[Qgis-user] Node Tool - proposing improvements

[Nyall Dawson]

On Mon, 26 Nov 2018 at 21:39, Bernhard Ströbl <bernhard.stroebl at jena.de> wrote:
>
> Dear all,
>
> I want to apologize, this has become an extremely long mail...
>
> A lot of discussion has been going on about the recent reimplementation
> of the node tool in QGIS 3.

Hi Bernhard,

Thanks for the detailed proposal, and for taking the time to come up
with a constructive way forward here.

Can I encourage you to copy the contents of your proposal across to
the "QEP" repository:
https://github.com/qgis/QGIS-Enhancement-Proposals/issues ? I think
that's the correct channel to discuss these ideas so that the
conversation is kept central and recorded permanently for reference.

Nyall

>
> I see two reasons for this:
> 1) The way the tool works is very different from the way it used to work
> in QGIS 2:
> a) in QGIS 2 it was choose feature - choose node(s) - do something
> whereas in QGIS 3 it is choose node - do something
> b) to move a node was click - (keep pressed) - move - release which was
> changed to click - release - move - click - release
> 2) There have been several bugs (as could be expected with a new
> implementation). These, however, were used to question the whole feature
> (most of the bugs are fixed now).
>
> Apart from bugs and people not being used to the new tool the critics
> concentrate around:
> 1) Probably most annoying: Mouse movements for choosing an existing
> vertex/adding a new vertex at the middle of the line are not well
> defined (especially important if features and its vertices are very
> close together). Imagine a polygon surrounded (or even worse:
> overlapped) by others, now try to click a particular vertex. You will
> fail if always the neighbouring polygon is highlighted. The workaround
> is to select the vertex with a mouse window while its feature is
> highlighted (or previously select the feature e.g. with the
> Select-Feature tool). For overlapping features it is even harder.
> 2) Highlighting effect is disturbing.
> 3) Adding a new vertex puts the new vertex on the mouse ready to be
> moved but user has no intention to move it but to leave it where it has
> been added (e.g. for topological reasons).
> 4) Vertices are not visible all the time but only when the feature is
> highlighted. This can make choosing a particular vertex difficult (see
> also 1).
> 5) It is easy to accidentally add or move a vertex because the most
> intuitive way of selecting something is to click it. But when you click
> a vertex/segment/cross while being highlighted you are already on your
> way to move it.
> 6) The behaviour is not consistent:
> a) If you want to move _one_ vertex, try to grab it when it is
> highlighted then move it; if you want to move several vertices, first
> select them, then click them, then move them.
> b) If you want to delete a vertex, try to grab it when it is
> highlighted; if you want to delete a segment, do not try to grab it when
> it is highlighted but select its two vertices and delete them.
>
> The German user group thinks that the points raised above are valid,
> even if all pending bugs are fixed. The node tool is still not perfect
> (it wasn't in QGIS 2 either).
>
> So we propose a change in the way the node tool works and would like to
> hear other users' s opinions.
> While the click - move - click change has valid reasons (use advance
> digitizing panel, pan or zoom map while moving vertices) the dropping of
> the first choose feature - then choose vertex workflow to immediately
> move a vertex has no real reasoning (except that it is less clicks in
> those cases where the node can be easily grabbed in the first place).
> But this new workflow is the main cause for the problems listed above.
>
> Therefore we would like to see the old workflow reimplemented with some
> of the new ideas added plus some new ingredients. This is the draft for
> how the tool might work in the future:
>
> 1) While the mouse is moved around features are highlighted to indicate
> they can be edited. Furthermore eventual vertices, segments or crosses
> are highlighted, too (as in QGIS 3).
> 2) While a feature is being highlighted, it can be chosen with a left
> click (new).
> 3) If the user makes a right click instead, another (adjacent) feature
> is highlighted and can be chosen with a subsequent left click and so on
> (new).
> 4) As soon as a feature is chosen, the Vertex-Editor panel is opened (as
> in QGIS 2).
> 5) A chosen feature is the only feature whose vertices can be edited at
> that point* (as in QGIS 2). The chosen feature and all its vertices stay
> visible until the end of this feature's editing session (as in QGIS 2).
> If a vertex was highlighted it is immediately selected, if a segment was
> highlighted, its two vertices are immediately selected, if the middle of
> a segment was highlighted with a cross a new vertex is created there and
> immediately selected (new).
> 6) A vertex is selected by left clicking on it (as in QGIS 2).
> 7) Several vertices are selected by using a mouse window (as in QGIS 2
> and 3).
> 8) A click on a segment selects its two vertices (as in QGIS 2).
> 9) Vertices can be selected via the Vertex-Editor panel, too (as was in
> QGIS 2)
> 10) Every new vertex selection clears any previuos selection except if
> Crtl is pressed which adds the new selection to the current if vertices
> were not selected or subtracts them from the current selection if they
> were selected (as in QGIS 2).
> 11) Selected vertices can be deleted (as in QGIS 2 and 3).
> 12) Selected vertices can be moved by clicking either of them, thus the
> vertex (the vertices) are attached to the mouse and can be dropped with
> another left click (as in QGIS 3). A right click aborts the moving
> operation but the vertices are still selected (new).
> 13) A new vertex can be created by double clicking on any segment (as in
> QGIS 2 and 3), the new vertex is immediately selected (new).
> 14) A right click ends the chosen feature's editing session, if another
> feature is within reach it is immediately highlighted, continue as in 1)
> (new).
> 14b) To be discussed: Left clicking another feature immediately chooses
> this feature (as in QGIS 2).
>
> * topological editing is still posssible, of course
>
> We see the following advantages in this approach:
> 1) The new quick editing possibilities are preserved, there is just one
> additional click (compared to current QGIS 3) to move an existing vertex
> or segment or to create and immediately move a new vertex.
> 2) It is easier to create a new vertex in place.
> 3) It is a lot easier to graphically choose the feature to edit.
> 4) The highlighting indicates, which feature will be chosen by an
> immediate click, no surprises for the user.
> 5) It is easier to graphically select the vertices to edit.
> 6) The workflow is always the same: Choose feature - select vertices -
> do something with them.
> 7) The workflow is consistent with creating a new feature (right click
> to finish editing).
> 8) The application is more consistent because graphically selecting
> vertices works the exact same way as graphically selecting features with
> the Select-features tool.
>
> I appreciate your feedback
>
> Bernhard
>
>
> __________ Information from ESET Mail Security, version of virus signature database 18443 (20181126) __________
>
> The message was checked by ESET Mail Security.
> http://www.eset.com
>
>
> _______________________________________________
> Qgis-user mailing list
> Qgis-user at lists.osgeo.org
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user