[aprssig] Symbol set revisions

Heikki Hannikainen hessu at hes.iki.fi
Thu Apr 17 03:21:43 EDT 2008

   Hi everyone,

Stephen H. Smith wrote:
> 3)     Decreeing new symbols is not a trivial task.

   It's a very large task, especially since every application uses it's own 
file formats for mapping the symbol characters to the respective images, 
and each application requires it's own image formats, too. I'm not sure, 
but it seems to me that it requires plenty of manual work from someone to 
update each and every application to support a new symbol set. I know it's 
a large pain for me to fix aprs.fi to support a new modified set. Lots of 
manual work.

   And I'm not exactly sure which source should I trust to be *the* 
definitive standard for current symbols. Is it Bob's symbolsX.txt, or 
should I look at what other applications are actually using? For now, I'm 
inclined to go for most compatibility with others.

   I don't personally care so much about the contents of the symbol set. 
But I think it's not wise to modify it every year, because that way the 
symbol sets in applications will never be synchronized. Even if the 
applications would be updated, the users will not be upgrading a working 
installation of an application (unless the application automagically makes 
it really easy or unavoidable, like modern Linux and Windows versions 

   If it is modified, it should be made as easy as possible for everyone to 
update their applications. This requires two technical things:

   1) A machine-readable configuration file, which has an extendable and 
parseable format, which will not require changing the configuration file 
format when new attributes are added. symbolsX.txt is as far as possible 
from this. symbols.ini is slightly better, but not extendable, and it 
relies on "magic" prefix strings in the descriptions, and you cannot have 
a ',' in the description. There are good formats out there. XML is one but 
not necessarily the most lightweight one. symbols.ini is close to CSV but 
not quite extendable.

   2) A single standard source for the symbol images, so that everyone 
doesn't need to draw their own. The standard config file should clearly 
point to the symbol images in a clearly defined way. The images should be 
in a format which is easy to convert to the formats used by each 
application, and be of sufficient quality for everyone to use. They should 
have consistent transparency, for one (transparent color per symbol image 
file, or an alpha channel). The symbol image files should be downloadable 
from a single place, as a single archive file (zip?) containing the images 
in a standardized file structure / directory tree, *and* the 
configuration file which maps each image to the symbol table/character.

   I'd be happy to put in updated symbols every 3 months, but only if I 
wouldn't have to manually figure out which symbols have changed, and where 
can I find the new images, and what I need to do to convert them to an 
usable format.

   If the symbol images + configuration format would be standardized well, 
and stored in a good static place on the web (always the same URL, not 
some person's home directory, but maybe TAPR's web or something) it would 
be possible for each application to download an updated set and install it 
automatically for the user. Much like the current satellite tracking 
software downloads kepler files from somewhere and installs them without 
bothering the user. It'd even be possible to write an ui-view addon to do 

> The alpha-numeric overlay character assignments (recently discussed on this 
> list)  are even more of a problem.   The only Windows application that even 
> renders overlay characters is UI-View.

   I'd like to implement them in the aprs.fi service, but for browser 
performance reasons I'll have to pre-render all the overlay characters on 
top of the symbol images, and on top of the pre-rendered *rotated* symbol 
icons too (applicable only for symbols which are rotatable). If it would 
be possible to automate importing new symbol sets, I'd be happy to 
automate the overlay rendering, too.

   - Hessu, OH7LZB

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