Add some basic QDateTime rounding/truncation functions

qt_helpers.cpp

@@ -5,6 +5,7 @@
 #include <QWidget>
 #include <QStyle>
 #include <QVariant>
+#include <QDateTime>
 
 QString font_as_stylesheet (QFont const& font)
 {
@@ -35,3 +36,15 @@ void update_dynamic_property (QWidget * widget, char const * property, QVariant
   widget->style ()->polish (widget);
   widget->update ();
 }
+
+QDateTime qt_round_date_time_to (QDateTime dt, int seconds)
+{
+  dt.setSecsSinceEpoch (dt.addSecs (seconds - 1).toSecsSinceEpoch () / seconds * seconds);
+  return dt;
+}
+
+QDateTime qt_truncate_date_time_to (QDateTime dt, int seconds)
+{
+  dt.setSecsSinceEpoch (dt.toSecsSinceEpoch () / seconds * seconds);
+  return dt;
+}