[Qgis-developer] Python/Qgis API questions

Chris Crook ccrook at linz.govt.nz
Wed Feb 10 17:37:04 EST 2010


I have a scenario in a plugin where a change to a (python plugin) renderer on one layer may cause a change to other layers rendered with the same renderer.  Logically this should emit a signal (directly or indirectly) to request request the other layers to be refreshed.

I can sort of do this at the moment because layer change triggers a map refresh, and which in turn calls the startRender event in the renderer of the affected layers, which can then update themselves as necessary.  (Another probably better way to do it would be to raise a signal when the renderer changes which a handler uses to update all the affected layers.)

However I'm worried that this won't work if the render cache is in use.  I'm guessing this caches rendered layers and only refreshes the changed layers, rather than the entire map?

If so, then I need to be able to do signal to a layer that it needs refreshing.  At the moment I can only see how to refresh the entire map canvas.  Have I missed something in the API?



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