[GRASS-dev] [GRASS GIS] #1942: v.label.sa not working with areas

[GRASS GIS]

#1942: v.label.sa not working with areas
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 Reporter:  richardc     |       Owner:  grass-dev@…              
     Type:  enhancement  |      Status:  new                      
 Priority:  normal       |   Milestone:  6.4.4                    
Component:  Vector       |     Version:  6.4.3 RCs                
 Keywords:  v.label.sa   |    Platform:  Linux                    
      Cpu:  x86-32       |  
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Comment(by mlennert):

 Replying to [comment:4 wolf]:
 > Oh I'm so happy to someone working on v.label.sa. I didn't really
 implement it for areas yet, but now that I see someone is looking for that
 feature I'm more than happy to work on it. Assigning this to me. I can't
 promise a time, but I'm definitely going to work on this!

 As mentioned my comment reproduced in the original report, I don't think
 this is much work, as areas can be considered as their centroids and so it
 becomes a placement of labels for points. Unless you want to optimise in
 terms of size of areas, etc. I would suggest to implement a simple
 solution at first in just replacing GV_AREA by GV_CENTROID. You can then
 always optimize specifically for areas later.

 AFAICT, the problem now is that in labels.c you have


 {{{
 legal_types = Vect_option_to_types(p->type)
 }}}

 which results in legal_types = GV_AREA if area is chosen, but further on



 {{{
 label_sz = Vect_get_num_primitives(&Map, legal_types);
 }}}

 but Vect_get_num_primitives() does not allow for GV_AREA.

 So probably just replacing GV_AREA by GV_CENTROID in legal_types before
 calling Vect_get_num_primitives should work (but this is just after a very
 superficial look...).

 The other, easier, solution is to replace area by centroid in the possible
 answers to the type option.

 Moritz

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Ticket URL: <https://trac.osgeo.org/grass/ticket/1942#comment:8>
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