Add context managers to use a loading icon

This is a bit simpler than Gtk.Spinner, which doesn't seem to actually
spin if some code is blocking. Some kind of an async dance would
probably be required to make that work as intended.

There's a bizarre need for a tiny sleep here for the icon to actually
change. It could be that the 1/100 s that is enough on my system might
not be enough on someone else's system.

Closes #18

catapult/plugin.py

@@ -16,6 +16,7 @@
 # along with this program. If not, see <https://www.gnu.org/licenses/>.
 
 import catapult
+import contextlib
 
 from catapult.i18n import _
 from threading import Thread
@@ -70,6 +71,12 @@ def read_configuration(cls):
     def search(self, query):
         raise NotImplementedError
 
+    @contextlib.contextmanager
+    def spinner(self):
+        window = catapult.app.get_active_window()
+        with window.spinner():
+            yield
+
     def update(self):
         pass
 

catapult/window.py

@@ -17,8 +17,10 @@
 # along with this program. If not, see <https://www.gnu.org/licenses/>.
 
 import catapult
+import contextlib
 import itertools
 import logging
+import time
 
 from catapult import util
 from gi.repository import Gdk
@@ -28,6 +30,20 @@
 from gi.repository import Gtk
 from gi.repository import Pango
 
+ICON_NAMES_LOADING = [
+    "content-loading-symbolic",
+    "image-loading-symbolic",
+    "content-loading",
+    "image-loading",
+]
+
+ICON_NAMES_SEARCH = [
+    "system-search-symbolic",
+    "edit-find-symbolic",
+    "system-search",
+    "edit-find",
+]
+
 ICON_SIZE = Gtk.IconSize.LARGE
 ICON_SIZE_PX = 48
 
@@ -78,6 +94,7 @@ def __init__(self):
         self._icon_theme = Gtk.IconTheme.get_for_display(Gdk.Display.get_default())
         self._icon_theme_handler_id = None
         self._input_entry = Gtk.Entry()
+        self._input_icon = Gtk.Image()
         self._plugins = []
         self._position = (0, 0)
         self._prev_query = ""
@@ -126,22 +143,16 @@ def _init_signal_handlers(self):
 
     def _init_widgets(self):
         screen_width, screen_height = catapult.util.get_screen_size()
-        input_icon = Gtk.Image()
-        input_icon.set_pixel_size(ICON_SIZE_PX/2)
-        input_icon.set_from_icon_name(util.lookup_icon(
-            "system-search-symbolic",
-            "edit-find-symbolic",
-            "system-search",
-            "edit-find",
-        ) or "")
-        input_icon.set_icon_size(Gtk.IconSize.LARGE)
-        input_icon.add_css_class("catapult-input-icon")
+        self._input_icon.set_pixel_size(ICON_SIZE_PX/2)
+        self._input_icon.set_from_icon_name(util.lookup_icon(*ICON_NAMES_SEARCH) or "")
+        self._input_icon.set_icon_size(Gtk.IconSize.LARGE)
+        self._input_icon.add_css_class("catapult-input-icon")
         self._input_entry.add_css_class("catapult-input-entry")
         self._input_entry.set_hexpand(True)
         input_box = Gtk.Box(orientation=Gtk.Orientation.HORIZONTAL, spacing=0)
         input_box.add_css_class("catapult-input-box")
         input_box.set_hexpand(True)
-        input_box.append(input_icon)
+        input_box.append(self._input_icon)
         input_box.append(self._input_entry)
         self._body = Gtk.Box(orientation=Gtk.Orientation.VERTICAL, spacing=0)
         self._body.add_css_class("catapult-body")
@@ -410,6 +421,32 @@ def show(self):
         self._input_entry.grab_focus()
         super().show()
 
+    def spin_start(self):
+        # XXX: Main context iteration doesn't seem to be enough,
+        # we need to sleep a brief moment for the icon to actually change.
+        icon_name = util.lookup_icon(*ICON_NAMES_LOADING) or ""
+        self._input_icon.set_from_icon_name(icon_name)
+        time.sleep(1/100)
+        main_context = GLib.MainContext.default()
+        while main_context.pending():
+            main_context.iteration()
+
+    def spin_stop(self):
+        # XXX: Main context iteration doesn't seem to be enough,
+        # we need to sleep a brief moment for the icon to actually change.
+        icon_name = util.lookup_icon(*ICON_NAMES_SEARCH) or ""
+        self._input_icon.set_from_icon_name(icon_name)
+        time.sleep(1/100)
+        main_context = GLib.MainContext.default()
+        while main_context.pending():
+            main_context.iteration()
+
+    @contextlib.contextmanager
+    def spinner(self):
+        self.spin_start()
+        yield
+        self.spin_stop()
+
     def toggle(self, *args, **kwargs):
         self.hide() if self.is_visible() else self.show()