support Makie.AbstractPattern as color in CairoMakie for non-mesh plots

[Moelf]

Demo

julia> p = Pattern('/');

julia> save("/tmp/f.png", poly(Point2f[(0, 0), (2, 0), (3, 1), (1, 1)], color = p, strokecolor=:red, strokewidth=2))

using CairoMakie, Random
Random.seed!(3)
const Vec2f0 = CairoMakie.Vec2f0
# patterns
# `'/'`, `'\\'`, `'-'`, `'|'`, `'x'`, and `'+'`
directions = [Vec2f0(1), Vec2f0(1, -1), Vec2f0(1, 0), Vec2f0(0, 1),
    [Vec2f0(1), Vec2f0(1, -1)], [Vec2f0(1, 0), Vec2f0(0, 1)]]
colors = [:white, :red, (:green, 0.5), :white, (:navy, 0.85),:black]
patterns = [Makie.LinePattern(direction= hatch; width = 5, tilesize=(20,20),
    linecolor = colors[indx], background_color = colors[end-indx+1])
    for (indx, hatch) in enumerate(directions)]
fig = Figure(resolution = (1200,800), fontsize = 32)

ax = Axis(fig[1,1])
for (idx, pattern) in enumerate(patterns)
    barplot!(ax, [idx], [idx*(2rand()+1)], color = pattern, strokewidth = 2)
end
ax.xticks = (1:6, ["/", "\\", "-", "|", "x", "+"])
save("/tmp/strippedPatterns.png", fig)

first	second

Description

fix #1385

Type of change

Delete options that do not apply:

• New feature (non-breaking change which adds functionality)

Checklist

• Added an entry in NEWS.md (for new features and breaking changes)
• Added or changed relevant sections in the documentation [NO NEED]
• Added unit tests for new algorithms, conversion methods, etc.
• Added reference image tests for new plotting functions, recipes, visual options, etc. [ALREADY PRESENT]

[asinghvi17]

I will try this out soon but it looks good so far! Thanks for the PR :)

[asinghvi17]

You should also set the filter so that Cairo doesn't interpolate...

Suggested change

	Cairo.pattern_set_extend(cairopattern, Cairo.EXTEND_REPEAT);
	Cairo.pattern_set_extend(cairopattern, Cairo.EXTEND_REPEAT);
	Cairo.pattern_set_filter(cairopattern, Cairo.FILTER_NEAREST); # or something like this anyway

[jkrumbiegel]

not sure, why no interpolation? should make diagonal line patterns look better no

[asinghvi17]

Makes sense - was looking at it from the perspective of ImagePattern, where you may not want the pattern to be interpolated. Maybe we could make this user-configurable somehow, perhaps by checking the interpolate keyword...

[asinghvi17]

Makes sense to me, and looks good so far!

This looks mergeable to me.

At a later point I would like to have a vectorized version of LinePattern in CairoMakie, but that sounds like something for a different PR!

As for the Cairo recording surface: basically, one can draw on it using cairo_move_to or cairo_line_to, and then "replay" it onto a surface. It would be something like drawing lines across the surface in a pattern and the rest of the code would likely remain the same.