Re: Patch that enables visibility settings in org-mode iCalendar export

[Eric Abrahamsen <eric@ericabrahamsen.net>]

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Nicolas Goaziou <mail@nicolasgoaziou.fr> writes:

> Hello,
>
> Tobias Schlemmer <keinstein.junior@gmail.com> writes:
>
>> for some reasons I need to control the visibility of individual entries
>> of my caldav calendars. I have implemented a small patch that passes the
>> `CLASS' propery to the iCalendar export:
>>
>> https://github.com/keinstein/org-mode/pull/1
>>
>> I'd like to have this patch integrated in the short term. It is mostly
>> done by cut and paste from the same file.
>
> Thank you!
>
> Could you send a patch on this mailing list using git's "format-patch"
> sub-command?
>
> Also, could you document the feature in org.texi.
>
>> For long term I think a configurable framework would be more useful:
>>
>> • It would be helpful to have a configuration variable that tells which
>> properties are passed more or less verbatim as iCalendar fields
>
> This doesn't sound too hard, if you have a list of such properties and
> are willing to document them.

Hey, now's the time to bring up something I've wanted to do for a while:
adding support for per-entry timezones to the ical export. I've attached
a draft patch that shows what I mean. Basically you give an entry a
TIMEZONE property in the tz database format (eg "Europe/London") and it
will pass that on to the DTSTART/DTEND properties.

I suppose it would also be possible to have separate properties for
start and end timezones, then we could do plane trips!

Further work would be necessary to pass this through org-caldav
correctly, but it's a first step.

If this works out, I'll do a proper commit with docs and all that.

Eric


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diff --git a/lisp/ox-icalendar.el b/lisp/ox-icalendar.el
index ba7a62f8b..a955469b5 100644
--- a/lisp/ox-icalendar.el
+++ b/lisp/ox-icalendar.el
@@ -341,7 +341,7 @@ A headline is blocked when either
 		   (1- (length org-icalendar-date-time-format))) ?Z))
 
 (defvar org-agenda-default-appointment-duration) ; From org-agenda.el.
-(defun org-icalendar-convert-timestamp (timestamp keyword &optional end utc)
+(defun org-icalendar-convert-timestamp (timestamp keyword &optional end tz)
   "Convert TIMESTAMP to iCalendar format.
 
 TIMESTAMP is a timestamp object.  KEYWORD is added in front of
@@ -352,8 +352,11 @@ Also increase the hour by two (if time string contains a time),
 or the day by one (if it does not contain a time) when no
 explicit ending time is specified.
 
-When optional argument UTC is non-nil, time will be expressed in
-Universal Time, ignoring `org-icalendar-date-time-format'."
+When optional argument TZ is non-nil, timezone data time will be
+added to the timestamp.  It can be the string \"UTC\", to use UTC
+time, or a string in the IANA TZ database
+format (e.g. \"Europe/London\").  In either case, the value of
+`org-icalendar-date-time-format' will be ignored."
   (let* ((year-start (org-element-property :year-start timestamp))
 	 (year-end (org-element-property :year-end timestamp))
 	 (month-start (org-element-property :month-start timestamp))
@@ -387,8 +390,9 @@ Universal Time, ignoring `org-icalendar-date-time-format'."
     (concat
      keyword
      (format-time-string
-      (cond (utc ":%Y%m%dT%H%M%SZ")
+      (cond ((string-equal tz "UTC") ":%Y%m%dT%H%M%SZ")
 	    ((not with-time-p) ";VALUE=DATE:%Y%m%d")
+	    ((stringp tz) (concat ";TZID=" tz ":%Y%m%dT%H%M%S"))
 	    (t (replace-regexp-in-string "%Z"
 					 org-icalendar-timezone
 					 org-icalendar-date-time-format
@@ -396,7 +400,10 @@ Universal Time, ignoring `org-icalendar-date-time-format'."
       ;; Convert timestamp into internal time in order to use
       ;; `format-time-string' and fix any mistake (i.e. MI >= 60).
       (encode-time 0 mi h d m y)
-      (and (or utc (and with-time-p (org-icalendar-use-UTC-date-time-p)))
+      (and (or (string-equal tz "UTC")
+	       (and (null tz)
+		    with-time-p
+		    (org-icalendar-use-UTC-date-time-p)))
 	   t)))))
 
 (defun org-icalendar-dtstamp ()
@@ -545,7 +552,8 @@ inlinetask within the section."
 			  contents 0 (min (length contents)
 					  org-icalendar-include-body))))
 		      (org-icalendar-include-body (org-trim contents)))))))
-	     (cat (org-icalendar-get-categories entry info)))
+	     (cat (org-icalendar-get-categories entry info))
+	     (tz (org-element-property :TIMEZONE entry)))
 	 (concat
 	  ;; Events: Delegate to `org-icalendar--vevent' to generate
 	  ;; "VEVENT" component from scheduled, deadline, or any
@@ -556,14 +564,14 @@ inlinetask within the section."
 		       org-icalendar-use-deadline)
 		 (org-icalendar--vevent
 		  entry deadline (concat "DL-" uid)
-		  (concat "DL: " summary) loc desc cat)))
+		  (concat "DL: " summary) loc desc cat tz)))
 	  (let ((scheduled (org-element-property :scheduled entry)))
 	    (and scheduled
 		 (memq (if todo-type 'event-if-todo 'event-if-not-todo)
 		       org-icalendar-use-scheduled)
 		 (org-icalendar--vevent
 		  entry scheduled (concat "SC-" uid)
-		  (concat "S: " summary) loc desc cat)))
+		  (concat "S: " summary) loc desc cat tz)))
 	  ;; When collecting plain timestamps from a headline and its
 	  ;; title, skip inlinetasks since collection will happen once
 	  ;; ENTRY is one of them.
@@ -581,7 +589,7 @@ inlinetask within the section."
 			   ((t) t)))
 		   (let ((uid (format "TS%d-%s" (cl-incf counter) uid)))
 		     (org-icalendar--vevent
-		      entry ts uid summary loc desc cat))))
+		      entry ts uid summary loc desc cat tz))))
 	       info nil (and (eq type 'headline) 'inlinetask))
 	     ""))
 	  ;; Task: First check if it is appropriate to export it.  If
@@ -626,7 +634,7 @@ inlinetask within the section."
        contents))))
 
 (defun org-icalendar--vevent
-    (entry timestamp uid summary location description categories)
+    (entry timestamp uid summary location description categories timezone)
   "Create a VEVENT component.
 
 ENTRY is either a headline or an inlinetask element.  TIMESTAMP
@@ -635,7 +643,8 @@ is the unique identifier for the event.  SUMMARY defines a short
 summary or subject for the event.  LOCATION defines the intended
 venue for the event.  DESCRIPTION provides the complete
 description of the event.  CATEGORIES defines the categories the
-event belongs to.
+event belongs to.  If TIMEZONE is non-nil, use the specified
+timezone for this event only.
 
 Return VEVENT component as a string."
   (org-icalendar-fold-string
@@ -645,8 +654,8 @@ Return VEVENT component as a string."
      (concat "BEGIN:VEVENT\n"
 	     (org-icalendar-dtstamp) "\n"
 	     "UID:" uid "\n"
-	     (org-icalendar-convert-timestamp timestamp "DTSTART") "\n"
-	     (org-icalendar-convert-timestamp timestamp "DTEND" t) "\n"
+	     (org-icalendar-convert-timestamp timestamp "DTSTART" nil timezone) "\n"
+	     (org-icalendar-convert-timestamp timestamp "DTEND" t timezone) "\n"
 	     ;; RRULE.
 	     (when (org-element-property :repeater-type timestamp)
 	       (format "RRULE:FREQ=%s;INTERVAL=%d\n"