关于php：wordpress从哪里得到daylight savings信息？

Where does WordPress get it’s daylight savings info

我的问题是，WordPress从何处获取与自动时区和DST更改相关的数据，以及如何实现相同的原则，将用户选择的本地日期和时间转换为存储的偏移量，以便在日光节约期间前后移动时钟？

显然，我可以将其存储为UTC，然后将时间动态转换为其本地时区，但如果它们与创建记录时处于相反的夏令时设置中，这仍然不能准确反映它们输入的日期和时间。我正在将ASP.NET C用于SQL服务器。

WordPress通过在wp admin>settings>general>timezone中选择一个城市，而不是偏移小时数，自动反映夏令时。然后您将看到这样的通知：

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This timezone is currently in daylight saving time.

Standard time begins on: Sunday 25.10. 04:00,

它在/wp admin/options-general.php的代码中。

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<?php
$current_offset = get_option('gmt_offset');
$tzstring = get_option('timezone_string');

$check_zone_info = true;

// Remove old Etc mappings. Fallback to gmt_offset.
if ( false !== strpos($tzstring,'Etc/GMT') )
$tzstring = '';

if ( empty($tzstring) ) { // Create a UTC+- zone if no timezone string exists
$check_zone_info = false;
if ( 0 == $current_offset )
$tzstring = 'UTC+0';
elseif ($current_offset < 0)
$tzstring = 'UTC' . $current_offset;
else
$tzstring = 'UTC+' . $current_offset;
}

?>
<th scope="row"><label for="timezone_string"><?php _e('Timezone') ?></label></th>
<td>

<select id="timezone_string" name="timezone_string" aria-describedby="timezone-description">
<?php echo wp_timezone_choice( $tzstring, get_user_locale() ); ?>
</select>

<?php _e( 'Choose either a city in the same timezone as you or a UTC timezone offset.' ); ?>



<?php
/* translators: 1: UTC abbreviation, 2: UTC time */
printf( __( 'Universal time (%1$s) is %2$s.' ),
'' . __( 'UTC' ) . '</abbr>',
'<wyn>' . date_i18n( $timezone_format, false, true ) . '</wyn>'
);
?>
<?php if ( get_option( 'timezone_string' ) || ! empty( $current_offset ) ) : ?>
<?php
/* translators: %s: local time */
printf( __( 'Local time is %s.' ),
'<wyn>' . date_i18n( $timezone_format ) . '</wyn>'
);
?>
<?php endif; ?>



<?php if ( $check_zone_info && $tzstring ) : ?>


<?php
// Set TZ so localtime works.
date_default_timezone_set($tzstring);
$now = localtime(time(), true);
if ( $now['tm_isdst'] )
_e('This timezone is currently in daylight saving time.');
else
_e('This timezone is currently in standard time.');
?>
 
<?php
$allowed_zones = timezone_identifiers_list();

if ( in_array( $tzstring, $allowed_zones) ) {
$found = false;
$date_time_zone_selected = new DateTimeZone($tzstring);
$tz_offset = timezone_offset_get($date_time_zone_selected, date_create());
$right_now = time();
foreach ( timezone_transitions_get($date_time_zone_selected) as $tr) {
if ( $tr['ts'] > $right_now ) {
$found = true;
break;
}
}

if ( $found ) {
echo ' ';
$message = $tr['isdst'] ?
/* translators: %s: date and time */
__( 'Daylight saving time begins on: %s.') :
/* translators: %s: date and time */
__( 'Standard time begins on: %s.' );
// Add the difference between the current offset and the new offset to ts to get the correct transition time from date_i18n().
printf( $message,
'<wyn>' . date_i18n(
__( 'F j, Y' ) . ' ' . __( 'g:i a' ),
$tr['ts'] + ( $tz_offset - $tr['offset'] )
) . '</wyn>'
);
} else {
_e( 'This timezone does not observe daylight saving time.' );
}
}
// Set back to UTC.
date_default_timezone_set('UTC');
?>