KPropertiesDialog. Useful graph ?

[David Faure]

On Thursday 24 April 2008, Rafael Fernández López wrote:
> Hi all,
> 
> Some time ago, I wrote a simple class for drawing simple pie charts. I was 
> quickly helped out by somebody that wanted to improve it with painter paths. 
> After his patches, I worked on it for fixing small problems, and almost 
> finishing it.
> 
> Now, I added it experimentally to KPropertiesDialog, and I was wondering what 
> you think of that.
> 
> Before entering on any patch details (for that reason I am not posting it for 
> now). Do you think this would be good to have ?

This is just my opinion as a user, not as the maybe-maintainer-of-kpropertiesdialog...

What is the real reason for having such a pie, except copying MS Windows?
Personally I find this kind of graph completely useless. A percentage gives the exact
same information -- and has exactly the same problem: if you have a very large
partition then "5% free" (an "almost fully red pie") is probably plenty enough for what
you're going to do next on that volume, while if you have a very small partition
then "25% free" might not be enough for what you're going to add to the partition,
even though the pie will look much greener (in terms of your colorscheme).

I have seen that problem at home often - my wife keeps an eye on the partition where
we record TV, but "95% full" makes her think we're near catastrophy.... however this
completely depends on the size of the disks; before I added the last disk it was indeed
a near-catastrophy, while now it's perfectly fine and many hours of recording can still
fit....

Same problem if you compare two partitions to see where you have most space
for storing something: you'll pick the "greenest pie", but that might be the one
with the smallest amount of free space, since it's all relative to the partition size.
(So if you tell me just look at the partition size, we might as well get rid
of the pie completely, the disk space is available as a number too :)

To get a good GUI for this is difficult, but what about this idea:
It would be more useful to define a unit (say 100 MB in your case, but for larger
partitions it would have to be something else, maybe with a different color)
and show square blocks of that unit representing the free space. 
14 green blocks shown, in your case. [Hmm, maybe showing "red" blocks is useful too
(to see how much room one could make by deleting files), but in my initial
idea we would only see blocks of free space....]
So that if I want to put a "5 blocks" (500MB) file onto a partition that has "6 blocks free",
I know (graphically, even if I'm a user who is not good at all this size-prefix stuff)
that it will fit. Or if I want to check my TV-recording partition I can just check
that there is at least a few 5 GB blocks in the "free space" GUI. This way it doesn't
depend on the size of the partition, it's absolute information rather than relative.


Just my 2 cents.

-- 
David Faure, faure at kde.org, sponsored by Trolltech to work on KDE,
Konqueror (http://www.konqueror.org), and KOffice (http://www.koffice.org).