[pdf-devel] Re: Calendar spans

[Aleksander Morgado]

>    > The base date to resolve the span should be the specified point of
>    > time contained in OBJECT (would be better to name it TIME_OBJECT). In
>    > other case the function doesnt have sense at all! This should be
>    > documented in the Refman. entry for the function.
>
>    But even if the time origin is fixed, I see a problem: not all the 
>    months have the same number of days ( who the hell decided this? ). So 
>    if for example the time object represents January 31st and I want to add 
>    1 month coming in the calendar span... which would be the resulting 
>    date? February 28th/29th? March 1st? The same problem happens with years 
>    if the time object is 29th February and you want to add 1 year in the 
>    calendar span... which would be the resulting date?
>
> Maybe I dont understand the issue, but the calculation of the lenght
> of months is deterministic: you only need to determine if the year of
> the time object is a leap one.
>
> Or I missing something?

Yes, the number of days in a month can be easily computed. But which 
would be the result of the following situation?



pdf_time_t my_time;
struct pdf_time_cal_span_s cal_span;


/* Setting epoch as January 31st 2007 */
pdf_time_from_string(my_time,
                     "2007-01-31T00:00:00+00:00",
                     PDF_TIME_FORMAT_ISO_8601);

/* Setting calendar span as +1 month +1 year */
cal_span.sign = 0; /* add */
cal_span.years = 1;
cal_span.months = 1;
cal_span.days = 0;
cal_span.hours = 0;
cal_span.minutes = 0;
cal_span.seconds = 0;

/* Add calendar span to time object */
pdf_time_add_cal_span(my_time, cal_span);



/* Now... which should be the resulting date in my_time?
 * Hint: 2008 is also leap year :-) */

The problem is that the result cannot be February 31st. So which would 
be the resulting epoch?