Apply trace opacity to 'mode: 'lines' legend items

[etpinard]

fixes #1174

[alexcjohnson]

Would be a better test to set the opacity on a lines+markers trace - which I don't think is handled correctly in this PR, trace opacity should get set on traceGroup rather than independently to lines and markers (and fills!).

[etpinard]

First, see

trace opacity should get set on traceGroup

that would imply that the trace name (rendered in the <text class="legendtext"> node) would be semi-transparent whenever trace.opacity < 1.

So, in d009798 a new <g> is added grouping the fill, lines and symbols <g> and applying trace.opacity once.

[alexcjohnson]

So, in d009798 a new is added grouping the fill, lines and symbols and applying trace.opacity once.

👍

and then a test with lines+markers? Ideally with different line and marker colors?

Do you know why 28.png changed the way it did? I don't think the new one looks wrong per se, but in addition to the slight transparency to the legend lines, it seems like the lines got a little bit shorter. And in some of the other cases the semitransparent lines got a little thinner. Any idea why?

[etpinard]

and then a test with lines+markers?

Hopefully somethint like 849782d is what you had in mind.

I don't think the new one looks wrong per se, but in addition to the slight transparency to the legend lines,

as it should, all traces in 28.json have opacity: 0.84 which wasn't honored previously.

it seems like the lines got a little bit shorter.

I can't detect a difference to be honest, maybe I'm going blind 👓

[alexcjohnson]

it seems like the lines got a little bit shorter.

I can't detect a difference to be honest, maybe I'm going blind 👓

Ok, don't worry about it. Probably just some different antialiasing algorithm when opacity is included.

Hopefully something like 849782d is what you had in mind.

Technically it does show what I wanted to see - it will fail if the marker and line get trace.opacity applied separately rather than to the containing group - though that failure would be rather subtle, especially since you included marker opacity. I was imagining something that will make it blazingly obvious how the opacity was applied, like:

Plotly.newPlot(gd,[{
    x: [1, 2, 3],
    y: [1, 2, 3],
    opacity: 0.2,
    line: {width: 10, color: 'red'},
    marker: {size: 20, color: 'blue'}
}], {
    showlegend: true
})

And the legend matches the plot:

but if it was done wrong, the legend would look like:

[etpinard]

looks like it is done right.

[alexcjohnson]

Beautiful, thanks :) 💃

[etpinard]

Dropping from the 1.22.0 milestone and merging as the 1.21.x series will get another patch release early next week.

[flying-sheep]

Hi! I have a plot where I set per-marker opacity using a array.

The legend takes the opacity of the more transparent points. How can I force the legend’s opacity to be 1?