time zone other than UTC and local in QDateTimeEdit

kamorrissey

I have a QDateTimeEdit in a form that I need to show times from time zones other than UTC and local. It's showing the time from an embedded device that might not be in the same time zone as the running form. Is there a way to do this?

koahnig

@kamorrissey

You can basically set any date and time you want with setDateTime
or with the constructor

kamorrissey

@koahnig I know that, but I can only seem to get it to display in UTC or machine's local time zone. I need a way to have the functionality of QDateTimeEdit plus have it display the time in a specified time zone.

koahnig

@kamorrissey

You need to show code snippet.

QDateTime allows you to retrieve through its static members currentDateTime the current local date and time and there is also the UTC variant. When you are using those static members for initialization of QDateTimeEdit you are certainly getting local respectively UTC.

However, you would need to initialize an instance of QDateTime with the value you like to use (e.g. using setDate or setTime.

kamorrissey

@koahnig What I need is the editability of QDateTimeEdit, but have control over the time zone the widget displays in.

kamorrissey

What I discovered is that I needed to use QDateTime::toTimeZone(const QTineZone&) to convert the time and use QDateTimeEdit::setTimeSpec(Qt::TimeZone) on the widget.

agarvey

To me, it looks like even though the solution from @kamorrissey got it to display with the correct time zone, the time that is returned is not correct.

dte is a QDateTimeEdit*, timezone is a valid QByteArray and I'm using 5.15.2.

auto time = QDateTime::currentDateTime();

dte->setDateTime(time.toTimeZone(QTimeZone(timezone)));
dte->setTimeSpec(Qt::TimeZone);

auto test = dte->dateTime().toSecsSinceEpoch() - time.toSecsSinceEpoch();
auto test2 = time.toTimeZone(QTimeZone(timezone)).toSecsSinceEpoch() - time.toSecsSinceEpoch();

I'm seeing that test returns -3600 (the difference between my local time and the timezone) and test2 returns 0 (as expected). I believe both should return 0.

SGaist

@agarvey hi and welcome to devnet,

You need to provide more information about your timezone.

Showing all the different values you are using and getting would also help.

There's also the daylight saving time that might be at play at some point.

ChrisW67

@agarvey said in time zone other than UTC and local in QDateTimeEdit:

timezone is a valid QByteArray

On my Ubuntu system timezone is (also) an external long int declared in time.h. Without declaring a QByteArray called timezone this statement:

dte->setDateTime(time.toTimeZone(QTimeZone(timezone)));

compiles happily here and becomes (in my UTC+10 TZ):

dte->setDateTime(time.toTimeZone(QTimeZone(-36000)));

which takes the time given to the date edit on a wild excursion.
Make sure of what you are actually getting.