[Qgis-developer] Python/Qgis API questions

[Martin Dobias]

On Wed, Feb 10, 2010 at 11:37 PM, Chris Crook <ccrook at linz.govt.nz> wrote:
> Hi
>
> 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.

Please could you provide more details about your setup? Are you trying
to use one renderer instance for more layers? Or do you need some
means of communication among renderers of various 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?

In any case you can set layer's cached image to None (NULL in C++) to
force the redraw.

Martin