Fix show() method to reshape a copy

[kescobo]

Per discussion in Slack with @pfitzseb in #juno-bridged on slack, there's an issue with the show() method that causes weird errors in Juno. He suggested that this line should instead be:

show(io, MIME"image/svg+xml"(), reshape(copy(cs), (1, length(cs))))

[timholy]

Won't change this without clearer justification: what's the error on Juno and why can't it be fixed within Juno?

[pfitzseb]

This isn't a Juno specific issue:

λ j1 --quiet
julia> using Colors, ColorBrewer

julia> colors = ColorBrewer.palette("Set1", 9);

julia> show(stdout, MIME"image/svg+xml"(), colors)
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
 "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg xmlns="http://www.w3.org/2000/svg" version="1.1"
     width="180.0mm" height="25.0mm"
     shape-rendering="crispEdges">
<rect x="0.0mm" y="0.0mm"
      width="19.0mm" height="24.0mm"
      fill="#E41A1C" stroke="none" />
<rect x="20.0mm" y="0.0mm"
      width="19.0mm" height="24.0mm"
      fill="#377EB8" stroke="none" />
<rect x="40.0mm" y="0.0mm"
      width="19.0mm" height="24.0mm"
      fill="#4DAF4A" stroke="none" />
<rect x="60.0mm" y="0.0mm"
      width="19.0mm" height="24.0mm"
      fill="#984EA3" stroke="none" />
<rect x="80.0mm" y="0.0mm"
      width="19.0mm" height="24.0mm"
      fill="#FF7F00" stroke="none" />
<rect x="100.0mm" y="0.0mm"
      width="19.0mm" height="24.0mm"
      fill="#FFFF33" stroke="none" />
<rect x="120.0mm" y="0.0mm"
      width="19.0mm" height="24.0mm"
      fill="#A65628" stroke="none" />
<rect x="140.0mm" y="0.0mm"
      width="19.0mm" height="24.0mm"
      fill="#F781BF" stroke="none" />
<rect x="160.0mm" y="0.0mm"
      width="19.0mm" height="24.0mm"
      fill="#999999" stroke="none" />
</svg>6

julia> append!(colors, [colorant"white"])
ERROR: cannot resize array with shared data
Stacktrace:
 [1] _growend! at ./array.jl:814 [inlined]
 [2] append!(::Array{RGB{FixedPointNumbers.Normed{UInt8,8}},1}, ::Array{RGB{FixedPointNumbers.Normed{UInt8,8}},1}) at ./array.jl:897
 [3] top-level scope at none:0

[timholy]

I'd suggest transpose instead, since it doesn't prevent growth:

julia> a = [1,2]
2-element Array{Int64,1}:
 1
 2

julia> b = transpose(a)
1×2 LinearAlgebra.Transpose{Int64,Array{Int64,1}}:
 1  2

julia> push!(a, 3)
3-element Array{Int64,1}:
 1
 2
 3

Though I guess colors don't support transpose, so make that Base.ReshapedArray(colors, (1, length(colors)), ()).

PR welcome.

[kescobo]

@timholy sorry for the terseness and thanks @pfitzseb for jumping in. TBH I wasn't really sure what was going on, but wanted to plant the flag after discussing it on slack, since @pfitzseb said he couldn't get to it right away.

[timholy]

Want to try a pull request? The answer is right above you, just needs someone to push it over the finish line.

[kescobo]

Sure! ☝️