Pick the correct timezoneoffset for the day in question

Calculating the timezoneoffset for the current date really makes no sense
whatsoever when displaying a time that isn't "now".

Fixes #605

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

1 files changed, 7 insertions, 3 deletions

diff --git a/qt-gui.cpp b/qt-gui.cpp
index 68f65e76a..0f5342921 100644
--- a/qt-gui.cpp
+++ b/qt-gui.cpp
@@ -372,10 +372,14 @@ QString getSubsurfaceDataPath(QString folderToFind)
 	return QString("");
 }
 
-int gettimezoneoffset()
+int gettimezoneoffset(time_t when)
 {
-	QDateTime dt1 = QDateTime::currentDateTime();
-	QDateTime dt2 = dt1.toUTC();
+	QDateTime dt1, dt2;
+	if (when == 0)
+		dt1 = QDateTime::currentDateTime();
+	else
+		dt1 = QDateTime::fromMSecsSinceEpoch(when * 1000);
+	dt2 = dt1.toUTC();
 	dt1.setTimeSpec(Qt::UTC);
 	return dt2.secsTo(dt1);
 }