[Qgis-developer] Identified features vs. Selected features : could we merge those ?

[Olivier Dalang]

Hi !

The discussions about this issue http://hub.qgis.org/issues/9907 raised the
question (at least for me) of merging the concepts of Identified features
and Selected features.

I don't know if it's the good moment to discuss this, but since we have a
few other threads talking about a bit more deep user interaction changes, I
thought it could be good to think of this also (even if it's not urgent)...

In short, the idea would be to have both identified features and selected
features be exactly the same thing.
The only difference between the select tool and the identify tool would
then be that the identify tool opens a form window (either the single
feature form or the attribute table in form mode).
The identify tool could then also work in "single","rectangle","polygon"
etc modes.


Rationale FOR:

1. There is already a feature overlap

When identifying one feature only, the "identify tool" can open the form
(provided "open feature form if a single feature is identified" is
checked). But when identifying several features, the way to go is a
selection, which dynamically refreshes the attribute table, and where the
features can be edited in the form mode.
This is also a problem in the scenario of issue #9907 : to open the form of
overlapping features, you have to use a selection, if you don't want to
spend too many clicks expanding the "identify window" tree, finding the
right feature, and clicking on it's "open feature form" button. This also
has the annoying consequence of being unpredicable : the effect of the tool
will sometimes be opening the form (when one feature gets identified), and
sometimes to open that "identifying results" window (when several features
got identified).

*2. The attribute table in form mode is actually great*

The "identify results" window is not very practical: the folded tree
requires expanding, it does not provide a good overview of what is
selected, does not take editing widgets into account etc.
Meanwhile, the form view is great (both the single feature form and the
multiple features form in the attribute table). It's clear, neat, even
allows to choose which field to use to list the selection, etc... It's sad
that it's a bit hidden in the UI, I find it one of the best additions to
the UI that has been made lately.

*3. Both functions are very similar in how they work and look*

Both require you to click on a feature, and have a visual feedback
consisting of highlighting the feature. It's very confusing for beginners
as it's uncommon for softwares to implement two different types of
selections.

*4. Having the attribute table in form mode for editing is promising for
the future*

Because we could implement edition on several feature at once (currently,
one needs a plugin to set an attribute on different features at once, and
those plugin do not yet take the field widgets into account).



Rationale AGAINST (and of course counterarguments) :

*1. Identification is not the same than selection*
Users sometimes want to work on a selection, while still being able to
identify features.
To allow this usage, either we could offer workaround features by
implementing store/restore selections and/or have selections in the undo
stack (grouped), or we could make an exception for the "identify single
feature", which would not set the selection, but only open the feature form
(current behavior).

*2. Identification would stop working across several layers (top-down mode)*
Since it is difficult to imagine having the attribute table window display
selections from several layers. Technically, it would be doable in the form
view, since it does show only one form at a time, but it may be more clear
simply to remove this possibility.
However, we could keep the current behaviour when using "identify single
feature" though. This tool's behviour could keep the same functions that
currently, adding the feature #9907 and an "open attribute table in form
mode even if only one feature is selected" option. (to be clarified)

I guess I missed some uses of the "identify results" window ?


What do you think ?


Best regards,

Olivier
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