I need to produce the legend of a plot which encodes a color gradient together with a color gradient. In particular, I would like the image bellow to have the blueish edge faded and the redish solid:
I thought Graphics would be a good way to implement it, but I couldn't figure out how to implement such varying opacity. This would be the legend of the following plot
as you can see, the points at the plot display such gradient, but the way I implemented it was assigning an opacity to each point at the listplot, and this does not seem to work either for Graphics or for the above shown Bar Legend.