Add custom timezones in PHP?

Question

TL;DR

Is there any way to add timezones customized in PHP?

Goal

I would like to be able to register a schedule (using new DateTime(...)) with an arbitrary time offset value (Timezone), for example 13 minutes, 51 minutes or 3 hours and 27 minutes, to use the method DateTime::diff() to calculate the time interval between two events recorded by two separate watches which may be out of sync with each other by an arbitrary (but known) time difference.

Practical example:

Event 1: 17h40min (registered per clock 1)

Event 2: 19:40 (recorded per clock 2, which is 4 minutes behind the clock 1)

Time interval between events: 2 hours and 4 minutes.

Answer 1

Maybe what you could use, beyond the possibility that the mgibsonbr indicated, is the Modify:

So I could change the Datetime object to give the modified date with the difference inserted.

Example:

$data1 = new DateTime();
$data2 = new DateTime();
$data2->modify("+124 minutes");

$diferenca = $data2->diff($data1);
$resultado = $diferenca->format('%y Anos %m meses %a dias %h horas %i minutos %S segundos');
echo $resultado; // dá 0 Anos 0 meses 0 dias 2 horas 4 minutos 00 segundos

Example

Answer 2

I don’t know any way to create timezones customized, but I can suggest an alternative using timestamps.

1. Convert your date to a timestamp (int), via strtotime (if your date is in format string) or DateTime::getTimestamp (if it is in that format):

   $timestamp1 = strtotime($hora1);
   $timestamp2 = $hora2->getTimestamp();
   

2. Adjust difference in seconds of one of them (or both):

   function ajustar($timestamp, $horas = 0, $minutos = 0, $segundos = 0)
   {
       return $timestamp + ($segundos + 60 * ($minutos + 60 * $horas);
   }
   
   $timestamp1_ajustado = ajustar($timestamp1);
   $timestamp2_ajustado = ajustar($timestamp1, 0, 4);
   

3. Convert them back to one DateTime, using DateTime::setTimestamp:

   $hora1_ajustada = new DateTime();
   $hora1_ajustada->setTimestamp($timestamp1_ajustado);
   
   $hora2_ajustada = new DateTime();
   $hora2_ajustada->setTimestamp($timestamp2_ajustado);
   

Now you can calculate the difference between them normally. Full code:

function diferenca_ajustada($hora1, $hora2, $horas = 0, $minutos = 0, $segundos = 0)
{
    $timestamp1 = $hora1->getTimestamp();
    $timestamp2 = $hora2->getTimestamp() + $segundos + 60*($minutos + 60*$horas);

    $ajustada1 = new DateTime();
    $ajustada1->setTimestamp($timestamp1);
    $ajustada2 = new DateTime();
    $ajustada2->setTimestamp($timestamp2);

    return $ajustada1->diff($ajustada2);
}

Example in Phpfiddle. Note: if dates are in different timezones, you may first need to convert them to UTC before comparing them:

function para_utc($timestamp)
{
    return $timestamp - date("Z", $timestamp);
}

Answer 3

From what I’ve read of Dercik Rethans, that developed much of the class Datetime, by 2010 'create a 'custom Timezone' not even considered by him. Uniting this to current documentation of Datetimezone, I understand that it is not yet possible to create a specific Timezone (by default). Still, the answers of mgibsonbr and Sergio are alternatives.