[QGIS-Developer] QGIS composer print layout

[JD L]

Hi Giulio,

add the flags methods to tell your algorithm is not thread-safe. From the
documentation :
https://docs.qgis.org/3.16/en/docs/user_manual/processing/scripts.html#flags

If your algorithm is regularly crashing, you are probably using API calls
which are not safe to do in a background thread. Try returning the
*QgsProcessingAlgorithm.FlagNoThreading
flag from your algorithm’s flags() method* to force Processing to run your
algorithm in the main thread instead.

I just tested and it works.

Regards,

Le ven. 22 janv. 2021 à 14:56, Giulio Fattori <giulio.fattori at tin.it> a
écrit :

> Hello,
> i'm developing a QGIS plugin algorithm that composes a print layout.
> The attached code works but the map window appears in the composer with
> the word "Rendering map".
> and I get these messages:
>
> WARNING    QObject::connect: Cannot queue arguments of type
> 'QItemSelection'
>              (Make sure 'QItemSelection' is registered using
> qRegisterMetaType().)
> WARNING    QObject::connect: Cannot queue arguments of type
> 'QItemSelection'
>              (Make sure 'QItemSelection' is registered using
> qRegisterMetaType().)
> WARNING    QObject::connect: Cannot queue arguments of type
> 'QItemSelection'
>              (Make sure 'QItemSelection' is registered using
> qRegisterMetaType().)
> WARNING    QObject::startTimer: Timers cannot be started from another
> thread
>
> CRITICAL    Qt : QObject::killTimer: Timers cannot be stopped from another
> thread
> CRITICAL    Qt : QObject::startTimer: Timers cannot be started from
> another thread
> CRITICAL    Qt : QObject::killTimer: Timers cannot be stopped from another
> thread
> CRITICAL    Qt : QObject::startTimer: Timers can only be used with threads
> started with QThread
>
> Only after saving and reopening QGIS do I get the correct result in the
> composer.
>
> What is missing to make it work properly?
>
> Can someone help me?
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