Add marker.cornerradius to treemap

[emilykl]

This PR exposes the marker.fillet attribute for treemap and icicle plots, which allows users to create plots with rounded corners by setting the fillet radius in pixels.

Based on this comment from @archmoj.

Fillet radius is limited to half of the smallest dimension of a rectangle to avoid weird artifacts on small rectangles.

Example with marker.fillet set to 4:

[nicolaskruchten]

wow that looks great! Any chance we could get this on bars? :) #2196 is a long-standing one... Just need to make sure it's only the top-most bar in a stack.

[archmoj]

wow that looks great! Any chance we could get this on bars? :) #2196 is a long-standing one... Just need to make sure it's only the top-most bar in a stack.

Yes we are paving the way for bars here. But that should be a separate PR.
@nicolaskruchten your suggestions in terms of attribute naming and API design as always would be much appreciated.

[nicolaskruchten]

Hehe ok. I would vote for something like marker.cornerradius or something?

[alexcjohnson]

Looks like it's possible to make the radius so big that the text or smaller inner boxes poke out of their containers. Here's your mock bumped up to radius 40:

How about we make a dynamic max? If I did the math right, a safe value would be x+y+sqrt(2*x*y) where x is min(padding.l, padding.r) and y is min(padding.t, padding.b)
Actually might be more user-friendly to leave max undefined, but restrict it during rendering and describe this in the attribute description - since we're restricting the radius anyway if the box gets too small... something like "the actual radius we draw will be limited to half the box size, or smaller if necessary to prevent the box contents from overflowing its edges"

[alexcjohnson]

I like marker.cornerradius - a little verbose but totally unambiguous.

Looks beautiful for treemaps (if you don't try to break it like I did 😈 )

For icicle though, can we NOT round the edges where the parts abut the whole? Kind of the analog of bars "only the top bar" though I think rounding both sides is fine. I just don't like it rounded in the middle, as I think it obscures the "part of a whole" model. Also looks particularly bad where a very small slice isn't touching its parent at all:

If that's going to be too annoying to implement, perhaps better to leave icicle out of this pr?

[alexcjohnson]

@archmoj is my max radius comment #6351 (comment) still open?

[archmoj]

@archmoj is my max radius comment #6351 (comment) still open?

Now addressed by a814408.

[alexcjohnson]

It's still able to generate too big of a radius. On the latest commit if I load treemap_packages_colorscale_novalue and then run Plotly.restyle(gd,'marker.cornerradius', 40), the result is the same image as in #6351 (comment)

[archmoj]

Plotly.restyle(gd,'marker.cornerradius', 40)

It don't get the similar image. Perhaps you should git pull recent changes in your local branch?

[alexcjohnson]

Weird, I had the latest commit but somehow was still getting the old behavior. Yes, it looks good now! 💃