From: Todd Benson <caduceass@...>
Date: 2008-03-04T04:02:32+09:00
Subject: Re: making a monthly calendar...

On Mon, Mar 3, 2008 at 2:05 AM, Mikkel Bruun <mikkel@helenius.dk> wrote:
> So I ended up with:
>
>  def calendar_view
>     firstday = days[0] #all days in month
>     offset = firstday.wday-1
>     boxes =Array.new(5*7) # the viewport
>     i=0
>     #this month from wday of firstday
>     offset.upto(days.length+offset){boxes[offset+i]=days[i];i=i+1}
>     i=0
>     #pad with previous
>     1.upto(offset){boxes[i]=previous.days[-offset+i];i=i+1}
>     i=0
>     #pad with next...
>     (offset+days.length).upto(boxes.length){boxes[days.length+i+offset]=next_month.days[i];i=i+1}
>      return boxes
>   end
>
>  I show this in a rails app using array.groups_of(7) which chops the
>  boxes array into parts of 7
>
>  which works ok...untill i hit june 08....where the first week starts
>  with jun 2nd...
>
>  How are your algorithms working??

You can use my code (with the correction in my last post), and omit
the each_slice part (you do want one big array right?).

To explain what I was doing in a different way,  I build three arrays
with the correct number of days in each, centered around the current
month (that's why I add -1, 0, and 1 to the current month number).  I
use (didn't with the first code, sorry) the first day of the current
month as the offset.  I build ranges after I get the month numbers,
then build arrays off those ranges.  So I have a single array of three
arrays.  When I #pop off the first array and #unshift _onto_ the
second array, it moves the last day number of the previous month array
onto the first day of the current month array; sort of what you are
doing by hand.  I do this offset number of times using the #times
method.  Then I flatten (the weird current month array rolled into the
next month array -- the use of the 1..2 range).  I used each_slice for
display, but, obviously, you won't have to do that, because you have
#groups_of.  Just flatten and slice.

In any case, google calendar uses a 7 x 7 grid.  I would recommend at
least a 7 x 6 grid for reasons I pointed out earlier.  When you
display March, for example, you will only go up to 29 with 7 x 5.

Here's the script code without the previous comments, and
surreptitiously using a 7 x 6 grid (I still would code this
differently by separating out into methods, and also probably a Month
and/or Calendar class)...

today = Date.today #use whatever date you want
offset = Date.new(today.year, today.month, 1).wday
# ^^^^^^ that was the line I screwed up at first
months_of_concern = (-1..1).inject([]) {|a, i| a << (today.month + i)}
month_ranges = months_of_concern.map {|month| 1..Date.new( today.year,
month, -1 ).day}
day_sets = month_ranges.map {|i| i.map}
offset.times {day_sets[1].unshift day_sets[0].pop}
p day_sets[1..2].flatten.slice(0..42)

Todd