Add gtk_calendar_day_is_marked() function

The marked state of calendar day is not accessible

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=627028

docs/reference/gtk/gtk3-sections.txt

@@ -594,6 +594,7 @@ gtk_calendar_select_month
 gtk_calendar_select_day
 gtk_calendar_mark_day
 gtk_calendar_unmark_day
+gtk_calendar_get_day_is_marked
 gtk_calendar_clear_marks
 
 <SUBSECTION>

gtk/gtk.symbols

@@ -554,6 +554,7 @@ gtk_button_set_use_underline
 #if IN_FILE(__GTK_CALENDAR_C__)
 gtk_calendar_clear_marks
 gtk_calendar_get_date
+gtk_calendar_get_day_is_marked
 gtk_calendar_get_detail_height_rows
 gtk_calendar_get_detail_width_chars
 gtk_calendar_get_display_options

gtk/gtkcalendar.c

@@ -4029,6 +4029,33 @@ gtk_calendar_mark_day (GtkCalendar *calendar,
     }
 }
 
+/**
+ * gtk_calendar_get_day_is_marked:
+ * @calendar: a #GtkCalendar
+ * @day: the day number between 1 and 31.
+ *
+ * Returns if the @day of the @calendar is already marked.
+ *
+ * Returns: whether the day is marked.
+ *
+ * Since: 3.0
+ */
+gboolean
+gtk_calendar_get_day_is_marked (GtkCalendar *calendar,
+                                guint        day)
+{
+  GtkCalendarPrivate *priv;
+
+  g_return_val_if_fail (GTK_IS_CALENDAR (calendar), FALSE);
+
+  priv = calendar->priv;
+
+  if (day >= 1 && day <= 31)
+    return priv->marked_date[day - 1];
+
+  return FALSE;
+}
+
 /**
  * gtk_calendar_unmark_day:
  * @calendar: a #GtkCalendar.

gtk/gtkcalendar.h

@@ -157,6 +157,9 @@ void       gtk_calendar_set_detail_height_rows (GtkCalendar    *calendar,
 gint       gtk_calendar_get_detail_width_chars (GtkCalendar    *calendar);
 gint       gtk_calendar_get_detail_height_rows (GtkCalendar    *calendar);
 
+gboolean   gtk_calendar_get_day_is_marked      (GtkCalendar    *calendar,
+                                                guint           day);
+
 G_END_DECLS
 
 #endif /* __GTK_CALENDAR_H__ */