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#
# Calendar
# ----------------------------------------------------------------------
# Implements a calendar widget for the selection of a date.  It displays
# a single month at a time.  Buttons exist on the top to change the 
# month in effect turning th pages of a calendar.  As a page is turned, 
# the dates for the month are modified.  Selection of a date visually 
# marks that date.  The selected value can be monitored via the 
# -command option or just retrieved using the get method.  Methods also
# exist to select a date and show a particular month.  The option set
# allows the calendars appearance to take on many forms.
# ----------------------------------------------------------------------
# AUTHOR:  Mark L. Ulferts             E-mail: mulferts@austin.dsccc.com
#            
# ACKNOWLEDGEMENTS: Michael McLennan   E-mail: mmclennan@lucent.com
#
# This code is an [incr Tk] port of the calendar code shown in Michael 
# J. McLennan's book "Effective Tcl" from Addison Wesley.  Small 
# modificiations were made to the logic here and there to make it a 
# mega-widget and the command and option interface was expanded to make 
# it even more configurable, but the underlying logic is the same.
#
# @(#) $Id: calendar.itk,v 1.1.1.1 2002-01-16 10:24:50 markom Exp $
# ----------------------------------------------------------------------
#            Copyright (c) 1997 DSC Technologies Corporation
# ======================================================================
# Permission to use, copy, modify, distribute and license this software 
# and its documentation for any purpose, and without fee or written 
# agreement with DSC, is hereby granted, provided that the above copyright 
# notice appears in all copies and that both the copyright notice and 
# warranty disclaimer below appear in supporting documentation, and that 
# the names of DSC Technologies Corporation or DSC Communications 
# Corporation not be used in advertising or publicity pertaining to the 
# software without specific, written prior permission.
# 
# DSC DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING 
# ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, AND NON-
# INFRINGEMENT. THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, AND THE
# AUTHORS AND DISTRIBUTORS HAVE NO OBLIGATION TO PROVIDE MAINTENANCE, 
# SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. IN NO EVENT SHALL 
# DSC BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR 
# ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, 
# WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTUOUS ACTION,
# ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 
# SOFTWARE.
# ======================================================================

#
# Usual options.
#
itk::usual Calendar {
    keep -background -cursor 
}

# ------------------------------------------------------------------
#                            CALENDAR
# ------------------------------------------------------------------
class iwidgets::Calendar {
    inherit itk::Widget
    
    constructor {args} {}

    itk_option define -days days Days {Su Mo Tu We Th Fr Sa}
    itk_option define -command command Command {}
    itk_option define -forwardimage forwardImage Image {}
    itk_option define -backwardimage backwardImage Image {}
    itk_option define -weekdaybackground weekdayBackground Background \#d9d9d9
    itk_option define -weekendbackground weekendBackground Background \#d9d9d9
    itk_option define -outline outline Outline \#d9d9d9
    itk_option define -buttonforeground buttonForeground Foreground blue
    itk_option define -foreground foreground Foreground black
    itk_option define -selectcolor selectColor Foreground red
    itk_option define -selectthickness selectThickness SelectThickness 3
    itk_option define -titlefont titleFont Font \
        -*-helvetica-bold-r-normal--*-140-*
    itk_option define -dayfont dayFont Font \
        -*-helvetica-medium-r-normal--*-120-*
    itk_option define -datefont dateFont Font \
        -*-helvetica-medium-r-normal--*-120-*
    itk_option define -currentdatefont currentDateFont Font \
        -*-helvetica-bold-r-normal--*-120-*
    itk_option define -startday startDay Day sunday

    public method get {{format "-string"}} ;# Returns the selected date
    public method select {{date_ "now"}}   ;# Selects date, moving select ring
    public method show {{date_ "now"}}     ;# Displays a specific date

    protected method _drawtext {canvas_ day_ date_ now_ x0_ y0_ x1_ y1_} 

    private method _change {delta_}
    private method _configureHandler {}
    private method _redraw {}
    private method _days {{wmax {}}}
    private method _layout {time_}
    private method _select {date_}
    private method _selectEvent {date_}
    private method _adjustday {day_}
    private method _percentSubst {pattern_ string_ subst_}

    private variable _time {}
    private variable _selected {}
    private variable _initialized 0
    private variable _offset 0
}

#
# Provide a lowercased access method for the Calendar class.
# 
proc ::iwidgets::calendar {pathName args} {
    uplevel ::iwidgets::Calendar $pathName $args
}

#
# Use option database to override default resources of base classes.
#
option add *Calendar.width 200 widgetDefault
option add *Calendar.height 165 widgetDefault

# ------------------------------------------------------------------
#                        CONSTRUCTOR
# ------------------------------------------------------------------
body iwidgets::Calendar::constructor {args} {
    #
    # Create the canvas which displays each page of the calendar.
    #
    itk_component add page {
        canvas $itk_interior.page
    } {
        keep -background -cursor -width -height
    }
    pack $itk_component(page) -expand yes -fill both
    
    #
    # Create the forward and backward buttons.  Rather than pack
    # them directly in the hull, we'll waittill later and make
    # them canvas window items.
    #
    itk_component add backward {
        button $itk_component(page).backward \
                -command [code $this _change -1]
    } {
        keep -background -cursor 
    }

    itk_component add forward {
        button $itk_component(page).forward \
                -command [code $this _change +1]
    } {
        keep -background -cursor 
    }

    #
    # Set the initial time to now.
    #
    set _time [clock seconds]

    # 
    # Bind to the configure event which will be used to redraw
    # the calendar and display the month.
    #
    bind $itk_component(page) <Configure> [code $this _configureHandler]
    
    #
    # Evaluate the option arguments.
    #
    eval itk_initialize $args
}

# ------------------------------------------------------------------
#                             OPTIONS
# ------------------------------------------------------------------

# ------------------------------------------------------------------
# OPTION: -command
#
# Sets the selection command for the calendar.  When the user 
# selects a date on the calendar, the date is substituted in
# place of "%d" in this command, and the command is executed.
# ------------------------------------------------------------------
configbody iwidgets::Calendar::command {}

# ------------------------------------------------------------------
# OPTION: -days
#
# The days option takes a list of values to set the text used to display the 
# days of the week header above the dates.  The default value is 
# {Su Mo Tu We Th Fr Sa}.
# ------------------------------------------------------------------
configbody iwidgets::Calendar::days {
    if {$_initialized} {
        if {[$itk_component(page) find withtag days] != {}} {
            $itk_component(page) delete days
            _days
        }
    }
}

# ------------------------------------------------------------------
# OPTION: -backwardimage
#
# Specifies a image to be displayed on the backwards calendar 
# button.  If none is specified, a default is provided.
# ------------------------------------------------------------------
configbody iwidgets::Calendar::backwardimage {

    #
    # If no image is given, then we'll use the default image.
    #
    if {$itk_option(-backwardimage) == {}} {

        #
        # If the default image hasn't yet been created, then we
        # need to create it.
        #
        if {[lsearch [image names] $this-backward] == -1} {
            image create bitmap $this-backward \
                    -foreground $itk_option(-buttonforeground) -data {
                #define back_width 16
                #define back_height 16
                static unsigned char back_bits[] = {
                    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xc0, 0x30, 
                    0xe0, 0x38, 0xf0, 0x3c, 0xf8, 0x3e, 0xfc, 0x3f, 
                    0xfc, 0x3f, 0xf8, 0x3e, 0xf0, 0x3c, 0xe0, 0x38,
                    0xc0, 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
                }
        }

        #
        # Configure the button to use the default image.
        #
        $itk_component(backward) configure -image $this-backward
        
    #
    # Else, an image has been specified.  First, we'll need to make sure
    # the image really exists before configuring the button to use it.  
    # If it doesn't generate an error.
    #
    } else {
        if {[lsearch [image names] $itk_option(-backwardimage)] != -1} {
            $itk_component(backward) configure \
                    -image $itk_option(-backwardimage)
        } else {
            error "bad image name \"$itk_option(-backwardimage)\":\
                    image does not exist"
        }

        #
        # If we previously created a default image, we'll just remove it.
        #
        if {[lsearch [image names] $this-backward] != -1} {
            image delete $this-backward
        }
    }
}


# ------------------------------------------------------------------
# OPTION: -forwardimage
#
# Specifies a image to be displayed on the forwards calendar 
# button.  If none is specified, a default is provided.
# ------------------------------------------------------------------
configbody iwidgets::Calendar::forwardimage {

    #
    # If no image is given, then we'll use the default image.
    #
    if {$itk_option(-forwardimage) == {}} {

        #
        # If the default image hasn't yet been created, then we
        # need to create it.
        #
        if {[lsearch [image names] $this-forward] == -1} {
            image create bitmap $this-forward \
                    -foreground $itk_option(-buttonforeground) -data {
                #define fwd_width 16
                #define fwd_height 16
                static unsigned char fwd_bits[] = {
                    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0c, 0x03, 
                    0x1c, 0x07, 0x3c, 0x0f, 0x7c, 0x1f, 0xfc, 0x3f, 
                    0xfc, 0x3f, 0x7c, 0x1f, 0x3c, 0x0f, 0x1c, 0x07,
                    0x0c, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
                }
        }

        #
        # Configure the button to use the default image.
        #
        $itk_component(forward) configure -image $this-forward
        
    #
    # Else, an image has been specified.  First, we'll need to make sure
    # the image really exists before configuring the button to use it.  
    # If it doesn't generate an error.
    #
    } else {
        if {[lsearch [image names] $itk_option(-forwardimage)] != -1} {
            $itk_component(forward) configure \
                    -image $itk_option(-forwardimage)
        } else {
            error "bad image name \"$itk_option(-forwardimage)\":\
                    image does not exist"
        }

        #
        # If we previously created a default image, we'll just remove it.
        #
        if {[lsearch [image names] $this-forward] != -1} {
            image delete $this-forward
        }
    }
}

# ------------------------------------------------------------------
# OPTION: -weekdaybackground
#
# Specifies the background for the weekdays which allows it to
# be visually distinguished from the weekend.
# ------------------------------------------------------------------
configbody iwidgets::Calendar::weekdaybackground {
    if {$_initialized} {
        $itk_component(page) itemconfigure weekday \
                -fill $itk_option(-weekdaybackground)
    }
}

# ------------------------------------------------------------------
# OPTION: -weekendbackground
#
# Specifies the background for the weekdays which allows it to
# be visually distinguished from the weekdays.
# ------------------------------------------------------------------
configbody iwidgets::Calendar::weekendbackground {
    if {$_initialized} {
        $itk_component(page) itemconfigure weekend \
                -fill $itk_option(-weekendbackground)
    }
}

# ------------------------------------------------------------------
# OPTION: -foreground
#
# Specifies the foreground color for the textual items, buttons,
# and divider on the calendar.
# ------------------------------------------------------------------
configbody iwidgets::Calendar::foreground {
    if {$_initialized} {
        $itk_component(page) itemconfigure text \
                -fill $itk_option(-foreground)
        $itk_component(page) itemconfigure line \
                -fill $itk_option(-foreground)
    }
}

# ------------------------------------------------------------------
# OPTION: -outline
#
# Specifies the outline color used to surround the date text.
# ------------------------------------------------------------------
configbody iwidgets::Calendar::outline {
    if {$_initialized} {
        $itk_component(page) itemconfigure square \
                -outline $itk_option(-outline)
    }
}

# ------------------------------------------------------------------
# OPTION: -buttonforeground
#
# Specifies the foreground color of the forward and backward buttons.
# ------------------------------------------------------------------
configbody iwidgets::Calendar::buttonforeground {
    if {$_initialized} {
        if {$itk_option(-forwardimage) == {}} {
            if {[lsearch [image names] $this-forward] != -1} {
                $this-forward configure \
                    -foreground $itk_option(-buttonforeground)
            }
        } else {
            $itk_option(-forwardimage) configure \
                    -foreground $itk_option(-buttonforeground)
        }
        
        if {$itk_option(-backwardimage) == {}} {
            if {[lsearch [image names] $this-backward] != -1} {
                $this-backward configure \
                    -foreground $itk_option(-buttonforeground)
            }
        } else {
            $itk_option(-backwardimage) configure \
                    -foreground $itk_option(-buttonforeground)
        }
    }
}

# ------------------------------------------------------------------
# OPTION: -selectcolor
#
# Specifies the color of the ring displayed that distinguishes the 
# currently selected date.  
# ------------------------------------------------------------------
configbody iwidgets::Calendar::selectcolor {
    if {$_initialized} {
        $itk_component(page) itemconfigure $_selected-sensor \
                -outline $itk_option(-selectcolor) 
    }
}

# ------------------------------------------------------------------
# OPTION: -selectthickness
#
# Specifies the thickness of the ring displayed that distinguishes 
# the currently selected date.  
# ------------------------------------------------------------------
configbody iwidgets::Calendar::selectthickness {
    if {$_initialized} {
        $itk_component(page) itemconfigure $_selected-sensor \
                -width $itk_option(-selectthickness) 
    }
}

# ------------------------------------------------------------------
# OPTION: -titlefont
#
# Specifies the font used for the title text that consists of the 
# month and year.
# ------------------------------------------------------------------
configbody iwidgets::Calendar::titlefont {
    if {$_initialized} {
        $itk_component(page) itemconfigure title \
                -font $itk_option(-titlefont)
    }
}

# ------------------------------------------------------------------
# OPTION: -datefont
#
# Specifies the font used for the date text that consists of the 
# day of the month.
# ------------------------------------------------------------------
configbody iwidgets::Calendar::datefont {
    if {$_initialized} {
        $itk_component(page) itemconfigure date \
                -font $itk_option(-datefont)
    }
}

# ------------------------------------------------------------------
# OPTION: -currentdatefont
#
# Specifies the font used for the current date text.
# ------------------------------------------------------------------
configbody iwidgets::Calendar::currentdatefont {
    if {$_initialized} {
        $itk_component(page) itemconfigure now \
                -font $itk_option(-currentdatefont)
    }
}

# ------------------------------------------------------------------
# OPTION: -dayfont
#
# Specifies the font used for the day of the week text.
# ------------------------------------------------------------------
configbody iwidgets::Calendar::dayfont {
    if {$_initialized} {
        $itk_component(page) itemconfigure days \
                -font $itk_option(-dayfont)
    }
}

# ------------------------------------------------------------------
# OPTION: -startday
#
# Specifies the starting day for the week.  The value must be a day of the
# week: sunday, monday, tuesday, wednesday, thursday, friday, or
# saturday.  The default is sunday.
# ------------------------------------------------------------------
configbody iwidgets::Calendar::startday {
    set day [string tolower $itk_option(-startday)]

    switch $day {
        sunday {set _offset 0}
        monday {set _offset 1}
        tuesday {set _offset 2}
        wednesday {set _offset 3}
        thursday {set _offset 4}
        friday {set _offset 5}
        saturday {set _offset 6}
        default {
            error "bad startday option \"$itk_option(-startday)\":\
                   should be sunday, monday, tuesday, wednesday,\
                   thursday, friday, or saturday"
        }
    }

    if {$_initialized} {
        $itk_component(page) delete all-page
        _redraw
    }
}

# ------------------------------------------------------------------
#                            METHODS
# ------------------------------------------------------------------

# ------------------------------------------------------------------
# PUBLIC METHOD: get ?format?
#
# Returns the currently selected date in one of two formats, string 
# or as an integer clock value using the -string and -clicks
# options respectively.  The default is by string.  Reference the 
# clock command for more information on obtaining dates and their 
# formats.
# ------------------------------------------------------------------
body iwidgets::Calendar::get {{format "-string"}} {
    switch -- $format {
        "-string" {
            return $_selected
        }
        "-clicks" {
            return [clock scan $_selected]
        }
        default {
            error "bad format option \"$format\":\
                   should be -string or -clicks"
        }
    }
}

# ------------------------------------------------------------------
# PUBLIC METHOD: select date_
#
# Changes the currently selected date to the value specified.
# ------------------------------------------------------------------
body iwidgets::Calendar::select {{date_ "now"}} {
    if {$date_ == "now"} {
        set time [clock seconds]
    } else {
        if {[catch {clock format $date_}] == 0} {
            set time $date_
        } elseif {[catch {set time [clock scan $date_]}] != 0} {
            error "bad date: \"$date_\", must be a valid date string, clock clicks value or the keyword now"
        }
    }

    _select [clock format $time -format "%m/%d/%Y"]
}

# ------------------------------------------------------------------
# PUBLIC METHOD: show date_
#
# Changes the currently display month to be that of the specified 
# date.
# ------------------------------------------------------------------
body iwidgets::Calendar::show {{date_ "now"}} {
    if {$date_ == "now"} {
        set _time [clock seconds]
    } else {
        if {[catch {clock format $date_}] == 0} {
            set _time $date_
        } elseif {[catch {set _time [clock scan $date_]}] != 0} {
            error "bad date: \"$date_\", must be a valid date string, clock clicks value or the keyword now"
        }
    }

    $itk_component(page) delete all-page
    _redraw
}

# ------------------------------------------------------------------
# PROTECTED METHOD: _drawtext canvas_ day_ date_ now_
#                             x0_ y0_ x1_ y1_
#
# Draws the text in the date square.  The method is protected such that
# it can be overridden in derived classes that may wish to add their
# own unique text.  The method receives the day to draw along with
# the coordinates of the square.
# ------------------------------------------------------------------
body iwidgets::Calendar::_drawtext {canvas_ day_ date_ now_ x0_ y0_ x1_ y1_} {
    set item [$canvas_ create text \
                  [expr (($x1_ - $x0_) / 2) + $x0_] \
                  [expr (($y1_ -$y0_) / 2) + $y0_ + 1] \
                  -anchor center -text "$day_" \
                  -fill $itk_option(-foreground)]

    if {$date_ == $now_} {
        $canvas_ itemconfigure $item \
            -font $itk_option(-currentdatefont) \
            -tags [list all-page date text now]
    } else {
        $canvas_ itemconfigure $item \
            -font $itk_option(-datefont) \
            -tags [list all-page date text]
    }
}

# ------------------------------------------------------------------
# PRIVATE METHOD: _configureHandler
#
# Processes a configure event received on the canvas.  The method
# deletes all the current canvas items and forces a redraw.
# ------------------------------------------------------------------
body iwidgets::Calendar::_configureHandler {} {
    set _initialized 1

    $itk_component(page) delete all
    _redraw
}

# ------------------------------------------------------------------
# PRIVATE METHOD: _change delta_
#
# Changes the current month displayed in the calendar, moving
# forward or backward by <delta_> months where <delta_> is +/-
# some number.
# ------------------------------------------------------------------
body iwidgets::Calendar::_change {delta_} {
    set dir [expr ($delta_ > 0) ? 1 : -1]
    set month [clock format $_time -format "%m"]
    set month [string trimleft $month 0]
    set year [clock format $_time -format "%Y"]

    for {set i 0} {$i < abs($delta_)} {incr i} {
        incr month $dir
        if {$month < 1} {
            set month 12
            incr year -1
        } elseif {$month > 12} {
            set month 1
            incr year 1
        }
    }
    if {[catch {set _time [clock scan "$month/1/$year"]}]} {
        bell
    } else {
        _redraw 
    }
}

# ------------------------------------------------------------------
# PRIVATE METHOD: _redraw
#
# Redraws the calendar.  This method is invoked whenever the 
# calendar changes size or we need to effect a change such as draw
# it with a new month.
# ------------------------------------------------------------------
body iwidgets::Calendar::_redraw {} {
    #
    # Remove all the items that typically change per redraw request
    # such as the title and dates.  Also, get the maximum width and
    # height of the page.
    #
    $itk_component(page) delete all-page

    set wmax [winfo width $itk_component(page)]
    set hmax [winfo height $itk_component(page)]

    #
    # If we haven't yet created the forward and backwards buttons,
    # then dot it; otherwise, skip it.
    #
    if {[$itk_component(page) find withtag button] == {}} {
        $itk_component(page) create window 3 3 -anchor nw \
                -window $itk_component(backward) -tags button
        $itk_component(page) create window [expr $wmax-3] 3 -anchor ne \
                -window $itk_component(forward) -tags button
    }

    #
    # Create the title centered between the buttons.
    #
    foreach {x0 y0 x1 y1} [$itk_component(page) bbox button] {
        set x [expr (($x1-$x0)/2)+$x0]
        set y [expr (($y1-$y0)/2)+$y0]
    }

    set title [clock format $_time -format "%B %Y"]
    $itk_component(page) create text $x $y -anchor center \
        -text $title -font $itk_option(-titlefont) \
        -fill $itk_option(-foreground) \
        -tags [list title text all-page]

    #
    # Add the days of the week labels if they haven't yet been created.
    #
    if {[$itk_component(page) find withtag days] == {}} {
        _days $wmax
    }

    #
    # Add a line between the calendar header and the dates if needed.
    #
    set bottom [expr [lindex [$itk_component(page) bbox all] 3] + 3]

    if {[$itk_component(page) find withtag line] == {}} {
        $itk_component(page) create line 0 $bottom $wmax $bottom \
                -width 2 -tags line
    }

    incr bottom 3

    #
    # Get the layout for the time value and create the date squares.
    # This includes the surrounding date rectangle, the date text,
    # and the sensor.  Bind selection to the sensor.
    #
    set current ""
    set now [clock format [clock seconds] -format "%m/%d/%Y"]

    set layout [_layout $_time]
    set weeks [expr [lindex $layout end] + 1]

    foreach {day date kind dcol wrow} $layout {
        set x0 [expr $dcol*($wmax-7)/7+3]
        set y0 [expr $wrow*($hmax-$bottom-4)/$weeks+$bottom]
        set x1 [expr ($dcol+1)*($wmax-7)/7+3]
        set y1 [expr ($wrow+1)*($hmax-$bottom-4)/$weeks+$bottom]

        if {$date == $_selected} {
            set current $date
        }

        #
        # Create the rectangle that surrounds the date and configure
        # its background based on the wheather it is a weekday or
        # a weekend.
        #
        set item [$itk_component(page) create rectangle $x0 $y0 $x1 $y1 \
                -outline $itk_option(-outline)]

        if {$kind == "weekend"} {
            $itk_component(page) itemconfigure $item \
                    -fill $itk_option(-weekendbackground) \
                    -tags [list all-page square weekend]
        } else {
            $itk_component(page) itemconfigure $item \
                    -fill $itk_option(-weekdaybackground) \
                    -tags [list all-page square weekday]
        }

        #
        # Create the date text and configure its font based on the 
        # wheather or not it is the current date.
        #
        _drawtext $itk_component(page) $day $date $now $x0 $y0 $x1 $y1

        #
        # Create a sensor area to detect selections.  Bind the 
        # sensor and pass the date to the bind script.
        #
        $itk_component(page) create rectangle $x0 $y0 $x1 $y1 \
            -outline "" -fill "" \
            -tags [list $date-sensor all-sensor all-page]

        $itk_component(page) bind $date-sensor <ButtonPress-1> \
            [code $this _selectEvent $date]
    }

    #
    # Highlight the selected date if it is on this page.
    #
    if {$current != ""} {
        $itk_component(page) itemconfigure $current-sensor \
            -outline $itk_option(-selectcolor) \
            -width $itk_option(-selectthickness)

        $itk_component(page) raise $current-sensor

    } elseif {$_selected == ""} {
        set date [clock format $_time -format "%m/%d/%Y"]
        _select $date
    }
}

# ------------------------------------------------------------------
# PRIVATE METHOD: _days
#
# Used to rewite the days of the week label just below the month 
# title string.  The days are given in the -days option.
# ------------------------------------------------------------------
body iwidgets::Calendar::_days {{wmax {}}} {
    if {$wmax == {}} {
        set wmax [winfo width $itk_component(page)]
    }

    set col 0
    set bottom [expr [lindex [$itk_component(page) bbox title buttons] 3] + 7]

    foreach dayoweek $itk_option(-days) {
        set x0 [expr $col*($wmax/7)]
        set x1 [expr ($col+1)*($wmax/7)]

        $itk_component(page) create text \
            [expr (($x1 - $x0) / 2) + $x0] $bottom \
            -anchor n -text "$dayoweek" \
            -fill $itk_option(-foreground) \
            -font $itk_option(-dayfont) \
            -tags [list days text]

        incr col
    }
}

# ------------------------------------------------------------------
# PRIVATE METHOD: _layout time_
#
# Used whenever the calendar is redrawn.  Finds the month containing
# a <time_> in seconds, and returns a list for all of the days in 
# that month.  The list looks like this:
#
#    {day1 date1 kind1 c1 r1  day2 date2 kind2 c2 r2  ...}
#
# where dayN is a day number like 1,2,3,..., dateN is the date for
# dayN, kindN is the day type of weekday or weekend, and cN,rN 
# are the column/row indices for the square containing that date.
# ------------------------------------------------------------------
body iwidgets::Calendar::_layout {time_} {
    set month [clock format $time_ -format "%m"]
    set year  [clock format $time_ -format "%Y"]

    foreach lastday {31 30 29 28} {
        if {[catch {clock scan "$month/$lastday/$year"}] == 0} {
            break
        }
    }
    set seconds [clock scan "$month/1/$year"]
    set firstday [_adjustday [clock format $seconds -format %w]]

    set weeks [expr ceil(double($lastday+$firstday)/7)]

    set rlist ""
    for {set day 1} {$day <= $lastday} {incr day} {
        set seconds [clock scan "$month/$day/$year"]
        set date [clock format $seconds -format "%m/%d/%Y"]
        set dayoweek [clock format $seconds -format %w]

        if {$dayoweek == 0 || $dayoweek == 6} {
            set kind "weekend"
        } else {
            set kind "weekday"
        }

        set daycol [_adjustday $dayoweek]

        set weekrow [expr ($firstday+$day-1)/7]
        lappend rlist $day $date $kind $daycol $weekrow 
    }
    return $rlist
}

# ------------------------------------------------------------------
# PRIVATE METHOD: _adjustday day_
#
# Modifies the day to be in accordance with the startday option.
# ------------------------------------------------------------------
body iwidgets::Calendar::_adjustday {day_} {
    set retday [expr $day_ - $_offset]

    if {$retday < 0} {
        set retday [expr $retday + 7]
    }

    return $retday
}

# ------------------------------------------------------------------
# PRIVATE METHOD: _select date_
#
# Selects the current <date_> on the calendar.  Highlights the date 
# on the calendar, and executes the command associated with the 
# calendar, with the selected date substituted in place of "%d".
# ------------------------------------------------------------------
body iwidgets::Calendar::_select {date_} {
    set time [clock scan $date_]
    set date [clock format $time -format "%m/%d/%Y"]

    set _selected $date

    set current [clock format $_time -format "%m %Y"]
    set selected [clock format $time -format "%m %Y"]

    if {$current == $selected} {
        $itk_component(page) itemconfigure all-sensor \
            -outline "" -width 1

        $itk_component(page) itemconfigure $date-sensor \
            -outline $itk_option(-selectcolor) \
            -width $itk_option(-selectthickness)
        $itk_component(page) raise $date-sensor
    } else {
        set $_time $time
        _redraw 
    }
}

# ------------------------------------------------------------------
# PRIVATE METHOD: _selectEvent date_
#
# Selects the current <date_> on the calendar.  Highlights the date 
# on the calendar, and executes the command associated with the 
# calendar, with the selected date substituted in place of "%d".
# ------------------------------------------------------------------
body iwidgets::Calendar::_selectEvent {date_} {
    _select $date_

    if {[string trim $itk_option(-command)] != ""} {
        set cmd $itk_option(-command)
        set cmd [_percentSubst %d $cmd [get]]
        uplevel #0 $cmd
    }
}

# ------------------------------------------------------------------
# PRIVATE METHOD: _percentSubst pattern_ string_ subst_
#
# This command is a "safe" version of regsub, for substituting
# each occurance of <%pattern_> in <string_> with <subst_>.  The
# usual Tcl "regsub" command does the same thing, but also
# converts characters like "&" and "\0", "\1", etc. that may
# be present in the <subst_> string.
#
# Returns <string_> with <subst_> substituted in place of each
# <%pattern_>.
# ------------------------------------------------------------------
body iwidgets::Calendar::_percentSubst {pattern_ string_ subst_} {
    if {![string match %* $pattern_]} {
        error "bad pattern \"$pattern_\": should be %something"
    }

    set rval ""
    while {[regexp "(.*)${pattern_}(.*)" $string_ all head tail]} {
        set rval "$subst_$tail$rval"
        set string_ $head
    }
    set rval "$string_$rval"
}