[PATCH] Don't allow creation of self-overlapping ways

[Ben]

If I create a set of nodes in a circle, and then draw way-segments between them, I can overlap. I can make a circle using 8 nodes have infinite sides therefore. Bad mapping comes of this, and there isn't anyway to really see it.

Different ways shoudl of corse be able to have way-semgnets in the same places as other ways, but not the same way.

[Gabriel Ebner <ge@…>]

In case you didn't know: The current validator plugin highlights overlapping ways (you might have to enable it by going to the validator preferences dialog).

If you want to repair such a way without creating it from scratch, you can split it at a node and then combine the pieces (this will automatically remove any duplicate waysegments)

[Ben]

I had noticed both these things, but is there any reason why you should be able to create this mistake in the first place? I beleive the ability to create the bad data is maybe what needs solving, rather than being forced to scan for a potentially common error after making edits.

[tag-osm-trac@…]

While true segments are gone, this error persists.

This comment is just to keep it open. :)

[xeen]

The attached patch prevents the user from creating self-overlapping ways. Instead, it will stop drawing. If the user forces drawing from "that" node, it will create a new way to prevent self-overlapping.

It also fixes #696 ("Don't continue drawing when way is closed").

I'm unsure if we want to change from drawing to selecting mode or not once the "stop drawing" kicks in:

currently:

• easy tagging, but rubber band line annoys users. Thus: 1 step (choose select mode)
• adding another way: 1 step (unselecting)
• selecting another way: 1 step (choose select mode)

staying in drawing mode:

• easy tagging
• adding another way: 1 step (unselecting)
• selecting another way: 1 step (choose select mode)

setting select mode:

• easy tagging
• adding another way: 2 steps (unselecting, choose draw mode)
• selecting another way: 0 steps (just click)

I prefer staying in drawing mode, as adding a bunch of buildings from WMS would be very annoying otherwise. It also keeps current behaviour and I believe it's rather seldom that someone draws something and then wants to select something entirely different.

I'm unsure about the self-overlapping ways though: Normally you don't want to draw self-overlapping ways, thus this is an advantage, but think of when adding ways of a park. They have no name, intersect very often and will probably all get the same tagging. I know about Shift+Click, but it's still not easy to click, press shift, click, release shift, click. But just creating a new way would ease things very much. Any thoughts on this?

[xeen]

Prevents creation of self overlapping ways and stops drawing when ways are closed

[anonymous]

Applied in r1287.