Extensions: Implement translationdomain functionality

Inkscape will read the "translationdomain" attribute from the
<inkscape-extension> root element in the .inx file.

It will then attempt to lookup a message catalog that matches
this domain, register it with gettext, and use it for translations.

Message catalogs may be located in either
- the .inx file's location
- the root of the "extensions" directory containing the .inx
- the system location Inkscape's own catalog is loaded from

To make this functionality available to script extensions, Inkscape
will set the environment variables
  INKEX_GETTEXT_DOMAIN
and
  INKEX_GETTEXT_DIRECTORY
so extension scripts can then use something like
  bindtextdomain(INKEX_GETTEXT_DOMAIN, INKEX_GETTEXT_DIRECTORY)
  textdomain(INKEX_GETTEXT_DOMAIN)
to enable the feature.

See also
  https://gitlab.com/inkscape/inkscape/issues/333
  https://gitlab.com/inkscape/extensions/issues/117

1 files changed, 6 insertions, 0 deletions

diff --git a/src/extension/extension.h b/src/extension/extension.h
index 2ddd8f3f4..476be37d5 100644
--- a/src/extension/extension.h
+++ b/src/extension/extension.h
@@ -126,8 +126,13 @@ protected:
                                                  *  relative paths in the extension should usually be relative to it */
     ExpirationTimer * timer = nullptr;         /**< Timeout to unload after a given time */
     bool _translation_enabled = true;          /**< Attempt translation of strings provided by the extension? */
+
+private:
     const char *_translationdomain = nullptr;  /**< Domainname of gettext textdomain that should
                                                  *  be used for translation of the extension's strings */
+    std::string _gettext_catalog_dir;          /**< Directory containing the gettext catalog for _translationdomain */
+
+    void lookup_translation_catalog();
 
 public:
     Extension(Inkscape::XML::Node *in_repr, Implementation::Implementation *in_imp, std::string *base_directory);
@@ -151,6 +156,7 @@ public:
     void          set_base_directory(std::string base_directory) { _base_directory = base_directory; };
     std::string   get_dependency_location(const char *name);
     const char   *get_translation(const char* msgid, const char *msgctxt=nullptr);
+    void          set_environment();
 
 /* Parameter Stuff */
 private: