCHECK_MSG( firstDay, false, wxS("output parameter must be non-null") );
+	
+    NSCalendar *calendar = [NSCalendar currentCalendar];
+    [calendar setLocale:[NSLocale autoupdatingCurrentLocale]];
+
+    *firstDay = wxDateTime::WeekDay(([calendar firstWeekday] - 1) % 7);
+    return true;
+}