ysimon
asked on
How to get system's Daylight setting?
In Delphi programming, I'd like to obtain the system date and time and know if current time is daylight or not.
Thanks
ysimon
Thanks
ysimon
yeah something like this should work:
function isDayLightSavings:boolean;
var
tz : TTimeZoneInformation;
begin
result := getTimeZoneInformation(tz) = TIME_ZONE_ID_DAYLIGHT;
end;
GL
Mike
function isDayLightSavings:boolean;
var
tz : TTimeZoneInformation;
begin
result := getTimeZoneInformation(tz)
end;
GL
Mike
ysimon,
In addition to the previous comments, the following code will extract the local time, UTC, the offset bias and a flag to indicate whether daylight saving is in operation:
type TTimeInfo = record
LocalTime: TDateTime;
UTC : TDateTime;
TZBias : TDateTime;
IsDayLight: Boolean;
end;
function GetTimeInfo: TTimeInfo;
var
rTZ : TTimeZoneInformation;
begin
// Get Timezone Info...
case GetTimeZoneInformation(rTZ ) of
TIME_ZONE_ID_UNKNOWN : begin
// Don't know the SystemTime value. Assume PC is using UTC at the moment.
Result.TZBias := 0;
Result.IsDayLight := False;
end;
TIME_ZONE_ID_STANDARD : begin
// PC is using "standard" time
Result.TZBias := (rTZ.StandardBias / 1440);
Result.IsDayLight := False;
end;
TIME_ZONE_ID_DAYLIGHT : begin
// PC is using "daylight" time
Result.TZBias := (rTZ.DaylightBias / 1440);
Result.IsDayLight := True;
end;
TIME_ZONE_ID_INVALID : begin
Result.TZBias := 0;
Result.IsDayLight := False;
end;
else begin
Result.TZBias := 0;
Result.IsDayLight := False;
end;
end;
with Result do begin
LocalTime := Now;
UTC := LocalTime + TZBias;
end;
end;
To use it, the following code shows you what you can do (you'll need 3 TEdit and 1 TLabel components on a form):
var
lInfo: TTimeInfo;
begin
lInfo:= GetTimeInfo;
Edit1.Text := FormatDateTime('hh:nn:ss, dd/mm/yyyy', lInfo.LocalTime);
Edit2.Text := FormatDateTime('hh:nn:ss, dd/mm/yyyy', lInfo.UTC);
Edit3.Text := FormatDateTime('hh:nn:ss', lInfo.TZBias);
if (lInfo.TZBias < 0) then
Edit3.Text := '+' + Edit3.Text
else
Edit3.Text := '-' + Edit3.Text;
if lInfo.IsDayLight then
Label4.Caption := 'In Daylight time now'
else
Label4.Caption := 'Using Standard time now'
end;
In addition to the previous comments, the following code will extract the local time, UTC, the offset bias and a flag to indicate whether daylight saving is in operation:
type TTimeInfo = record
LocalTime: TDateTime;
UTC : TDateTime;
TZBias : TDateTime;
IsDayLight: Boolean;
end;
function GetTimeInfo: TTimeInfo;
var
rTZ : TTimeZoneInformation;
begin
// Get Timezone Info...
case GetTimeZoneInformation(rTZ
TIME_ZONE_ID_UNKNOWN : begin
// Don't know the SystemTime value. Assume PC is using UTC at the moment.
Result.TZBias := 0;
Result.IsDayLight := False;
end;
TIME_ZONE_ID_STANDARD : begin
// PC is using "standard" time
Result.TZBias := (rTZ.StandardBias / 1440);
Result.IsDayLight := False;
end;
TIME_ZONE_ID_DAYLIGHT : begin
// PC is using "daylight" time
Result.TZBias := (rTZ.DaylightBias / 1440);
Result.IsDayLight := True;
end;
TIME_ZONE_ID_INVALID : begin
Result.TZBias := 0;
Result.IsDayLight := False;
end;
else begin
Result.TZBias := 0;
Result.IsDayLight := False;
end;
end;
with Result do begin
LocalTime := Now;
UTC := LocalTime + TZBias;
end;
end;
To use it, the following code shows you what you can do (you'll need 3 TEdit and 1 TLabel components on a form):
var
lInfo: TTimeInfo;
begin
lInfo:= GetTimeInfo;
Edit1.Text := FormatDateTime('hh:nn:ss, dd/mm/yyyy', lInfo.LocalTime);
Edit2.Text := FormatDateTime('hh:nn:ss, dd/mm/yyyy', lInfo.UTC);
Edit3.Text := FormatDateTime('hh:nn:ss',
if (lInfo.TZBias < 0) then
Edit3.Text := '+' + Edit3.Text
else
Edit3.Text := '-' + Edit3.Text;
if lInfo.IsDayLight then
Label4.Caption := 'In Daylight time now'
else
Label4.Caption := 'Using Standard time now'
end;
Wow !
Would you mind adding that to the Delphi section of HowToDoThings.com ? I love it !
Pete
Would you mind adding that to the Delphi section of HowToDoThings.com ? I love it !
Pete
ASKER
Thanks edey and malsoft, you solved my problem.
BTW I'd like know that if there is a table to record all time difference between local standard time and GMT.
Maybe it doesn't exist.
ysimon
BTW I'd like know that if there is a table to record all time difference between local standard time and GMT.
Maybe it doesn't exist.
ysimon
ASKER
Thanks edey and malsoft, you solved my problem.
BTW I'd like know that if there is a table to record all time difference between local standard time and GMT.
Maybe it doesn't exist.
ysimon
BTW I'd like know that if there is a table to record all time difference between local standard time and GMT.
Maybe it doesn't exist.
ysimon
ysimon,
On my Win98SE machine, there's a whole slew of timezone information in the registry at:
HKEY_LOCAL_MACHINE\Softwar e\Microsof t\Windows\ CurrentVer sion\Time Zones
and the current setting is at:
HKEY_LOCAL_MACHINE\System\ CurrentCon trolSet\Co ntrol\Time ZoneInform ation
Unfortunately, the information you need to get at is held in a TZI binary field - the format of which I'm not 100% sure about (it may be a copy of the structure, but I would bet on that!)
Happy coding!
On my Win98SE machine, there's a whole slew of timezone information in the registry at:
HKEY_LOCAL_MACHINE\Softwar
and the current setting is at:
HKEY_LOCAL_MACHINE\System\
Unfortunately, the information you need to get at is held in a TZI binary field - the format of which I'm not 100% sure about (it may be a copy of the structure, but I would bet on that!)
Happy coding!
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GL
Mike