Add progress bar for NDPI to DZI conversion and update .gitignore

.gitignore

@@ -160,3 +160,5 @@ cython_debug/
 #  and can be added to the global gitignore or merged into this file.  For a more nuclear
 #  option (not recommended) you can uncomment the following to ignore the entire idea folder.
 #.idea/
+
+output/

ndpi_to_dzi.py

@@ -24,7 +24,20 @@ def convert_ndpi_to_dzi(
     except pyvips.Error as exc:
         raise click.ClickException(f"Failed to open '{input_ndpi}': {exc}") from exc
 
+    image.set_progress(True)
+
     try:
+        with click.progressbar(length=100, label="Converting") as bar:
+            last_percent = [0]
+
+            def eval_cb(_image, progress):
+                delta = progress.percent - last_percent[0]
+                if delta > 0:
+                    bar.update(delta)
+                    last_percent[0] = progress.percent
+
+            image.signal_connect("eval", eval_cb)
+
             image.dzsave(
                 output,
                 suffix=f".jpeg[Q={quality}]",