NAME

Tk::Date - a date/time widget for perl/Tk

SYNOPSIS

use Tk::Date;
$date_widget = $top->Date->pack;
$date_widget->get("%x %X");

DESCRIPTION

Tk::Date implements a date/time widget. There are three ways to input a date:

• Using the keyboard to input the digits and the tab key or the mouse pointer to move focus between fields.

• Using up and down cursor keys to increment/decrement the date (only with installed Tk::NumEntryPlain widget).

• Selecting up and down arrow buttons will increment or decrement the value of the active field (only with installed Tk::FireButton widget).

The Date/Time Format

Unlike Java, Perl does not have a date/time object. However, it is possible to use the unix time (seconds since epoch, that is 1st January 1970) as a replacement. This is limited, since on most architectures, the valid range is between 14th December 1901 and 19th January 2038. For other dates, it is possible to use a hash notation:

{ y => year,
  m => month,
  d => day,
  H => hour,
  M => minute,
  S => second }

The abbreviations are derivated from the format letters of strftime. Note that year is the full year (1998 instead of 98) and month is the real month number, as opposed to the output of localtime(), where the month is subtracted by one.

In this document, the first method will be referred as unixtime and the second method as datehash.

STANDARD OPTIONS

Tk::Date descends from Frame and inherits all of its options.

-orient

Specified orientation of the increment and decrements buttons. May be vertical (default) or horizontal.

WIDGET-SPECIFIC OPTIONS

Some options are only available if the prerequisite modules from the Tk-GBARR distribution are installed too.

-allarrows

If true then all entry fields will obtain arrows. Otherwise only one arrow pair for each date and time will be drawn. This option can be set only while creating the widget. This option needs the Tk::NumEntry widget to be installed.

-bell

Specifies a boolean value. If true then a bell will ring if the user attempts to enter an illegal character (e.g. a non-digit).

-check

If set to a true value, Tk::Date makes sure that the user can't input incorrect dates. This option can be set only while creating the widget.

-choices

Creates an additional choice button. The argument to -choices must be one of now, today, yesterday or tomorrow, or an array with a combination of those. If only one is used, only a simple button is created, otherwise an optionmenu. This option can be set only while creating the widget.

Examples:

-choices => 'now'
-choices => ['today', 'yesterday', 'tomorrow']

It is possible to specify user-defined values. User-defined values should be defined as array elements with two elements. The first element is the label for the button or optionmenu entry. The second element specifies the time associated with this value. It may be either a date hash (missing values are set to the current date) or a subroutine which calculates unix seconds.

Here are two examples. The first defines an additional optionmenu entry for this year's christmas and the second defines an entry for the day before yesterday.

	-choices => ['today',
                     ['christmas' => { 'm' => 12, 'd' => 25}]
                    ]
        -choices => ['today',
		     'yesterday',
                     ['the day before yesterday' => sub { time()-86400*2 }]
                    ]

-command

Specifies a callback which is executed every time after an arrow button is selected. The callback is called with the following arguments: reference of date widget, field specifier, increment value. The field specifier is either "date" or "time" or one of "H", "M", "S", "d", "m", "y" for the possible time and date fields.

-datefmt

This is a sprintf/printf-like format string for setting the order and format of the date entries. By default, the format string is "%2d.%2m.%4y" meaning a two-character wide day entry, followed by a dot, followed by a two-character wide month entry, another dot, and finally a four-character wide year entry. The characters are the same as in the strftime function (see POSIX). It is also possible to use the 'A' letter for displaying the (localized) weekday name. See below in the EXAMPLES section for a more US-like date format. This option can be set only while creating the widget.

-decbitmap

Sets the bitmap for the decrease button. Defaults to FireButton's default decrease bitmap.

-editable

If set to a false value, disables editing of the date widget. All entries are converted to labels and there are no arrow buttons. Defaults to true (widget is editable). This option can be set only while creating the widget.

-fields

Specifies which fields are constructed: date, time or both. Defaults to both. This option can be set only while creating the widget.

-incbitmap

Sets the bitmap for the increase button. Defaults to FireButton's default increase bitmap.

-monthmenu

Use an optionmenu for input of the month.

-monthnames

Replace the standard month names (either English or as supplied by the locale system) with a user-defined array. The argument should be a reference to a hash with 12 elements.

-precommand

Specifies a callback which is executed every time when an arrow button is selected and before actually execute the increment or decrement command. The callback is called with following arguments: date widget, type (either date or time) and increment (+1 or -1). If the callback returns with a false value, the increment or decrement command will not be executed.

-readonly

"readonly" means only that the entry fields are readonly. However, the user is still able to use the increment/decrement buttons to change the date value. Use -state => "disabled" to make a date widget completely unchangable by the user.

-repeatinterval

Specifies the amount of time between invokations of the increment or decrement. Defaults to 50 milliseconds.

-repeatdelay

Specifies the amount of time before the increment or decrement is first done after the Button-1 is pressed over the widget. Defaults to 500 milliseconds.

-state

Specifies one of two states for the date widget: normal or disabled. If the date widget is disabled then the value may not be changed using the user interface (that is, by typing in the entry subwidgets or pressing on the increment/decrement buttons).

-timefmt

This is a sprintf/printf-like format string for setting the order and format of the time entries. By default, the format string is "%2H.%2M.%2S" meaning a two-character wide hour entry, followed by a dot, followed by a two-character wide minute entry, another dot, and finally a two-character wide seconds entry. The characters are the same as in the strftime function (see POSIX). This option can be set only while creating the widget.

-selectlabel

Change label text for choice menu. Defaults to 'Select:'. This option can be set only while creating the widget.

-value

Sets an initial value for the widget. The argument may be unixtime, datehash or now (for the current time).

-varfmt

Specifies the format of the -variable or -value argument. May be unixtime (default) or datehash. This option can be set only while creating the widget.

-variable

Ties the specified variable to the widget. (See Bugs)

-weekdays

Replace the standard weekday names (either English or as supplied by the locale system) with a user-defined array. The argument should be a reference to a hash with seven elements. The names have to start with Sunday.

METHODS

The Date widget supports the following non-standard method:

get([fmt])

Gets the current value of the date widget. If fmt is not given or equal "%s", the returned value is in unix time (seconds since epoch). This should work on all systems.

Otherwise, fmt is a format string which is fed to strftime. strftime needs the POSIX module installed and therefore may not work on all systems.

EXAMPLES

Display a date widget with only the date field in the format dd/mm/yyyy and get the value in the same format:

  $date = $top->Date(-datefmt => '%2d/%2m/%4y',
	  	     -fields => 'date',
		     -value => 'now')->pack;
  # this "get" only works for systems with POSIX.pm
  $top->Button(-text => 'Get date',
	       -command => sub { warn $date->get("%d/%m/%Y") })->pack;

Use the datehash format instead of unixtime:

  $top->Date(-fields  => 'date',
	     -value   => {'d' => '13', 'm' => '12', 'y' => '1957'},
	     -varfmt => 'datehash',
	    )->pack;

NOTES

Please note that the full set of features only available, if the Tk-GBARR distribution is also installed. However, the widget also works without this distribution, only lacking the arrow buttons.

If the POSIX module is available, localised weekday and month names will be used instead of English names. Otherwise you have to use the -weekday and -monthnames options. The POSIX strftime function does not work correctly before version 1.03 (that is, before 5.6.0), so this feature is disabled for older perl versions.

BUGS/TODO

- The -orient option can be only set while creating the widget. Also
  other options are only settable at create time.

- waiting for a real perl Date/Time object
- tie interface (-variable) does not work if the date widget gets destroyed
  (see uncommented DESTROY)
- get and set must use the tied variable, otherwise tieying does no work
  at all
- -from/-to is missing (limit) (or -minvalue, -maxvalue?)
- range check (in DateNumEntryPlain::incdec)
- am/pm
- more interactive examples are needed for some design issues (how strong
  signal errors? ...)
- check date-Function
- optionally use Tk::DateEntry for the date part
- -command is not fully implemented

SEE ALSO

Tk, Tk::NumEntryPlain, Tk::FireButton, POSIX

AUTHOR

Slaven Rezic <eserte@cs.tu-berlin.de>

COPYRIGHT

Copyright (C) 1997, 1998, 1999, 2000, 2001, 2005, 2007, 2008, 2010 Slaven Rezic. All rights reserved. This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

cpanm Tk::Date

perl -MCPAN -e shell
install Tk::Date