fiji_scripts: allow value validation to include old value

FIJI.pm

@@ -17,7 +17,10 @@ use warnings;
 #             natural: values must be oct, hex, binary strings looking like a real number.
 #             hexadecimal: values must be hexadecimal numbers.
 #             boolean: will be convert to a truth value by Perl semantics
-#    - values = (optional) an array reference listing all valid values (emulates an enum)
+#    - values = (optional) used to restrict valid values. Can be...
+#                - an array reference listing all valid values (emulates an enum)
+#                - a code reference to a function that gets the new and old values and
+#                  returns true if the new value is allowed, or false otherwise.
 #    - phases_opt = (optional) list of phases (subset of "setup", "instrument", "download")
 #                  where no value must be present in input (e.g. ID is only necessary while downloading).
 #    - default = (optional) default value if not given in file and not determinable otherwise

FIJI/Settings.pm

@@ -292,10 +292,18 @@ sub validate_fiu_value {
   return validate_value(FIUMAP, $k, $v_ref);
 }
 
-# Do validation (and conversation from external->internal representation)
-sub validate_value ($$$;$) {
+## @function validate_value (%$map_ref, $k, $$v_ref, $old, $log_func)
+#   Do validation (and conversation from external->internal representation)
+#
+#   \param map_ref  reference to FIJI Settings mappings
+#   \param k        key identifying the respective setting
+#   \param v_ref    scalar reference to the proposed value (that may be modified)
+#   \param old      (optional) previously valid value
+#   \param log_func (optional) the (log4perl) log function to use
+#                   (defaul is \&Log::Log4perl::Logger::trace)
+sub validate_value ($$$;$$) {
   my $logger = get_logger();
-  my ($map_ref, $k, $v_ref, $log_func) = @_;
+  my ($map_ref, $k, $v_ref, $old, $log_func) = @_;
   $log_func = \&Log::Log4perl::Logger::trace if !defined($log_func);
   if (defined($map_ref->{$k}->{'type'})) {
     my $orig = ${$v_ref};
@@ -357,7 +365,7 @@ sub validate_value ($$$;$) {
         return 0;
       }
     } elsif (ref($values_ref) eq 'CODE') {
-      if (!$values_ref->(${$v_ref})) {
+      if (!$values_ref->(${$v_ref}, $old)) {
         $log_func->($logger, "$k: ${$v_ref} is not allowed.");
         return 0;
       }

Tk/FIJISettingsViewer.pm

@@ -504,9 +504,10 @@ sub _validate_fiu_entry {
 
 
 sub _validate_entry {
-      my ($map, $widget, $name, $new, $diff, $old, $char_idx, $type) = @_;
+      my ($map, $widget, $name, $new, $diff, $old_str, $char_idx, $type) = @_;
       my $new_bak = $new;
-      my $ok = FIJI::Settings::validate_value($map, $name, \$new);
+      my $old_val = ${$widget->{'fiji_backend_ref'}};
+      my $ok = FIJI::Settings::validate_value($map, $name, \$new, $old_val);
       _highlight_widget($widget, (!$ok));
       if ($ok) {
         ${$widget->{'fiji_backend_ref'}} = $new;