[gnome-calendar] month-view: fix various reference issues with GDateTime

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 692a9639a319ac05abcebd2d6fb224cd932bfaba
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Wed May 18 11:20:00 2016 -0300

    month-view: fix various reference issues with GDateTime
    
    The current code does multiple needless unrefs, uses the
    GDateTime API in a wrongly manner and leaks references
    all around.
    
    This causes the Calendar application to emit multiple warning
    messages and in the worst case, crash immediately.
    
    Fix that by rewriting the critical sections of the code that
    deals with the start and end mark cells.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=763641

 src/gcal-month-view.c |   52 +++++++++++++++++++++++++++++++++++++-----------
 1 files changed, 40 insertions(+), 12 deletions(-)
---
diff --git a/src/gcal-month-view.c b/src/gcal-month-view.c
index 96c52d3..7dde81e 100644
--- a/src/gcal-month-view.c
+++ b/src/gcal-month-view.c
@@ -261,12 +261,13 @@ show_popover_for_position (GcalMonthView *view,
   if (priv->start_mark_cell == NULL)
     return FALSE;
 
-  if (priv->pressed_overflow_indicator != -1 && !g_date_time_equal (priv->start_mark_cell, 
priv->end_mark_cell) &&
+  if (priv->pressed_overflow_indicator != -1 &&
+      g_date_time_equal (start_dt, end_dt) &&
       g_hash_table_contains (ppriv->overflow_cells, GINT_TO_POINTER (priv->pressed_overflow_indicator)))
     {
       priv->hovered_overflow_indicator = priv->pressed_overflow_indicator;
 
-      rebuild_popover_for_day (GCAL_MONTH_VIEW (widget), g_date_time_get_day_of_month (priv->end_mark_cell));
+      rebuild_popover_for_day (GCAL_MONTH_VIEW (widget), g_date_time_get_day_of_month (end_dt));
       gtk_widget_show_all (priv->overflow_popover);
 
       gtk_widget_queue_draw (widget);
@@ -287,7 +288,7 @@ show_popover_for_position (GcalMonthView *view,
         }
 
       /* Only setup an end date when days are different */
-      if (g_date_time_compare (priv->start_mark_cell, priv->end_mark_cell))
+      if (!g_date_time_compare (start_dt, end_dt))
         {
           GDateTime *tmp_dt;
 
@@ -301,9 +302,6 @@ show_popover_for_position (GcalMonthView *view,
         }
 
       g_signal_emit_by_name (GCAL_VIEW (widget), "create-event", start_dt, end_dt, x, y);
-
-      g_clear_pointer (&start_dt, g_date_time_unref);
-      g_clear_pointer (&end_dt, g_date_time_unref);
     }
 
   gtk_widget_queue_draw (widget);
@@ -1870,10 +1868,13 @@ gcal_month_view_button_press (GtkWidget      *widget,
 
   if (clicked_cell >= priv->days_delay && clicked_cell < days)
     {
+      g_clear_pointer (&priv->start_mark_cell, g_date_time_unref);
+
       priv->keyboard_cell = clicked_cell;
       priv->start_mark_cell = g_date_time_new_local (priv->date->year, priv->date->month,
-                                                    priv->keyboard_cell - priv->days_delay + 1,
-                                                    0, 0, 0);
+                                                     priv->keyboard_cell - priv->days_delay + 1,
+                                                     0, 0, 0);
+      gtk_widget_queue_draw (widget);
     }
 
   if (pressed_indicator && g_hash_table_contains (ppriv->overflow_cells, GINT_TO_POINTER (clicked_cell)))
@@ -1916,14 +1917,39 @@ gcal_month_view_motion_notify_event (GtkWidget      *widget,
 
       if (new_end_cell >= priv->days_delay && new_end_cell < days)
         {
+          guint previous_end_cell;
+
+          previous_end_cell = new_end_cell;
+
+          /* Let the keyboard focus track the pointer */
           priv->keyboard_cell = new_end_cell;
 
-          if (g_date_time_compare (priv->start_mark_cell, priv->end_mark_cell))
-            priv->hovered_overflow_indicator = -1;
-          if (g_date_time_get_day_of_month (priv->end_mark_cell) + priv->days_delay - 1 != new_end_cell)
+          /*
+           * When there is a previously set end mark, it should be
+           * cleared before assigning a new one.
+           */
+          if (priv->end_mark_cell)
+            {
+              previous_end_cell = g_date_time_get_day_of_month (priv->end_mark_cell) - 1;
+
+              g_clear_pointer (&priv->end_mark_cell, g_date_time_unref);
+            }
+
+          if (priv->start_mark_cell &&
+              priv->end_mark_cell &&
+              !g_date_time_equal (priv->start_mark_cell, priv->end_mark_cell))
+            {
+              priv->hovered_overflow_indicator = -1;
+            }
+
+          if (previous_end_cell != new_end_cell)
             gtk_widget_queue_draw (widget);
 
-          priv->end_mark_cell = g_date_time_new_local (priv->date->year, priv->date->month, new_end_cell - 
priv->days_delay + 1, 0, 0, 0);
+          priv->end_mark_cell = g_date_time_new_local (priv->date->year,
+                                                       priv->date->month,
+                                                       new_end_cell - priv->days_delay + 1,
+                                                       0, 0, 0);
+
           return TRUE;
         }
     }
@@ -1965,6 +1991,8 @@ gcal_month_view_button_release (GtkWidget      *widget,
 
   if (current_day >= priv->days_delay && current_day < days)
     {
+      g_clear_pointer (&priv->end_mark_cell, g_date_time_unref);
+
       priv->keyboard_cell = current_day;
       priv->end_mark_cell = g_date_time_new_local (priv->date->year, priv->date->month, current_day - 
priv->days_delay + 1, 0, 0, 0);
       return show_popover_for_position (GCAL_MONTH_VIEW (widget), x, y, released_indicator);