[Patch RFC] Circle Arc tool creates unconnected nodes

[Hb---]

What steps will reproduce the problem?

1. Draw a way with some nodes.
2. Select non-adjacent nodes like 2, 4 and 5 and the way.
3. Invoke Circle Arc tool (Shift+C)

What is the expected result?

A circle arc formed between the segments 2, 3 and 4.

What happens instead?

Some free nodes gets created (under node 3 in the screenshot).

The current behavior does not fit to the "Method 3" from the help and not to the authors comments in the ​class header.

URL:https://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2020-02-29 00:28:12 +0100 (Sat, 29 Feb 2020)
Build-Date:2020-02-29 02:31:03
Revision:15958
Relative:URL: ^/trunk

Identification: JOSM/1.5 (15958 en) Windows 7 64-Bit
OS Build number: Windows 7 Professional (7601)
Memory Usage: 1450 MB / 3604 MB (1269 MB allocated, but free)
Java version: 1.8.0_212-b03, AdoptOpenJDK, OpenJDK 64-Bit Server VM
Screen: \Display0 1280x1024
Maximum Screen Size: 1280x1024
VM arguments: [-Djosm.home=testrun]
Program arguments: [--language=en]
Dataset consistency test: No problems found

Plugins:
+ utilsplugin2 (35334)

Last errors/warnings:
- W: Failed to parse external taginfo data at https://josm.openstreetmap.de/remote/geofabrik-index-v1-nogeom.json: Invalid token=EOF at (line no=6119, column no=2252, offset=359085). Expected tokens are: [CURLYOPEN, SQUAREOPEN, STRING, NUMBER, TRUE, FALSE, NULL]
- E: Failed to locate image 'https://josm.openstreetmap.de/browser/trunk/images/copy.svg?format=raw'

[GerdP]

Seems the algo calculates the points at the right place but fails to join the way to them.

[GerdP]

IIGTR the action should just show a notification saying e.g. "select three consecutive way nodes" in this case?

[GerdP]

Replying to GerdP:

IIGTR the action should just show a notification saying e.g. "select three consecutive way nodes" in this case?

Forget that. The help clearly states what should happen.

[GerdP]

Looking at the code I don't think that it ever worked as described in the pictures for "One way and three of its nodes selected"

I wonder what to do when other ways are connected to the selected nodes. Try my modified example and watch how way w2 changes its position.
What should happen when a way is connected to a node which is not selected but between the selected nodes?

[skyper]

It should be similar to complete circles. Have a look at roundabouts. There the nodes with other parents are moved as less as possible and the nodes without another parent are squeezed around them. Better even change the order of the nodes in the way than moving nodes with additional parents a lot.

[GerdP]

OK, sounds reasonable. I've never used that action.

[GerdP]

The patch changes the code to work similar to "Align Nodes in Circle" but it adds nodes to produce a circle.
The patched code still uses preference circlearc.angle-separation which has a default of 20 while actions like "Create Circle" calculate a value near 4 for large circles and much higher value for small circles (see #10777)
I think it would be better to use the same calculation and ignore circlearc.angle-separation.

[GerdP]

18847.2.patch removes the evaluation of circlearc.angle-separation as suggested in comment:8
A lot of the code is a copy of CreateCircleAction or AlignInCircleAction.
If nobody complains I'll commit this tomorrow.

[skyper]

Replying to GerdP:

I think it would be better to use the same calculation and ignore circlearc.angle-separation.

+1

[GerdP]

see [o35384:35385]

[GerdP]

In 16297/josm:

see #18847, #19076: Changing value of curves.circlearc.angle-separation value in advanced preferences no longer appears to have any effect.

• add curves.circlearc.angle-separation to the list of obsolete preference keys

[skyper]

Found issues with a closed way, see #19188.