[SOLVED] datetimepicker mindate problem

[kdalibor]

Hi, I need help again.

I am using 2 datetimepicker controls in my app. First is FromDate and second is ToDate control. I need when user select date in FromDate next day from that date be MinDate value of ToDate datetimepicker to prevent user to select previous date. I prevented today mark in both controls like this:

procedure TfrmGlavna.FromDateDropDown(Sender: TObject);
var
wnd: HWND;
style: Integer;
begin
wnd:= DateTime_GetMonthCal(dtpOd.Handle);
if wnd <> 0 then
begin
style := GetWindowLong(wnd, GWL_STYLE) ;
SetWindowLong(wnd, GWL_STYLE, style or MCS_NOTODAY or MCS_NOTODAYCIRCLE) ;
end;
end;

Then this:

procedure TfrmGlavna.FromDateExit(Sender: TObject);
begin
ToDate.MinDate:= FromDate.Date + 1;
end;

When I execute app I get a error message. For example if FromDate selected date is 07.01.2012 and ToDate I select 08.01.2012 i get error

"Project raised exception class EDateTimeError with message 'Date is less than minimum 8.1.2012'. Process stoped."

When I click 09.01.2012 everything is fine. What am I doing wrong?

[OldTurtle]

It seems that there are some bugs in TDateTimePicker routines.

A way to bypass this is to avoid the default error checks of component:

In OnChange of FromDate event:
procedure TForm1.FromDateChange(Sender: TObject);
begin
ToDate.Date:= FromDate.Date + 1;
end;

In OnCloseUp event of ToDate:

procedure TForm1.ToDateCloseUp(Sender: TObject);
begin
if DateToStr(ToDate.Date) <= DateToStr(FromDate.Date) then
ShowMessage('wrong date');
end;

This bypass the system error messages. DateToStr is necessary because seems that the component use also the Time part.

Good luck.

[kdalibor]

Thanks for the reply. I bypassed system message with ShowMessage, but now I want to do something else and getting strange result.

I want to set ToDate.Date to be 31.12 of the current year and FromDate.Date to be 01.01. of the current year.

Here is the code i wrote:

procedure TMainForm.FormCreate(Sender: TObject);
var
D, M, G: Word;
begin
ShortDateFormat:= 'dd.mm.yyyy';
DecodeDate(Date, G, M, D);
grdTabela.Cells[0,0]:= 'Group';
grdTabela.Cells[1,0]:= 'Zone';
grdTabela.Cells[2,0]:= 'Full tax amount';
grdTabela.Cells[3,0]:= 'Tax reduction';
grdTabela.Cells[4,0]:= 'Period';
grdTabela.Cells[5,0]:= 'Whole year';
grdTabela.Cells[6,0]:= 'Calculated';
grdTabela.Selection := TGridRect(Rect(-1,-1,-1,-1));
FromDate.MinDate:= Date - DayOfTheYear(Date) + 1;
FromDate.MaxDate:= Date + DaysInAYear(G) - DayOfTheYear(Date);
FromDate.Date:= FromDate.MinDate;
ToDate.MinDate:= FromDate.MinDate;
ToDate.MaxDate:= FromDate.MaxDate;
FromDate.Date:= FromDate.MaxDate;
MainForm.Caption:= 'Tax for the ' + IntToStr(G) + '. year, control value: ' + DateToStr(ToDate.Date);
end;

FromDate works perfectly, but I can't make ToDate to work properly. Line in red is my problem. I put last line of code to check value of Date in ToDate datetimepicker and I get that Date value is correct, showing it in form caption (31.12.2012), but in datetimepicker showing wrong date (in this case 01.01.2012).

I don't know how to solve this, I can't understand how in one datetimepicker working perfectly and in other not. I even tried to put this code in new application to test and get similar result, ToDate refuse to change value that it shows. Repaint, Refresh, Update procedures not helping.

Please people, help me with this, I am out of ideas.

[OldTurtle]

Try to change your code this way:

procedure TMainForm.FormCreate(Sender: TObject);
var
D, M, G: Word;
begin
ShortDateFormat:= 'dd.mm.yyyy';
DecodeDate(Date, G, M, D);
grdTabela.Cells[0,0]:= 'Group';
grdTabela.Cells[1,0]:= 'Zone';
grdTabela.Cells[2,0]:= 'Full tax amount';
grdTabela.Cells[3,0]:= 'Tax reduction';
grdTabela.Cells[4,0]:= 'Period';
grdTabela.Cells[5,0]:= 'Whole year';
grdTabela.Cells[6,0]:= 'Calculated';
grdTabela.Selection := TGridRect(Rect(-1,-1,-1,-1));
FromDate.MinDate:= Date - DayOfTheYear(Date) + 1;
FromDate.MaxDate:= Date + DaysInAYear(G) - DayOfTheYear(Date);
FromDate.Date:= FromDate.MinDate;
ToDate.MinDate:= FromDate.MinDate;

//changed
ToDate.MaxDate:= FromDate.MaxDate + 1;
ToDate.Date:= FromDate.Date + DaysInAYear(G) - 1;
//end
MainForm.Caption:= 'Tax for the ' + IntToStr(G) + '. year, control value: ' + DateToStr(ToDate.Date);
end;


If you have the same value for Date and MaxDate, the DateTimerPicker raise an exception (ERROR), so you must set the ToDate.MaxDate to 01/01/ year+1

[kdalibor]

That works perfectly. Thank you a lot.