Hello Lazarus-List,

I had written an unit to handle time change between zones at a given past time (and future if rules does not change). Maybe somebody wants to add it to the Lazarus CCR but the unit should work in plain fpc programas (without GUI) but I had only tested it with Lazarus.

This is the description:

-----------------------------------------
This unit is designed to convert local times across different time zones at any given time in the past and probably in the future, this can not be ensured as time change rules could change in the future. For this purpose it uses the time rules database available at
http://www.twinsun.com/tz/tz-link.htm

License: The same as freepascal packages (basically LGPL)

The database is presented in different files so you can use one of them using "ParseDatabaseFromFile" or concatenate the interested ones in a single file or stream. Once the database is loaded calling "ParseDatabaseFromXXXX" deletes the in memory parsed data.

ProcessedLines
Amount of read lines in database.

DetectInvalidLocalTimes [True|False] (default true) When converting it will check if the given time is impossible (does not exists). This happends, in example, when a local time changes from 2:00 to 3:00, if the time to be converted is 2:01 at the change date, that time does not exists as it is not linear.

  GetTimeZoneNames(const AZones: TStringList; const AOnlyGeoZones: Boolean=true);
    Returns a TStringList with the time zones available in the database. This
    names must be used for local times to perform conversions. It is not a
    country list, as many countries have several time zones. AOnlyGeoZones
    removes from the list the usual "GMT, BST, PST" from the list.
  GMTToLocalTime
    Converts a GMT/UTC/Zulu time to a time zone (AToZone). ATimeZoneSubFix
    returns the subfix for that zone like "GMT, BST, ...".
  LocalTimeToGMT
    Converts a local time at time zone "AFromZone" to GMT/UTC/Zulu time.
  TimeZoneToTimeZone
    Converts time across zones. Basically this performs a local time to
    GMT and GTM to the new local time.
  ParseDatabaseFromFile(const AFileName: String): Boolean;
    Reads the database from a file.
  ParseDatabaseFromStream(const AStream: TStream): Boolean;
    Reads the database from a stream.

2009 - Jos? Mejuto
-----------------------------------------

I do not know if there is already an equivalent code available in Lazarus or fpc :-?

Attached is the source code without database, I hope it passes the size restriction of the list.

JoshyFun wrote

I had written an unit to handle time change between zones at a given past time (and future if rules does not change). Maybe somebody wants to add it to the Lazarus CCR but the unit should work in plain fpc programas (without GUI) but I had only tested it with Lazarus.

Jos?-

Thanks for doing this and sharing the code!

Hello Lazarus-List,

Tuesday, November 10, 2009, 2:49:26 PM, you wrote:

VS> I gladly upload it to Lazarus-CCR.
VS> Can you create wiki page like
VS> http://wiki.lazarus.freepascal.org/CmdLine for VS> example. That way there is some docs with the component on line.

I'll try but my skills with wiki are... well "they are not" :) Anyway I'll try or ask for help.

Hello Lazarus-List,

you wrote

> VS> I gladly upload it to Lazarus-CCR.

[...]
VS> You can start on
VS> http://wiki.lazarus.freepascal.org/Release_new_component

Done http://wiki.lazarus.freepascal.org/PascalTZ

When uploaded to CCR I'll add the package and demo project and maybe a recent copy of the tz database (I already have access to CCR SVN, but write out of "folder" where I already collaborate is etiquette forbidden).

Thank you for the help.