[ocrfeeder] util: Change how ISO_CODES_PATH is set

[Joaquim Rocha <jrocha src gnome org>]

commit bb5c47a5323411fd9d7d5f36307f3640ca441506
Author: Joaquim Rocha <me joaquimrocha com>
Date:   Sat Apr 18 22:27:27 2020 +0200

    util: Change how ISO_CODES_PATH is set
    
    The ISO_CODES_PATH was hardcoded, and this means that the path may not
    be the correct one in some systems. Therefore, these changes allow to
    set an ISO_CODES_DIR as an environment variable or, in case it is not
    set, it looks for the "xml/iso-codes" path within the system's data
    dirs.

 src/ocrfeeder/util/constants.py.in | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)
---
diff --git a/src/ocrfeeder/util/constants.py.in b/src/ocrfeeder/util/constants.py.in
index ae4ae65..dc00b4c 100644
--- a/src/ocrfeeder/util/constants.py.in
+++ b/src/ocrfeeder/util/constants.py.in
@@ -93,7 +93,14 @@ OCRFEEDER_SPELLCHECKER_UI = os.path.join(RESOURCES_DIR, 'spell-checker.ui')
 OCRFEEDER_MENUBAR_UI = os.path.join(RESOURCES_DIR, 'menubar.ui')
 
 # ISO-codes location
-ISO_CODES_PATH = '/usr/share/xml/iso-codes/'
+iso_codes_dir = os.environ.get('ISO_CODES_DIR')
+if iso_codes_dir is None:
+    for dir in GLib.get_system_data_dirs():
+        iso_codes_dir = os.path.join(dir, 'xml', 'iso-codes')
+        if os.path.isdir(iso_codes_dir):
+            break
+
+ISO_CODES_PATH = iso_codes_dir
 
 APP_ID = 'org.gnome.OCRFeeder'