test if 'lmodern' exists

* specific non-ASCII characters related to our locale are not displayed on PDF
* date cannot be parsed (one calendar format and in english)
genealogytree macro needs a lang set in english

gramps/gen/plug/docgen/treedoc.py

@@ -46,8 +46,14 @@ from ..menu import NumberOption, TextOption, EnumeratedListOption
 from ...constfunc import win
 from ...config import config
 from ...const import GRAMPS_LOCALE as glocale
+from ...utils.grampslocale import GrampsLocale
 _ = glocale.translation.gettext
 
+LOCALE = GrampsLocale(lang='en')
+
+LATIN = ['french', 'italian', 'spanish']
+LANG_SUPPORT = ['danish', 'dutch', 'german', 'swedish'] + LATIN
+
 #-------------------------------------------------------------------------
 #
 # set up logging
@@ -339,6 +345,14 @@ class TreeDocBase(BaseDoc, TreeDoc):
         self.write(0, '\\usepackage[%s,%s]{geometry}\n' % (paper, margin))
         self.write(0, '\\usepackage[all]{genealogytree}\n')
         self.write(0, '\\usepackage{color}\n')
+        trans = glocale.language[0][:2]
+        lang = LOCALE._get_language_string(trans).lower()
+        if lang in LANG_SUPPORT:
+            self.write(0, '\\gtrset{language=%s}\n' % lang)
+        if lang in LATIN:
+            self.write(0, '\\IfFileExists{lmodern.sty}{\n')
+            self.write(0, '    \\usepackage{lmodern}\n')
+            self.write(0, '}{}\n')
         self.write(0, '\\begin{document}\n')
 
         if self.nodecolor == 'preferences':