[Qgis-developer] Re: [Qgis-user] vector editing in QGIS - questions and issues (PostGIS biased)

[Maciej Sieczka]

Marco Hugentobler pisze:
> Am Dienstag 04 März 2008 20:28:56 schrieb Maciej Sieczka:
>> Marco Hugentobler pisze:

>>> I changed the behaviour now such that the snapping settings is only
>>> changed if the user really opened the project snapping dialog and clicked
>>> 'ok'.

>> Do you mean you submitted it to SVN? I'm asking because I can't see it
>> in the commit ML.

> Yes, in r8189. The commit ML is sometimes slow.

OK. Fetched it and built OK. It is better this way now. Still not as 
convenient as it could be though - once OK in Snapping Options is 
clicked, the Default Snapping looses it's purpose until a new project is 
started. It is confusing that the user can still modify Default 
Snapping, while it has no effect.

This could be easily fixed I guess. Please read below.

>> Before I think of it again, can you please first let me know if the two
>> in "Snapping options":
>>
>> 1. tolerance set to 0 and the layer checked
>> 2. tolerance set to anything and the layer not checked
>>
>> result both in snapping disabled? I guess they are supposed to, but want
>> to make sure.

> Yes, it has the same effect. At the moment, disabling is a bit more efficient. 
> But in principle, that could also be done for snapping tol 0 by adding a 
> query earlier in the code.

Got it.

> In my opinion, the advantage of the check boxes is that it is
> possible to disable the snapping during digitising without
> overwriting the previous settings (e.g. during a certain stage of
> digitising). Then, it can be quickly enabled by selecting the box again.

You are right.


Thinking it all over again, I imagine the whole thing this way now:

In Options > Digitizing > Default Snapping give it a "mode" selector and 
a checkbox (alike Project Properties > Snapping Options). These settings 
are stored in QGIS preferences file. Until Default Snapping *is 
checked*, it takes precedence over individual layer's settings, thus 
it's enabled for *all* layers, in any project.

Modifying individual snapping of a layer, through Project Properties > 
Snapping Options, is not possible then - layers are greyed-out in the 
dialog. The latter is also a signal for the user that global snapping 
setting is enabled, and he should turn it off to be able to tweak 
snapping per layer.

If Options > Digitizing > Default Snapping *is not checked*, modifying 
individual snapping Project Properties > Snapping Options for any layer 
becomes possible, and this setting takes precedence over the default.


Opinions? Could this be implemented?

Maciek