[QGIS-Developer] QGIS Server 2.x: issue with @map_scale variable vs. $scale

[Nyall Dawson]

On 4 July 2017 at 01:46, Neumann, Andreas <a.neumann at carto.net> wrote:
> Hi,
>
> In a QGIS project that should be published with QGIS Server, I used the
> @map_scale variable to define the font size with an expression, depending on
> the map scale. It works fine on QGIS Desktop, but on QGIS server GetMap
> requests it fails - the font-size (defined in map units) is constant and
> doesn't react to my scale dependent rule. The interesting thing, is, that
> the same rule works fine in GetPrint requests.
>
> If I change my rule to use $scale instead of @map_scale, my label rule works
> fine.
>
> Could it be that the @map_scale variable doesn't work in QGIS server GetMap
> requests?

Exactly - it's a consequence of QGIS 2.x server using the really old
map renderer, which means it doesn't have access to any variables
relating to the current map scale/extent/etc. This is also why 2.5d
renderer is quite broken on server under 2.x.

The good news is that it's all fixed with 3.0.

Nyall



>
> Here is my expression:
>
> CASE
>    WHEN @map_scale <= 251 THEN 1
>    WHEN @map_scale > 251 AND @map_scale <= 501 THEN 2
>    WHEN @map_scale > 501 AND @map_scale <= 1001 THEN 3
>    WHEN @map_scale > 1001 AND @map_scale <= 2001 THEN 4
>    WHEN @map_scale > 2001 AND @map_scale <= 3001 THEN 6
>    WHEN @map_scale > 3001 AND @map_scale <= 4001 THEN 7
>    WHEN @map_scale > 4001  THEN 8
> END
>
> Thanks for your ideas.
>
> Andreas
>
>
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