How can I automatically block out “free time” in an org-agenda view?

Question

Was just thinking. I've noticed a lot of people schedule their free time in to their agendas/planners.

I think it would be useful to automatically schedule out free time when opening the agenda. For example, if I have schedule tennis practice, and a meeting, my current agenda would like like this:

8:00-10:00 Scheduled: Tennis Practice

16:30-18:00 Meeting

Whereas, it could look like this:

8:00-10:00 Scheduled: Tennis Practice

10:00-16:30 Free

16:30-18:00 Scheduled: Meeeting

18:00-20:00 Free

...without having to schedule to free time explicitly.

To me, this is a lot easier to comprehend than the above time graph, particularly since I find looking at my watch more useful than the time grid.

How can I do this?

Answer 1

This does not quite reproduce what you want, but it's close.

Try setting org-agenda-use-time-grid to t. That will show you a time grid like this:

  Weather:     6:34...... Sunrise 
               8:00...... ----------------
              10:00...... ----------------
              12:00...... ----------------
              14:00...... ----------------
              16:00...... ----------------
              18:00...... ----------------
  Weather:    18:37...... Sunset 
              20:00...... ----------------

Then check out the variable org-agenda-time-grid. Its doc string says:

org-agenda-time-grid is a variable defined in ‘org-agenda.el’.
Its value is
((daily today require-timed)
 (800 1000 1200 1400 1600 1800 2000)
 "......" "----------------")

  You can customize this variable.

Documentation:
The settings for time grid for agenda display.
This is a list of four items.  The first item is again a list.  It contains
symbols specifying conditions when the grid should be displayed:

 daily         if the agenda shows a single day
 weekly        if the agenda shows an entire week
 today         show grid on current date, independent of daily/weekly display
 require-timed show grid only if at least one item has a time specification
 remove-match  skip grid times already present in an entry

The second item is a list of integers, indicating the times that
should have a grid line.

The third item is a string which will be placed right after the
times that have a grid line.

The fourth item is a string placed after the grid times.  This
will align with agenda items.

So changing the fourth item (or not: you might leave it as a bunch of dashes) should do what you want:

  (setq org-agenda-use-time-grid t)
  (setq org-agenda-time-grid '((daily today require-timed)
                               (800 1000 1200 1400 1600 1800 2000)
                               "......" "----Free----"))

What this does not do is coalesce a range of free times into one. I think that would require substantial changes in the code.