Add --meta option

Co-Authored-By: François Dinel <fdinel@gmail.com>

Closes varietywalls#794.

Author: jlu5

variety/VarietyOptionParser.py

@@ -107,6 +107,15 @@ def parse_options(arguments, report_errors=True):
         ),
     )
 
+    parser.add_option(
+        "--meta",
+        action="store_true",
+        dest="show_meta",
+        help=_(
+            "Print the current wallpaper metadata. Used only when the application is already running."
+        ),
+    )
+
     parser.add_option(
         "--set",
         "--set-wallpaper",

variety/VarietyWindow.py

@@ -14,6 +14,7 @@
 # You should have received a copy of the GNU General Public License along
 # with this program.  If not, see <http://www.gnu.org/licenses/>.
 ### END LICENSE
+import json
 import logging
 import os
 import random
@@ -2531,6 +2532,13 @@ def _process_command():
 
             GObject.timeout_add(3000 if initial_run else 1, _process_command)
 
+            if options.show_meta:
+                try:
+                    return json.dumps(Util.read_metadata(self.current))
+                except Exception:
+                    logger.exception(lambda: "Could not retrieve metadata for current wallpaper")
+                    return ""
+
             return self.current if options.show_current else ""
         except Exception:
             logger.exception(lambda: "Could not process passed command")