added debug option

histoqc/__main__.py

@@ -65,6 +65,7 @@ def main(argv=None):
     parser.add_argument('--symlink', metavar="TARGET_DIR",
                         help="create symlink to outdir in TARGET_DIR",
                         default=None)
+    parser.add_argument('--debug', action='store_true', help="trigger debugging behavior")
     args = parser.parse_args(argv)
 
     # --- multiprocessing and logging setup -----------------------------------
@@ -162,10 +163,11 @@ def main(argv=None):
         'shared_dict': mpm.dict(),
         'num_files': num_files,
         'force': args.force,
-        'seed': args.seed
+        'seed': args.seed,
+        'debug': args.debug
     }
     failed = mpm.list()
-    setup_plotting_backend(lm.logger)
+    setup_plotting_backend(lm.logger, debug=args.debug)
 
     try:
         if args.nprocesses > 1:

histoqc/_pipeline.py

@@ -188,7 +188,7 @@ def log_pipeline(config, log_manager):
 
 # --- worker process helpers ------------------------------------------
 
-def setup_plotting_backend(logger=None):
+def setup_plotting_backend(logger=None, debug=False):
     """loads the correct matplotlib backend
 
     Parameters
@@ -197,13 +197,13 @@ def setup_plotting_backend(logger=None):
         the logging.Logger instance
     """
     import matplotlib
-    if platform.system() != "Windows" and not os.environ.get('DISPLAY'):
-        if logger is not None:
-            logger.info('no display found. Using non-interactive Agg backend')
-        matplotlib.use('Agg')
-    else:
+
+    if debug and (platform.system() == "Windows" or os.environ.get('DISPLAY')):
         matplotlib.use('TkAgg')
 
+    else:
+        matplotlib.use('Agg')
+
 
 class BatchedResultFile:
     """BatchedResultFile encapsulates the results writing