Resolves: tdf#100452 class Date full (BCE,CE) proleptic Gregorian calendar

... implementing signed years with year 0 gap.
Date(31,12,-1) last day BCE
Date(1,1,1) first day CE

New class Date member functions:
* AddYears(sal_Int16) to be used instead of
  aDate.SetYear(aDate.GetYear()+sal_Int16) to handle year 0 gap.
* convenience GetNextYear() to be used insted of GetYear()+1
* convenience GetPrevYear() to be used insted of GetYear()-1
* AddMonths(sal_Int32)
* operator=(const css::util::Date&)

New class DateTime member functions:
* operator=(const css::util::DateTime&)

Made some conversion ctors explicit, specifically Date(sal_Int32)

Adapted hopefully all places that used a sal_uInt16 year to use
sal_Int16 where appropriate.

Eliminated some quirks in date handling found on the fly.

Added era handling to i18npool icu calendar setting interface, which
missing was responsible for 0001-01-01 entered in Calc being set as
-0001-01-01, hence subtracting one day resulted in -0002-12-31.

Change-Id: I77b39fba9599ebd5067d7864f6c9ebe01f6f578f
Reviewed-on: https://gerrit.libreoffice.org/27049
Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Jenkins <ci@libreoffice.org>

3 files changed, 8 insertions, 17 deletions

diff --git a/chart2/source/tools/NumberFormatterWrapper.cxx b/chart2/source/tools/NumberFormatterWrapper.cxx
index 52c6a5250a55..1151aa4aeaab 100644
--- a/chart2/source/tools/NumberFormatterWrapper.cxx
+++ b/chart2/source/tools/NumberFormatterWrapper.cxx
@@ -98,7 +98,8 @@ OUString NumberFormatterWrapper::getFormattedString( sal_Int32 nNumberFormatKey,
         return aText;
     }
     // i99104 handle null date correctly
-    sal_uInt16 nYear = 1899,nDay = 30,nMonth = 12;
+    sal_Int16 nYear = 1899;
+    sal_uInt16 nDay = 30,nMonth = 12;
     if ( m_aNullDate.hasValue() )
     {
         Date* pDate = m_pNumberFormatter->GetNullDate();
diff --git a/chart2/source/view/axes/DateHelper.cxx b/chart2/source/view/axes/DateHelper.cxx
index d8c872711c51..42a77cd045ec 100644
--- a/chart2/source/view/axes/DateHelper.cxx
+++ b/chart2/source/view/axes/DateHelper.cxx
@@ -37,27 +37,17 @@ bool DateHelper::IsInSameMonth( const Date& rD1, const Date& rD2 )
         && (rD1.GetMonth() == rD2.GetMonth());
 }
 
-Date DateHelper::GetDateSomeMonthsAway( const Date& rD, long nMonthDistance )
+Date DateHelper::GetDateSomeMonthsAway( const Date& rD, sal_Int32 nMonthDistance )
 {
     Date aRet(rD);
-    long nMonth = rD.GetMonth()+nMonthDistance;
-    long nNewMonth = nMonth%12;
-    long nNewYear = rD.GetYear() + nMonth/12;
-    if( nMonth <= 0 || !nNewMonth )
-        nNewYear--;
-    if( nNewMonth <= 0 )
-        nNewMonth += 12;
-    aRet.SetMonth( sal_uInt16(nNewMonth) );
-    aRet.SetYear( sal_uInt16(nNewYear) );
-    aRet.Normalize();
+    aRet.AddMonths( nMonthDistance );
     return aRet;
 }
 
-Date DateHelper::GetDateSomeYearsAway( const Date& rD, long nYearDistance )
+Date DateHelper::GetDateSomeYearsAway( const Date& rD, sal_Int32 nYearDistance )
 {
     Date aRet(rD);
-    aRet.SetYear( static_cast<sal_uInt16>(rD.GetYear()+nYearDistance) );
-    aRet.Normalize();
+    aRet.AddYears( static_cast<sal_Int16>(nYearDistance) );
     return aRet;
 }
 
diff --git a/chart2/source/view/inc/DateHelper.hxx b/chart2/source/view/inc/DateHelper.hxx
index 3142e90c9f1d..099985533853 100644
--- a/chart2/source/view/inc/DateHelper.hxx
+++ b/chart2/source/view/inc/DateHelper.hxx
@@ -31,8 +31,8 @@ public:
     static bool IsInSameYear( const Date& rD1, const Date& rD2 );
     static bool IsInSameMonth( const Date& rD1, const Date& rD2 );
 
-    static Date GetDateSomeMonthsAway( const Date& rD, long nMonthDistance );
-    static Date GetDateSomeYearsAway( const Date& rD, long nYearDistance );
+    static Date GetDateSomeMonthsAway( const Date& rD, sal_Int32 nMonthDistance );
+    static Date GetDateSomeYearsAway( const Date& rD, sal_Int32 nYearDistance );
     static bool IsLessThanOneMonthAway( const Date& rD1, const Date& rD2 );
     static bool IsLessThanOneYearAway( const Date& rD1, const Date& rD2 );