Try to fix the contour label visibility problem as described in issue…

[Framstag]

… #1220

• Improved spacing values and fix projection calculation.

[sonarcloud]

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[Karry]

Nice. It is better. But still, some street names visible previously are hidden. Seems that short streets, like https://www.openstreetmap.org/way/22561047#map=19/43.62046/6.97074 are problematic.

[Framstag]

@Karry The problem is, that the current (new) implementation only evaluates labelSpaces which is now a correct but still rather high value. This result in the requirement, that the way has to be rather long to get a label shown. It should take labelOffset also into account, which should then be a smaller value.
I'm also not yet satisfied with the overall result, I would like the label count to be a sequence of 1,3,7...labels to have a smoother effect on zooming in and out (the overall number of labels would be 1+2+4+8+16....). However that is currently not yet the implementation.

I'll merge this one in the evening and will take a look for an overall improvement in a later separate pull request.

[Karry]

For shorter way, I would rather ignore spacing (break the rules), instead of not showing label at all.

[Karry]

I tried to use this modification:

countLabels=std::max(size_t(1), size_t(pow(2.0,floor(log2(double(countLabels))))));

on line 792, as exception for short ways, but the "Rue Pasteur" label was filtered out because of variance test (line 801). It will be hard to find some heuristics for label placement to fill requirements:

• show at least some label even for shorter ways
• make it stable to avoid label movements during zooming