[QGIS-Developer] Line feature callout labels not rendering in headless/server QGIS 3.22, but work fine in Desktop 3.28

[Greg Troxel]

吉見 崚 via QGIS-Developer <qgis-developer at lists.osgeo.org> writes:

> Question: Is there a known behavioral difference between QGIS 3.22 and
> 3.28 (or between interactive Desktop rendering and headless/server
> rendering via QgsLayoutExporter) regarding callout placement for line
> geometries? Or any known issue/limitation with calloutType="simple"
> specifically in non-interactive/headless rendering contexts?

You are asking a question about ancient history.  3.22 was released in
2021-10 and 3.28 in 2022-10.  The current LTR is 3.44 and the current
release is 4.2.  It would not be surprising if there were bugs in 3.22,
but I doubt anyone is paying attention or has any interest in thinking
about them.

> Any pointers on where to look (label engine internals, GEOS version
> dependency, changelog entries between 3.22 and 3.28 related to
> labeling/callouts, missing processEvents() calls, etc.) would be
> greatly appreciated.

My advice is don't look into that, and update both your headless
rendering and desktop to 3.44.  If you aren't willing to upgrade, it
seems like the obvious experiments are to try 3.28.0 on Ubuntu both
headless and desktop.