Added custom PolyVertexEditTool

[philippjfr]

Adds customized PolyEditTool which supports dragging shared nodes and allows coloring feature vertices differently from regular vertices.

[philippjfr]

@kcpevey Would be great if you could try this out.

[kcpevey]

I think this is heading in the right direction. As expected, it still needs more work which I think you can proceed on.

Some bugs I noticed:

• it seems to randomly decide to finish the polygon and start a new one, despite me only single-clicking.
• it randomly snaps to vertices cuts polygons even though I'm click a location very far from the node in which it snapped.
• sometimes it correctly cuts the polygon (maybe the first cut?) but if I continue drawing, I eventually end up with overlapping polygons - something I'm hoping to avoid

I didn't see the different color vertices/nodes, but that's probably because I wasn't sure how to trigger that visualization.

[philippjfr]

@kcpevey This is ready for you to try out again.

[kcpevey]

@philippjfr I'm seeing some strange behavior. It feels like there is a bug or two in there somewhere but I couldn't get a recipe to reproduce most things:

• deleting is a little buggy - sometimes deleting a path leaves behind a stray node - seems random, this has been a bug for a long time I think
• at some point, it seemed to have swapped the "double-click makes an endpoint" and "single click makes a vertex". I managed to get a vertex as an endpoint to a path
• draw a multi-line with multiple connection points doesn't trigger an update to node - I'm pretty sure
  this is due to the swapped bug above
• I have two videos that I can show you on the call tomorrow that demo some usability stuff.

Questions:

• is it possible to drag an existing path endpoint and attach it (via snapping to an existing node)?

• is there a plan to allow for adding vertices/adding nodes to midpoint of line?

• eventually we need a 'clean' tool (perhaps part of polygon 'build' tool) that takes all the paths that a user has drawn and at every location. Probably need to add that to the roadmap for the 'building a polygon from multiple paths' task.

[kcpevey]

Also, do we have a roadmap for this task? It seems to have come a long way since #272 .

[philippjfr]

is there a plan to allow for adding vertices/adding nodes to midpoint of line?

By clicking somewhere on an existing line.

eventually we need a 'clean' tool (perhaps part of polygon 'build' tool) that takes all the paths that a user has drawn and at every location.

Should consider whether this is a tool in the toolbar or a separate button in the polygon builder class.

Tasks:

• The VertexEditTool should not allow selecting lines with single click
• Use zero-alpha large line width on nodes to improve hit testing
• Make new issue outlining a roadmap for drawing tool enhancements