[QGIS-Developer] Missing custom rendering properties in QGIS3 Server

[Nyall Dawson]

On 23 May 2018 at 18:56, Sören Gebbert <soerengebbert at googlemail.com> wrote:
> Dear developers,
> i am trying to use the undocumented custom vector layer property
> "rendering/renderAboveLabels" in QGIS3 server with no success.
>
> Storing this property in a QGIS project file enables the rendering of
> vector layers after the labeling is done. This works fine on QGIS3
> desktop, but not on QGIS3 server. I looked into the server code and
> realized that the QGS WMS server uses two renderers
> (QgsMapRendererParallelJob, QgsMapRendererCustomPainterJob) of which
> one (QgsMapRendererParallelJob) should support the custom property.
> However, i can not convince the server to apply the custom property
> when parallel rendering is enabled.
>
> What am i doing wrong? Are there differences between GQIS3 desktop and
> server in handling project files and layer properties?
>
> Why does QgsMapRendererCustomPainterJob not support the custom
> property  "rendering/renderAboveLabels"?

It's undocumented for a reason - it was added as a quick hack to
support this function in very limited circumstances, but isn't part of
the stable or public API as it's not officially supported.

In the long term we need a proper, officially supported and stable way
to handle this use case.

Nyall