Date Selection

TTMSFNCCalendar supports single and multi-date selection, keyboard navigation, and programmatic range selection. The same API applies to TTMSFNCDatePicker, which displays the calendar in a dropdown.

Selecting dates

// --- Single date selection ---
TMSFNCCalendar1.SelectADate(Now + 2);   // select one date, deselects all others

// --- Multi-date selection (requires MultiSelect) ---
TMSFNCCalendar1.Interaction.MultiSelect := True;
TMSFNCCalendar1.SelectDate(Now - 3);                 // add a date to the selection
TMSFNCCalendar1.SelectDate(EncodeDate(2025, 12, 25));

// Range selection: select all dates from AStartDate to AEndDate (clears prior selection)
TMSFNCCalendar1.SelectMultiDates(Now - 10, Now + 5);

// --- Reading selected dates ---
var
  d: TDate;
begin
  d := TMSFNCCalendar1.SelectedDate;  // last / only selected date
  if TMSFNCCalendar1.SelectedDates.Count > 0 then
    d := TMSFNCCalendar1.SelectedDates.Items[0];
end;

// --- Deselecting ---
TMSFNCCalendar1.SelectedDates.UnselectAll;
TMSFNCCalendar1.SelectedDates.UnselectDate(Now);

// --- Date limits ---
TMSFNCCalendar1.MinDate := EncodeDate(2024, 1, 1);
TMSFNCCalendar1.MaxDate := EncodeDate(2026, 12, 31);

// --- Navigate the calendar view ---
TMSFNCCalendar1.Date  := EncodeDate(2025, 6, 1);  // jump to June 2025
TMSFNCCalendar1.Month := 12;
TMSFNCCalendar1.Year  := 2025;

// React to selection
procedure TForm1.TMSFNCCalendar1SelectDate(Sender: TObject; ADate: TDate);
begin
  ShowMessage(DateToStr(ADate) + ' selected');
end;

SelectADate — replace selection

TMSFNCCalendar1.SelectADate(Now + 2);

Selects one date and deselects everything else. Also moves the focused date to the selected date.

SelectDate — add to selection

TMSFNCCalendar1.Interaction.MultiSelect := True;
TMSFNCCalendar1.SelectDate(Now - 3);
TMSFNCCalendar1.SelectDate(EncodeDate(2025, 12, 25));

Keeps existing selected dates and adds the new one. Requires MultiSelect = True for more than one date.

SelectMultiDates — range selection

TMSFNCCalendar1.SelectMultiDates(Now - 10, Now + 5);

Selects all dates from AStartDate to AEndDate and clears any previous selection.

Reading selected dates

var d: TDate;
begin
  d := TMSFNCCalendar1.SelectedDate;  // last/only selected date
  if TMSFNCCalendar1.SelectedDates.Count > 0 then
    d := TMSFNCCalendar1.SelectedDates.Items[0];
end;

Deselecting dates

TMSFNCCalendar1.SelectedDates.UnselectAll;         // clear all
TMSFNCCalendar1.SelectedDates.UnselectDate(Now);   // clear one date

Date limits

TMSFNCCalendar1.MinDate := EncodeDate(2024, 1, 1);
TMSFNCCalendar1.MaxDate := EncodeDate(2026, 12, 31);

Dates outside the min/max range are disabled and cannot be selected.

Interaction options

Set on TTMSFNCCalendar.Interaction:

Property	Description
`MultiSelect`	Enable selecting more than one date.
`KeyboardSupport`	Allow keyboard navigation of the focused date.
`ReadOnlyMode`	Disable all user date selection.

Events

Reach for the selection events whenever something outside the calendar has to follow the selection — a detail panel, an agenda list, a Save command, or a persisted user preference. Read the selection from the after event (OnSelectDate / OnSelectMultiDate), where SelectedDates already reflects the change; OnBeforeSelectDate still sees the previous state.

Event	Signature	Fires
`OnBeforeSelectDate`	`(Sender: TObject; ADate: TDate)`	Once per date, before it is added to `SelectedDates`.
`OnSelectDate`	`(Sender: TObject; ADate: TDate)`	Once per date, after it has been added.
`OnSelectMultiDate`	`(Sender: TObject; AStartDate, AEndDate: TDate)`	Once for a whole range instead of once per day.

procedure TForm1.FormCreate(Sender: TObject);
begin
  TMSFNCCalendar1.Interaction.MultiSelect := True;

  TMSFNCCalendar1.OnBeforeSelectDate := DoBeforeSelectDate;
  TMSFNCCalendar1.OnSelectDate       := DoSelectDate;
  TMSFNCCalendar1.OnSelectMultiDate  := DoSelectMultiDate;
end;

{ Fires once per date, just before it is added to SelectedDates. The handler has
  no cancel parameter, so use it to observe or prefetch only - block a date with
  MinDate / MaxDate or Interaction.ReadOnlyMode instead. }
procedure TForm1.DoBeforeSelectDate(Sender: TObject; ADate: TDate);
begin
  StatusLabel.Text := 'Loading agenda for ' + DateToStr(ADate);
end;

{ Fires after the date has been added. SelectedDates is already up to date here,
  so this is the right place to read the full selection. }
procedure TForm1.DoSelectDate(Sender: TObject; ADate: TDate);
begin
  StatusLabel.Text := Format('%s selected (%d day(s) in total)',
    [DateToStr(ADate), TMSFNCCalendar1.SelectedDates.Count]);
end;

{ Fires once for a range selection - either SelectMultiDates or a shift-click
  drag - instead of once per day. AStartDate and AEndDate are the range bounds. }
procedure TForm1.DoSelectMultiDate(Sender: TObject; AStartDate, AEndDate: TDate);
begin
  StatusLabel.Text := Format('Range %s - %s',
    [DateToStr(AStartDate), DateToStr(AEndDate)]);
  SaveDateRange(AStartDate, AEndDate);
end;

Note

OnBeforeSelectDate carries no cancel parameter, so it cannot veto a selection. Prevent a date from being selected with MinDate / MaxDate, or block selection entirely with Interaction.ReadOnlyMode.

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