Use VariantTimeToSystemTime() in wxConvertOleToVariant().

Fix the problem with variants containing only time (but not date) information.

Also check in the symmetric changes to wxConvertVariantToOle() but disable
them for now as they were not tested.

Closes #11177.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_2_8_BRANCH@61846 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/ole/automtn.cpp

@@ -606,11 +606,31 @@ WXDLLEXPORT bool wxConvertVariantToOle(const wxVariant& variant, VARIANTARG& ole
         wxDateTime date( variant.GetDateTime() );
         oleVariant.vt = VT_DATE;
 
+        // we ought to use SystemTimeToVariantTime() here but this code is
+        // untested and hence currently disabled, please let us know if it
+        // works for you and we'll enable it
+#if 0
+        const wxDateTime::Tm tm(date.GetTm());
+
+        SYSTEMTIME st;
+        st.wYear = (WXWORD)tm.year;
+        st.wMonth = (WXWORD)(tm.mon - wxDateTime::Jan + 1);
+        st.wDay = tm.mday;
+
+        st.wDayOfWeek = 0;
+        st.wHour = tm.hour;
+        st.wMinute = tm.min;
+        st.wSecond = tm.sec;
+        st.wMilliseconds = tm.msec;
+
+        SystemTimeToVariantTime(&st, &oleVariant.date);
+#else
         long dosDateTime = date.GetAsDOS();
         short dosDate = short((dosDateTime & 0xFFFF0000) >> 16);
         short dosTime = short(dosDateTime & 0xFFFF);
 
         DosDateTimeToVariantTime(dosDate, dosTime, & oleVariant.date);
+#endif
     }
 #endif
     else if (type == wxT("void*"))
@@ -689,14 +709,17 @@ WXDLLEXPORT bool wxConvertOleToVariant(const VARIANTARG& oleVariant, wxVariant&
     case VT_DATE:
         {
 #if wxUSE_DATETIME
-            unsigned short dosDate = 0;
+            SYSTEMTIME st;
-            unsigned short dosTime = 0;
+            VariantTimeToSystemTime(oleVariant.date, &st);
-            VariantTimeToDosDateTime(oleVariant.date, & dosDate, & dosTime);
 
-            long dosDateTime = (dosDate << 16) | dosTime;
             wxDateTime date;
-            date.SetFromDOS(dosDateTime);
             variant = date;
+            date.Set(st.wDay,
+                     (wxDateTime::Month)(wxDateTime::Jan + st.wMonth - 1),
+                     st.wYear,
+                     st.wHour,
+                     st.wMinute,
+                     st.wSecond);
 #endif
             break;
         }