DATETIMEPICKER otras funciones posiblemente interesantes

uses
ComCtrls;

const
DTM_SETFORMAT = $1005;

procedure TForm1.Button1Click(Sender: TObject);
var
sFormat: string;
begin
DateTimePicker1.kind := dtkTime;

// Don't show the seconds, Sekunden nicht anzeigen
SendMessage(DateTimePicker1.Handle, DTM_SETFORMAT, 0, Longint(PChar('hh:mm')));

// To show AM/PM
SendMessage(DateTimePicker1.Handle, DTM_SETFORMAT, 0, Longint(PChar('hh:mm tt')));

// 24-hour clock: Be sure to set Kind to dtkTime
DateTime_SetFormat(DateTimePickerTest.Handle, pChar('H:mm:ss'));

// To show Date and Time, Datum und Zeit anzeigen
// Note that you can only edit the date or the time depending
// on the Kind (dtkTime or dtkDate).
SendMessage(DateTimePicker1.Handle, DTM_SETFORMAT, 0, Longint(PChar('dd/MM/yyyy hh:ss')));

// You could also use the DateTime_SetFormat macro:
DateTime_SetFormat(DateTimePicker1.Handle, PChar('M/d/yyy'));

// Instead of using the DateTime_SetFormat function, you can
// send a message to the control directly:
sFormat := 'dd-MMMM-yyyy';
DateTimePicker1.Perform(DTM_SETFORMAT, 0, DWORD(sFormat));
end;

// Show the Week Number in a TDateTimePicker

procedure DateToWeek(dtDate: TDateTime; var AWeek, AYear: Word);
const
FIRST_WEEKDAY: Integer = 2;
FIRST_WEEKDATE: Integer = 4;
var
wMonth, wDay: Word;
begin
dtDate := dtDate - ((DayOfWeek(dtDate) - FIRST_WEEKDAY + 7) mod 7) + 7 - FIRST_WEEKDATE;
DecodeDate(dtDate, AYear, wMonth, wDay);
AWeek := (Trunc(dtDate - EncodeDate(AYear, 1, 1)) div 7) + 1;
end;

procedure TForm1.DateTimePicker1Change(Sender: TObject);
var
sFormat: string;
wWeek, wYear: Word;
begin
DateToWeek(DateTimePicker1.date, wWeek, wYear);
sFormat := 'dd/MM/yy Week:' + IntToStr(wWeek) + '';
DateTimePicker1.Perform(DTM_SETFORMAT, 0, DWORD(sFormat));
end;

procedure TForm1.FormShow(Sender: TObject);
begin
DateTimePicker1Change(Self);
end;