svtools FormattedField: don't reparse value from text after ReFormat

If our format is lossy / not a bijection
(as is e.g. our default date format, because of 2-digit year),
then reparsing the string that came from the format
leads to data loss (the value is changed to something else).

The existing code tried to do that, by calling Modify()
and then setting m_bValueDirty to false.
However, this fails because listeners are called
while m_bValueDirty is true. If any of them calls
e.g. GetValue(), the reparse happens.

Change-Id: I272f377927f83c71ede1eb80eafbc689f36fb17a

include/svtools/fmtfield.hxx

@@ -236,6 +236,7 @@ public:
 
 protected:
     virtual long Notify(NotifyEvent& rNEvt);
+    void impl_Modify(bool makeValueDirty = true);
     virtual void Modify();
 
     // CheckText ueberschreiben fuer Ueberpruefung zur Eingabezeit

svtools/source/control/fmtfield.cxx

@@ -487,13 +487,14 @@ void FormattedField::SetAutoColor(sal_Bool _bAutomatic)
 }
 
 //------------------------------------------------------------------------------
-void FormattedField::Modify()
+void FormattedField::impl_Modify(bool makeValueDirty)
 {
     DBG_CHKTHIS(FormattedField, NULL);
 
     if (!IsStrictFormat())
     {
-        m_bValueDirty = sal_True;
+        if(makeValueDirty)
+            m_bValueDirty = sal_True;
         SpinField::Modify();
         return;
     }
@@ -503,7 +504,8 @@ void FormattedField::Modify()
     {
         m_sLastValidText = sCheck;
         m_aLastSelection = GetSelection();
-        m_bValueDirty = sal_True;
+        if(makeValueDirty)
+            m_bValueDirty = sal_True;
     }
     else
     {
@@ -513,6 +515,14 @@ void FormattedField::Modify()
     SpinField::Modify();
 }
 
+//------------------------------------------------------------------------------
+void FormattedField::Modify()
+{
+    DBG_CHKTHIS(FormattedField, NULL);
+
+    impl_Modify();
+}
+
 //------------------------------------------------------------------------------
 void FormattedField::ImplSetTextImpl(const OUString& rNew, Selection* pNewSel)
 {
@@ -789,10 +799,12 @@ void FormattedField::Commit()
 
     // did the text change?
     if ( GetText() != sOld )
-    {   // consider the field as modified
-        Modify();
-        // but we have the most recent value now
-        m_bValueDirty = sal_False;
+    {   // consider the field as modified,
+        // but we already have the most recent value;
+        // don't reparse it from the text
+        // (can lead to data loss when the format is lossy,
+        //  as is e.g. our default date format: 2-digit year!)
+        impl_Modify(false);
     }
 }