[pitivi] Use virtual methods instead of connecting to signals

[Alexandru Băluț <alexbalut src gnome org>]

commit 51c94ab3331e45796b425e4e843bb3b166f81276
Author: Alexandru Băluț <alexandru balut gmail com>
Date:   Tue Aug 30 16:49:11 2016 +0200

    Use virtual methods instead of connecting to signals
    
    This can be done when the signal is always connected. Saves one line of
    code and one parameter and makes a bit more clear that the handler
    reacts to something happening to `self`.
    
    Differential Revision: https://phabricator.freedesktop.org/D1293

 pitivi/mediafilespreviewer.py  |    5 ++---
 pitivi/tabsmanager.py          |    5 ++---
 pitivi/viewer/overlay_stack.py |    4 ++--
 pitivi/viewer/viewer.py        |    4 ++--
 4 files changed, 8 insertions(+), 10 deletions(-)
---
diff --git a/pitivi/mediafilespreviewer.py b/pitivi/mediafilespreviewer.py
index 4b0be04..5bc55fa 100644
--- a/pitivi/mediafilespreviewer.py
+++ b/pitivi/mediafilespreviewer.py
@@ -80,8 +80,6 @@ class PreviewWidget(Gtk.Grid, Loggable):
         Loggable.__init__(self)
 
         self.log("Init PreviewWidget")
-        self.connect('destroy', self._destroy_cb)
-
         self.settings = settings
         self.error_message = None
 
@@ -455,7 +453,8 @@ class PreviewWidget(Gtk.Grid, Loggable):
         dialog.run()
         dialog.destroy()
 
-    def _destroy_cb(self, widget):
+    def do_destroy(self):
+        """Handles the destruction of the widget."""
         self.player.release()
         self.is_playing = False
 
diff --git a/pitivi/tabsmanager.py b/pitivi/tabsmanager.py
index d0420b2..3a9063e 100644
--- a/pitivi/tabsmanager.py
+++ b/pitivi/tabsmanager.py
@@ -40,7 +40,6 @@ class BaseTabs(Gtk.Notebook, Loggable):
         Loggable.__init__(self)
         self.set_border_width(SPACING)
         self.set_scrollable(True)
-        self.connect("create-window", self.__create_window_cb)
         self.settings = app.settings
         notebook_widget_settings = self.get_settings()
         notebook_widget_settings.props.gtk_dnd_drag_threshold = 1
@@ -79,8 +78,8 @@ class BaseTabs(Gtk.Notebook, Loggable):
         self.insert_page(child, label, original_position)
         self._set_child_properties(child, label)
 
-    def __create_window_cb(self, unused_notebook, child, unused_x, unused_y):
-        """Creates a window for the detached page.
+    def do_create_window(self, child, unused_x, unused_y):
+        """Handles the detachment of a page.
 
         Args:
             child (Gtk.Widget): The detached page.
diff --git a/pitivi/viewer/overlay_stack.py b/pitivi/viewer/overlay_stack.py
index 6880416..689ac76 100644
--- a/pitivi/viewer/overlay_stack.py
+++ b/pitivi/viewer/overlay_stack.py
@@ -45,9 +45,9 @@ class OverlayStack(Gtk.Overlay, Loggable):
                         Gdk.EventMask.LEAVE_NOTIFY_MASK |
                         Gdk.EventMask.ALL_EVENTS_MASK)
         self.add(sink_widget)
-        self.connect("size-allocate", self.__on_size_allocate)
 
-    def __on_size_allocate(self, widget, rectangle):
+    def do_size_allocate(self, rectangle):
+        """Handles size allocation."""
         self.window_size = numpy.array([rectangle.width,
                                         rectangle.height])
         for overlay in self.__overlays.values():
diff --git a/pitivi/viewer/viewer.py b/pitivi/viewer/viewer.py
index e02b012..1235a95 100644
--- a/pitivi/viewer/viewer.py
+++ b/pitivi/viewer/viewer.py
@@ -519,12 +519,12 @@ class PlayPauseButton(Gtk.Button, Loggable):
         self.add(self.image)
         self.playing = False
         self.setPlay()
-        self.connect('clicked', self._clickedCb)
 
     def set_sensitive(self, value):
         Gtk.Button.set_sensitive(self, value)
 
-    def _clickedCb(self, unused):
+    def do_clicked(self):
+        """Handles the click events to toggle playback."""
         self.playing = not self.playing
         self.emit("play", self.playing)