Re: [gpsd-users] Create an SVG skyview image from JSON data

[Niccolo Rigacci]

Hi Gary!

I made some changes to the script! This is a resumee.

With your suggestion, now it runs also with Python3.

Now the program can run in pipe with gpspipe, as documented into 
the first lines of docstring.

Now I get no complaint from pycodestyle nor pylint, EXCEPT for 
the "line-too-long". I think that leaving that long lines is 
compliant with PEP 8, (paragraph #2, point #1), because "applying 
the guideline would make the code less readable". There are many 
literal strings that are theirself over 80 chars: is there a 
trick to break them without loosing readability?

I sorted the satellite bar char by PRN.

You said that "Signal Strength" is flat wrong, because it is 
actually a Signal/Noise Ratio: yes, you are right! But I'm 
preparing the SVG for non-expert people, which ignores the SNR 
meaning. I supposed that "signal strengt" was an acceptable 
approssimation, considering alsto that the JSON key is "ss" and 
it is referred as "Signal strength in dB" in the doc 
(http://www.catb.org/gpsd/gpsd_json.html).

Also you said that "horizontal precision" is wrong, it is DOP! 
Actually the displayed bars are not DOP ("less is better"), but 
somewhat the inverse: a cutted-off value between a max and a min. 
Can we call it "concentration" of precision? I had non-expert 
people in mind, which understand "more is better". The 
"precision" bars in my SGV are a simple "long bars = good, short 
bars = evil", no unit of measure required.

About your question about the SVG viewer: it seems that in the 
GNU/Linux world there are two main families: Imagemagick's 
convert uses the library modules-Q16/coders/svg.so (installed by 
the libmagickcore-6.q16-3-extra Debian packages), other tools 
uses the librsvg2 library (installed by the librsvg2-bin Debian 
package). Programs that uses the latter are rsvg-convert, Gimp, 
Geeqie, etc. It turned out that the librsvg2 has a bug with 
multiple (chained) CSS class selectors, see 
https://bugzilla.gnome.org/show_bug.cgi?id=702537.
So I changed my script a bit, to circumvent this bug. Now I can 
watch the produced SVG graphics with both families of tools.

I attach the new version of the script and a new SVG produced.

Thanks again for your time!

-- 
Niccolo Rigacci - http://www.rigacci.net/
Campi Bisenzio - Firenze - Italy
Tel. Mobile: +39-327-5619352

skyview2svg.gz
Description: application/gzip

skyview.svg.gz
Description: application/gzip