Cannot determine the type of QgsComposerItem

[anitagraser]

In Python console, type(item) will only return <class 'qgis.core.QgsComposerItem?'>

From IRC:

[09:49] <anita1> how can i get all QgsComposerLabels? from a composer? currently, i can just access all QgsComposerItems? but don't know how to filter only labels from them

[10:50] <marco> hi anita1

[10:50] <marco> dynamic cast in (C++) or query the class type (in python)

[10:51] <anita1> marco: hi. but that returns only QgsComposerItem?, not label

[10:51] <anita1> type(items[0]) <class 'qgis.core.QgsComposerItem?'>

[10:52] <marco> in python? Then there is probably missing a 'convertToSubclass' somewhere in the python bindings...

[NathanW]

I have added what is my attempt at fixing the bug, I gave it a run this morning and the types are returned correctly in Python however if you try and call any of the methods on the returned types you get a segfault. Eg calling .displayText() on a QgsComposerLabel? causes a segmentation fault. C and C++ aren't my normal programming languages, so I may have done something wrong or missed something.

[NathanW]

Attempted fix at bug

[mhugent]

Thanks, NathanW! The patch is applied in r14736. I noticed those crashes too. The strange thing is it does not happen for items added via the python bindings, only for the already existing ones.

[NathanW]

Thanks. I'm doing some testing now, not sure how much help it will be but if you cast in python using something like:

label = selectedComposerItems()[0] /* The first label on the composer */ label.class = qgis.core.qgscomposerlabel

You can call label.displayText() fine. The above will still crash sometimes even with the code I added to the SIP.

[wonder]

Fixed in r14766