Make the databrowser min max lines configurable along with the main line

[jacomago]

Green here is the raw values, red is the optimized call.

From here I see a faint line that the red max matches the max of the raw values, but it looks strange.

I can configure the width and style of the main line but not of the min/max lines. I think it would be nice to have the min max configurable, and it would make comparing raw vs optimized (and any future downsampling we support) better.

[kasemir]

The idea is that raw vs. optimized give the same outline.

Optimized should provide around N min/max/average buckets, with N close to or larger than the plot width in pixels.
When simply drawing lines between all the raw samples vs lines from min0 to max0 to min1 to max1 to min2 to max2, ..., that should look the same. For the optimized, we instead draw a line from avg0 to avg1 to avg2 ... and fill the min/max outline with a lighter color. That way, you get the filled outline that looks like the raw data (albeit lighter), PLUS you get the average so you can tell if the value tended to be smack in the middle vs for example mostly at the upper end.

So bottom line, optimized should result in faster plot updates because there are only (pixel width) x (min, max, avg) values to handle, it gives the same outline, plus you see where the average is within the outline.
Downsampling would hide detail, and then users wonder why a brief spike in the data is hidden.
Asking for much more than (pixel width) buckets simply wastes resources.

[jacomago]

Right, this ticket isn't to change the down sampling. I think optimised is best here, but to be able to change the styling of the minmax area. For instance, the colour or the faintness.

For this particular graph, on my MacBook air high density whatever screen, I could not see the minmax area at all. If I moved it to a lower density screen, I could just make it out.

I think it makes sense to be able to change the style of the min max area plot for these spiky PVs, just in general as a feature. And then hopefully users could change that, rather than reverting to raw.

[kasemir]

Interesting. You can change org.csstudio.trends.databrowser3/opacity