libs/js/globalize/generator/HijriCalendar.js

   1                     // Adapted to Script from System.Globalization.HijriCalendar
   2                     ticks1970: 62135596800000,
   3                     // number of days leading up to each month
   4                     monthDays: [0, 30, 59, 89, 118, 148, 177, 207, 236, 266, 295, 325, 355],
   5                     minDate: -42521673600000,
   6                     maxDate: 253402300799999,
   7                     // The number of days to add or subtract from the calendar to accommodate the variances
   8                     // in the start and the end of Ramadan and to accommodate the date difference between
   9                     // countries/regions. May be dynamically adjusted based on user preference, but should
  10                     // remain in the range of -2 to 2, inclusive.
  11                     hijriAdjustment: %HIJRIADJUSTMENT%,
  12                     toGregorian: function(hyear, hmonth, hday) {
  13                         var daysSinceJan0101 = this.daysToYear(hyear) + this.monthDays[hmonth] + hday - 1 - this.hijriAdjustment;
  14                         // 86400000 = ticks per day
  15                         var gdate = new Date(daysSinceJan0101 * 86400000 - this.ticks1970);
  16                         // adjust for timezone, because we are interested in the gregorian date for the same timezone
  17                         // but ticks in javascript is always from GMT, unlike the server were ticks counts from the base
  18                         // date in the current timezone.
  19                         gdate.setMinutes(gdate.getMinutes() + gdate.getTimezoneOffset());
  20                         return gdate;
  21                     },
  22                     fromGregorian: function(gdate) {
  23                         if ((gdate < this.minDate) || (gdate > this.maxDate)) return null;
  24                         var ticks = this.ticks1970 + (gdate-0) - gdate.getTimezoneOffset() * 60000,
  25                             daysSinceJan0101 = Math.floor(ticks / 86400000) + 1 + this.hijriAdjustment;
  26                         // very particular formula determined by someone smart, adapted from the server-side implementation.
  27                         // it approximates the hijri year.
  28                         var hday, hmonth, hyear = Math.floor(((daysSinceJan0101 - 227013) * 30) / 10631) + 1,
  29                             absDays = this.daysToYear(hyear),
  30                             daysInYear = this.isLeapYear(hyear) ? 355 : 354;
  31                         // hyear is just approximate, it may need adjustment up or down by 1.
  32                         if (daysSinceJan0101 < absDays) {
  33                             hyear--;
  34                             absDays -= daysInYear;
  35                         }
  36                         else if (daysSinceJan0101 === absDays) {
  37                             hyear--;
  38                             absDays = this.daysToYear(hyear);
  39                         }
  40                         else {
  41                             if (daysSinceJan0101 > (absDays + daysInYear)) {
  42                                 absDays += daysInYear;
  43                                 hyear++;
  44                             }
  45                         }
  46                         // determine month by looking at how many days into the hyear we are
  47                         // monthDays contains the number of days up to each month.
  48                         hmonth = 0;
  49                         var daysIntoYear = daysSinceJan0101 - absDays;
  50                         while (hmonth <= 11 && daysIntoYear > this.monthDays[hmonth]) {
  51                             hmonth++;
  52                         }
  53                         hmonth--;
  54                         hday = daysIntoYear - this.monthDays[hmonth];
  55                         return [hyear, hmonth, hday];
  56                     },
  57                     daysToYear: function(year) {
  58                         // calculates how many days since Jan 1, 0001
  59                         var yearsToYear30 = Math.floor((year - 1) / 30) * 30,
  60                             yearsInto30 = year - yearsToYear30 - 1,
  61                             days = Math.floor((yearsToYear30 * 10631) / 30) + 227013;
  62                         while (yearsInto30 > 0) {
  63                             days += (this.isLeapYear(yearsInto30) ? 355 : 354);
  64                             yearsInto30--;
  65                         }
  66                         return days;
  67                     },
  68                     isLeapYear: function(year) {
  69                         return ((((year * 11) + 14) % 30) < 11);
  70                     }