[gnome-calendar] week-grid: consider daylight when calculating event position

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

commit d4ef9b22cac5c7e8e0d2be9b31bc37d2c3753fb6
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Wed Mar 15 04:52:33 2017 -0700

    week-grid: consider daylight when calculating event position
    
    There are some weird cases around the globe where the timezone
    changes in the middle of the day. In GMT-8:00, for example, the
    DST changes at 2:00 am. This makes the timezone of thestart of
    the week different from the event's timezone, and somehow the
    GLib API doesn't take that into account when calculating the
    diff between two dates.
    
    Fix that by also considering different timezones when calculating
    the event start and end positions.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=780079

 src/views/gcal-week-grid.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)
---
diff --git a/src/views/gcal-week-grid.c b/src/views/gcal-week-grid.c
index 891396d..f469583 100644
--- a/src/views/gcal-week-grid.c
+++ b/src/views/gcal-week-grid.c
@@ -138,20 +138,26 @@ get_event_range (GcalWeekGrid *self,
 {
   GDateTime *week_start;
   GTimeSpan diff;
+  gboolean week_start_dst;
 
   if (!self->active_date)
     return;
 
   week_start = get_start_of_week (self->active_date);
+  week_start_dst = g_date_time_is_daylight_savings (week_start);
 
   if (start)
     {
       GDateTime *event_start;
+      gboolean event_start_dst;
 
       event_start = g_date_time_to_local (gcal_event_get_date_start (event));
+      event_start_dst = g_date_time_is_daylight_savings (event_start);
 
       diff = g_date_time_difference (event_start, week_start);
+
       *start = CLAMP (diff / G_TIME_SPAN_MINUTE, 0, MAX_MINUTES);
+      *start += 60 * (event_start_dst - week_start_dst);
 
       g_clear_pointer (&event_start, g_date_time_unref);
     }
@@ -160,11 +166,15 @@ get_event_range (GcalWeekGrid *self,
     {
 
       GDateTime *event_end;
+      gboolean event_end_dst;
 
       event_end = g_date_time_to_local (gcal_event_get_date_end (event));
+      event_end_dst = g_date_time_is_daylight_savings (event_end);
 
       diff = g_date_time_difference (event_end, week_start);
+
       *end = CLAMP (diff / G_TIME_SPAN_MINUTE, 0, MAX_MINUTES);
+      *end += 60 * (event_end_dst - week_start_dst);
 
       /*
        * XXX: it may happen that the event has the same start and end