Improve ruler

[vallsv]

This PR improve the ruler from the plot with a default fixed dashed style

No need changelog, it's a new feature

• Move PlotToolButton as an independent module
• Move RulerToolButton as an independent module
• Move inner class as a private class
• Update the style

[payno]

short answer: fine with me 👍 . Try to get something as much as possible 'readable' by default for colormap like 'grayscale' and that's it.

[t20100]

Regarding dashed line support, as a general rule, I prefer to stick to matplotlib naming/default style whenever possible and to have the OpenGL backend behave as close as possible to it.

So I'd prefer to add support for (offset, (dashes)) as in matplotlib set_linestyle than defining our own names.
I'll check how complex this is (it shouldn't be) and sync OpenGL dashes with default from matplotlib.
Anyway, this is not for this PR.

[t20100]

BTW, did you try with dashed dot: -.?

[vallsv]

BTW, did you try with dashed dot: -.?

I just try, that's not very nice

[vallsv]

Regarding dashed line support, as a general rule, I prefer to stick to matplotlib naming/default style whenever possible and to have the OpenGL backend behave as close as possible to it.

So I'd prefer to add support for (offset, (dashes)) as in matplotlib set_linestyle than defining our own names. I'll check how complex this is (it shouldn't be) and sync OpenGL dashes with default from matplotlib. Anyway, this is not for this PR.

Only supporting the subset (offset, (dash1, dash2)) would be already very nice, and i will try to use it for sure.

[t20100]

ok, then I'll add this

[vallsv]

Everything was rebased using the new features from the main branch.

Still some commit could be cherry picked alone to the main branch, but it's mostly typing.

This can be reviewed.

[payno]

Fine with the source code, works well on my side. I don't have any strong opinion regarding splitting out the PlotToolButton.