[Qgis-developer] Official Plugin candidates

Martin Dobias wonder.sk at gmail.com
Sat Jan 3 12:08:34 EST 2009

On Wed, Dec 31, 2008 at 10:03 PM, Barry Rowlingson
<b.rowlingson at lancaster.ac.uk> wrote:
>  * SelectPlus has a big problem in that I wasn't aware that some
> layers (GRASS) didn't allow random-access selections, and you have to
> loop through features and select sequentially. Graargh. Plus it has
> problems with projections when circles aren't circles and straight
> lines aren't straight lines. These things can be fixed but I'd see a
> lot of people going "I can't select my grass layer points with a
> polygon" until it's fixed.


looking at grass provider code, it really doesn't come with efficient
implementation of featureAtId(), however it should be quite easy to
implement it for GRASS layers because features ("lines") are always
accessed by their ID. But still there are cases where sequential
select is needed (e.g. some OGR drivers).

I was thinking also about adding a new vector provider call which
would fetch "some" features at once - you would provide a list of IDs
and provider would return you a list of features. This would either
simplify the problem with some providers needing to fall back to
sequential select and also would allow faster fetching for some
providers which have greater overhead when accessing features (e.g.
SQL parsing and communication).


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