/// <summary>
/// Returns the time bias specification for the specified year.
/// </summary>
/// <param name="year">The year for which the bias applies.</param>
private BiasSettings GetBiasSettings(int year)
{
// Check whether the time zone uses dynamic DST
if (!isDaylightDynamic)
{
return(actualSettings);
}
if (year < firstDaylightEntry)
{
year = firstDaylightEntry;
}
else if (year > lastDaylightEntry)
{
year = lastDaylightEntry;
}
// Get the collection of dynamic DST data
Dictionary <int, BiasSettings> years = null;
lock (standardName)
{
string key = standardName + " Dynamic DST data";
//TODO: Use caching to increase performance
//years = (Dictionary<int, BiasSettings>)Application.Cache[key];
if (years == null)
{
years = new Dictionary <int, BiasSettings>();
//Application.Cache.Add(key, years);
}
}
// Get the DST data for the specified year
BiasSettings result = null;
lock (years)
{
if (years.TryGetValue(year, out result))
{
return(result);
}
string keyName = TimeZoneManager.TimeZoneDatabaseKey;
keyName += string.Format(@"\{0}\Dynamic DST", standardName);
using (RegistryKey key = Registry.
LocalMachine.OpenSubKey(keyName))
{
byte[] rawData = (byte[])key.GetValue(year.ToString());
result = (rawData == null) ? actualSettings :
new BiasSettings(rawData);
}
years.Add(year, result);
}
return(result);
}
/// <summary>
/// Initializes a new instance of the <see cref="UITimeZone"/> class.
/// </summary>
/// <param name="name">The name of the time zone
/// as recorded in the Windows registry.</param>
/// <param name="data">The time zone's registry data.</param>
internal UITimeZone(string name, RegistryKey data)
{
cachedDaylightChanges = new Dictionary <int, DaylightTime>();
// Convert the signed number obtained from the registry
// to the unsigned value of the system index.
int?indexValue = (int?)data.GetValue("Index");
if (indexValue.HasValue)
{
index = (((uint)(indexValue.Value >> 16)) << 16) |
((uint)(indexValue.Value & 0xFFFF));
}
// Get the display name of the time zone.
displayName = (string)data.GetValue("Display");
Match m = displayNameRegex.Match(displayName);
description = m.Groups["Dscr"].Value;
// Get other descriptive data of the time zone
standardName = (string)data.GetValue("Std");
daylightName = (string)data.GetValue("Dlt");
actualSettings = new BiasSettings(
(byte[])data.GetValue("TZI"));
// Check whether the time zone uses dynamic DST
string[] subKeyNames = data.GetSubKeyNames();
foreach (string subKeyName in subKeyNames)
{
if (subKeyName != "Dynamic DST")
{
continue;
}
isDaylightDynamic = true;
using (RegistryKey subKey = data.OpenSubKey(subKeyName))
{
firstDaylightEntry = (int)subKey.GetValue("FirstEntry");
lastDaylightEntry = (int)subKey.GetValue("LastEntry");
}
if (standardName != name) // it should not be
{
standardName = name; // is used when accessing the registry
}
return;
}
isDaylightDynamic = false;
firstDaylightEntry = int.MinValue;
lastDaylightEntry = int.MaxValue;
}
/// <summary>
/// Returns the coordinated universal time (UTC) offset
/// for the specified local time.
/// </summary>
/// <param name="time">The local date and time.</param>
public override TimeSpan GetUtcOffset(DateTime time)
{
if (time.Kind == DateTimeKind.Utc)
{
return(TimeSpan.Zero);
}
int year = time.Year;
DaylightTime daylightTimes = GetDaylightChanges(year);
BiasSettings settings = GetBiasSettings(year);
if (!IsDaylightSavingTime(time, daylightTimes))
{
return(settings.ZoneBias);
}
return(settings.ZoneBias + daylightTimes.Delta);
}
/// <summary>
/// Returns the daylight saving time period for a particular year.
/// </summary>
/// <param name="year">The year to which
/// the daylight saving time period applies.</param>
/// <exception cref="T:System.ArgumentOutOfRangeException">
/// <paramref name="year"/> is less than 1 or greater than 9999.</exception>
public override DaylightTime GetDaylightChanges(int year)
{
if ((year < 1) || (year > 9999))
{
throw new ArgumentOutOfRangeException("year");
}
lock (cachedDaylightChanges)
{
DaylightTime result = null;
if (cachedDaylightChanges.TryGetValue(year, out result))
{
return(result);
}
BiasSettings settings = GetBiasSettings(year);
result = settings.GetDaylightChanges(year);
cachedDaylightChanges.Add(year, result);
return(result);
}
}
/// <summary>
/// Returns the coordinated universal time (UTC) offset
/// for the specified universal time.
/// </summary>
/// <param name="time">The UTC date and time.</param>
private TimeSpan GetUtcOffsetFromUniversalTime(DateTime time)
{
int year = time.Year;
DaylightTime daylightTimes = GetDaylightChanges(year);
BiasSettings settings = GetBiasSettings(year);
TimeSpan result = settings.ZoneBias;
if ((daylightTimes == null) || (daylightTimes.Delta.Ticks == 0))
{
return(result);
}
DateTime time3 = daylightTimes.Start - result;
DateTime time4 = (daylightTimes.End - result) - daylightTimes.Delta;
DateTime time5, time6;
if (daylightTimes.Delta.Ticks > 0)
{
time5 = time4 - daylightTimes.Delta;
time6 = time4;
}
else
{
time5 = time3;
time6 = time3 - daylightTimes.Delta;
}
bool flag = false;
if (time3 > time4)
{
flag = (time < time4) || (time >= time3);
}
else
{
flag = (time >= time3) && (time < time4);
}
return(flag ? result + daylightTimes.Delta : result);
}
