On 27/09/2010 18:47, saulgoode@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx wrote: > Quoting Ofnuts<ofnuts@xxxxxxxxxxx>: > >> My code needs to do a one-pixel-wide selection, at distance "x" from the >> current selection. This looks a lot like a border selection except that >> the border selection creates at best a two-pixel wide ribbon and I only >> want one (but if I'm wrong, please tell me how to :-) >> >> So far my code goes like this: >> >> # Selects pixels that are between x and x+1 pixels from >> # the original selection. Bumping the selection by one >> # each time doesn't work, a small circle degenerates into >> # a square with rounded corners instead of a big circle. >> def select_ribbon(self,image,selection,dist): >> pdb.gimp_selection_load(selection) >> pdb.gimp_selection_grow(image,dist+1) >> outer=pdb.gimp_selection_save(image) >> pdb.gimp_selection_load(selection) >> pdb.gimp_selection_grow(image,dist) >> inner=pdb.gimp_selection_save(image) >> pdb.gimp_channel_combine_masks(outer,inner,CHANNEL_OP_SUBTRACT,0,0) >> pdb.gimp_selection_load(outer) >> image.remove_channel(outer) >> image.remove_channel(inner) >> >> That works, but can be slow (especially since it's at the core of a >> loop). Is there any better way? Or useless code to jettison? > There is no need to create (and later delete) the 'outer' channel. > Just use the selection itself. In Script-fu, this would be done as > follows: > > (gimp-selection-load selection) > (gimp-selection-grow image dist) > (set! inner (car (gimp-selection-save image))) > (gimp-selection-load selection) > (gimp-selection-grow image (+ dist 1)) > (gimp-channel-combine-masks (car (gimp-image-get-selection image)) > inner > CHANNEL-OP-SUBTRACT 0 0) > (gimp-image-remove-channel image inner) Implemented your code. It runs 10 to 20% faster, and uses only half the memory... So you have been duly credited in the V0.2 history. Thx. _______________________________________________ Gimp-developer mailing list Gimp-developer@xxxxxxxxxxxxxxxxxxxxxx https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
