[FOSS-GPS] Instance-IDs for osm-gps-map's `image' API (was: FoxtrotGPS Mapping Library)

[John Stowers]

On Thu, May 20, 2010 at 5:14 PM, Joshua Judson Rosen
<rozzin at geekspace.com> wrote:
> John Stowers <john.stowers.lists at gmail.com> writes:
>>
>> > > Yes, a patch for this would be great. It would also be worthwhile to
>> > > rename the functions to osm_gps_map_poi_{add,remove} to match the work
>> > > going on in the tracks-rework / gtk-3.0 branch.
>> >
>> >  Please no, keep it generic! I think the _image interface is more
>> >  then enough (once it uses opaque pointers) to handle POIs and
>> >  anything else that might be rendered this way. So don't make it
>> >  POI specific please!
>>
>> Good point. I had overlooked this. The image/poi stuff should be the
>> same API (excepting for the opaque pointer change)
>
> Indeed--not just the interface, but the implementation would also be
> identical. Ideally, I'd suggest just adding the extra argument to
> osm_gps_map_image_remove(), and changing the osm_gps_image_add() so
> that it returns its image_t pointer as the opaque identifier
> (cf. attached patch).
>
> The only reasons that I suggested a new function with "poi"
> in the name were that I wasn't sure you were ready to break
> backward-compatibility, and I couldn't think of a better term for
> a `specific instance of an image associated with a distinct point'
> (or `specific image-bearing point in which client code is interested')
> than "POI" :)

Looking over the patch, I wonder if this implementation is flexible
enough, while not making the API too confusing, for the behavior you
are trying to enable (removing either a single poi/image, or a whole
group of pois/images).

The limitation appears to be the assumption that the same pixbuf be
used as a handle for a group of pois/images. Is this something that is
useful/true in practice or will the app still need to keep around the
pointer to each added poi/image anyway (in which case we might as well
keep the implementation simple, and thus remove() only accepts the
opaque pointer)

What do you think?

John

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