On Wed, Nov 14, 2012 at 11:11 AM, Andreas Neumann <[email protected]> wrote: > Hi, > > Thanks to Radim we now have multi-column legends in print composer.
Thanks to Régis and Agence de l'eau Adour as it was already mentioned by others. > This > was one of my long-time feature requests - but it never got to the top > of my requests so that we could pay for the work. > > Generally it works great, but I noticed two strange behaviors: > > * when having only one column (default) - the background rectangle is > way too small, not covering the full bouding box of the legend Width? Fixed. > * when going beyong 4 columns, QGIS gets really slow, hangs or crashes. Splitting of layers into columns is not that easy as it seems to be. It is a special sort of bin packing problem (NP-hard). Maybe it has its own name? I have used brute force because: - I thought that the number of layer will never be too big - implementaion of heuristic algorithm for such a marginal feature seemed to be overkill - suboptimal solution could look quite bad You proved immediately that I was wrong. How many layers do you have? 70 I have read somewhere? My original idea was to calculate number of possibilities first and decide if heuristic should be used. Now it seems a necessity. Maybe I am wrong and there is a simple solution? Well, I did not know at the beginning that I am going to solve combinatorial exercises. Regarding the crash, I was quite careful, using value() where there was minimum suspicion that it could run out of range. Many combinations should not mean allocation of a lot of memory, just more computational time. Only one combination is always evaluated at time. Does it seem to be a memory allocation problem or out of list bounds? Could you send me backtrace off list? Please follow/comment http://hub.qgis.org/issues/1841 Radim > Did other test the new multicolumn legends? > > Thanks Radim for your work! > > Andreas > _______________________________________________ > Qgis-developer mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/qgis-developer _______________________________________________ Qgis-developer mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-developer
