DayLightTime
In an attempt to better understand what’s available and come up with new ways of doing things, I often browse through various class definitions. As I was browsing through some classes this morning, I came across the DaylightTime Class. The DaylightTime Class is part of the System.Globalization namespace. This class is used to define the period of daylight-savings time. The GetDaylightChanges Method of the TimeZone Class returns a timezone’s DaylightTime for a specified year. This may not all sound so interesting, however using this in an ASP.NET application a semi-useful utility can be developed. This example also shows how to dynamically work with a System.Web.UI.WebControls.Table Class. Dynamically created table data is not persistent and would need to be ‘refreshed’ on each postback page display. In this example I just use one row for displaying a year’s calculation. A System.Web.UI.WebControls.RangeValidator is also used in this demonstration. Check out my new DayLightTime Display.
In the page class:
public
localzone: TimeZone;
daylight: System.Globalization.DaylightTime;
tr: TableRow;
tcYear,
tcStart,
tcEnd,
tcChange: TableCell;
procedure TWebForm1.Page_Load(sender: System.Object; e: System.EventArgs);
begin
localzone:= TimeZone.CurrentTimeZone;
lblTimeZone.Text:= localzone.StandardName;
//txtYear.Text:= '1999';
end;
procedure TWebForm1.btnProcess_Click(sender: System.Object; e: System.EventArgs);
var
year: Integer;
begin
if RangeValidator1.IsValid then
begin
try
year:= Convert.ToInt32(txtYear.Text);
except
//dynamically setting it to the current year
//is also an option
year:= 2006;
txtYear.Text:= year.ToString;
end;
tblOutput.Rows.Add(CreateDaylightRow(year));
end;
end;
function TWebForm1.CreateDaylightRow(year: integer): TableRow;
begin
daylight:= localzone.GetDaylightChanges(year);
tr:= TableRow.Create;
tcYear:= TableCell.Create;
tcStart:= TableCell.Create;
tcEnd:= TableCell.Create;
tcChange:= TableCell.Create;
tcYear.Text:= year.ToString;
tr.Cells.Add(tcYear);
tcStart:= TableCell.Create;
tcStart.HorizontalAlign:= HorizontalAlign.Right;
tcStart.Text:= daylight.Start.ToString('yyyy-MM-dd HH:mm');
tr.Cells.Add(tcStart);
tcEnd:= TableCell.Create;
tcEnd.HorizontalAlign:= HorizontalAlign.Right;
tcEnd.Text:= daylight.&End.ToString('yyyy-MM-dd HH:mm');
tr.Cells.Add(tcEnd);
tcChange:= TableCell.Create;
tcChange.HorizontalAlign:= HorizontalAlign.Right;
tcChange.Text:= daylight.Delta.ToString;
tr.Cells.Add(tcChange);
Result:= tr;
end;