gui/plotxy: opacity on even y axis ticks

[sophiekovalevsky]

What if we can add an option to set an opacity for all even y axis ticks when using plots in xy, turning into something like this:

If someone just doesn't want this feature it all I can add an option to disable it on preferences -> graphs menu if that make sense.

[sophiekovalevsky]

I forgot to mention that I would be happy to incorporate this feature by myself.

[jankae]

This could certainly be useful. Maybe add the option for a different color instead of opacity? I could imagine that opacity does not work well for certain background colors (e.g. white).

[sophiekovalevsky]

@jankae i ran several tests and I guess that if we don't set opacity would be more difficult for user to select the right color so it can combined at same time with actual background. On the other side, if I set the opacity with a different color, what I will get won't be exactly the color I think would be, that's the downside.

I set plotAreaTop variable because I will work this week on the other implementation and for that I think we need to set an offset on plot so traces background don't overlap with the actual start of plot.

[sophiekovalevsky]

@jankae just found out a bug in my implementation, I will fix it soon and let you know when you are actually review it. Thanks.

[sophiekovalevsky]

I think I fixed the issue. I revert the opacity feature since when viewing trace in auto-mode it seems like ticks width are not evenly spaced which completely disappears if opacity is disabled.

[jankae]

I still had some issues on my system with the X axis ticks not being visible everywhere, because the second background color was drawing over them, but that was a simple fix by just moving around some lines of code, looks good to me now. I also changed the default value to better match the default of black for the "normal" background, I hope you don't mind

[sophiekovalevsky]

I didn't noticed this and thanks for fixed.