[QGIS] Snapping on invisible feature

dsavary commented 7 years ago

In QGIS, we can snap on invisible features even if the snapping options have been defined as "snap on all visible layers". The snapping options don't take into accoount the layer style.
Will this be fixed for QGIS 3.0 ?

Démo GIF : https://share.oslandia.net/public/b91c8e

haubourg commented 7 years ago

Hi @dsavary let's split it in two phases:

do you have qgis 2.99 installed? That could let you test directly in qgis nightlies. You can have them using the osgeo4w installer, and updating is only a 5-6 click job (just run the osgeo4w/bin/setup.bat and choose advanced installer)
before fixing what appears to you as a bug, it must be discussed and see if it really is a bug or a feature for all users. When it appears strange to you, it might be a useful feature to other. When you say layer style is not taken into account, are you talking about invisible feature that are:
- unchecked classes ?
- unclassified object (ie object not in any category or range class and not falling in a Else Filter)
- fully transparent ?
- not visible because of a blending mode effect ?
- classified but set with "no symbol" style

For unchecked classes, that would make sense not to have a snapping index. For the others, we'll need to discuss this largely with the community.

dsavary commented 7 years ago

I tested with QGIS 2.99 3 week ago. The bug is still not fixed. I talk about invisible feature that are unchecked classes . The snapping options check only if the layer are checked. Perhaps, it's not a bug, but a new feature request .

haubourg commented 7 years ago

Ok, this case is probably an issue. Let's raise the issue on the mailing list.

haubourg commented 7 years ago

thread opened here http://osgeo-org.1560.x6.nabble.com/issue-with-snapping-on-unchecked-legend-classes-td5322685.html

ponceta commented 7 years ago

About snapping in QGIS 3 https://github.com/QGEP/QGEP/issues/330

dsavary commented 7 years ago

For Lausanne, this issue is important. In the priority, it should be fix for QGIS 3.0 , ideally for QGIS 2.18 LTR if it's still possible. I don't understand the use cases where you would snap the new feature to invisible features on the map ...

haubourg commented 7 years ago

ticket created upstream https://issues.qgis.org/issues/16838

My guess is that the whole snapping workflow deserves something consistent. We have quite a bunch of good issues and feature requests in that area

haubourg commented 7 years ago

@dsavary backporting a change to 2.18 seems not possible according to @wonder-sk, it's a little bit more than only a bugfix. @qwat-psc: what is the priority of this issue when compared to all other issues with snapping? I have in mind the following needs:

improve and fix the new snapping dialog (help to display the dock, intensive test ) #228
add snapping priority and interactive selection (visual snapping - part 2)
allow select all and deselect all in advanced snapping options
layer finder filter (for projects with lots of layers)

ponceta commented 7 years ago

IMHO, Snapping on invisible features is a feature.

Removing it completely would be wrong. I suggest to set it optionnal in the same way that snapping on intersections is optionnal.

Default could be set to visible only.