Regression: Curve dragging via Node Tool sometimes won't work

[ScislaC]

Done on Linux, SVN rev 20100.

In attached file use the node tool and select the object and then hover over the path segments between nodes. You will notice that the hand cursor doesn't appear on the bottom path segment... so it can't be directly dragged.

If you change the node type for the node on the bottom right it will then let you directly manipulate that segment from then on.

I've also noticed something else that may be related. Sometimes when Ctrl+Clicking nodes to change node types, after cusp, the other node types will not pop out both handles (although it appears that the new Auto node type will force the second handle out). Unfortunately I don't have a test case for this second issue... when I do I will file a separate report on it.

[Pablo Trabajos (pajarico)]

I'm afraid this is still present on r21627. And is really annoying because I can move the handles but not drag the path (only some parts). In the video I'm attaching you can observe how once I moved the upper part of the path to form a close angle around the smooth node, the lower part started to be responsive.

Just for trying, I copied the problematic path on my document to a new one and the problem disappears.

[jazzynico (jazzynico)]

Confirmed on Windows XP, Inkscape rev. 21627.
But I can't reproduce it with 21920. Probably fixed elsewhere.

[Pablo Trabajos (pajarico)]

Can't confirm that JazzyNico, because there is no compiled exe for that revision (modevia is a month behind). I'm guessing you compiled it yourself. You tested 21920 on XP too, right?

[Pablo Trabajos (pajarico)]

Could you send the packaged exe so I can test it myself?

[jazzynico (jazzynico)]

> I'm guessing you compiled it yourself. You tested 21920 on XP too, right?

Yes. But you can find more recent builds here: http://sourceforge.net/projects/inkscape/files/

[Pablo Trabajos (pajarico)]

Which ones do you mean? Most recent for windows is pre1-1 from 22 Jul (tested: it fails). Snapshots are quite outdated.

[jazzynico (jazzynico)]

pre1-1 is the last available build for Windows (except if you compile it yourself).
Sadly, I've tested again (on Vista this time, and Inkscape 21920) and reproduced this bug.
Status reverted to "confirmed".

[Krzysztof Kosinski (tweenk)]

This looks more like a 2geom bug, because it is also present in my new node tool. It might have something to do with the fact that some control points are at (0, 0).

[Luca Bruno (lucabru)]

Right way to reproduce with latest svn tip:
1. Create a grid
2. Create a path with at least 4 nodes, they should be all corners
3. Select two adiacent nodes and make them smooth
4. Unable to select adiacent segments two the smooth nodes

If you can't reproduce I'll make a video, let me know.

[Luca Bruno (lucabru)]

Notice that the non-selectable segments have one node without a control point. In fact this is a workaround: make nodes of non-selectable segments have control points (by using shift+click on the node).

[su_v (suv-lp)]

Luca's steps in comment #10 reproduced with
Inkscape 0.46+devel r22465 on OS X 10.5.8

workaround that don't wfm:
- shift-click the end node
- simple translation of the path on-canvas dragging

workaround that wfm:
- turn off grid visibility while drawing
- turn off snapping to grid while drawing
- move away and back (using snapping to the grid) the end
  node of an unselectable segment
- any arbitrary rotation of the object (with bbox handles)

[Pablo Trabajos (pajarico)]

I can reproduce this in official 0.48 too. Regards.

[Adolf Mathias (adolf-mathias-gmail)]

It is easy to reproduce all the described issues in 0.48 (Linux)

1. Go into Bezier drawing mode
2. click (producing a cusp node A without handles)
3. click-drag, and while dragging, hit shift, breaking the smooth node (producing a cusp node B with handles)
4. click back on the first node A (closing the curve, leaving A a cusp node without handles)

This produces a two-segment closed curve of which none of the segments are selectable. Ctrl-clicking on the first node A does not change its node type, just the node symbol.

Doing anything with node A always makes it become a cusp without tangents again.
Even when you shift-drag tangents out of node A, and then ctrl-click to change node type, it'll fall back to cusp without tangents.

The described mis-behavior seems to vanish when three nodes are involved (repeating step 3 above). You get a three-segment curve that so far seems to work as desired.

Update: the recipe doesn't work always, but frequently :(

[su_v (suv-lp)]

This issue also prevents inserting new nodes by double-clicking (or Ctrl+Alt+clicking) the segment which cannot be dragged (no 'hand' symbol when hovering over the segment with the cursor).

See related (or duplicate) report:
Bug #662762 “Double click segment don't work on outermost segments”
<https://bugs.launchpad.net/inkscape/+bug/662762>

[jazzynico (jazzynico)]

Still present revision 11649.

[zoqaeski (zoqaeski)]

This bug also occurs for me, similar to how Adolf Mathias describes. It also effects the entire document: once one path starts misbehaving, they ALL do. Some paths refuse to insert or delete nodes, or only delete nodes.

I'm using revision 11865 on 64-bit Arch Linux. I'll try building the latest revision to see if it still occurs.

[zoqaeski (zoqaeski)]

Confirmed in revision 11997. Anyone else experiencing this?

[zoqaeski (zoqaeski)]

Here's a screenshot showing the result of trying to move a path's handles. The paths that it seems to forcing look similar to the results of the auto-smooth nodes.

[su_v (suv-lp)]

> The paths that it seems to forcing look similar to the results
> of the auto-smooth nodes.

Do you have the spiro path effect applied to that path (maybe unintentionally)? A screenshot doesn't really allow to investigate…

[su_v (suv-lp)]

<off-topic>
On 29/12/2012 16:23, zoqaeski wrote:
> (…) It also effects the entire document: once one path starts
> misbehaving, they ALL do. (…)

On 29/12/2012 19:33, ~suv wrote:
>> The paths that it seems to forcing look similar to the results
>> of the auto-smooth nodes.
>
> Do you have the spiro path effect applied to that path (maybe
> unintentionally)? A screenshot doesn't really allow to investigate…

Note that the 'Spiro splines' path effect could even have been applied to the parent group (or even a layer, if the layer group was selected via XML Editor), which could explain why existing paths suddenly behave differently. Or maybe you are referring to newly drawn paths recently, or just in the current editing session), which would indicate that you inadvertently switched the drawing mode for the pencil and/or pen tool to use Spiro splines instead of regular bezier curves.

Besides checking whether the path has a path effect applied (the message in the status bar when selecting the path with the select tool will tell you), it is always helpful to turn on the path outlines in the node tool when trying to understand what's happening: if a Spiro path effect is active for that path, you will notice that the path outline is following the changed handles as expected, but the actually rendered path itself is only determined by the node type(s) (or rather whether the two extract handles are colinear or not).
</off-topic>

[zoqaeski (zoqaeski)]

The path outline was showing the same result; I normally draw in outline mode as it's quicker to render lots of small changes.

And it seems that the path had the Spiro effect applied unintentionally. Is there a keyboard shortcut that could turn it on without the user being aware?

[jazzynico (jazzynico)]

Reproduced again on Windows XP, Inkscape trunk revision 12511.
Not reproduced with revision 12688.

Could someone else confirm it's fixed?

[su_v (suv-lp)]

Attaching a sample file with a path segment which is not draggable with latest r12691 (on OS X) either (the bottom segment of the second object).

The file had been created with 0.48+devel r9832 back on October 18, 2010, based on the instructions in earlier comments (IIRC).

[jazzynico (jazzynico)]

> Attaching a sample file with a path segment which is not draggable with latest r12691

Confirmed with r12698.
I tested 5 times with different shapes in #23. And each time it worked with 12688 and not with 12511.
Probably in the "the recipe doesn't work always, but frequently" effect...

[Jabiertxof (jabiertxof)]

Another svg with the problem in 0.92.

[Jonathan Hofinger (jhofinger)]

I'm unable to replicate this issue in Inkscape 1.1-dev (c990a67, 2020-04-09), Windows 10. None of the attached files, and also the instructions given in #14, have unselectable segments. The fact that there are a lot of replications here, but this issue hasn't been opened at Gitlab yet, also indicates that it's probably fixed. Please reopen on http://inkscape.org/report if the problem occurs again.

Closed by: https://gitlab.com/jhofinger