+ update_status ();
+}
+
+void
+EAN13MetadataField::update_status ()
+{
+ int len = _value.length ();
+ if (len == 13) {
+ // calculate EAN-13 modulo 10 check digit
+ int sum = 0;
+ const char *p = _value.c_str();
+ for (int i = 0; i < 12; i++) {
+ char c = p[i] - '0';
+ if (i % 2) {
+ sum += c * 3;
+ } else {
+ sum += c;
+ }
+ }
+ sum %= 10;
+ if (sum)
+ sum = 10 - sum;
+
+ if (sum == p[12] - '0') {
+ status_label->set_markup (string_compose(
+ "<span color=\"green\">%1: %2</span>",
+ _("EAN Check digit OK"), sum));
+ } else {
+ status_label->set_markup (string_compose(
+ "<span color=\"#ffa755\">%1: %2 (%3 %4)</span>",
+ _("EAN Check digit error"), p[12] - '0', _("expected"), sum));
+ }
+ } else if (len > 0) {
+ status_label->set_markup (string_compose(
+ "<span color=\"#ffa755\">%1: %2 (<13)</span>",
+ _("EAN Length error"), len));
+ } else {
+ status_label->set_text("");
+ }