[Rigo] use only cached UGC metadata if user is scrolling the TreeView

This improves the scrolling speed greatly and reduces the network
pressure.

rigo/rigo/ui/gtk3/widgets/apptreeview.py

@@ -20,6 +20,7 @@ this program; if not, write to the Free Software Foundation, Inc.,
 """
 from gi.repository import Gtk, Gdk, GObject
 import os
+from threading import Timer
 
 from entropy.i18n import _
 
@@ -48,6 +49,12 @@ class AppTreeView(GenericTreeView):
                  icon_size, store=None):
         Gtk.TreeView.__init__(self)
 
+        self._scrolling_timer = None
+        self._scrolled_view = None
+        self._scrolled_view_vadj = None
+        def _is_scrolling():
+            return self._scrolling_timer is not None
+
         self._entropy = entropy_client
         self._apc = apc
         self._service = rigo_service
@@ -55,7 +62,8 @@ class AppTreeView(GenericTreeView):
         tr = CellRendererAppView(icons,
                                  self.create_pango_layout(""),
                                  show_ratings,
-                                 Icons.INSTALLED_OVERLAY)
+                                 Icons.INSTALLED_OVERLAY,
+                                 scrolling_cb=_is_scrolling)
         tr.set_pixbuf_width(icon_size)
 
         # create buttons and set initial strings
@@ -105,6 +113,51 @@ class AppTreeView(GenericTreeView):
         self.set_search_equal_func(self._app_search, None)
         self.set_property("enable-search", True)
 
+    def _scrolling_event(self, vadj):
+        """
+        Event received from the Gtk.VAdjustment of the
+        Gtk.ScrolledView containing this widget.
+        We expose the scrolling state to upper and lower layers.
+        """
+        if self._scrolling_timer:
+            return
+
+        def unset():
+            # This may cause a race condition
+            # because an event of the past can
+            # reset the state right after scrolling_timer
+            # has been back set. But we don't really care in
+            # this case. We don't want to be *that* precise.
+            self._scrolling_timer = None
+
+        def set_timer():
+            t = Timer(1.0, unset)
+            t.name = "UnsetScrollingTimer"
+            t.daemon = True
+            return t
+
+        t = self._scrolling_timer
+        if t is not None:
+            t.cancel()
+
+        t = set_timer()
+        t.start()
+        self._scrolling_timer = t
+
+    def set_scrolled_view(self, scrolled_view):
+        """
+        Set the Gtk.ScrolledView container of this TreeView.
+        """
+        vadj = scrolled_view.get_vadjustment()
+        vadj.connect("value-changed", self._scrolling_event)
+        self._scrolled_view = scrolled_view
+        self._scrolled_view_vadj = vadj
+
+    def get_vadjustment(self):
+        sv = self._scrolled_view
+        if sv:
+            return sv.get_vadjustment()
+
     def _row_activated_callback(self, path, rowref):
         self._apc.emit("application-activated",
                        self.model.get_application(rowref))

rigo/rigo/ui/gtk3/widgets/cellrenderers.py

@@ -21,9 +21,9 @@ You should have received a copy of the GNU General Public License along with
 this program; if not, write to the Free Software Foundation, Inc.,
 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 """
-from gi.repository import Gtk, Gdk, GObject, Pango
+from gi.repository import GLib, Gtk, Gdk, GObject, Pango
 
-from threading import Lock
+from threading import Lock, Timer
 
 from rigo.em import Ems
 from rigo.utils import escape_markup
@@ -62,9 +62,17 @@ class CellRendererAppView(Gtk.CellRendererText):
                          GObject.PARAM_READWRITE),
                      }
 
-    def __init__(self, icons, layout, show_ratings, overlay_icon_name):
+    def __init__(self, icons, layout, show_ratings,
+                 overlay_icon_name, scrolling_cb=None):
         super(CellRendererAppView, self).__init__()
 
+        self._is_scrolling = scrolling_cb
+        if scrolling_cb is None:
+            def _is_scrolling(): return False
+            self._is_scrolling = _is_scrolling
+        else:
+            self._is_scrolling = scrolling_cb
+
         # geometry-state values
         self.pixbuf_width = 0
         self.apptitle_width = 0
@@ -93,7 +101,6 @@ class CellRendererAppView(Gtk.CellRendererText):
             # icon not present in theme, probably because running uninstalled
             self._installed = icons.load_icon('emblem-system',
                                               self.OVERLAY_SIZE, 0)
-        return
 
     def _layout_get_pixel_width(self, layout):
         return layout.get_size()[0] / Pango.SCALE
@@ -104,7 +111,7 @@ class CellRendererAppView(Gtk.CellRendererText):
     def _render_icon(self, cr, app, cell_area, xpad, ypad, is_rtl):
 
         # calc offsets so icon is nicely centered
-        icon = self.model.get_icon(app)
+        icon = self.model.get_icon(app, cached=self._is_scrolling())
         xo = (self.pixbuf_width - icon.get_width())/2
 
         if not is_rtl:
@@ -142,11 +149,7 @@ class CellRendererAppView(Gtk.CellRendererText):
 
         max_layout_width = cell_area.width - self.pixbuf_width - 3*xpad
 
-        def _still_visible():
-            return self.model.visible(app.get_details().pkg)
-        stats = app.get_review_stats(_still_visible_cb=_still_visible)
-
-        if self.show_ratings and stats:
+        if self.show_ratings:
             max_layout_width -= star_width+6*xpad
 
         if self.props.isactive:
@@ -187,7 +190,10 @@ class CellRendererAppView(Gtk.CellRendererText):
 
         def _still_visible():
             return self.model.visible(app.get_details().pkg)
-        stats = app.get_review_stats(_still_visible_cb=_still_visible)
+        stats = app.get_review_stats(
+            _still_visible_cb=_still_visible,
+            cached=self._is_scrolling())
+
         if not stats:
             return
         sr = self._stars

rigo/rigo_app.py

@@ -272,6 +272,7 @@ class Rigo(Gtk.Application):
             self._entropy, self._service, self._app_view_c, icons,
             True, AppListStore.ICON_SIZE, store=None)
         self._scrolled_view.add(self._view)
+        self._view.set_scrolled_view(self._scrolled_view)
 
         self._app_store = AppListStore(
             self._entropy, self._entropy_ws,