Make code reading BMP files more robust.

[wxWidgets.git] / src / common / datetime.cpp

diff --git a/src/common/datetime.cpp b/src/common/datetime.cpp
index a2ca5d4ed8e4dc8cb545dbced056bff8af1aebb6..6ea7a0a37a3a01f0845483387a4333c2a5c3adcf 100644 (file)
--- a/src/common/datetime.cpp
+++ b/src/common/datetime.cpp
@@ -1602,6 +1602,56 @@ wxDateTime& wxDateTime::Add(const wxDateSpan& diff)
     return *this;
 }
 
+wxDateSpan wxDateTime::DiffAsDateSpan(const wxDateTime& dt) const
+{
+    wxASSERT_MSG( IsValid() && dt.IsValid(), wxT("invalid wxDateTime"));
+
+    // If dt is larger than this, calculations below needs to be inverted.
+    int inv = 1;
+    if ( dt > *this )
+        inv = -1;
+
+    int y = GetYear() - dt.GetYear();
+    int m = GetMonth() - dt.GetMonth();
+    int d = GetDay() - dt.GetDay();
+
+    // If month diff is negative, dt is the year before, so decrease year
+    // and set month diff to its inverse, e.g. January - December should be 1,
+    // not -11.
+    if ( m * inv < 0 || (m == 0 && d * inv < 0))
+    {
+        m += inv * MONTHS_IN_YEAR;
+        y -= inv;
+    }
+
+    // Same logic for days as for months above.
+    if ( d * inv < 0 )
+    {
+        // Use number of days in month from the month which end date we're
+        // crossing. That is month before this for positive diff, and this
+        // month for negative diff.
+        // If we're on january and using previous month, we get december
+        // previous year, but don't care, december has same amount of days
+        // every year.
+        wxDateTime::Month monthfordays = GetMonth();
+        if (inv > 0 && monthfordays == wxDateTime::Jan)
+            monthfordays = wxDateTime::Dec;
+        else if (inv > 0)
+            monthfordays = static_cast<wxDateTime::Month>(monthfordays - 1);
+
+        d += inv * wxDateTime::GetNumberOfDays(monthfordays, GetYear());
+        m -= inv;
+    }
+
+    int w =  d / DAYS_PER_WEEK;
+
+    // Remove weeks from d, since wxDateSpan only keep days as the ones
+    // not in complete weeks
+    d -= w * DAYS_PER_WEEK;
+
+    return wxDateSpan(y, m, w, d);
+}
+
 // ----------------------------------------------------------------------------
 // Weekday and monthday stuff
 // ----------------------------------------------------------------------------
@@ -1871,7 +1921,6 @@ wxDateTime::GetWeekOfYear(wxDateTime::WeekFlags flags, const TimeZone& tz) const
     {
         // adjust the weekdays to non-US style.
         wdYearStart = ConvertWeekDayToMondayBase(wdYearStart);
-        wdTarget = ConvertWeekDayToMondayBase(wdTarget);
 
         // quoting from http://www.cl.cam.ac.uk/~mgk25/iso-time.html:
         //
@@ -1887,22 +1936,24 @@ wxDateTime::GetWeekOfYear(wxDateTime::WeekFlags flags, const TimeZone& tz) const
         //
 
         // if Jan 1 is Thursday or less, it is in the first week of this year
-        if ( wdYearStart < 4 )
-        {
-            // count the number of entire weeks between Jan 1 and this date
-            week = (nDayInYear + wdYearStart + 6 - wdTarget)/7;
+        int dayCountFix = wdYearStart < 4 ? 6 : -1;
+
+        // count the number of week
+        week = (nDayInYear + wdYearStart + dayCountFix) / DAYS_PER_WEEK;
 
-            // be careful to check for overflow in the next year
-            if ( week == 53 && tm.mday - wdTarget > 28 )
-                    week = 1;
+        // check if we happen to be at the last week of previous year:
+        if ( week == 0 )
+        {
+            week = wxDateTime(31, Dec, GetYear() - 1).GetWeekOfYear();
         }
-        else // Jan 1 is in the last week of the previous year
+        else if ( week == 53 )
         {
-            // check if we happen to be at the last week of previous year:
-            if ( tm.mon == Jan && tm.mday < 8 - wdYearStart )
-                week = wxDateTime(31, Dec, GetYear()-1).GetWeekOfYear();
-            else
-                week = (nDayInYear + wdYearStart - 1 - wdTarget)/7;
+            int wdYearEnd = (wdYearStart + 364 + IsLeapYear(GetYear()))
+                                % DAYS_PER_WEEK;
+
+            // Week 53 only if last day of year is Thursday or later.
+            if ( wdYearEnd < 3 )
+                week = 1;
         }
     }