Improve ImageBrowserDialog

src/gourmet/image_utils.py

@@ -3,6 +3,7 @@
 from enum import Enum
 from pathlib import Path
 from pkgutil import get_data
+from threading import Event, Thread
 from typing import Dict, List, Optional
 from urllib.parse import unquote, urlparse
 
@@ -121,34 +122,54 @@ def image_to_pixbuf(image: Image.Image) -> Pixbuf:
 
 class ImageBrowser(Gtk.Dialog):
     def __init__(self, parent: Gtk.Window, uris: List[str]):
+        """Retrieve the images from the uris and let user select one.
+
+        Image retrieval is done in another thread which is cancelled when the
+        dialog is destroyed, if not completed already.
+        """
         Gtk.Dialog.__init__(self, title="Choose an image",
                             transient_for=parent, flags=0)
         self.set_default_size(600, 600)
 
-        self.image: Image.Image = None
-
+        self.image: Optional[Image.Image] = None
         self.liststore = Gtk.ListStore(GdkPixbuf.Pixbuf)
+
         iconview = Gtk.IconView.new()
         iconview.set_model(self.liststore)
         iconview.set_pixbuf_column(0)
+        iconview.connect('selection-changed', self.on_selection)
+
+        scrollable = Gtk.ScrolledWindow()
+        scrollable.set_vexpand(True)
+        scrollable.add(iconview)
+
+        box = self.get_content_area()
+        box.pack_end(scrollable, True, True, 0)
+        self.add_buttons(Gtk.STOCK_CANCEL, Gtk.ResponseType.CANCEL,
+                         Gtk.STOCK_OK, Gtk.ResponseType.OK)
+        self.show_all()
 
+        self._stop_retrieval = Event()
+        self._image_retrieve_task = Thread(target=self._load_uris, args=[uris])
+        self._image_retrieve_task.start()
+
+    def _load_uris(self, uris: List[str]):
         for uri in uris:
+            if self._stop_retrieval.is_set():
+                return  # Cancel retrieval of image as user selection is done.
             image = make_thumbnail(uri, ThumbnailSize.SMALL)
             if image is None:
                 continue
             pixbuf = bytes_to_pixbuf(image_to_bytes(image))
             self.liststore.append([pixbuf])
 
-        iconview.connect('selection-changed', self.on_selection)
-
-        box = self.get_content_area()
-        box.pack_end(iconview, True, True, 0)
-        self.add_buttons(Gtk.STOCK_CANCEL, Gtk.ResponseType.CANCEL,
-                         Gtk.STOCK_OK, Gtk.ResponseType.OK)
-        self.show_all()
-
     def on_selection(self, iconview: Gtk.IconView):
         item = iconview.get_selected_items()
         if item:
             itr = self.liststore.get_iter(item[0])
             self.image = pixbuf_to_image(self.liststore.get_value(itr, 0))
+
+    def destroy(self):
+        self._stop_retrieval.set()
+        self._image_retrieve_task.join()
+        super().destroy()

src/gourmet/importers/interactive_importer.py

@@ -461,13 +461,13 @@ def commit_changes(self):
             for rec in self.added_recs:
                 browser = ImageBrowser(self.w, self.images)
                 response = browser.run()
+                browser.destroy()
                 if response == Gtk.ResponseType.OK:
                     thumb = browser.image.copy()
                     thumb.thumbnail((40, 40))
                     self.rd.modify_rec(rec,
                                        {'image': image_to_bytes(browser.image),
                                         'thumb': image_to_bytes(thumb)})
-                browser.destroy()
 
         if self.modal:
             self.w.hide()