I'm trying to make a layer redraw when the underlying data changes. This seemed to work well in 2.8 but is very unreliable in 2.10.
I am trying to do the following: * create a point shapefile (from R) with a 'z' attribute having values between 0 and 1 * load into qgis, use a graduated renderer to colour points according to z * overwrite the shapefile with the same points but z set to 0.9 for all points * *** wave magic wand *** points are now coloured for z=0.9 (dark blue) * overwrite the shapefile with the same points but z set to 0.1 for all points * *** wave magic wand *** points are now coloured for z=0.1 (white) The trouble is the magic wand waving. Assorted StackOverflow posts and mailing list threads point at: layer.triggerRepaint() layer.setCacheImage(None) layer.dataProvider().dataChanged.emit() none, or all, of which seem to update the visible layer. Not even if I drag and zoom a bit. Although sometimes, after a while doing nothing, it updates. I can't figure out what's triggering it, and I'm fairly sure the first two of the above worked well in 2.8 (have upgraded all my 2.8s to 2.10s now...). I've deselected "Use render caching..." in the Rendering tab of the Options dialog. The only reliable way of updating a layer I've found is to right-click on the legend and "Duplicate", and then the duplicate layer and the original both get drawn using the new z values from the updated on-disk shapefile after toggling the legend visibility. So, I'm stuck. Apologies for cross-posting to GIS.SE: http://gis.stackexchange.com/questions/159950/make-a-qgis-layer-update-from-a-changed-data-source but you might want to comment/answer there if you crack it. Version details follow, running on Linux Mint 17: QGIS version 2.10.1-Pisa QGIS code revision exported Compiled against Qt 4.8.6 Running against Qt 4.8.6 Compiled against GDAL/OGR 1.10.1 Running against GDAL/OGR 1.10.1 Compiled against GEOS 3.4.2-CAPI-1.8.2 Running against GEOS 3.4.2-CAPI-1.8.2 r3921 PostgreSQL Client Version 9.3.4 SpatiaLite Version 4.1.1 QWT Version 5.2.3 PROJ.4 Version 480 QScintilla2 Version 2.8.1 thanks Barry _______________________________________________ Qgis-developer mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-developer
