[meld: 40/63] meldapp, meldwindow: Rework window deletion logic for async closing

[Kai Willadsen <kaiw src gnome org>]

commit 2b21de668d89105f5f76ccdd1eb437b479469bf0
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Sun Sep 27 08:59:17 2015 +1000

    meldapp, meldwindow: Rework window deletion logic for async closing
    
    Because we're not doing asynchronous saving, we need a significantly
    more complicated flow of should-I-close logic. Currently this works by
     having MeldWindow register whether it thinks it should try to close,
    and having it destroy itself if it thinks it's trying to close and
    doesn't have any tabs left. MeldApp now does something similar, and
    dies if its last window ever destroys itself.
    
    The delete/destroy logic in MeldWindow.page_removed still seems weird
    to me, but it's definitely necessary for the window to close correctly
    when e.g., an unsaved file comparison is present, the user saves it
    from the quit dialog, and the async save finishes.

 meld/meldapp.py    |    2 ++
 meld/meldwindow.py |   22 ++++++++++++++++++++--
 2 files changed, 22 insertions(+), 2 deletions(-)
---
diff --git a/meld/meldapp.py b/meld/meldapp.py
index 153783a..5ebf023 100644
--- a/meld/meldapp.py
+++ b/meld/meldapp.py
@@ -92,6 +92,8 @@ class MeldApp(Gtk.Application):
     def do_window_removed(self, widget):
         widget.meldwindow = None
         Gtk.Application.do_window_removed(self, widget)
+        if not self.get_windows():
+            self.quit()
 
     # We can't override do_local_command_line because it has no introspection
     # annotations: https://bugzilla.gnome.org/show_bug.cgi?id=687912
diff --git a/meld/meldwindow.py b/meld/meldwindow.py
index 0a67e8c..13b865e 100644
--- a/meld/meldwindow.py
+++ b/meld/meldwindow.py
@@ -238,6 +238,8 @@ class MeldWindow(gnomeglade.Component):
         self.widget.drag_dest_add_uri_targets()
         self.widget.connect("drag_data_received",
                             self.on_widget_drag_data_received)
+
+        self.should_close = False
         self.idle_hooked = 0
         self.scheduler = task.LifoScheduler()
         self.scheduler.connect("runnable", self.on_scheduler_runnable)
@@ -291,6 +293,7 @@ class MeldWindow(gnomeglade.Component):
             self.idle_hooked = GLib.idle_add(self.on_idle)
 
     def on_delete_event(self, *extra):
+        should_cancel = False
         # Delete pages from right-to-left.  This ensures that if a version
         # control page is open in the far left page, it will be closed last.
         for c in reversed(self.notebook.get_children()):
@@ -298,11 +301,15 @@ class MeldWindow(gnomeglade.Component):
             self.notebook.set_current_page(self.notebook.page_num(page.widget))
             response = page.on_delete_event()
             if response == Gtk.ResponseType.CANCEL:
-                return True
+                should_cancel = True
         # TODO: Now also need to check whether any page is in an error
         # state, or is asynchronously closing, or... etc. Some errors
         # or cancellation requests will be returned from the page's
         # on_delete_event, but not all.
+        should_cancel = should_cancel or self.has_pages()
+        if should_cancel:
+            self.should_close = True
+        return should_cancel
 
     def has_pages(self):
         return self.notebook.get_n_pages() > 0
@@ -579,9 +586,19 @@ class MeldWindow(gnomeglade.Component):
         page_num = self.notebook.page_num(page.widget)
 
         self.notebook.remove_page(page_num)
-        if self.notebook.get_n_pages() == 0:
+        if not self.has_pages():
             self.on_switch_page(self.notebook, page, -1)
             self._update_page_action_sensitivity()
+            if self.should_close:
+                cancelled = self.widget.emit(
+                    'delete-event', Gdk.Event.new(Gdk.EventType.DELETE))
+                if not cancelled:
+                    self.widget.emit('destroy')
+
+    def on_page_state_changed(self, page, old_state, new_state):
+        if self.should_close and old_state == melddoc.STATE_CLOSING:
+            # Cancel closing if one of our tabs does
+            self.should_close = False
 
     def on_file_changed(self, srcpage, filename):
         for c in self.notebook.get_children():
@@ -609,6 +626,7 @@ class MeldWindow(gnomeglade.Component):
             page.connect("file-changed", self.on_file_changed)
             page.connect("create-diff", lambda obj, arg, kwargs:
                          self.append_diff(arg, **kwargs))
+            page.connect("state-changed", self.on_page_state_changed)
         page.connect("close", self.page_removed)
 
         self.notebook.set_tab_reorderable(page.widget, True)