Hi >> 2014-08-19 22:48 GMT+02:00 Nyall Dawson <nyall.daw...@gmail.com>: >>> > >>> >>> Does it make any difference if you change: >>> c = QgsComposition(QgsMapSettings()) >>> >>> To: >>> ms=QgsMapSettings() >>> c=QgsComposition(ms) >>> >>> ? > > Martin/other python experts, > > What's the best way to fix this? Is /Transfer/ appropriate, given that the > c++ code would never delete this object? Or is there an alternative sip flag > which is more appropriate for this?
I think this is really API problem rather than Python-specific issue. The QgsComposition is designed in a way that it always had QgsMapRenderer from map canvas accessible (now changed to QgsMapSettings). Worst of all, it is supposed to be the same instance as used by map canvas - so it keeps just reference/pointer to QgsMapSettings/QgsMapRenderer. The QgsComposition should be fixed so that it does not require QgsMapSettings/QgsMapRenderer - after all, it does not make much sense, there may be several composer map items with different configuration. Each QgsComposerMap should have its own QgsMapSettings instance. The root of the problem here is that the QgsMapSettings() will create an instance and then destroy it - while QgsComposition just keeps blindly using dead reference. /Transfer/ or other annotations will IMHO not solve the problem. I would consider is as a known issue and live with it until API is not fixed. Btw. using "c = QgsComposition( QgsMapRenderer() )" is also wrong because of the same reasons. If it worked, it was just luck :-) Regards Martin _______________________________________________ Qgis-developer mailing list Qgis-developer@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-developer
