SVG multiline text

[Mattriks]

This PR:

• Enables multiline text for SVG
• Fixes text alignment so it's consistent with PNG
• Adds gallery example
• closes Line break not working in color key title Gadfly.jl#1225

Example:

using Compose
set_default_graphic_size(10cm, 8cm)

txt = [x*"\n"*y for  x in ["hleft", "hcenter","hright"], 
        y in ["vtop","vcenter","vbottom"] ]
x = repeat(0.1w.*[1,5,9], outer=3)
y = repeat(0.1h.*[1,5,9], inner=3)
xp = repeat([hleft,hcenter,hright], outer=3)
yp = repeat([vtop,vcenter,vbottom], inner=3)

img = compose(context(),
        (context(), circle(x, y, [0.01]), fill("red")),
        text(x, y, txt, xp, yp), fontsize(14pt))

[codecov-io]

Codecov Report

Merging #336 into master will increase coverage by 0.11%.
The diff coverage is 75%.

@@            Coverage Diff             @@
##           master     #336      +/-   ##
==========================================
+ Coverage   37.01%   37.13%   +0.11%     
==========================================
  Files          18       18              
  Lines        3093     3089       -4     
==========================================
+ Hits         1145     1147       +2     
+ Misses       1948     1942       -6

Impacted Files	Coverage Δ
src/svg.jl	69.04% <75%> (+0.75%)	⬆️

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[bjarthur]

looks great! looking at the code, it seems that the problem was nesting versus sequential </tspan>s, is that right? which issues will this close?

[Mattriks]

For svg multiline text you also need to know that svg translate is used before svg_newlines, so text position is relative (which simplifies things).

I've also used this PR to produce a Gadfly plot (below), and added a "closes" item to the list in my OP. The svg multiline text issue is also mentioned in #330, but I'm not sure why #330 is still opened?

using DataFrames, Gadfly
set_default_plot_size(5inch,4inch)
palette = ["Midnight\nBlue","Forest\nGreen","Fire\nbrick"]

D = DataFrame(x=["Gold\nrings","Calling\nbirds", "French\nhens","Turtle\ndoves", "Partridges\nin a\nPear tree"],
    y=[5,4,3,2,1], col=["a","a","b","b","c"])
p = plot(D, x=:x, y=:y, color=:col, Geom.bar,
    Guide.colorkey(title="Colors", labels=palette),
    Guide.title("Five essential items\nfor the Yule Season"),
    Scale.color_discrete_manual(replace.(palette, ["\n"=>""])...),
    Guide.ylabel("Number of"),
    Theme(bar_spacing=8pt)
)

# draw(PNG(),p)
draw(SVG(),p)