SysWin Gui DTP

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DTP

Reads and sets the date and time, range, format and drop-down calendar of a date picker.

A date and time picker is a one-line field showing a date or a time, with a button that drops down a month calendar (or, with DTS_UPDOWN or DTS_TIMEFORMAT, arrows instead). Create one with CWindow.AddControl( "DateTimePicker", ... ), which gives it the DTS_SHORTDATEFORMAT style and the window's font for the drop-down calendar too. Every function here takes the control's handle first and is written with the namespace: DTP.GetSystemtime( hDtp ).

Values travel in SYSTEMTIME structures. A control with the DTS_SHOWNONE style has a check box and can hold no date: GetSystemtime then returns GDT_NONE. Ranges are arrays of two SYSTEMTIME, the earlier first. The drop-down calendar exists only while it is open; its colours, font and style are kept by the picker and given to it each time. When the value changes the parent receives WM_NOTIFY with DTN_DATETIMECHANGE.

CloseMonthCal, GetDateTimePickerInfo, GetIdealSize and the month-calendar style functions need version 6 of the common controls: call EnableVisualStyles() at start-up or give the program a manifest.

Importing

#import "sys/win"
#import "sys/win/gui"
using win, gui

Example

A date field showing dates as "29 Feb 2024", limited to this year, and sized to fit its text; the caption follows every change.

#import "sys/win"
#import "sys/win/gui"
using win, gui

const IDC_DTP = 101

declare function WndProc( byval hwnd as HWND, byval uMsg as UINT, byval wParam as WPARAM, byval lParam as LPARAM ) as LRESULT

function main() as long
    SetProcessDpiAwareness( PROCESS_SYSTEM_DPI_AWARE )
    EnableVisualStyles()
    dim pWindow as CWindow = "DtpDemo"
    dim hWin as HWND = pWindow.Create( NULL, "Pick a date", @WndProc )
    pWindow.SetClientSize( 300, 100 )
    pWindow.Center()
    dim hDtp as HWND = pWindow.AddControl( "DateTimePicker", hWin, IDC_DTP, "", 40, 35, 200, 26 )
    DTP.SetFormat( hDtp, "dd MMM yyyy" )
    dim today as SYSTEMTIME = DTP.GetSystemtime( hDtp )
    dim rg(1) as SYSTEMTIME
    rg(0).wYear = today.wYear : rg(0).wMonth = 1 : rg(0).wDay = 1
    rg(1).wYear = today.wYear : rg(1).wMonth = 12 : rg(1).wDay = 31
    DTP.SetRange( hDtp, GDTR_MIN or GDTR_MAX, @rg(0) )
    var (cx, cy) = DTP.GetIdealSize( hDtp )
    if GetLastError() then SetWindowPos( hDtp, NULL, 0, 0, cx, cy, SWP_NOMOVE or SWP_NOZORDER )
    return pWindow.DoEvents( SW_NORMAL )
end function

function WndProc( byval hwnd as HWND, byval uMsg as UINT, byval wParam as WPARAM, byval lParam as LPARAM ) as LRESULT
    select case uMsg
        case WM_NOTIFY
            dim pnmh as NMHDR ptr = cast( NMHDR ptr, lParam )
            if pnmh->idFrom = IDC_DTP andalso pnmh->code = DTN_DATETIMECHANGE then
                SetWindowText( hwnd, "Chosen: " & GetWindowText( pnmh->hwndFrom ) )
            end if
            return 0
        case WM_DESTROY
            PostQuitMessage( 0 )
            return 0
    end select
    return DefWindowProcW( hwnd, uMsg, wParam, lParam )
end function

end main()

Functions

Function	Does
GetSystemtime	Returns or reads the date and time shown.
SetSystemtime	Sets the date and time, or no date.
GetRange	Reads the earliest and latest values allowed.
SetRange	Sets the earliest and latest values allowed.
SetFormat	Sets how the value is written in the field.
GetMonthCal	Returns the drop-down calendar while it is open.
CloseMonthCal	Closes the drop-down calendar.
GetMonthCalColor	Returns a colour of the drop-down calendar.
SetMonthCalColor	Sets a colour of the drop-down calendar.
GetMonthCalFont	Returns the font of the drop-down calendar.
SetMonthCalFont	Sets the font of the drop-down calendar.
GetMonthCalStyle	Returns the style of the drop-down calendar.
SetMonthCalStyle	Sets the style of the drop-down calendar.
GetDateTimePickerInfo	Reads the rectangles, states and windows of the control's parts.
GetIdealSize	Returns the size that shows the value without clipping.

Reference

GetSystemtime

function GetSystemtime overload( byval hDtp as HWND, byval pst as SYSTEMTIME ptr ) as DWORD
function GetSystemtime overload( byval hDtp as HWND, byref st as SYSTEMTIME ) as DWORD
function GetSystemtime overload( byval hDtp as HWND ) as SYSTEMTIME

Reads the date and time the control shows. A new control shows the current date and time.

Returns GDT_VALID (0) when the structure holds the value, GDT_NONE when a DTS_SHOWNONE control's box is unchecked, GDT_ERROR on failure; the third form returns the structure (all zero unless GDT_VALID).

Example

dim st as SYSTEMTIME
if DTP.GetSystemtime( hCtrl, st ) = GDT_VALID then print st.wDay; "/"; st.wMonth; "/"; st.wYear

Microsoft Learn: DTM_GETSYSTEMTIME

SetSystemtime

function SetSystemtime overload( byval hDtp as HWND, byval gd as DWORD, byval pst as SYSTEMTIME ptr ) as DWORD
function SetSystemtime overload( byval hDtp as HWND, byval gd as DWORD, byref st as SYSTEMTIME ) as DWORD

With gd GDT_VALID, shows the date and time in the structure. With GDT_NONE, unchecks the box of a DTS_SHOWNONE control and the structure is not read (pass NULL); without that style it fails. No DTN_DATETIMECHANGE is sent.

Returns nonzero on success, 0 on failure.

Example

dim st as SYSTEMTIME
st.wYear = 2024 : st.wMonth = 2 : st.wDay = 29
DTP.SetSystemtime( hCtrl, GDT_VALID, st )

Microsoft Learn: DTM_SETSYSTEMTIME

GetRange

function GetRange( byval hDtp as HWND, byval rgst as SYSTEMTIME ptr ) as DWORD

Reads the earliest allowed value into rgst[0] and the latest into rgst[1].

Returns which limits are set: GDTR_MIN, GDTR_MAX, both, or 0 for none.

Example

dim rg(1) as SYSTEMTIME
if DTP.GetRange( hCtrl, @rg(0) ) and GDTR_MIN then print "nothing before"; rg(0).wYear

Microsoft Learn: DTM_GETRANGE

SetRange

function SetRange( byval hDtp as HWND, byval gd as DWORD, byval rgst as SYSTEMTIME ptr ) as DWORD

Sets the earliest (rgst[0]) and latest (rgst[1]) values the user can choose. gd says which of the two are set: GDTR_MIN, GDTR_MAX or both; a limit left out is removed.

Returns nonzero on success, 0 on failure.

Example

dim rg(1) as SYSTEMTIME
rg(0).wYear = 2020 : rg(0).wMonth = 1 : rg(0).wDay = 1
rg(1).wYear = 2030 : rg(1).wMonth = 12 : rg(1).wDay = 31
DTP.SetRange( hCtrl, GDTR_MIN or GDTR_MAX, @rg(0) )

Microsoft Learn: DTM_SETRANGE

SetFormat

sub SetFormat( byval hDtp as HWND, byval pwsz as wstring ptr ) as boolean

Sets how the field writes the value, with a format string built from d, dd, ddd, dddd, M, MM, MMM, MMMM, y, yy, yyyy, h, hh, H, HH, m, mm, s, ss, t, tt; other text goes between single quotes. "dd'/'MM'/'yyyy" shows 29 February 2024 as 29/02/2024. NULL goes back to the format of the control's style.

It is declared as a sub with a result type, and is a sub: it gives no value, so it cannot be used in an expression.

Example

DTP.SetFormat( hCtrl, "dddd, d MMMM yyyy" )

Microsoft Learn: DTM_SETFORMAT

GetMonthCal

function GetMonthCal( byval hDtp as HWND ) as HWND

Returns the drop-down month calendar. It exists only while it is open, so call this from the DTN_DROPDOWN notification; the MonthCal functions work on it.

Returns the calendar's handle, or NULL when it is closed.

Example

dim hCal as HWND = DTP.GetMonthCal( hCtrl )
if hCal then MonthCal.SetCurrentView( hCal, MCMV_YEAR )

Microsoft Learn: DTM_GETMONTHCAL

CloseMonthCal

sub CloseMonthCal( byval hDtp as HWND )

Closes the drop-down calendar if it is open.

Example

DTP.CloseMonthCal( hCtrl )

Microsoft Learn: DTM_CLOSEMONTHCAL

GetMonthCalColor

function GetMonthCalColor( byval hDtp as HWND, byval iColor as long ) as COLORREF

Returns a colour the drop-down calendar is given: iColor is MCSC_BACKGROUND, MCSC_MONTHBK, MCSC_TEXT, MCSC_TITLEBK, MCSC_TITLETEXT or MCSC_TRAILINGTEXT.

Returns the colour, or -1 on failure.

Example

print "calendar text: &h"; hex( DTP.GetMonthCalColor( hCtrl, MCSC_TEXT ) )

Microsoft Learn: DTM_GETMCCOLOR

SetMonthCalColor

function SetMonthCalColor( byval hDtp as HWND, byval iColor as long, byval clr as COLORREF ) as COLORREF

Sets a colour the drop-down calendar is given, named as for GetMonthCalColor.

Returns the previous colour, or -1 on failure.

Example

DTP.SetMonthCalColor( hCtrl, MCSC_TITLEBK, BGR( 0, 0, 128 ) )

Microsoft Learn: DTM_SETMCCOLOR

GetMonthCalFont

function GetMonthCalFont( byval hDtp as HWND ) as HFONT

Returns the font the drop-down calendar is given. After AddControl it is the window's font.

Example

dim hFont as HFONT = DTP.GetMonthCalFont( hCtrl )

Microsoft Learn: DTM_GETMCFONT

SetMonthCalFont

sub SetMonthCalFont( byval hDtp as HWND, byval hfont as HFONT, byval fRedraw as boolean )

Sets the font the drop-down calendar is given; fRedraw true redraws an open calendar. The picker does not take ownership: keep the font until the control is gone, then delete it.

Example

DTP.SetMonthCalFont( hCtrl, GetStockObject( DEFAULT_GUI_FONT ), true )

Microsoft Learn: DTM_SETMCFONT

GetMonthCalStyle

function GetMonthCalStyle( byval hDtp as HWND ) as LRESULT

Returns the window style the drop-down calendar is created with, its MCS_* bits included.

Example

if DTP.GetMonthCalStyle( hCtrl ) and MCS_WEEKNUMBERS then print "shows week numbers"

Microsoft Learn: DTM_GETMCSTYLE

SetMonthCalStyle

function SetMonthCalStyle( byval hDtp as HWND, byval dwStyle as DWORD ) as LRESULT

Replaces the style the drop-down calendar is created with by dwStyle, for example MCS_WEEKNUMBERS or MCS_NOTODAY; GetMonthCalStyle then returns exactly dwStyle. To add a style, combine it with the old one.

Returns the previous style.

Example

DTP.SetMonthCalStyle( hCtrl, DTP.GetMonthCalStyle( hCtrl ) or MCS_WEEKNUMBERS )

Microsoft Learn: DTM_SETMCSTYLE

GetDateTimePickerInfo

sub GetDateTimePickerInfo overload( byval hDtp as HWND, byval pdtpi as DATETIMEPICKERINFO ptr )
sub GetDateTimePickerInfo overload( byval hDtp as HWND, byref dtpi as DATETIMEPICKERINFO )
function GetDateTimePickerInfo overload( byval hDtp as HWND ) as DATETIMEPICKERINFO

Fills a DATETIMEPICKERINFO (the function sets cbSize): the rectangles of the check box and the drop-down button, their states, and the edit and up-down windows (NULL when the control has none). The pointer form does nothing for NULL.

Returns the structure (third form).

Example

dim dtpi as DATETIMEPICKERINFO = DTP.GetDateTimePickerInfo( hCtrl )
print "button from x ="; dtpi.rcButton.left; " to"; dtpi.rcButton.right

Microsoft Learn: DTM_GETDATETIMEPICKERINFO

GetIdealSize

function GetIdealSize overload( byval hDtp as HWND, byval psize as SIZE ptr ) as boolean
function GetIdealSize overload( byval hDtp as HWND, byref sz as SIZE ) as boolean
function GetIdealSize overload( byval hDtp as HWND ) as ( long, long )

Reads the width and height that show the current value in the current format without clipping. The tuple form returns ( cx, cy ) and sets GetLastError() to 1 on success and 0 on failure.

Returns true on success, or the size.

Example

var (cx, cy) = DTP.GetIdealSize( hCtrl )
if GetLastError() then SetWindowPos( hCtrl, NULL, 0, 0, cx, cy, SWP_NOMOVE or SWP_NOZORDER )

Microsoft Learn: DTM_GETIDEALSIZE

See also

• sys/win/gui
• MonthCal for the drop-down calendar
• CWindow for AddControl( "DateTimePicker", ... )
• Window text and styles for EnableVisualStyles
• gui macros and helpers for reading WM_NOTIFY