[FOSS-GPS] Tango/Foxtrot GPS - Plotting locations of multiple things

[Guilhem Bonnefille]

Hi,

2011/4/26 Ben McCarthy <b.mccarthy at lancaster.ac.uk>:
> I want to develop a mapping interface that can plot my own location plus the
> location of others (where the location of others is transmitted directly
> between one another, not via a central server).
>
>
>
> To do this I searched around and came across TangoGPS, I changed the
> interface a bit and added the new functionality I required (by adapting the
> “Friends” functionality, cutting out the Curl code and replacing it with
> some socket code). After doing this, I came across an email thread that lead
> me to find out about the problems that lead to the creation of FoxtrotGPS.
>
>
>
> I was looking around because I have hit a stumbling block. Whenever I update
> the location of a different person it redraws the chosen icon in a new
> location, but doesn’t remove the existing icon from the previous location.
> The icons representing the previous locations aren’t removed unless the map
> is physically dragged using a left mouse click. I need the new location of a
> person to be updated and the previous location to be removed immediately as
> soon as new coordinates are received via the respective socket. Using my
> limited understanding of GTK+ I have not been able to achieve this after
> trying for quite some time.
>
>
>
> So this has lead me to look around, and at the same time I have come across
> osm-gps-map too, which looks potentially very useful for what I want to do.
> I dl’d the source, compiled and ran the example... I then tried integrating
> some of the osm-gps-map functionality into my own application, but ran into
> problems during compilation. I have however seen some other emails
> suggesting FoxtrotGPS may already have integrated with osm-gps-map in some
> way, is that correct?
>
>
>
> ...So before continuing it seemed like a good time to take stock. For what I
> want to achieve, I’m trying to determine whether I am best:
>
> 1) Sticking with what I have and trying to solve the icon redrawing problem.
>
> 2) Trying to invest some more time into integrating osm-gps-map into what I
> have.
>
> 3) Throwing out my interface changes and migrating to FoxtrotGPS (in which
> case I’d need to learn about how to work with the XML UI).
>
>
>
> I’d be really grateful if any of you guys could give me your opinion on any
> of this.

It's quite hard to help you, particularly for (1), without more
details. Do you have any code published somewhere?

For the matter you spotted, there is generally two options:
- you use a sort of canvas API, where you only handle high level
object, and graphics is done by the associated code;
- you directly handle graphics, so you have to redraw from scratch
each time an "object" moved on your map.

Hope that's help.
-- 
Guilhem BONNEFILLE
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