[QGIS-Developer] Provide a max. legend size in case of map unit sized symbols

[David Signer]

Hi Nyall  
  
I think, you're right. If there's no max size defined (enabled) on the GetLegendGraphics, it responds with memory error (so possibly because the size gets infinite because of zero scale).   
I thought that it has been the issue in the print layout as well, but I'm not sure anymore and I will check again when I'm back in the office. If it's not the issue on print layout - like you say - then I agree on your approach. Where should this default scale be defined in your opinion?  
  
Thanks  
Dave  
  
  
  
   


David Signer  
[david at opengis.ch](mailto:david at opengis.ch)  
[+41 (0)78 766 13 03](tel:+41787661303)  
  
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> On Tue, 19 Feb 2019 at 19:03, David Signer wrote:  
> >  
> > Hi there  
> >  
> > I'm struggling with the following issue https://issues.qgis.org/issues/21309 summarized like this:  
> > When using map units as symbol size and having a max value in mm, this value is always taken in the GetLegendGraphics request with QGIS Server, what leads to huge symbols there (same in legend of print layout).  
> >  
> > I think it's not always needed to adapt the exact size to the legend.  
> > So I see three approaches:  
> > - Don't adapt the size to the legend at all  
> > - Provide a configuration "Maximum size for legend"  
> > - Provide a max size property for the server (does not solve it for print composer)  
> >  
> > Where I would prefer the "Maximum size for legend" configuration.  
> >  
> > What do you think?  
>   
> Isn't the underlying issue here that server generates the legend  
> without any knowledge of map scale? (And presumably uses a scale of 0  
> or some other huge scale, resulting in the symbols taking their  
> maximum size)?  
>   
> If so, then i think the solution is:  
>   
> 1. Expose the choice of scale within the GetLegendGraphics call  
> 2. Allow users to set a "default" legend scale for a particular  
> project, and use this scale when generating the legend.  
>   
> > (same in legend of print layout).  
>   
> Can you elaborate? The legend in print layout correctly follows the  
> scale of the linked map item (and there's unit tests covering this).  
>   
> Nyall  
>   
>   
>   
> >  
> > Thanks  
> > Dave  
> >  
> >  
> >  
> > David Signer  
> > david at opengis.ch  
> > +41 (0)78 766 13 03  
> >  
> >  
> >  
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