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

[Nyall Dawson]

On Tue, 19 Feb 2019 at 19:03, David Signer <david at opengis.ch> 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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