Lately I have been dealing with snappings in QGIS. I have been able, with help of people from this site, and also, having a look at other peoples plugins, to ensemble a small plugin with forms.
My question is regarding the units of snapping, my layers are spatialite layers in WGS84, the project units is meters, but I could not set snapping to project units, so that left me degrees or pixels, for the time being I set the tolerance to 10 pixels, but what I really wanted is to set the snapping tolerance to length units.
If I use decimals degrees, the number is very small and I could not entered it in the box of tolerance, the minimal tolerance in degrees would be equivalent to a big tolerance in meters.
So now I have to ask, how do I calculate the equivalence between pixels and meters? Are pixels fixed or zooming affects the size of the pixels?
iface.mapCanvas().mapUnitsPerPixel()useful, though it will still be in degrees if your project is in WGS 84.